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1,700 | Triptan use preceding life-threatening arrhythmias in charcot-marie-tooth: a case report and review of the literature. | Charcot-Marie-Tooth (CMT) identifies a rare group of inherited disorders of the peripheral nervous system that share clinical features of sensory and motor defects, but rarely affect cardiac function. The few references that relate CMT to cardiac pathology of any sort are so rare that their finding was considered either fortuitous or suggestive of an erroneous diagnosis. The 5-HT1B/1D agonists or triptan drug class was introduced to the clinical practice arena in the early 1990s, and since then several cardiac adverse events have been associated with its use. The authors report the case of a 41-year-old white woman with CMT who had been recently prescribed sumatriptan and who presented with sudden loss of consciousness associated with ventricular fibrillation. These findings have been reported in the literature, but the association of triptan-induced arrhythmias and degenerative neuropathies remains to be established. The authors propose, through this case report and review, that the relative rarity of CMT coupled with the lack of further investigation of their association with conduction abnormalities might have set the stage for underestimation of the potentially synergistic effect with triptans in their capacity to generate life-threatening arrhythmias. |
1,701 | Usefulness of the percentage of plasma lymphocytes as a prognostic marker in patients with congestive heart failure. | This prospective study was designed to evaluate the prognostic value of the percentage of plasma lymphocytes in patients with diastolic dysfunction as well as systolic dysfunction of the left ventricle. The subjects were 70 consecutive patients who were hospitalized in our institution from April 2001 to August 2002. Following the improvement of congestive heart failure, leukocyte differentiation and neurohumoral factors (plasma levels of atrial and brain natriuretic peptide, norepinephrine, epinephrine, and dopamine) were measured. During the follow-up period (17 +/- 9 months), 18 patients experienced a cardiac event. In the univariate analysis, the percentage of plasma lymphocytes in the cardiac event group was significantly less than that in the noncardiac event group (24.7 +/- 8.40 vs 33.3 +/- 7.64%, P = 0.0006), and brain natriuretic peptide was significantly larger in the cardiac event group (402 +/- 168 vs 153 +/- 51 pg/mL, P = 0.04). However, in patients with preserved systolic function, there was a significant difference in the percentage of plasma lymphocytes between the cardiac and noncardiac event groups (21.7 +/- 9.42 vs 34.2 +/- 8.21%, P = 0.037), although no difference was observed in brain natriuretic peptide (133 +/- 43 vs 125 +/- 50 pg/mL, P = 0.87). Multivariate analysis showed the percentage of plasma lymphocytes was an independent predictor of a cardiac event. The percentage of plasma lymphocytes may be useful for predicting the course of patients with congestive heart failure based on diastolic dysfunction as well as systolic dysfunction. |
1,702 | Restitution dynamics during pacing and arrhythmias in isolated pig hearts. | The dependence of action potential duration (APD) on the preceding diastolic interval (DI), i.e., restitution, has been purported to predict the development of alternans and reentrant arrhythmias. However, restitution depends on the history of activation (i.e., memory), and its relevance to arrhythmia induction and maintenance is unknown.</AbstractText>Using a dual-camera video imaging system, we recorded action potentials from thousands of sites on the surface of the isolated pig heart. A steady-state pacing (SSP) protocol was performed to generate the SSP APD restitution curve. During SSP, the minimum DI and APD were 57 +/- 6 ms and 107 +/- 6 ms, respectively. The restitution slope was >1 for DIs <85 +/- 5 ms; however, alternans were not observed. Abrupt decreases in cycle length (CL) resulted in a rapid (<5 beats) decrease in APD followed by a slower decrease to "steady state." DI, APD pairs for the initial beats following these rate changes were significantly above the SSP restitution curve. DI, APD pairs measured during sustained ventricular fibrillation clustered significantly below the SSP restitution curve, at significantly shorter APDs (57 +/- 4 ms) and DIs (49 +/- 6 ms) than could be achieved during SSP. In addition, abrupt increases in CL following SSP resulted in APDs significantly shorter than those predicted from the SSP restitution curve.</AbstractText>Our results indicate that the responses of APD and DI to sudden rate changes and during arrhythmias are not predicted by the SSP restitution relationship. Acute dynamics act to damp out the proarrhythmic oscillations predicted from the SSP restitution curve.</AbstractText> |
1,703 | Analysis of the defibrillation efficacy for 5-ms waveforms. | Empirical studies have shown that biphasic defibrillation waveforms are more efficacious than monophasic waveforms. However, a more systematic approach to waveform development might be more productive. This study tested 147 multiphasic waveforms uniformly sampled from all possible 5-ms waveforms.</AbstractText>One hundred ninety-eight guinea pigs (850-1,050 g) received 30 episodes of ventricular fibrillation followed by transthoracic defibrillation. The first 10 shocks were used to determine the ED(50) for a biphasic control. Then, 20 waveforms including 2 controls were tested once at the ED(50). Of the 147 waveforms tested here, 21 waveforms showed equivalent or greater efficacies than the biphasic control, with one being statistically more efficacious (P < 0.05). Two fundamental assumptions were addressed: (1) similarly efficacious waveforms are analytically similar, and (2) a single optimal waveform can be described. The mean percentage of similarly efficacious waveforms with similar shapes was greater than zero in the most efficacious 21 waveforms (P = 0.023), but less efficacious waveforms showed randomly distributed shapes. Cluster analysis revealed that the best waveforms share a major phase containing most of the defibrillation energy. The optimal waveform shape extrapolated from the sample waveforms was a 2.5/1-ms biphasic-type waveform (highest correlation r = 0.701, P < 0.001).</AbstractText>This work supports the assumption that efficacious waveforms are similarly shaped and the notion that one single optimum exists.</AbstractText> |
1,704 | Inhibitors of the Na+/H+ exchanger cannot prevent atrial electrical remodeling in the goat. | It has been suggested that blockade of the Na+/H+ exchanger (NHE1) can prevent atrial fibrillation (AF)-induced electrical remodeling and the development of AF.</AbstractText>AF was maintained by burst pacing in 10 chronically instrumented conscious goats. Intravenous and oral dosages of two NHE1 blockers (EMD87580 and EMD125021) resulted in plasma levels several magnitudes higher than required for effective NHE1 blockade. Shortening of atrial refractoriness immediately after 5 minutes of AF was not prevented by NHE1 blockade. In remodeled atria, increasing dosages of EMD87580 and EMD125021 did not reverse shortening of the atrial refractory period or reduce the duration of AF episodes. The cycle length during persistent AF also was not affected. Oral pretreatment with EMD87580 (8 mg/kg bid) starting 3 days before AF could not prevent electrical remodeling. After 24 and 48 hours of remodeling, the duration of AF paroxysms was 47 +/- 32 seconds and 135 +/- 63 seconds compared to 56 +/- 17 seconds and 136 +/- 52 seconds in placebo-treated animals (P > 0.8), respectively.</AbstractText>In the goat model of AF, the Na+/H+ exchanger inhibitors EMD87580 and EMD125021 did not prevent or revert AF-induced electrical remodeling. This indicates that activation of the Na+/H+ exchanger is not involved in the intracellular pathways of electrical remodeling. This does not support the suggestion that blockers of the Na+/H+ exchanger may be beneficial for prevention and treatment of AF.</AbstractText> |
1,705 | [Surgical treatment for left ventricle aneurysms. Five-year analysis]. | The objective of this study was to present results of surgical repair of left ventricle aneurysms with or without myocardial revascularization and or valve replacement.</AbstractText>We analyzed risk factors, clinical conditions, coronary arteries affected, surgical procedure carried out, morbidity, and mortality in patients with left ventricle aneurysms treated between January 1, 1998 and December 31, 2002.</AbstractText>Of 1,620 patients submitted to myocardial revascularization, 24 (18 male and four females), had ventricular aneurysms. Mean age was 59.22 years. One case (4.54%) had mitral valve lesion, while remaining patients had ischemic heart disease. A total of 77.27% were in functional class III. Left anterior descending artery was most affected vessel (95.45%). Main location was anteroapical and anterolateral in 90.9%. Surgery was indicated for angina in 72.72%, while surgical repair was done for plicature in 10 cases, aneurismectomy and linear closure in six cases, and resection and geometric reconstruction in six combined with myocardial revascularization. There were no differences in times for ischemic period, cardiopulmonary bypass, and length of hospital stay. There were two deaths: one due to cardiogenic shock and the other 2 months later due to ventricular fibrillation. Follow-up time was 31.9 months and 85% of patients were in functional class I.</AbstractText>We concluded that the previously mentioned procedures for surgical repair of left ventricle aneurysms combined with complete myocardial revascularization offers improvement in functional class with acceptable morbidity and mortality rates.</AbstractText> |
1,706 | Enzyme replacement therapy with agalsidase beta in kidney transplant patients with Fabry disease: a pilot study. | We sought to assess the safety and efficacy of enzyme replacement therapy (ERT) with recombinant human-alpha-galactosidase A (rh-alpha-Gal A) in kidney transplant recipients with Fabry disease, a previously unstudied population.</AbstractText>Three male kidney transplant recipients with biochemically, genetically, and histologically confirmed Fabry disease and documented Fabry myocardiopathy received the rh-alpha-Gal A, agalsidase beta, 1 mg/kg of body weight every 2 weeks by intravenous infusion and were monitored biochemically, clinically, and electrocardiographically and echocardiographically for 18 months.</AbstractText>Patients showed biochemical, clinical/functional, and morphologic response to ERT. Plasma globotriaosylceramide decreased 23% to 50%. Extremity pain resolved within 2 months in the patient with this manifestation. On echocardiography, left ventricular mass, end diastolic diameter (EDD), and cardiac contractility, shown by ejection fraction (EF), improved in 2 of the 3 patients receiving essentially all planned infusions. EDD and EF remained basically stable, but cardiac morphologic abnormalities progressed in the other patient, who had a 5-month interruption in ERT after the initial month. Mild mitral insufficiency persisted in all patients, as did atrial fibrillation in the affected individual. After a combined total of 116 infusions, no treatment-related adverse event, intolerance, or seroconversion was seen. Renal function remained stable and the immunosuppression regimen unchanged in all patients.</AbstractText>Our pilot study provides preliminary evidence that ERT with agalsidase beta, 1 mg/kg every 2 weeks, is safe and often effective against extra-renal manifestations in kidney transplant patients with Fabry disease. Studies with longer courses of this and higher doses of ERT are merited in this population.</AbstractText> |
1,707 | Reoperation for severe right ventricular dilatation after tetralogy of Fallot repair: pulmonary infundibuloplasty should be added to homograft implantation. | Right ventricular dilatation observed after tetralogy of Fallot repair regresses after pulmonary valve implantation, unless the dilation is too severe. The presence of an akinetic patch in the right ventricular outflow tract (RVOT), a known factor promoting right ventricular dilatation, may prevent right ventricular recovery after valve implantation. The exclusion of a large akinetic RVOT area during reoperation of patients presenting with severe post-repair right ventricular dilatation was investigated.</AbstractText>Eight patients underwent a pulmonary infundibuloplasty between May 2000 and October 2002. Their mean preoperative cardothoracic index was 0.66 +/- 0.08, and preoperative NYHA class II (n = 4), III (n = 3) or IV (n = 1). Three patients were offered heart transplantation but refused. All had severe pulmonary regurgitation and underwent a RVOT valve implantation except one patient who had a previous homograft pulmonary valve insertion. Concomitant procedures were tricuspid ring implantation (n = 3), atrial septal defect closure (n = 2), mitral valve repair (n = 1) and modified right atrial Maze (n = 1).</AbstractText>Median follow up time was 13 months (range: 6 -29 months). One patient suffered a fatal ventricular fibrillation at home. All patients but one were in NYHA class I. After a mean of 5 +/- 3 months, their mean workload capacity rose from 115 +/- 19 W to 155 +/- 62 W, and mean VO2max rose from 16.5 +/- 2 to 18.3 +/- 2 ml/min/kg.</AbstractText>Pulmonary infundibuloplasty may be a useful adjunct in reoperation of tetralogy of Fallot patients presenting with severe right ventricular dilatation and large akinetic area of the RVOT.</AbstractText> |
1,708 | Influence of atypical symptoms and electrocardiographic signs of left ventricular hypertrophy or ST-segment/T-wave abnormalities on the natural history of otherwise asymptomatic adults with moderate to severe aortic stenosis: preliminary communication. | Current guidelines recommend that aortic valve replacement (AVR) is deferred in asymptomatic patients with aortic stenosis until symptoms develop. Classical symptoms include exertional dyspnea, angina pectoris and syncope. The influence of atypical symptoms (dizziness, exertional intolerance, fatigue, palpitations/arrhythmias) and electrocardiographic signs of left ventricular hypertrophy or ST-segment/T-wave abnormalities on the natural course of the disease is unknown.</AbstractText>The clinical course of 100 patients with a preliminary diagnosis of asymptomatic aortic stenosis with respect to clinical signs and symptoms mentioned above was examined. All patients underwent serial echocardiographic examinations with calculation of aortic valve area by the continuity equation.</AbstractText>Two patients died during a mean follow up period of 34 +/- 32 months (range: 1-116 months). There were no peri- or postoperative deaths. Seven patients with hemodynamically severe aortic stenosis and concomitant atrial fibrillation, four with classical symptoms after re-evaluation, and five with left ventricular dysfunction underwent short-term AVR and were excluded from any subsequent analysis. In total, 84 patients were either entirely asymptomatic (n = 57; group A) or had atypical symptoms (n = 27; group B). Of these patients, 18 underwent AVR before onset of classical symptoms for various reasons, and 21 were treated medically. The remaining 15 group B patients exhibited classical symptoms significantly earlier than the remaining 30 group A patients (15 +/- 7 versus 35 +/- 24 months; p < 0.002). Aortic valve area tended to decrease more rapidly in group B patients than in group A patients (-0.16 +/- 0.12 versus -0.11 +/- 0.07 cm2 per year; p = 0.053). Clinical and hemodynamic progression were further increased if additional electrocardiographic abnormalities were present.</AbstractText>Both atypical symptoms and electrocardiographic signs of left ventricular hypertrophy/strain shorten the time interval until otherwise asymptomatic patients exhibit classical symptoms of advanced aortic stenosis requiring prosthetic valve replacement.</AbstractText> |
1,709 | Relationship between control of ventricular rate in atrial fibrillation and systemic coagulation activation in patients with mitral stenosis. | Systemic thromboembolism is a major complication in patients with mitral stenosis (MS), especially in those who have atrial fibrillation (AF). It has been suggested that systemic coagulation activity may be increased in these patients. The study aim was to investigate the relationship between control of ventricular rate and systemic coagulation factors in patients with MS and AF by measuring plasma levels of prothrombin fragment (PF) 1+2, thrombin-antithrombin III complex (TAT) and plasminogen activator inhibitor-1.</AbstractText>Fifty-four consecutive patients with moderate to severe MS and AF were included in the study. Patients with resting heart rates < 100 beats per min were considered as having a controlled ventricular response rate (group A; n = 28) and those with > 100 beats per min as an uncontrolled ventricular response rate (group B; n = 26).</AbstractText>Group A patients had a lower mean mitral gradient and pulmonary artery pressure than group B patients (11 +/- 6 versus 15 +/- 5 and 35 +/- 7 versus 39 +/- 8; p < 0.05, respectively). Plasma concentrations of PF 1+2 (4.17 +/- 2.1 versus 2.95 +/- 1.21; p < 0.01) and TAT III (4.61 +/- 1.75 versus 3.12 +/- 1.01; p < 0.01) were elevated in group B compared with group A. Similarly, group B patients had higher plasminogen activator inhibitor-1 levels than group A patients (7.87 +/- 3.8 versus 5.8 +/- 2.9; p < 0.05). A significant correlation was found between heart rate and plasma PF 1+2 and TAT levels. Multiple logistic regression analysis revealed that heart rate and mean mitral gradient were independent predictors of systemic coagulation activation.</AbstractText>Besides contributing towards hemodynamic and symptomatic relief, the control of AF rate in MS patients induces a drastic decline in coagulation activation, and may also reduce the incidence of thromboembolism.</AbstractText> |
1,710 | Oral antiarrhythmic drugs in converting recent onset atrial fibrillation. | This article reviews clinical studies on oral antiarrhythmic drugs in converting recent onset atrial fibrillation. An oral loading dose of an antiarrhythmic drug for cardioversion of atrial fibrillation could be an option, due to its simplicity, both for patients admitted to outpatient departments and for episodic treatment by self administration outside the hospital. The latter treatment strategy has recently been pointed out by the American College of Cardiology, the American Heart Association and the European Society of Cardiology as the 'pill in the pocket approach'.</AbstractText>Articles were identified by Medline 1966 to November 2001 and Embase 1966 to November 2001. Randomized studies of oral antiarrhythmic drugs versus placebo or comparative treatment, which are written in the English language, were selected. Non-randomized or non-comparative studies were selected if the results of an analysis to identify predictors for successful conversion are described. The review of clinical trials is followed by a description of pharmacokinetic parameters of the antiarrhythmic drugs.</AbstractText>Studies meeting the inclusion criteria were on propafenone, flecainide, sotalol, amiodarone, quinidine, digoxin and verapamil. Conversion rates of a single oral loading dose of 600 mg propafenone varied between 37% and 41% at 4 h after ingestion. Propafenone was more effective than quinidine, amiodarone and placebo. A single oral dose of 300 mg flecainide restored sinus rhythm in 59% and 68% of patients at 3 h. Flecainide was more effective than amiodarone and placebo. Oral sotalol, digoxin and verapamil were not effective in converting atrial fibrillation to sinus rhythm.</AbstractText>Propafenone and flecainide are effective in converting recent onset atrial fibrillation. No serious ventricular arrhythmia, other serious proarrhythmic effects or serious non cardiac adverse events were observed. Regular supraventricular tachyarrhythmias with 1:1 AV conduction were rare and were also observed in placebo treated patients. Propafenone and flecainide are more effective in patients with atrial fibrillation of less than 24 h. The association between cardioversion and patient characteristics are not consistent between studies. The pharmacokinetics of flecainide, with lower interindividual variability of absorption kinetics, no genetically determined formation of an active metabolite and a more rapid distribution to myocardial tissue, are more favourable for episodic treatment as compared to propafenone. Both flecainide and propafenone are safe in hospitalized patients. Out of hospital self administration of antiarrhythmic drugs, also described as the 'pill in the pocket approach', could be an option for selected patients, after the treatment has proven to be safe in hospital.</AbstractText> |
1,711 | Anticoagulation in elective surgery. | Several categories of patients may be receiving anticoagulation therapy and require surgery. Many patients take cardioprotective aspirin or warfarin for atrial fibrillation, the presence of a mechanical heart valve, prior thromboembolism, a documented left ventricular thrombus, or a history of venous thromboembolism with or without a pulmonary embolism. Inpatients may be receiving injectable forms of anticoagulation to reduce risk of deep venous thrombosis or for other conditions, such as atrial fibrillation. Patients receiving any type of anticoagulation present a problem when they require surgery because the interruption of anticoagulant therapy increases their risk of thromboembolism and stroke (Schanbacher & Bennett, 2000). Rational decisions regarding the appropriateness of perioperative anticoagulation depend on individual patient factors and can only be made when the risk of perioperative thromboembolism is balanced against the risk of perioperative bleeding. |
1,712 | Assessment of severity of mechanical prosthetic mitral regurgitation by transoesophageal echocardiography. | To evaluate the ability of colour Doppler transoesophageal echocardiography (TOE) to assess quantitatively prosthetic mitral valve insufficiency.</AbstractText>47 patients were studied with multiplane TOE and cardiac catheterisation. Proximal jet diameter was measured as the largest diameter of the vena contracta. Regurgitant area was measured by planimetry of the largest turbulent jet during systole. Flow convergence zone was considered to be present when a localised area of increased systolic velocities was apparent on the left ventricular side of the valve prosthesis. Pulmonary vein flow velocity was measured at peak systole and diastole.</AbstractText>Mean (SD) proximal jet diameter was 0.63 (0.16) cm, with good correlation with angiographic grades (r = 0.83). Mean (SD) maximum colour jet area was 7.9 (2.5) cm2 (r = 0.69) with worse correlation if a single imaging plane was used for measurements (r = 0.62). The ratio of systolic to diastolic peak pulmonary flow velocity averaged 0.7 (1.3) cm (r = -0.66) with better correlation (r = -0.71) if patients with atrial fibrillation were excluded. Mean (SD) regurgitant flow rate was 168 (135) ml/s and regurgitant orifice area was 0.56 (0.43) cm2, with good correlation with angiography (r = 0.77 and r = 0.78, respectively).</AbstractText>TOE correctly identified angiographically severe prosthetic mitral regurgitation, mainly by the assessment of the flow convergence region and the proximal diameter of the regurgitant jet.</AbstractText> |
1,713 | A multicenter risk index for atrial fibrillation after cardiac surgery. | Atrial fibrillation is a common, but potentially preventable, complication following coronary artery bypass graft (CABG) surgery.</AbstractText>To assess the nature and consequences of atrial fibrillation after CABG surgery and to develop a comprehensive risk index that can better identify patients at risk for atrial fibrillation.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PARTICIPANTS" NlmCategory="METHODS">Prospective observational study of 4657 patients undergoing CABG surgery between November 1996 and June 2000 at 70 centers located within 17 countries, selected using a systematic sampling technique. From a derivation cohort of 3093 patients, associations between predictor variables and postoperative atrial fibrillation were identified to develop a risk model, which was assessed in a validation cohort of 1564 patients.</AbstractText>New-onset atrial fibrillation after CABG surgery.</AbstractText>A total of 1503 patients (32.3%) developed atrial fibrillation after CABG surgery. Postoperative atrial fibrillation was associated with subsequent greater resource use as well as with cognitive changes, renal dysfunction, and infection. Among patients in the derivation cohort, risk factors associated with atrial fibrillation were advanced age (odds ratio [OR] for 10-year increase, 1.75; 95% confidence interval [CI], 1.59-1.93); history of atrial fibrillation (OR, 2.11; 95% CI, 1.57-2.85) or chronic obstructive pulmonary disease (OR, 1.43; 95% CI, 1.09-1.87); valve surgery (OR, 1.74; 95% CI, 1.31-2.32); and postoperative withdrawal of a beta-blocker (OR, 1.91; 95% CI, 1.52-2.40) or an angiotensin-converting enzyme (ACE) inhibitor (OR 1.69; 95% CI, 1.38-2.08). Conversely, reduced risk was associated with postoperative administration of beta-blockers (OR, 0.32; 95% CI, 0.22-0.46), ACE inhibitors (OR, 0.62; 95% CI, 0.48-0.79), potassium supplementation (OR, 0.53; 95% CI, 0.42-0.68), and nonsteroidal anti-inflammatory drugs (OR, 0.49; 95% CI, 0.40-0.60). The resulting multivariable risk index had adequate discriminative power with an area under the receiver operating characteristic (ROC) curve of 0.77 in the validation sample. Forty-three percent (640/1503) of patients who had atrial fibrillation after CABG surgery experienced more than 1 episode of atrial fibrillation. Predictors of recurrent atrial fibrillation included older age, history of congestive heart failure, left ventricular hypertrophy, aortic atherosclerosis, bicaval venous cannulation, withdrawal of ACE inhibitor or beta-blocker therapy, and use of amiodarone or digoxin (area under the ROC curve of 0.66). Patients with recurrent atrial fibrillation had longer hospital stays and experienced greater infectious, renal, and neurological complications than those with a single episode.</AbstractText>We have developed and validated models predicting the occurrence of atrial fibrillation after CABG surgery based on an analysis of a large multicenter international cohort. Our findings suggest that treatment with beta-blockers, ACE inhibitors, and/or nonsteroidal anti-inflammatory drugs may offer protection. Atrial fibrillation after CABG surgery is associated with important complications.</AbstractText> |
1,714 | Do valved stents compromise coronary flow? | The aim of the present study is to evaluate a new self-expanding valved stent design for minimal invasive aortic valve implantation and its interference with coronary flow.</AbstractText>An equine pericardial valve mounted onto a self-expanding nitinol stent (3F Therapeutics trade mark, CA, USA), outer diameter 23 mm, was evaluated (A) in vitro in a dynamic pulsatile mock loop and (B) in vivo in six calves (75+/-2.5 kg). In four animals valve stents were implanted on-pump and in two animals off-pump after induction of ventricular fibrillation. Target site for deployment was the orthotopic aorta, over the native valves. In vivo assessment was performed with intracardiac (AcuNav) and intravascular ultrasound including leaflet motion, planimetric valve orifice and residual-coronary\sinus-stent-index (RCSSI, distance stent to aortic wall/coronary diameter) calculations, coronary blood flow characteristics, transvalvular gradient, regurgitation and paravalvular leaking, in combination with continuous cardiac output measures. Macroscopic analysis was performed at necropsy.</AbstractText>Two-dimensional intracardiac ultrasound showed good leaflet motion, with full valvular opening and closing in five of six valves. Planimetric valve orifice was 1.75+/-0.4 cm(2). There were no signs of coronary flow impairment with an RCSSI of 1.8+/-1.2. The implanted valved stents showed a low transvalvular gradient of 5.3+/-3.9 mmHg (mean, peak-to-peak) on invasive measurements and 4.7+/-2.5 mmHg in two-dimensional intracardiac sonography. One of six valves showed mild to moderate regurgitation and one of six valves a minor to moderate paravalvular leak due to size mismatch.</AbstractText>This new self-expanding valved stent design allows for on- and off-pump aortic valve implantation in the orthotopic aorta, over the native valves without interference of the coronary blood flow and excellent acute valve function in properly sized devices.</AbstractText> |
1,715 | Prognostic implication of early ejection fraction on long-term mortality and quality of life following out-of-hospital cardiac arrest. | In this study of a unique cohort of out-of-hospital cardiac arrest survivors with ventricular fibrillation, the initial ejection fraction was predictive of increased long-term mortality. However, overall long-term quality-of-life was favorable and independent of the ejection fraction. |
1,716 | Time course of fibrillation and defibrillation thresholds after an intravenous bolus of amiodarone--an experimental study. | Experimental studies have described an increase in ventricular fibrillation threshold (VFT) by intravenous amiodarone. The aim of this study was to examine the early time course of changes in VFT and defibrillation thresholds (DFT) after an intravenous bolus of amiodarone in an experimental pig model of transient myocardial ischemia.</AbstractText>VFT and relative effective ventricular refractory period (ERP) were measured in 15 anaesthetized open-chest pigs after 3 min of regional coronary ischaemia before (time 0) and 2, 15, 30, 60, and 90 min after the intravenous injection of normal saline (group A, n = 5) or amiodarone, 5 mg/kg over 15 s (group B, n = 10). DFT was measured by increasing the strength of DC shocks until defibrillation was accomplished. Amiodarone caused an increase in VFT, starting at 2 min after the infusion (11.4 +/- 8.4 mA versus 9.2 +/- 4.6 mA, P = 0.03), became significant at 15 min (13.7 +/- 6.5 mA, P = 0.009), continued to rise at 30 min (34.2 +/- 28.7 mA, P = 0.03) and reached a plateau at 60 min (50.3 +/- 37.8 mA, P = 0.008). An increase was also observed in the ERP (204 +/- 25 ms at 2 min versus 197 +/- 26 ms at baseline, P = 0.074, 211 +/- 38 ms at 15 min, P = 0.084, 212 +/- 40 ms at 30 min, P = 0.037, 220 +/- 34 ms at 60 min, P = 0.002, and 227 +/- 32 ms at 90 min, P = 0.008). No change was observed in DFT after amiodarone administration. No significant change in VFT, ERP, or DFT occurred in the control group.</AbstractText>In this porcine model, the intravenous administration of amiodarone increased VFT and ERP over 60 min after the injection, without effect on DFT.</AbstractText> |
1,717 | Reducing ventilation frequency combined with an inspiratory impedance device improves CPR efficiency in swine model of cardiac arrest. | The basic premise that frequent ventilations during cardiopulmonary resuscitation (CPR) are a necessity for tissue oxygenation has recently been challenged. An inspiratory impedance threshold device (ITD) recently has also been shown to increase CPR efficiency, principally by augmenting circulation with little impact on ventilation. The optimal compression to ventilation (C/V) is not known for this new device. The purpose of this study was to compare the currently recommended C/V ratio of 5:1 with a 10:1 ratio, +/- the ITD, to optimize circulation and oxygenation during CPR.</AbstractText>Thirty-two adult pigs weighing 26-31 kg were randomized to CPR with varying C/V ratios +/- the ITD as follows: A = 5:1, B = 5:1+ITD, C = 10:1, D = 10:1+ITD. After 6 min of untreated ventricular fibrillation (VF), closed-chest standard CPR was performed with an automatic piston device that does not impede passive chest wall recoil, at a continuous compression rate of 100 min(-1). Synchronous breaths were given every 5 or 10 compressions during the decompression phase depending on the group. CPR was performed for 6 min and physiological variables were measured throughout the experimental protocol.</AbstractText>A reduction in the frequency of ventilation from 5:1 to 10:1 resulted in significantly improved arterial and coronary perfusion pressure in a pig model of cardiac arrest. Addition of an ITD resulted in further increases in arterial and coronary perfusion pressures with both 5:1 and 10:1 C/V ratios, without compromising oxygenation.</AbstractText>CPR efficiency can be optimized by changing the compression: ventilation ratio from 5:1 to 10:1 and with concurrent use of the inspiratory threshold device.</AbstractText> |
1,718 | Automated external defibrillators for children: what is new? | Although automated external defibrillators (AEDs) have been available for adults for more than 20 years, their use in children under 8 years of age has been approved by the International Liaison Committee on Resuscitation (ILCOR) as recently as June 2003. The following concerns about AEDs limited their use in children: amount of delivered energy, effect of biphasic waveforms in children, pad size, and capacity of detecting pediatric shockable and non-shockable rhythms. Lately, a new generation of AEDs addressed these issues and new encouraging data are available. New AEDs safely identify pediatric shockable and non-shockable rhythms and deliver fixed lower energy shocks through pads of appropriate size. This perspective briefly describes the main advances which heralded the new recommendations of ILCOR. Randomized clinical trials are now needed to identify whether these new pediatric devices can improve the outcome of pediatric cardiac arrest. |
1,719 | [Late results of minimally invasive operations of myocardial revascularization in patients with acute coronary syndrome]. | The aim of the study was to compare late results of the minimally invasive operations of myocardial revascularization and conservative treatment in patients with acute ischemic syndrome.</AbstractText>Demographic, clinical and echocardiographic data was collected on patients with acute ischemic syndrome; data of 109 patients treated conservatively and data of 26 patients, who underwent minimal invasive operation of myocardial revascularization during acute phase of ischemic syndrome, were compared and ischemic consequences after one-year follow up period were determined in both groups.</AbstractText>The patients of both groups did not differ significantly according to the most clinical characteristics. One third of the patients in the surgery group had previous myocardial infarction, also they had higher rate of paroxysmal atrial fibrillation (26.9% vs 6.4%) and acute left ventricular failure (73.1% vs 44.0%) than the patients without operation. During one-year follow up period there were no cases of lethal events or myocardial infarction in the surgical group, however 37.5% of them had mild angina pectoris. At that time lethal outcome was observed in 6.1%, myocardial infarction in 3.5% and mild-severe angina pectoris in 68.8% of patients.</AbstractText>The functional status of the patients significantly improved during one-year period after minimally invasive operation of myocardial revascularization compared to the patients treated conservatively.</AbstractText> |
1,720 | Asymptomatic Brugada syndrome associated with postural orthostatic tachycardia syndrome: Does autonomic disorder increase propensity for future arrhythmic events? | Autonomic imbalance may work as a modifying factor for initiating lethal arrhythmia in patients with Brugada syndrome. A 26-year-old man with episodes of near syncope was given a diagnosis of an autonomic disorder, postural orthostatic tachycardia syndrome (POTS). The patient spontaneously showed typical Brugada-type ECG, and ventricular fibrillation was induced by programmed electrical stimulation, which allowed the further diagnosis of Brugada syndrome. Although it seems that Brugada syndrome is asymptomatic, its uncommon association of POTS may increase the risk for future arrhythmic events in this patient. |
1,721 | Intra- and interatrial conduction delay: implications for cardiac pacing. | Atrial conduction disorders are frequent in elderly subjects and/or those with structural heart diseases, mainly mitral valve disease, hyperthrophic cardiomyopathies, and hypertension. The resultant electrophysiological and electromechanical abnormalities are associated with a higher risk of paroxysmal or persistent atrial tachyarrhythmias, either atrial fibrillation, typical or atypical flutter or other forms of atrial tachycardias. Such an association is not fortuitous because intra- and interatrial conduction abnormalities delays disrupt (spatial and temporal dispersion) electrical activation, thus promoting the initiation and perpetuation of reentrant circuits. Preventive therapeutic interventions induce variable, sometimes paradoxical effects as with the proarrhythmic effect of class I antiarrhythmic drugs. Similarly, atrial pacing may promote proarrhythmias or an antiarrhythmic effect according to the pacing site(s) and mode. Multisite atrial pacing was conceived to correct, as much as possible, abnormal activation induced by spontaneous intra- or interatrial conduction disorders or by single site atrial pacing, which are situations responsible for commonly refractory arrhythmias. Atrial electrical resynchronization can also be used to correct mechanical abnormalities like left heart AV dyssynchrony resulting from intraatrial conduction delays. |
1,722 | Partial A(1) adenosine receptor agonists from a molecular perspective and their potential use as chronic ventricular rate control agents during atrial fibrillation (AF). | This review provides a molecular perspective of partial agonism at the A(1) adenosine receptor. The structure-activity relationships (SAR) for affinity and intrinsic efficacy of analogues of the full agonist N6-cyclopentyladenosine (CPA) are emphasized. Both general models of activation of G protein-coupled receptors and specific molecular models of the A(1)-adenosine receptor are used to interpret the results of efforts to synthesize and assay effects of partial agonists. The SAR of affinity and intrinsic efficacy of the 2', 3', and especially the 5'-deoxy derivatives of CPA is presented. From this analysis, the nature of the interactions of specific atoms and substituents of the CPA molecule with the A(1)-adenosine receptor are deduced and presented pictorially. As an example of the therapeutic potential of partial agonists, the design and testing of analogues of CPA to provide chronic ventricular rate control during atrial fibrillation is described. The challenges associated with designing a partial A(1)-adenosine receptor agonist for providing chronic ventricular rate control during atrial fibrillation are many. To meet these challenges, further medicinal chemistry efforts in the area of partial A(1)-adenosine receptor agonism are still needed. |
1,723 | A comparison between oral antiarrhythmic drugs in the prevention of atrial fibrillation after cardiac surgery: the pilot study of prevention of postoperative atrial fibrillation (SPPAF), a randomized, placebo-controlled trial. | Atrial fibrillation (AF) frequently occurs after cardiac surgical procedures, and beta-blockers, sotalol, and amiodarone may reduce the frequency of AF after open heart surgery. This pilot trial was designed to test whether each of the active oral drug regimens is superior to placebo for prevention of postoperative AF and whether there are differences in favor of 1 of the preventive strategies.</AbstractText>We conducted a randomized, double-blinded, placebo-controlled trial in which patients undergoing cardiac surgery in the absence of heart failure and without significant left ventricular dysfunction (n = 253; average age, 65 +/- 11 years) received oral amiodarone plus metoprolol (n = 63), metoprolol alone (n = 62), sotalol (n = 63), or placebo (n = 65). Patients receiving combination therapy (amiodarone plus metoprolol) and those receiving sotalol had a significantly lower frequency of AF (30.2% and 31.7%; absolute difference, 23.6% and 22.1%; odds ratios [OR], 0.37 [95% CI, 0.18 to 0.77, P <.01 vs placebo] and 0.40 [0.19 to 0.82, P =.01 vs placebo]) compared with patients receiving placebo (53.8%). Treatment with metoprolol was associated with a 13.5% absolute reduction of AF (P =.16; OR, 0.58 [0.29 to 1.17]. Treatment effects did not differ significantly between active drug groups. Adverse events including cerebrovascular accident, postoperative ventricular tachycardia, nausea, and dyspepsia, in hospital death, postoperative infections, and hypotension, were similar among the groups. Bradycardia necessitating dose reduction or drug withdrawal occurred in 3.1% (placebo), 3.2% (combined amiodarone and metoprolol; P =.65 vs placebo), 12.7% (sotalol; P <.05 vs placebo), and 16.1% (metoprolol; P <.05 vs placebo). Patients in the placebo group had a nonsignificantly longer length of hospital stay as compared with the active treatment groups (13.1 +/- 8.9 days vs 11.3 +/- 7; P =.10), with no significant difference between the active treatment groups.</AbstractText>Oral active prophylaxis with either sotalol or amiodarone plus metoprolol may reduce the rate of AF after cardiac surgery in a population at high risk for postoperative AF. Treatment with metoprolol alone resulted in a trend to a lower risk for postoperative AF.</AbstractText> |
1,724 | Prognostic significance of isolated, non-specific left ventricular repolarization abnormalities in hypertension. | Clinicians are often confronted with the incidental finding of isolated minor, non-specific repolarization changes on the electrocardiogram (ECG) in hypertensive patients. The aim of this study was to investigate the prognostic significance of such changes.</AbstractText>Prospective, observational study.</AbstractText>A total of 1970 hypertensive patients without prevalent cardiovascular disease were followed for up to 9.1 years (mean 4.7 years). Patients with ECG abnormalities including ischaemia, previous infarction, bundle branch block, atrial fibrillation and ventricular pre-excitation were excluded. Patients were divided into three groups: normal left ventricular (LV) repolarization (n = 1355); minor repolarization changes (n = 504); and typical LV strain (n = 111).</AbstractText>During follow-up, 78 patients developed new-onset ischaemic heart disease. The event rates were 0.50, 1.28 and 3.08 per 100 patient-years in the groups with normal repolarization, minor changes, and typical LV strain, respectively (P < 0.001). After adjustment for the effect of age, sex, diabetes, serum cholesterol, smoking, LV hypertrophy and 24-h pulse pressure, the risk for developing coronary events was higher in patients with minor repolarization changes (hazard ratio 2.07, 95% confidence interval 1.23-3.47; P < 0.01) or LV strain (hazard ratio 4.00, 95% confidence interval 2.09-7.65; P < 0.001) than in patients with normal repolarization (reference category). Population-attributable risks were 21 and 14%, respectively. Minor ST-T changes also retained an adverse prognostic value among patients without LV hypertrophy (hazard ratio 1.90, 95% confidence interval 1.08-3.33; P = 0.026).</AbstractText>We have identified minor, non-specific LV repolarization changes as a novel, independent risk factor for ischaemic heart disease in patients with uncomplicated hypertension.</AbstractText> |
1,725 | Recent advances in pacemaker and implantable defibrillator therapy for young patients. | This review is intended to highlight major clinical advances over the past year related to (1). biventricular pacing as a treatment for dilated myopathy, (2). growing clinical experience with implantable cardioverter defibrillators in pediatrics, (3). technical advances in standard antibradycardia pacing, and (4). an appraisal of the newly updated ACC/AHA/NASPE guidelines for device implant in children and adolescents.</AbstractText>Complex rhythm devices are being used more frequently in children. Biventricular pacing to improve ventricular contractility is a rapidly evolving technology that has now been applied to children and young adults with intraventricular conduction delay, such as bundle branch block after cardiac surgery. Implantable defibrillators are also being used for an expanding list of conditions, although lead dysfunction is seen as a fairly common complication in active young patients. Guidelines for device implantation have been developed, but the weight of evidence remains somewhat limited by the paucity of pediatric data in this field.</AbstractText>Thanks to refinements in lead design and generator technology, coupled with rapidly expanding clinical indications, pacemakers and implantable defibrillators have become increasingly important components of cardiac therapy for young patients. Expanded multicenter clinical studies will be needed to develop more objective guidelines for use of this advanced technology.</AbstractText> |
1,726 | [Cardiovascular diseases as a cause of sudden death in athletes]. | Cardiac arrhythmias are the reason of the most sudden deaths in athletes. The annual risk of sudden death at athletes is between 5 to 10 per one million. Benign arrhythmia including bradyarrhythmias, atrial and ventricular premature contractions are common in the athletes. Supraventricular arrhythmias such as atrial fibrillation, nodal reciprocal entrant tachycardia and Wolff-Parkinson-White syndrome are less common. Perhaps the rarest and the most dangerous arrhythmias are ventricular arrhythmias, among them arrhythmias secondary to hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, long QT syndrome, and anomalous origin of coronary arteries. Asymptomatic bradyarrhythmias (if the heart rate in bradyarrhythmia appropriate increases with exercise), supraventricularis tachycardias, and atrial premature contractions without structural heart disease are not the contraindication to sports Athletes with premature ventricular contraction, nonsustained ventricular tachycardia and non structural heart disease are without athletic restrictions as long as the arrhythmias do not worsen and they not cause dyspnea or presyncope during exertion. Frequent or multiform premature ventricular contraction or sustained ventricular tachycardia indicate a higher risk, and all participation in athletic should be restricted. |
1,727 | Anesthetic considerations during caval inflow occlusion in children with congenital heart disease. | Caval inflow occlusion (IO) was introduced to facilitate surgical pulmonary and aortic valvotomy without cardiopulmonary bypass (CPB). Although a technique that is used infrequently today, it remains useful in some patients with complex single-ventricle congenital cardiac defects who require an atrial septectomy. The potential for complications and anesthetic considerations have not been described previously.</AbstractText>Retrospective review.</AbstractText>A tertiary care university teaching children's hospital.</AbstractText>Eleven children, median age 3 months (range 3 days-3 years) who underwent (IO) technique for atrial septectomy.</AbstractText>Atrial septectomy under IO in patients with restrictive atrial septum.</AbstractText>Eleven children, median age 3 months (range 3 days-3 years), underwent IO for atrial septectomy. Mean duration of IO was 87.7 +/- 25.5 seconds. There was 1 intraoperative death (9%). After release of the caval clamps, inotropic support was necessary in 7 of 11 patients, arrhythmias occurred in 4 of 11 patients (2 atrial and 2 ventricular fibrillation), and 10 of 11 patients required blood transfusion along with boluses of calcium gluconate and sodium bicarbonate to support the circulation immediately post-IO. Duration of postoperative mechanical ventilation was 2.2 +/- 1.6 days; 10 of 11 patients (91%) survived to discharge with mean length of intensive care unit stay 3.7 +/- 2.2 days.</AbstractText>IO is an effective technique for short intracardiac procedures without the need for CPB. Close collaboration between anesthesia and surgical staff is essential to keep the duration of IO as short as possible and because of the potential for hemodynamic instability.</AbstractText> |
1,728 | Impact of age on long-term survival and quality of life following out-of-hospital cardiac arrest. | Early defibrillation programs have improved long-term outcomes following out-of-hospital cardiac arrest from ventricular fibrillation. Although long-term collective quality of life and survival are favorable, there are subsets of these patients who may be predisposed to worse outcomes. In particular, elderly patients may present with more comorbid medical conditions affecting their outcome. However, the impact of age on mortality rate and quality of life after rapid defibrillation is unknown.</AbstractText>Observational study.</AbstractText>Hospital.</AbstractText>All patients with an out-of-hospital cardiac arrest between November 1990 and January 2001 who received rapid defibrillation for ventricular fibrillation in Olmsted County, Minnesota. All patients received treatment at one hospital.</AbstractText>Long-term outcome and quality of life were followed. Survival was estimated using the Kaplan-Meier method. The quality of life was established by an SF-36 survey.</AbstractText>Two hundred patients presented in ventricular fibrillation out-of-hospital cardiac arrest; of these, 138 (69%) survived to hospital admission, seven (4%) died in the emergency department, and 79 (39%) were discharged neurologically intact. The average age was 62+/-16 yrs, with 51% (n = 40) of the population > or =65. The average length of follow-up was 4.8+/-3.0 yrs. The 5-yr survival in patients <65 was 94% (confidence interval, 86-100%) and 66% (confidence interval, 52-84%) in patients > or =65 (p <.001). The observed survival in the younger group was not different from that expected in a U.S. age- and gender-matched population. However, in the older group, the expected survival was significantly lower compared with an age- and gender-matched U.S. population (p =.01) but similar to an age-, gender-, and disease-matched cohort of patients from Olmsted County not experiencing an arrest. In both age-dependent cohort populations, the quality of life scores crossed the norm in all categories with exception of vitality in patients >65 yrs old (42.6+/-7.2). In direct comparison between the two patient groups, the older cohort reported lower levels of physical functioning (p =.002), role-emotional score (p =.03), and role-physical score (p =.007). Other SF-36 scores were not different between the groups. Sixty-five percent of patients <65 yrs returned to work compared with 56% of older patients.</AbstractText>The survival rate for ventricular fibrillation out-of-hospital cardiac arrest is significantly improved by the presence of a rapid defibrillation program. In patients <65 yrs old, long-term survival is equal to that of normal individuals and quality of life is similar to the general population. The survival, although high, in older patients is less than that in age-matched healthy controls, and physical and emotional quality of life scores are decreased.</AbstractText> |
1,729 | The Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial: rationale, design, results, clinical implications and lessons for future trials. | T he Dual Chamber and VVI Implantable Defibrillator (DAVID) trial randomized 506 patients and tested the hypothesis that the dual-chamber pacing mode would produce improved hemodynamics and would in turn reduce congestive heart failure, heart failure hospitalizations, heart failure deaths, atrial fibrillation, strokes, ventricular arrhythmias, and total mortality compared to backup ventricular pacing in patients indicated for implantable defibrillator therapy. Patients had either primary prevention indications (47%) or secondary prevention indications (53%) for implantable defibrillator therapy but had no indications for bradycardia pacemaker support. All the patients had moderate to severe left ventricular dysfunction with a left ventricular ejection fraction of 40% or less (mean = 27%) and were consistently treated with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers (86%) and beta adrenergic blocking agents (85%). The primary combined endpoint of hospitalization for congestive heart failure or death was paradoxically increased and statistically significant ( p = 0.03) at one year in the patients paced in the dual chamber mode (22.6%) compared to patients randomized to ventricular backup pacing (13.3%). Both heart failure hospitalization and mortality contributed outcome. Another perspective would consider this a randomized controlled study of presence or absence of pacemaker therapy in patients with left ventricular dysfunction and indications for implantable defibrillator therapy. Ventricular backup pacing produced less than 3% ventricular and no atrial pacing, while dual chamber pacing produced approximately 60% atrial and ventricular paced heart beats. The poor outcome in the dual chamber paced group correlated with the percentage of right ventricular pacing and suggests that right ventricular pacing caused ventricular dyssynchrony. The poor outcome associated with right ventricular pacing compared to intrinsic activation in the control group of the DAVID trial is reminiscent of the poor outcome associated with prolonged intraventricular conduction activation in the control groups compared to biventricular pacing in the intervention groups of the cardiac resynchronization trials. The direct conclusion from these results are that patients with indications for implantable defibrillators and no indication for pacing should not be paced in the dual chamber pacing mode. It is not appropriate to conclude that only single chamber implantable defibrillators should be implanted. There are other potential advantages to having an implanted atrial lead including improved secondary outcomes. However the DAVID trial results suggest that the dual chamber paced mode was not associated with improved quality of life or decreased frequency of hospitalization, inappropriate shocks from the defibrillator or atrial fibrillation. The more important question is what is the optimal pacing mode in these patients? The AAIR mode is under investigation in the DAVID II study in an attempt to identify a pacing mode that preserves atrio-ventricular synchrony, normal atrio-ventricular timing, prevents bradycardia and also prevents right ventricular stimulation. Caution should be taken to not directly apply these results to patients with either an indication for pacemaker therapy or to patients with an indication for cardiac resynchronization therapy since patients from neither population were included. However, considering the large magnitude of the deleterious effects associated with dual chamber pacing in the DAVID trial future studies should explore the possibility that left ventricular stimulation may be the only pacing mode capable of preventing bradycardia without increasing death and congestive heart failure. |
1,730 | Selecting the appropriate pacing mode for patients with sick sinus syndrome: evidence from randomized clinical trials. | Several observational studies have indicated that selection of pacing mode may be important for the clinical outcome in patients with symptomatic bradycardia, affecting the development of atrial fibrillation (AF), thromboembolism, congestive heart failure, mortality and quality of life. In this paper we present and discuss the most recent data from six randomized trials on mode selection in patients with sick sinus syndrome (SSS). In pacing mode selection, VVI(R) pacing is the least attractive solution, increasing the incidence of AF and-as compared with AAI(R) pacing, also the incidence of heart failure, thromboembolism and death. VVI(R) pacing should not be used as the primary pacing mode in patients with SSS, who haven't chronic AF. AAIR pacing is superior to DDDR pacing, reducing AF and preserving left ventricular function. Single site right ventricular pacing-VVI(R) or DDD(R) mode-causes an abnormal ventricular activation and contraction (called ventricular desynchronization), which results in a reduced left ventricular function. Despite the risk of AV block, we consider AAIR pacing to be the optimal pacing mode for isolated SSS today and an algorithm to select patients for AAIR pacing is suggested. Trials on new pacemaker algorithms minimizing right ventricular pacing as well as trials testing alternative pacing sites and multisite pacing to reduce ventricular desynchronization can be expected within the next years. |
1,731 | AFFIRM and RACE trials: implications for the management of atrial fibrillation. | The Atrial Fibrillation (AF) Follow-up Investigation of Rhythm Management (AFFIRM) and Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation Study (RACE) Trials evaluated strategies of rate control or rhythm control in atrial fibrillation. AFFIRM enrolled patients with recent onset AF, and at entry over half of all patients were in sinus rhythm. At any point in the trial, the achieved difference in cardiac rhythm was likely only about 30%. In RACE all patients were entered in AF, and at the end of the study, sinus rhythm was present in 10% vs 39%. The strategy of rate control was non-inferior to the rhythm control strategy in both trials, and permits consideration of rate control as primary therapy. However, the actual differences in rhythm were relatively small, and do not allow the conclusion that maintenance of sinus rhythm is inferior to non-maintenance. Current guidelines recommend that patients with paroxysmal AF receive warfarin if they have risk factors for stroke. This is supported by data from AFFIRM. Most strokes in AFFIRM occurred either during subtherapeutic INR, or after cessation of warfarin. Since more patients in the rhythm control arm of AFFIRM discontinued warfarin, it is possible that asymptomatic recurrences of paroxysmal AF fostered clot development and embolization. We cannot answer from the data available whether or not it is safe to discontinue anticoagulation if all episodes of AF are suppressed. Among the reasons that AF is associated with increased mortality may be that it encourages development of congestive heart failure or progressive left ventricular dysfunction. Congestive heart failure occurrence was monitored in both trials, and occurred at a rate of 2-5% without significant differences between rate and rhythm arms. In patients with heart failure at entry, a mortality trend in AFFIRM favored the rhythm control arm. The issue of survivorship and rhythm control in AF in congestive heart failure is undergoing further testing. |
1,732 | Atrial arrhythmia burden as an endpoint in clinical trials: is it the best surrogate? Lessons from a multicenter defibrillator trial. | Therapies to treat atrial tachyarrhythmias need to be evaluated in controlled, randomized clinical trials in order to optimize patient outcomes. If the maintenance of sinus rhythm is the ultimate goal, then atrial tachyarrhythmia burden may serve as a useful endpoint. Atrial tachyarrhythmia burden is defined as the total duration of all atrial tachyarrhythmias divided by the follow-up time and includes asymptomatic as well as symptomatic episodes. The measurement of atrial tachyarrhythmia burden is more practical now than in the past because of the availability of implantable devices capable of monitoring atrial tachyarrhythmia episodes. The advantage of burden over other endpoints is that it is not subject to investigator bias and it does not have the sampling error associated with episodic rhythm monitoring or the monitoring of patient symptoms. The use of burden as a surrogate endpoint for clinical outcome facilitates the demonstration of a biological effect of a therapy on the triggers or substrates responsible for the arrhythmia. Therapies that reduce burden can then be further studied to assess more traditional endpoints. A recent multicenter trial examined the effect of device-based atrial therapies on burden in patients receiving an implantable cardioverter defibrillator (Medtronic 7250 Jewel AF) to treat ventricular tachyarrhythmias. Patients were randomized to 3-month periods of atrial therapies "ON" or "OFF" and subsequently crossed over. The atrial therapies resulted in a reduction of atrial tachyarrhythmia burden from a mean of 58.5 hours/month to 7.8 hours/month (P = 0.007). Based on the evidence of a biological effect of the atrial therapies (burden reduction) studies to determine of the effects of AT/AF prevention and termination algorithms on morbidity and quality of life in ICD recipients are underway. |
1,733 | Efficacy of atrial antitachycardia functions for treating atrial fibrillation: observations in patients with a dual-chamber defibrillator. | In patients with conventional indication for ICD implantation, atrial fibrillation may occur in more than 50% during the life-span of the device and may lead to severe adverse events. Dual chamber defibrillators with atrial antitachycardia functions, including prevention algorithms, arrhythmia detection capability and atrial therapy options (antitachy pacing and cardioversion) have been recently introduced. The aim of this review is to examine the effectiveness of these new devices and to identify patients who may benefit. We recently studied 112 patients who received the device because of life-threatening ventricular arrhythmias. Fifty-five percent of them had atrial fibrillation prior to implantation. During the follow-up (one year on average), 27% had at least one episode of sustained atrial tachyarrhythmia. Effectiveness of atrial antitachy pacing was 71% on regular atrial tachycardia and 36% on irregular atrial tachyarrhythmias. Atrial shock efficacy was over 90% when adequately programmed. Interestingly, near half of the episodes started as regular atrial tachycardia and accelerated and became less organized in few minutes. Early delivery of antitachy pacing may increase success rate and decrease the need for atrial shock. Furthermore, it may prevent atrial remodeling and reduce atrial fibrillation burden. Based on our experience, we recommend that all patients with a class I indication for defibrillator implantation (related to risk of ventricular arrhythmias) who have a history of or are at risk of developing atrial tachyarrhythmias should receive a dual chamber defibrillator equipped with atrial antitachycardia functions. Furthermore, patients either with a history of heart failure, with poor functional capacity (functional class III or IV), depressed left ventricular ejection fraction, a need for monitoring of atrial rhythm, or in whom there is some concern about appropriate detection of ventricular arrhythmias, may benefit from a single device capable of managing ventricular and supraventricular arrhythmias. |
1,734 | Atrial pacing therapies for prevention of atrial fibrillation in patients with implantable defibrillators. | Atrial fibrillation (AF), atrial flutter and atrial tachycardia (AT) occur frequently in patients following implantation of an implantable cardioverter defibrillator (ICD) for the treatment of ventricular tachyarrhythmias. Some new generation ICDs have incorporated atrial antitachycardia pacing therapy (ATP) and atrial pacing algorithms designed specifically for the prevention of AF. In the GEM III AT clinical evaluation, atrial ATP efficacy for termination of AF and AT was assessed. Overall ATP efficacy for AF/AT, based on device classification, was 40% when adjusted using the Generalized Estimating Equations to account for correlated data that arises from utilizing multiple episodes in some patients. However, many episodes of AF/AT were noted to terminate within 10 minutes of onset. Applying a more conservative definition of efficacy, termination within 20 sec of delivery of the last atrial ATP, efficacy for termination of AF/AT was 26%. 50 Hz burst pacing was shown to have minimal efficacy for termination of AF and modest incremental benefit following ramp or burst pacing therapies for AT. These observations provide a more realistic expectation of the value of atrial ATP in the ICD population with AF. Atrial ATP terminates some episodes of AT but previously reported efficacy rates of 40-50% are exaggerated and in part reflect spontaneous terminations of some AF/AT episodes. |
1,735 | Effectiveness of rapid atrial pacing for termination of drug refractory atrial fibrillation: results of a dual chamber implantable cardioverter defibrillator trial. | There is increasing interest in the use of an implantable cardioverter defibrillator (ICD) to manage atrial tachyarrhythmias. Although device-based shock therapy is highly effective in terminating persistent atrial tachyarrhythmias, atrial overdrive pacing may also be useful, particularly when this therapy is applied early after the onset of an arrhythmia. A dual-chamber ICD (Medtronic 7250 Jewel AF(R)) has been studied in 267 patients with drug-refractory symptomatic AF. The patients were enrolled as part of multicenter clinical trial to evaluate the safety and efficacy of the device to manage atrial tachyarrhythmias in the absence of a standard ventricular ICD indication. The device discriminates atrial tachycardia (AT) from atrial fibrillation (AF) based on cycle length and regularity, and employs multiple methods of atrial overdrive pacing as well as shocks to terminate tachyarrhythmia episodes. Patients were followed for an average of 15.8 +/- 9.3 months. A majority (63%) of patients presented with a history of persistent AF and 34% presented with a history of paroxysmal AF. The pacing therapies terminated 54% of AT episodes and 27% of AF episodes. In patients with persistent AF, 75% of the AT/AF episodes that were successfully terminated by pacing lasted <or=9 minutes. When the pacing therapies failed, episodes lasted for several hours and 50% of the episodes received at least one shock. The results of this trial suggest that pace-termination plays an important role in device-based management of atrial tachyarrhythmias. It is estimated that early pace-termination of AT/AF episodes may reduce the need for device-based shocks among patients with persistent AF by about half. |
1,736 | Comparison of permanent left ventricular and biventricular pacing in patients with heart failure and chronic atrial fibrillation: a prospective hemodynamic study. | Left ventricular pacing (LVP) and biventricular pacing (BVP) have been proposed as treatments for patients with advanced heart failure complicated by discoordinate contraction due to intraventricular conduction delay. For patients in sinus rhythm, BVP works in part by modulating the electronic atrial-ventricular time delay and thus optimizing contractile synchrony, the contribution of atrial systole, and reducing mitral regurgitation. However, little is known of the mechanisms of BVP in heart failure patients with drug-resistant chronic atrial fibrillation. HYPOTHESIS AND METHODS: LVP differs from BVP because hemodynamic and clinical improvement occurs in association with prolongation rather than shortening of the QRS duration. We sought to determine if LVP or BVP improves mechanical synchronization in the presence of atrial fibrillation. Thirteen patients with chronic atrial fibrillation, severe heart failure and QRS >or=140 ms received (after His bundle ablation) a pacemaker providing both LVP and BVP. The mean age was 62 +/- 6 years and left ventricular ejection fraction was 24 +/- 8%. After a baseline phase of one month with right ventricular pacing, all patients underwent in random order 2 phases of 2 months (LVP and BVP). At the end of each phase, an echocardiogram, a hemodynamic analysis at rest and during a 6-minute walking test and a cardio-pulmonary exercise test were performed.</AbstractText>LVP and BVP provided similar performances at rest (p = ns). The 6-minute walking test revealed similar performances in both pacing modes but patients were significantly more symptomatic at the end of the test with LVP ( p = 0.035). The cardio-pulmonary exercise test showed higher performances with BVP (92 +/- 34 Watts) vs. LVP (77 +/- 23; p = 0.03). LVP was associated with significantly more premature ventricular complexes recorded during the 6 minute walking test (49 +/- 71) than BVP (10 +/- 23; p = 0.04).</AbstractText>In this small series of patients with atrial fibrillation, congestive heart failure and a prolonged QRS duration, LVP and BVP provided similar hemodynamic effects at rest whereas BVP was associated with better hemodynamic effects during exercise and fewer premature ventricular complexes. Although the mechanisms for the observed differences are uncertain, it is possible that there is worsening of right ventricular function due to a rise in left-to-right electromechanical delay during exercise. Increased catecholamines release might contribute to the lower exercise tolerance and greater number of premature ventricular complexes recorded during exercise observed during LVP compared to BVP.</AbstractText>Patients with atrial fibrillation, heart failure and QRS prolongation who are candidates for His-bundle ablation and cardiac resynchronization therapy may respond better to BVP rather than to LVP.</AbstractText> |
1,737 | Selection of pacing mode after interruption of atrioventricular conduction for atrial fibrillation: observations from the PA3 clinical trial. | The optimal pacing mode for patients with paroxysmal atrial fibrillation (AF) following AV junction ablation remains the subject of some debate. Recent clinical trials have not demonstrated a superior advantage of maintenance of sinus rhythm over the rate control approach. However, clinical trials in pacemaker populations have demonstrated that physiologic pacing reduces the probability of paroxysmal and persistent AF compared to ventricular pacing. In the second phase of the PA(3) study, patients were randomized to DDDR versus VDD pacing in a cross over study design. Of the 67 patients randomized, 42% developed permanent AF within one year following ablation. AF frequency and burden increases early following AV junction ablation suggesting that ventricular pacing even in an atrial synchronous mode promotes AF. Given the high probability of permanent AF developing early following ablation, VVIR pacing appears to be the appropriate pacing mode for symptomatic patients undergoing total AV junction ablation. |
1,738 | The sheep as a model for coronary artery bypass surgery. | The sheep is considered to be a suitable model for cardiovascular surgery because of its ease of handling, size, and vascular anatomy which bears close resemblance to the human. Several difficulties, however, have limited the use of the sheep for such a purpose-mainly the high infection rate resulting from median sternotomy incision and its susceptibility to intractable ventricular fibrillation (VF) with the slightest manipulation of the heart, and even the risk of short periods of myocardial ischaemia. We have used the sheep model extensively to perform coronary artery bypass surgery and were successful in overcoming these difficulties. Fifty-seven adult female sheep were used to test a new anastomotic device for the creation of a sutureless connection between venous and arterial grafts and the coronary arteries. The study required full access to the heart and great vessels and mobilization of one of the internal mammary arteries. Changing to the left lateral thoracotomy (LLT) approach solved the initial fatal problems of postoperative infected median sternotomy incisions. Aggressive prophylactic treatment with anti-arrhythmic drugs, maintenance of normothermia and myocardial preconditioning rendered the heart much less vulnerable to manipulations and ischaemia. These measures have reduced the mortality rate from 45% to 0% (P <0.0001). With specific operative techniques and pharmaceutical interventions, the sheep can be effectively and safely used as a model for coronary artery surgery. |
1,739 | Microvolt T-wave alternans as a predictor of ventricular tachyarrhythmias: a prospective study using atrial pacing. | Microvolt T-wave alternans (TWA) is reported to be closely associated with sudden cardiac death (SCD) and ventricular tachycardia (VT). Animal experiments revealed that microvolt TWA is highly dependent on heart rate. The purpose of this study was to determine whether patients with TWA at relatively low heart rates have increased vulnerability to ventricular tachyarrhythmias.</AbstractText>Subjects were 248 consecutive patients (158 men, 90 women; mean age, 59+/-17 years) who underwent electrophysiological study from 1997 to 2000. TWA recording was made in sinus rhythm and at atrial pacing rates of 90, 100, 110, and 120 bpm with the Cambridge Heart CH2000 system. Alternans voltage (V(alt)) was measured when the alternans ratio was >3 for a period of >1 minute in VM, X, Y, Z, or 2 adjacent precordial leads. Study end point was the first appearance of VT, ventricular fibrillation (VF), appropriate implantable cardioverter-defibrillator therapy with pacing or shocks, or SCD. During the 37+/-12-month follow-up period, 22 patients had sustained VT, and 5 patients died of SCD. In patients with >1.9-microV V(alt) at rates of 90, 100, and 110 bpm, the incidence of VT/VF/SCD was 56%, 28%, and 18%, respectively. V(alt) of >2.9 microV at a heart rate of 90 bpm had a 70% positive predictive value for VT/VF/SCD. However, when V(alt) was <0.9 microV at a rate of 120 bpm, negative predictive value was 100%.</AbstractText>Patients with TWA at relatively low heart rates are susceptible to ventricular tachyarrhythmias.</AbstractText> |
1,740 | Left regional cardiac perfusion in vitro with platelet-activating factor, norepinephrine and K+ reveals that ischaemic arrhythmias are caused by independent effects of endogenous "mediators" facilitated by interactions, and moderated by paradoxical antagonism. | Various putative drug targets for suppression of ischaemia-induced ventricular fibrillation (VF) have been proposed, but therapeutic success in the suppression of sudden cardiac death (SCD) has been disappointing. Platelet-activating factor (PAF) is a known component of the ischaemic milieu. We examined its arrhythmogenic activity, and its interaction with two other putative mediators, norepinephrine and K(+), using an ischaemia-free in vitro heart bioassay, and a specific PAF antagonist (BN-50739). PAF (0.1-100 nmol) was administered selectively to the left coronary bed of rat isolated hearts using a specially designed catheter. In some hearts, PAF was administered to the left coronary bed during concomitant regional perfusion with norepinephrine and/or K(+). In separate studies, PAF accumulation in the perfused cardiac tissue was evaluated using (3)H-PAF. PAF evoked ventricular arrhythmias concentration-dependently (P<0.05). It also widened QT interval and reduced coronary flow selectively in the PAF-exposed left coronary bed (both P<0.05). Two exposures of hearts to PAF were necessary to evoke the QT and rhythm effects. The PAF-induced arrhythmias and coronary vasoconstriction were partially suppressed by the PAF antagonist BN-50739 (10 microm), although BN-50739 itself widened QT interval. K(+) (8 and 15 mm) unexpectedly antagonised the arrhythmogenic effects of PAF without itself eliciting arrhythmias (P<0.05). Norepinephrine (0.1 microm) had little or no effect on the actions of PAF, while failing to evoke arrhythmias itself. Nevertheless, the combination of 15 mm K(+) and 0.1 microm norepinephrine evoked arrhythmias of a severity similar to arrhythmias evoked by PAF alone, without adding to or diminishing the arrhythmogenic effects of PAF. (3)H-PAF accumulated in the cardiac tissue, with 43+/-5% still present 5 min after bolus administration, accounting for the need for two exposures of the heart to PAF for evocation of arrhythmias. Thus, PAF, by activating specific receptors in the ventricle, can be expected to contribute to arrhythmogenesis during ischaemia. However, its interaction with other components of the ischaemic milieu is complex, and selective block of its actions (or its accumulation) in the ischaemic milieu is alone unlikely to reduce VF/SCD. |
1,741 | Hidden cardiac lesions and psychotropic drugs as a possible cause of sudden death in psychiatric patients: a report of 14 cases and review of the literature. | To confirm the hypothesis that psychotropic drugs, especially neuroleptics, lithium, and antidepressants, are implicated as a cause of unexpected sudden death in psychiatric patients because of their cardiotoxicity, especially when hidden cardiac lesions are present.</AbstractText>We performed a full pathological examination of 14 psychiatric patients who unexpectedly and suddenly died between 1980 and 1999.</AbstractText>Neuroleptics were involved in 13 instances, antidepressants in 9, and anxiolytics in 5. Psychotropic drugs were combined in all but a single patient. In all 14 patients, toxicological analyses discarded drug overdose as cause of death. At postmortem examination, the brain and abdominal organs were normal. In 13 patients, the following lesions were found in the heart and lungs: dilated cardiomyopathy (6 patients), left ventricular hypertrophy (2 patients, 1 of which was associated with mitral prolapse and anomalies of His bundle), arrhythmogenic cardiopathy of the right ventricle (1 patient), pericarditis (1 patient), mitral prolapse (1 patient), muscular bridge on the anterior interventricular artery (1 patient), and Mendelsons syndrome (1 patient). In 1 case, no changes were seen. Most of the drugs that were taken immediately prior to death can induce arrhythmias either by prolonging the QT interval, potentially resulting in torsades de pointes, or by widening QRS complexes, possibly leading to reentry and ventricular fibrillation.</AbstractText>Our findings suggest that the arrhythmogenic effects of psychotropic drugs can be exacer bated when preexisting hidden cardiac lesions are present and can result in sudden death. Patients should be systematically evaluated for cardiac lesions prior to starting any treatment with psychotropic drugs; the minimal effective dosage should be used.</AbstractText> |
1,742 | The effects of biphasic waveform design on post-resuscitation myocardial function. | This study examined the effects of biphasic truncated exponential waveform design on survival and post-resuscitation myocardial function after prolonged ventricular fibrillation (VF).</AbstractText>Biphasic waveforms are more effective than monophasic waveforms for successful defibrillation, but optimization of energy and current levels to minimize post-resuscitation myocardial dysfunction has been largely unexplored. We examined a low-capacitance waveform typical of low-energy application (low-energy biphasic truncated exponential [BTEL]; 100 microF, < or =200 J) and a high-capacitance waveform typical of high-energy application (high-energy biphasic truncated exponential [BTEH]; 200 microF, > or =200 J).</AbstractText>Four groups of anesthetized 40- to 45-kg pigs were investigated. After 7 min of electrically induced VF, a 15-min resuscitation attempt was made using sequences of up to three defibrillation shocks followed by 1 min of cardiopulmonary resuscitation. Animals were randomized to BTEL at 150 J or 200 J or to BTEH at 200 J or 360 J.</AbstractText>Resuscitation was unsuccessful in three of the five animals treated with BTEH at 200 J. All other attempts were successful. Significant therapy effects were observed for survival (p = 0.035), left ventricular ejection fraction (p < 0.001), stroke volume (p < 0.001), fractional area change (p < 0.001), cardiac output (p = 0.044), and mean aortic pressure (p < 0.001). Hemodynamic outcomes were negatively associated with energy and average current but positively associated with peak current. Peak current was the only significant predictor of survival (p < 0.001).</AbstractText>Maximum survival and minimum myocardial dysfunction were observed with the low-capacitance 150-J waveform, which delivered higher peak current while minimizing energy and average current.</AbstractText> |
1,743 | The efficacy of azimilide in the treatment of atrial fibrillation in the presence of left ventricular systolic dysfunction: results from the Azimilide Postinfarct Survival Evaluation (ALIVE) trial. | The purpose of this study was to assess the effect of oral azimilide dihydrochloride (AZ) 100 mg versus placebo on the onset, termination, and prevalence of atrial fibrillation (AF) in a subpopulation of patients in the Azimilide Postinfarct Survival Evaluation (ALIVE) trial.</AbstractText>Previous clinical trials have demonstrated the antiarrhythmic effects of AZ in patients with AF. Azimilide was investigated for its effects on mortality in patients with depressed left ventricular (LV) function after recent myocardial infarction (MI) and in a subpopulation of patients with AF.</AbstractText>A total of 3,381 post-MI patients with depressed LV function were enrolled in this randomized, placebo-controlled, double-blind study of AZ 100 mg on all-cause mortality. A total of 93 patients had AF on the baseline 12-lead electrocardiogram (ECG). An additional 27 patients developed AF after initially being in sinus rhythm at randomization. These patients were identified through 12-lead ECGs obtained during routine visits at week 2, months 1, 4, 8, and 12.</AbstractText>Patients with AF at baseline had a higher mortality than those without AF (p = 0.0006). Among AF patients, there was no difference in mortality between AZ patients and placebo patients (p = 0.82). Fewer AZ patients developed AF than placebo patients (p = 0.04). More AZ patients than placebo patients converted to sinus rhythm, but this difference did not achieve statistical significance (p = 0.076). Over one-year follow-up, more AZ patients were in sinus rhythm than placebo patients (p = 0.04).</AbstractText>Azimilide was safe and effective AF therapy in patients with depressed LV function after an MI.</AbstractText> |
1,744 | Sudden death in patients without structural heart disease. | Sudden unexpected cardiac death generally occurs in persons with known or previously unrecognized heart disease. However, it has become evident that it occurs often enough in patients without any identifiable structural abnormality to warrant the cardiologist's attention. Mostly, it concerns young, active, and otherwise healthy individuals. This paper focuses on various categories of patients with life-threatening events considered to have occurred on a solely "electrical" basis. Currently, several entities are recognized with distinct electrophysiological abnormalities, including Wolff-Parkinson-White syndrome, long QT syndrome, the Brugada syndrome, short-coupled torsade de pointes, and catecholamine-induced polymorphic ventricular tachyarrhythmia. The remaining patients without such distinct abnormalities are categorized as having idiopathic ventricular fibrillation. Although mechanical cardiac function may seem normal, such patients might have certain discrete anatomic abnormalities, unidentifiable with current investigational tools. Possibly in the future, with development of newer and more sophisticated tools (magnetic resonance imaging, positron emission tomography, genetic testing), some or all cases of idiopathic ventricular fibrillation must be redefined as having specific genetic and/or anatomic bases. All patients successfully resuscitated from cardiac arrest due to ventricular tachyarrhythmia without clear precipitating factors (acute myocardial infarction, severe electrolyte or metabolic disturbances) are at high risk of recurrences. Long-term prophylactic therapy is indicated. Contrasting with older belief, survivors of idiopathic ventricular fibrillation are now also considered high-risk patients. The implantable cardioverter-defibrillator appears to be the safest and most effective therapy. |
1,745 | Experimental studies on myocardial protection with intermittent cross-clamp fibrillation: additive effect of the sodium-hydrogen exchanger inhibitor, cariporide. | We previously showed that intermittent cross clamping with fibrillation affords myocardial protection equivalent to cardioplegic arrest. In this study, we examined whether cariporide (Aventis Pharma, Frankfurt, Germany), a specific sodium-hydrogen exchanger inhibitor, enhanced the protective effect of intermittent cross-clamp fibrillation (ICCF).</AbstractText>Isolated rat hearts were Langendorff-perfused (20 mins) with bicarbonate buffer and function (left ventricular developed pressure) measured. In each of three separate protocols that incorporated progressively longer ischemic durations, hearts were randomly allocated to one of three groups: group 1 was the control group with 40, 60, or 80 minutes of continuous global ischemia. Group 2 was the ICCF group with 4, 6, or 8 cycles of 10 minutes ICCF and 10 minutes of reperfusion in sinus rhythm. Group 3 was the ICCF plus cariporide group, which was the same as group 2, but also with 3 micromoles/L cariporide present in perfusate from 10 minutes before the ICCF cycles. Hearts were reperfused for 60 minutes with drug-free buffer and recovery (percentage of initial function) was measured. Hearts were maintained at 37 degrees C throughout the protocols. In protocol 3 (80 minutes ischemia per 8 cycles of ICCF), creatine kinase leakage (myocardial injury) and triphenyl tetrazolium chloride staining (myocardial viability) were also measured. Protocols 1, 2, and 3 had n = 8 hearts, n = 6 hearts, and n = 6 hearts in each group, respectively.</AbstractText>In the three protocols, the recoveries of left ventricular developed pressure in the control group, the ICCF group, and the ICCF plus cariporide group, respectively, for protocol 1 were: 26% +/- 3%, 70% +/- 2% (p < 0.05 vs the control group) and 74% +/- 2% (p < 0.05 vs the control group), respectively. For protocol 2 these were: 16% +/- 2%, 55% +/- 1% (p < 0.05 vs the control group), and 70% +/- 3% (p < 0.05 vs the control and ICCF groups), respectively. For protocol 3 these were: 8% +/- 2%, 41% +/- 3% (p < 0.05 vs the control group), and 63% +/- 2% (p < 0.05 vs the control and ICCF groups), respectively. Recovery of left ventricular end-diastolic pressure mirrored that of left ventricular developed pressure in all protocols. In protocol 3, total creatine kinase leakage (international units per gram wet weight) was 88 +/- 12, 47 +/- 4 (p < 0.05 vs the control group), and 17 +/- 1 (p < 0.05 vs the control and ICCF groups), respectively, and triphenyl tetrazolium chloride staining (arbitrary units per gram wet weight) was 0.17 +/- 0.04 in the control group, 0.39 +/- 0.04 (p < 0.05 vs the control group) in the ICCF group, and 0.47 +/- 0.08 (p < 0.05 vs the control group) in the ICCF plus cariporide group, respectively.</AbstractText>Sodium-hydrogen exchanger inhibition with cariporide enhances the myocardial protection afforded by ICCF, with the additive benefit becoming more apparent with increasing severity of the ischemic insult. Sodium-hydrogen exchanger inhibition may provide a significant protective reserve during ICCF, particularly when longer procedures are required.</AbstractText> |
1,746 | Atrial reduction plasty Cox maze procedure: extended indications for atrial fibrillation surgery. | The Cox maze procedure yields good results for atrial fibrillation (AF). However, patients with predictors of failure-chronic long-standing AF, low amplitude fibrillatory waves, and large left atriums-are generally thought not to benefit from a maze procedure. We report an aggressive approach for these patients, utilizing biatrial reduction plasty concomitantly with the Cox maze procedure for AF.</AbstractText>A complete Cox maze procedure utilizing supplemental RF ablation was performed in 36 patients. All underwent resection of both atrial appendages and biatrial reduction plasty encompassing resection of the left atrial posterior wall from left to right pulmonary veins and from inferior pulmonary veins to the mitral annulus, as well as removal of the right atrial lateral wall. Mitral or tricuspid valve repair, or both, was performed on 32 patients.</AbstractText>These patients had a mean AF duration of 45 +/- 89 months. Their preoperative left atria measured 66 +/- 16 mm, with mean AF waves of 0.74 +/- 0.3 mm. Mean preoperative New York Heart Association class was 2.7 +/- 0.7 and left ventricular ejection fraction was 48 +/- 9. Cross clamp and bypass times were 91 +/- 35 minutes and 124 +/- 33 minutes, respectively. The average posterior left atrial tissue resected was 5.4 x 2.1 cm, and mean resected atrial weight was 10.3 +/- 2 g. There were no deaths and length of stay was 5.5 +/- 2 days. At a follow-up time of 19 +/- 16 months, 32 of the 36 patients were in normal sinus rhythm and New York Heart Association class I.</AbstractText>Aggressive biatrial reduction plasty Cox maze procedure was effective in 89% of these "low success" AF patients. This simple procedure can extend utilization of the Cox maze procedure to more patients with chronic AF.</AbstractText> |
1,747 | [Anticoagulation therapy in paroxysmal atrial fibrillation]. | Patients with paroxysmal atrial fibrillation have a risk of thromboembolic complications probably equivalent to those with permanent atrial fibrillation. Patients with a previous cerebral infarction, hypertension, age above 65, diabetes, previous myocardial infarction, reduced left ventricular function, heart failure or enlarged left atrium with or without a visible thrombus are especially prone to thromboembolic complications. International guidelines recommend anticoagulation therapy with warfarin to INR levels between 2.0-3.0 for the majority of patients with atrial fibrillation. Acetylsalicylic acid provides inferior protection and can only be recommended for a selected subpopulation of patients. Patients with atrial fibrillation who convert spontaneously or after medical or electrical treatment, should have low molecular weight heparin administered prior to conversion and warfarin for at least four weeks after successful conversion. The rationale for choosing a treatment strategy in conflict with recommended guidelines should appear in writing in the patient's file in any individual case. |
1,748 | Defibrillators. | Sudden cardiac arrest can strike anyone, anywhere and at any time, often without warning. Reported survival rates for cardiac arrest with ventricular fibrillation are low: from 3 to 10 percent. Studies have shown that rapid defibrillation after out-of-hospital cardiac arrest with ventricular fibrillation is the most important determinant of survival. That is why training people to use automated external defibrillators, or AEDs, in public places can double the odds that a person in cardiac arrest will survive. The ADA recently awarded the Seal of Acceptance to HeartStart OnSite and FR2+ defibrillators. HeartStart defibrillators are easy to use. HeartStart defibrillators are designed specifically for the lay responder. They provide clear, easy-to-follow voice instructions and a simple user interface to guide the responder through an emergency reliable. HeartStart defibrillators perform comprehensive daily, weekly and monthly self-tests to help ensure readiness. A highly visible status indicator shows at a glance that the device is ready for use safe. HeartStart defibrillators have an innovative design that makes it virtually impossible to shock someone who is not in cardiac arrest. The heart rhythm first is analyzed to ensure that a shock is needed. The device will not allow the user to deliver a shock that the analysis determines is unnecessary. Philips offers two defibrillator models for the dental office: the HeartStart OnSite Defibrillator and the HeartStart FR2+ Defibrillator. The HeartStart OnSite Defibrillator is intended to be easy to use for responders in an office setting. It provides step-by-step verbal instructions on how to perform cardiopulmonary resuscitation, or CPR. The HeartStart FR2+ Defibrillator is designed for first responders, such as flight attendants, nurses, police officers and designated workplace responders who participate in regular training. Each HeartStart defibrillator comes with a nonrechargeable long-life battery, two sets of adult pads and complete instructions for use. |
1,749 | Loss of function associated with novel mutations of the SCN5A gene in patients with Brugada syndrome. | Ventricular fibrillation is one of the leading causes of death in North America. Brugada syndrome is characterized by ST segment elevation on the right precordial leads V1 through V3 and right bundle branch block, and may cause sudden death. Mutations in the SCN5A gene encoding the cardiac voltage-gated Na+ channel (hNav1.5) are associated with Brugada syndrome.</AbstractText>In this study, three novel mutations on the SCN5A gene were identified and characterized in different patients with Brugada syndrome.</AbstractText>Blood samples were collected from patients with Brugada syndrome for gene screening. Mutations found on the SCN5A gene in these patients were reproduced in vitro on hNav1.5 background. Wild type and mutant channels expressed in tsA201 cells were characterized using the patch clamp technique in whole cell configuration and/or confocal microscopy.</AbstractText>No current could be recorded from cells expressing the hNav1.5/G1740R mutant, incubated at 37 degrees C. However, at a lower incubation temperature (22 degrees C), macroscopic Na+ currents were recorded. Confocal microscopy study confirmed that at 37 degrees C, hNav1.5/G1740R mutant channels were retained in the endoplasmic reticulum. The E473X and N1774+12X mutants produced truncated proteins and did not express any currents; however, coexpression of each of these mutants with wild type channels shows 50% reduction of Na+ currents.</AbstractText>This study confirms that the loss of function of cardiac Na+ channels is the basis of the Brugada syndrome clinical phenotype.</AbstractText> |
1,750 | Relation between variability of ventricular response intervals and exercise capacity in patients with non-valvular atrial fibrillation. | Reduced variability of the ventricular response interval (VRI) has been reported to predict adverse prognosis in patients with atrial fibrillation (AF). To examine whether it could be related also to the quality of the daily life of patients with AF, the relationships between VRI variability and exercise tolerance, one of the markers for quality of life, were determined in patients with persistent AF.</AbstractText>Thirty-one patients with idiopathic AF were included in the present study. Holter monitoring results and symptom-limited treadmill exercise testing were correlated in these patients without medications for the rate control of AF. The VRI variability, both the SD of the mean R-R interval (SDNN) and the SD of the 5-min mean R-R interval (SDANN), showed significant positive correlation with the exercise capacity (r=0.583, p=0.0004, and r=0.543, p=0.0013, respectively), whereas age, left ventricular ejection fraction and body mass index did not have any significant relationships. Multiple regression analysis revealed that increased SDNN was the only independent predictor of good exercise capacity during the treadmill exercise testing.</AbstractText>Increased VRI variability, independently of other clinical variables, can predict good exercise capacity in patients with idiopathic AF, thus being a new sensitive maker for quality of life in AF.</AbstractText> |
1,751 | [Cardiac arrhythmias and ST changes in the perioperative period of elderly patients submitted to transurethral prostatectomy under spinal anesthesia: comparative study.]. | Elderly account for 25% of surgical patients. Several patients with arterial heart disease have normal preoperative ECG and a high incidence of silent myocardial acute infarction in the first postoperative week. Arrhythmias increase with age and supraventricular and ventricular premature complexes, atrial fibrillation and intraventricular conduction abnormalities are observed. This study aimed at evaluating the prevalence of perioperative arrhythmias and ST changes through Holter System in elderly patients submitted to transurethral prostatectomy and inguinal hernia repair under spinal anesthesia.</AbstractText>Participated in this study 21 patients aged 65 to 84 years submitted to transurethral prostatectomy (TUP) and 16 patients aged 63 to 86 years submitted to inguinal hernia repair under spinal anesthesia. Monitoring with Holter System was performed in the preoperative (12 hours), intraoperative (3 hours) and postoperative (12 hours) periods.</AbstractText>The prevalence of supraventricular premature complex was 85.7% vs. 93.7% in the preoperative period, 85.7% vs. 81.2% in the intraoperative and 76.2% vs. 100% in the postoperative period, respectively for groups TUP and control. The prevalence of ventricular premature complex was 76.2% vs. 81.2% in the preoperative period, 80.9% vs. 68.7% in the intraoperative period, and 80.9% vs. 81.2% in the postoperative period, respectively for groups TUP and control. The prevalence of ST changes was 19% vs. 18.7% in the preoperative period, 4.7% vs. 18.7% in the in the intraoperative period, and 14.3% vs. 18.7% in the postoperative period between groups TUP and control, without statistical significance.</AbstractText>Elderly patients have a high prevalence of supraventricular and ventricular cardiac arrhythmias. The total number of preoperative arrhythmias and ST changes was not changed as a function of transurethral prostatectomy surgery or inguinal hernia repair, in the intra and postoperative periods.</AbstractText> |
1,752 | Defibrillator implantation in a child with long QT syndrome. | We report the placement of an implantable cardiac defibrillator as preventative treatment in a 2-year-old with long QT syndrome. |
1,753 | Increased susceptibility of ventricular arrhythmias to aconitine in anaesthetized rats is attributed to the inhibition of baroreflex. | 1. Aconitine is widely used to produce ventricular arrhythmias in anaesthetized rats. The present work was designed to test the hypothesis that anaesthesia may increase the susceptibility of ventricular arrhythmia to aconitine due to the inhibition of arterial baroreflex. In addition, the susceptibility of ventricular arrhythmia to aconitine at different times during the course of a whole day was also investigated. 2. Male Sprague-Dawley rats were used. Arrhthymias were induced by aconitine infusion at six time points (01.00, 05.00, 09.00, 13.00, 17.00 and 21.00 h) with rats in both anaesthetized and conscious states. In sinoaortic-denervated (SAD) rats, ventricular arrhythmias were induced by aconitine infusion between 09.00 and 13.00 h. 3. There was a significant difference in the lethal dose of aconitine between anaesthetized and conscious rats (99.6 +/- 30.1 vs 58.2 +/- 14.7 micro g/kg; P < 0.001). Anaesthesia did increase the susceptibility of rats to ventricular arrhythmias following aconitine. 4. In SAD rats, the lethal dose of aconitine was less than that for baroreflex-intact rats when determined in the conscious state. The difference in the lethal dose of aconitine between SAD and baroreflex-intact rats disappeared when it was determined in anaesthetized rats. 5. The time of day did not affect the susceptibility of either anaesthetized or conscious rats to ventricular arrhythmias following aconitine, except for a difference in the ventricullar fibrillation threshold dose between 13.00 and 17.00 h in anaesthetized rats. 6. In conclusion, anaesthesia may increase the risk of ventricular arrhythmias following aconitine. Intact arterial baroreflex function is necessary to prevent drug-induced ventricular arrhythmias. |
1,754 | The mistakes of surgeons: "gossypiboma". | A foreign body retained in the abdominal cavity following surgery is a serious and medicolegal problem. To emphasize the importance of this operative iatrogenic complication, we reviewed our experience with six patients who had retained abdominal gossypibomas.</AbstractText>The records of six patients with a confirmed diagnosis of gossypiboma after abdominal surgery at Dicle University Hospital, between January 1994 and December 2000, were retrospectively reviewed.</AbstractText>Four of the six patients were female and two male. Previously, of the patients, three underwent elective operations and three were operated on for emergency. Types of previous operation were gynaecological in three cases, gastrointestinal in two cases and hepatobiliary in one case. The most common symptoms were mass, nausea, vomiting, abdominal distension and pain. The intestinal obstructions and pseudotumoral syndrome were determined in three and two cases, respectively. Abdominal ultrasonography clearly demonstrated the gossypiboma in four of our patients and CT demonstrated a more precise image of forgotten surgical sponges in the other two patients. One patient died due to ventricular fibrillation, the other five patients were discharged healthfully.</AbstractText>Small sponges should not be used during laparotomy. Compresses should only be used intraperitoneally, one by one, mounted on a forceps. Before closing the peritoneum, the surgeon should completely explore the abdominal cavity.</AbstractText> |
1,755 | Relation of ventricular late potentials and intradialytic changes in serum electrolytes, ultrafiltration, left ventricular ejection fraction and left ventricular mass index in haemodialysis patients. | End-stage renal failure patients on haemodialysis (HD) suffer from increased risk of sudden cardiac death. Abnormal late potentials (LP) on signal-averaged electrocardiogram (SAAECG) has proved valuable for identification of increased risk of malignant ventricular tachyarryhythmias in various settings of patients. Abnormalities in LP were reported in HD patients, but their role is still not clear. The aim of the study was to evaluate: 1. the influence of HD on SAECG, 2. the correlation of intradialytic changes of serum electrolytes, weight change and ultrafiltration with intradialytic changes of LP, 3. the correlation of left ventricular ejection fraction (LVEF) and left ventricular mass index (LVMI) with LP before and after HD.</AbstractText>LP (parameters fQRSd, RMS40, LAS40) were obtained in 39 patients in sinus rhythm within one hour before and after chronic maintenance HD. Patients with permanent atrial fibrillation or on antiarrhythmic therapy (other than betablockers) were excluded. Echocardiography was performed within three days before HD.</AbstractText>No difference in fQRSd before and after HD was found. Postdialytic RMS40 (47.0 +/- 30.1 microV vs 37.1 +/- 22.6 microV, p < 0.05) and LAS40 (25.9 +/- 9.7 ms vs 30.8 +/- 12.5 ms, p < 0.05) significantly improved. Weak significant negative correlation between intradialytic Na change and fQRSd change was found (R = -0.33, p < 0.05). Correlations between intradialytic changes of other electrolytes (K, Ca, P. Mg) and individual LP parameters were nonsignificant. There was no correlation found between intradialytic weight change/ultrafiltration and intradialytic differencies of SAECG. LVEF was weakly inversely correlated with predialytic fQRSd (R = -0.37, p < 0.05) and postdialytic fQRSd (R = -0.35, p < 0.05). LVMI was weakly positively correlated with predialytic fQRSd (R=0.39, p < 0.05) and postdialytic fQRSd (R = 0.40, p < 0.05). LVEF respectively LVMI did not correlate neither with RMS40 nor with LAS40 before or after HD.</AbstractText>SAECG partially improved in end-stage renal failure patients after HD (RMS40 and LAS40 but not fQRSd). Intradialytic differencies of SAECG were not correlated neither with ultrafiltration nor with weight change. Pre-/postdialytic fQRSd inversely correlated with LVEF and positively correlated with LVMI. Further controlled, prospective studies investigating the impact of LP on HD patient care are needed. (Tab. 6, Ref. 19.).</AbstractText> |
1,756 | Thromboembolic events after aortic valve replacement in elderly patients with a Carpentier-Edwards Perimount pericardial bioprosthesis. | Thromboembolic events after aortic valve replacement with a bioprosthesis were the most frequently occurring complications in elderly patients. Whether this was valve related or dependent on other factors needed further exploration.</AbstractText>Five hundred patients with a median age of 73 years were followed retrospectively after aortic valve replacement with a pericardial prosthesis for occurrence of thromboembolism. Of these, 348 also underwent coronary artery bypass grafting. Twenty-five factors were investigated for their potential effect by using univariate and multivariate analysis.</AbstractText>Univariate analysis revealed 6 significant factors: preoperative endocarditis (P =.0001), preoperative cerebrovascular accident (P =.002), use of postoperative warfarin sodium (Coumadin, DuPont Merck; P =.006), arterial hypertension (P =.023), size of valve prosthesis of 27 mm or larger (P =.023), and hospital thromboembolism (P =.040). There was a trend toward increased fatal thromboembolism in patients without medication. With a multivariate analysis, 4 factors remained significant: preoperative cerebrovascular accident (risk ratio, 4.8; P =.0016), warfarin sodium (risk ratio, 3.0; P =.0028), preoperative endocarditis (risk ratio, 5.6; P =.006), and hospital thromboembolism (risk ratio, 6.1; P =.016). Hypertension had a borderline effect. Age, sex, diabetes, 4 coronary artery factors, 3 other valvular factors, atrial fibrillation, and carotid artery disease had no significant effect.</AbstractText>Some emboli seemed triggered by the valve prosthesis. A proper anticoagulant protocol but also a treatment of hypertension is important in the prevention of thromboembolism after aortic valve replacement with a bioprosthesis. We did not find a significant role of atrial fibrillation and carotid artery disease.</AbstractText> |
1,757 | Reduction of systolic and diastolic dysfunction by retrograde coronary sinus perfusion during off-pump coronary surgery. | We evaluated the protective effects of retrograde coronary sinus perfusion to offset potential systolic and diastolic dysfunction (myocardial stunning) after temporary regional ischemia needed for off-pump coronary artery bypass grafting.</AbstractText>Twenty Yorkshire-Duroc pigs (31.8 +/- 3.9 kg) underwent 15 minutes of mid-left anterior descending coronary artery ischemia in the beating heart. In 8 pigs, no protective measures were used. In 12 pigs, an aorta-coronary sinus shunt (with conventional cannulas) allowed retrograde perfusion during temporary ischemia; in 6 of these pigs, no leakage to the right atrium was ensured. Regional endocardial contraction was measured with sonomicrometer crystals. Systolic dysfunction (impaired regional shortening), diastolic dysfunction (contraction extending into early diastole), and coronary sinus nitric oxide and endothelin-1 levels were recorded.</AbstractText>Before ischemia, contraction did not extend into the diastolic interval. During ischemia, paradoxic bulging occurred in all hearts except in the occlusive coronary sinus shunt group (16% +/- 6% of baseline, P <.01). Sixty minutes after ischemia, systolic segment shortening recovered 36% +/- 24% without retrograde perfusion versus 56% +/- 20% and 61% +/- 14% with coronary sinus shunting (P <.05). Diastolic dysfunction (as percentage of diastolic time in contraction) was 38% +/- 16% in the nontreated group versus 22% +/- 22% and 9% +/- 9% (P <.05) after shunting and occlusive shunting, respectively. This correlated with a left ventricular end-diastolic pressure increase of 4 mm Hg in the ischemic group versus no change in the retrograde perfusion groups. Nitric oxide decreased 15% without shunting and increased 8% after occlusive coronary sinus shunting (P <.05).</AbstractText>Retrograde coronary sinus perfusion during simulated off-pump coronary revascularization diminishes systolic and diastolic dysfunction. An aortic-coronary sinus shunt is a rapid, recognized approach that can improve myocardial muscle and endothelial safety during off-pump coronary artery bypass grafting.</AbstractText> |
1,758 | Worrisome thoughts about the diagnosis and treatment of patients with Brugada waves and the Brugada syndrome. | The Brugadas have made a significant contribution to medicine. Their discovery of a new clinical syndrome and ECG abnormalities has created a great deal of interest and has opened Pandora's box. Here, we discuss some worrisome thoughts about the condition. We stress the need for improved diagnostic criteria and treatment because it is not always possible to perform coronary arteriography, electrophysiological studies, right ventricular myocardial biopsy, and MRI in all patients in whom ST-segment abnormalities are seen in the ECG, especially in patients who are asymptomatic. Accordingly, further research is needed to guide the clinician in the diagnostic and therapeutic problems of patients who have unusual ST segments in leads V1 and V3. We present a patient who illustrates the problem. |
1,759 | Comparing the efficacy and safety of a novel monophasic waveform delivered by the passive implantable atrial defibrillator with biphasic waveforms in cardioversion of atrial fibrillation. | The passive implantable atrial defibrillator (PIAD) (with no battery or discharging capacitor and powered transcutaneously by radio-frequency energy) delivering a novel monophasic low-tilt waveform is more efficacious than the standard monophasic waveform at atrial defibrillation. Standard biphasic (STB) waveforms, however, are more efficacious and safer than monophasic waveforms. This study compared the efficacy and safety of the PIAD waveform with biphasic waveforms.</AbstractText>Sustained atrial fibrillation (AF) was induced by rapid atrial pacing. Cardioversion was attempted via 2 atrial defibrillation leads. The efficacy of the PIAD was compared with 3 biphasic waveforms (standard, single rounded, and double rounded) at varying voltage settings in 10 pigs. After a synchronized shock, hemodynamic changes between the PIAD, standard biphasic, and monophasic waveforms were compared at 1.5 and 3.0 J in 12 pigs. Myocardial injury (biochemical and histological) after ten 5-J PIAD shocks was compared with a no-shock group in 14 pigs. The PIAD 100-V setting was significantly more efficacious than the STB (100/-50 V: 100% [1.88+/-0.02 J] versus 90% [0.89+/-0.0 J]; P=0.025). No arrhythmic, hemodynamic, or myocardial injury was observed with the PIAD waveform.</AbstractText>Defibrillation with the PIAD is more efficacious than with the STB waveform and appears safe. This device could provide a more effective option for cardioversion.</AbstractText> |
1,760 | Cardiopulmonary resuscitation (CPR) using periodic acceleration (pGz) in an older porcine model of ventricular fibrillation. | Cardiopulmonary resuscitation (CPR) can be achieved by repetitive motion of the body headwards to footwards in the spinal axis, at 2 Hz and +/- 0.6 G in a juvenile pig model of ventricular fibrillation. Return of spontaneous circulation and normal neurological outcome occurred after a total of 22 min of ventricular fibrillation that included a 3-min noninterventional period [Resuscitation 56 (2003) 215; Resuscitation 51 (2001) 55]. Since older pigs have stiffer rib cages than juvenile pigs and their hemodynamic response to various stimuli might differ, this study was carried out to determine whether this method of CPR, termed pGz-CPR, was just as effective in older pigs. pGz-CPR was also compared to chest compression CPR using an automated mechanical device (CONV-CPR). Ventricular fibrillation was instituted in older pigs weighing 23-34 kg and a 3-min noninterventional period was observed, followed by 15 min pGz-CPR in eight pigs or 15 min CONV-CPR in eight pigs. Return of spontaneous circulation (ROSC) occurred after defibrillation in all eight pigs with pGz-CPR and in six of eight pigs with CONV-CPR. Two of eight pigs with CONV-CPR and none of the eight pigs with pGz-CPR had rib fractures. Hemodynamic instability 15 min after ROSC occurred in all animals with CONV-CPR whereas only three of eight pigs with pGz-CPR demonstrated hemodynamic instability (P < 0.05). We conclude that pGz-CPR in older pigs produces similar ROSC reported by other investigators in pigs without the risk of rib fractures. Further, pGz-CPR is associated with a lower incidence of periods of hemodynamic instability following ROSC than CONV-CPR. |
1,761 | Oxygen delivery and return of spontaneous circulation with ventilation:compression ratio 2:30 versus chest compressions only CPR in pigs. | The need for rescue breathing during the initial management of sudden cardiac arrest is currently being debated and reevaluated. The present study was designed to compare cerebral oxygen delivery during basic life support (BLS) by chest compressions only with chest compressions plus ventilation in pigs with an obstructed airway mimicked by a valve hindering passive inhalation. Resuscitability was then studied during the subsequent advanced life support (ALS) period. After 3 min of untreated ventricular fibrillation (VF) BLS was started. The animals were randomised into two groups. One group received chest compressions only. The other group received ventilations and chest compressions with a ratio of 2:30. A gas mixture of 17% oxygen and 4% carbon dioxide was used for ventilation during BLS. After 10 min of BLS, ALS was provided. All six pigs ventilated during BLS attained a return of spontaneous circulation (ROSC) within the first 2 min of advanced cardiopulmonary resuscitation (CPR) compared with only one of six compressions-only pigs. While all except one compressions-only animal achieved ROSC before the experiment was terminated, the median time to ROSC was shorter in the ventilated group. With a ventilation:compression ratio of 2:30 the arterial oxygen content stayed at 2/3 of normal, but with compressions-only, the arterial blood was virtually desaturated with no arterio-venous oxygen difference within 1.5-2 min. Haemodynamic data did not differ between the groups. In this model of very ideal BLS, ventilation improved arterial oxygenation and the median time to ROSC was shorter. We believe that in cardiac arrest with an obstructed airway, pulmonary ventilation should still be strongly recommended. |
1,762 | Decrease in the occurrence of ventricular fibrillation as the initially observed arrhythmia after out-of-hospital cardiac arrest during 11 years in Sweden. | To describe the change in the occurrence of ventricular fibrillation as initially observed arrhythmia among patients suffering from out-of-hospital cardiac arrest in Sweden.</AbstractText>All patients included in the Swedish cardiac arrest registry between 1991 until 2001. The registry covers 85% of the population in Sweden.</AbstractText>All patients with bystander witnessed out-of-hospital cardiac arrest included in the Swedish Cardiac Arrest Registry between 1991 and 2001 from the same ambulance organisation each year were included in the survey.</AbstractText>Over 11 years, among patients in Sweden with a bystander witnessed out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation (CPR) was attempted (n = 9666), the occurrence of ventricular fibrillation as the initially obseved arrhythmia decreased from 45% in 1991 to 28% in 2001 (P < 0.0001) if the arrest occurred at home, and from 57% to 41% if the arrest occurred outside home (P < 0.0001). This was found despite the fact that the proportion who received bystander CPR increased from 29% in 1991 to 39% in 2001 if the arrest occurred at home (P < 0.0001) and from 54% to 60% if the arrest occurred outside home (NS). There was a significant increase in age among patients with out-of-hospital cardiac arrest at home, no change in the estimated interval between collapse and call but an increase in the interval between call and arrival of the ambulance among patients with out-of-hospital cardiac arrest outside home.</AbstractText>During 11 years in Sweden, there was a marked decrease in the proportion of patients found in ventricular fibrillation among patients with a bystander witnessed cardiac arrest regardless whether the arrest occurred at home or outside home. A modest increase in age and interval between call for, and arrival of, the ambulance was associated with these findings.</AbstractText> |
1,763 | Can successful treatment of cardiac arrest be a performance indicator for hospitals? | Although resuscitation from cardiac arrest prevents more deaths from acute myocardial infarction (MI) than any other treatment, results have not been audited widely nor performance standards proposed.</AbstractText>The Myocardial Infarction National Audit Project (MINAP) uses electronic transmission of a 53-item dataset to a central cardiac audit database (CCAD). From October 2000 to August 2002, transmission by 218 hospitals of data from 55,906 cases of MI with 4934 attempted resuscitations from a first arrest, allowed for examination of factors determining survival, and for possible future measurement of success in resuscitation as a performance indicator. We investigated two possible indicators: (i) numbers of survivors from arrest in ventricular fibrillation or pulseless ventricular tachycardia (VF/VT) per 1000 cases of MI; and (ii) observed/expected (O/E) ratios for survival taking all VF/VT arrests rather than MI as the denominator, and adjusting for differing age structures and admission delays among individual hospitals.</AbstractText>Of the 4934 reported patients suffering a first arrest, 1778 (36%) survived to be discharged from hospital. The presenting rhythm was VF/VT in 2321 (47%) patients of whom 1461 (63%) survived. Survival for all 218 hospitals together had the relatively small 95% confidence limits of 26 (25-27) survivors from VF/VT per 1000 MI. However, the small numbers from individual hospitals made it impossible in most cases, whichever of the two indicators was used, to separate quality of performance and completeness of reporting from the factor of chance.</AbstractText>Audit of success in resuscitation is essential if performance in the treatment of MI is to be assessed. However, the relatively small numbers of arrests occurring in individual hospitals means that if year on year improvements are to be documented, audit must be carried out among groups of hospitals or on a national scale.</AbstractText> |
1,764 | A perspective on rate control in the treatment of atrial fibrillation. | Until recently, the standard approach to therapy of atrial fibrillation (AF) in most cases was restoration and maintenance of sinus rhythm (rhythm control). Although difficult to accomplish, and associated with potential serious adverse effects of antiarrhythmic agents, this therapeutic approach was influenced by the belief that rhythm control was associated with better survival, fewer symptoms, better exercise tolerance, lower risk of stroke, better quality of life, and absence of need for long-term anticoagulation. However, four clinical trials comparing rate control with rhythm control have failed to demonstrate these advantages, indicating that rate control should be considered a legitimate primary therapeutic option, particularly in patients at risk for stroke. Pursuit of rate or rhythm control should be decided on a case-by-case basis. |
1,765 | [End-stage cardiac manifestations and autopsy findings in patients with cardiac fabry disease]. | Fabry disease is an X-linked recessive disorder resulting from a deficiency of alpha-galactosidase A with multi-organ dysfunction. Patients with manifestations limited to the heart have been reported recently as a disease variant. We have previously reported a 3% prevalence of this cardiac variant in men with left ventricular hypertrophy, which we designated cardiac Fabry disease. The purposes of the current study were to evaluate the end-stage cardiac manifestations and autopsy findings in patients with cardiac Fabry disease.</AbstractText>We evaluated five autopsied male patients with cardiac Fabry disease. One died of ventricular fibrillation and four of heart failure. Electrocardiograms obtained at hospitalization revealed the presence of conduction abnormalities and nonsustained ventricular tachycardia. Echocardiograms and autopsy findings showed the presence of left ventricular hypertrophy in all patients. Localized thinning of the basal posterior wall of the left ventricle was detected in four patients who died of heart failure. All patients had severe left ventricular dysfunction. Histologically, myocardial cells showed glycosphingolipid accumulation in all of the patients but no accumulation was observed in other organs or in systemic vascular endothelial cells.</AbstractText>Severe left ventricular dysfunction, conduction disturbances and ventricular arrhythmias occur in end-stage cardiac Fabry patients. Furthermore, left ventricular hypertrophy commonly associated with thinning of the base of the left ventricular posterior wall is present. The accumulation of glycosphingolipids can be observed in myocardial cells but not in other organs.</AbstractText> |
1,766 | Abrogation of ventricular arrhythmias in a model of ischemia and reperfusion by targeting myocardial calcium cycling. | Abnormal intracellular Ca(2+) cycling plays an important role in cardiac dysfunction and ventricular arrhythmias in the setting of heart failure and transient cardiac ischemia followed by reperfusion (I/R). We hypothesized that overexpression of the sarcoplasmic reticulum Ca(2+) ATPase pump (SERCA2a) may improve both contractile dysfunction and ventricular arrhythmias. Continuous ECG recordings were obtained in 46 conscious rats after adenoviral gene transfer of either SERCA2a or the reporter gene beta-galactosidase (beta gal) or parvalbumin (PV), as early as 48 h before and 48 h after 30 min ligation of the left anterior descending artery by using an implantable telemetry system. Sham-operated animals were used for comparison for hemodynamic measurements, whereas within-animal baseline was used for electrocardiographic and echocardiographic parameters. All episodes of nonsustained ventricular tachycardia (VT) and ventricular fibrillation (VF) were counted, and their durations were summed by telemetry. I/R decreased regional cardiac wall thickening as well as the maximal rate of left ventricular pressure rise (+dP/dt) and ventricular pressure fall (-dP/dt). SERCA2a restored regional wall thickening and +dP/dt and -dP/dt to levels seen preoperatively. Regional-wall motion and anterior-wall thickening were improved in the SERCA2a animals, as assessed by echocardiography and piezoelectric crystals. To assess whether these effects are SERCA2a specific, we overexpressed a skeletal-muscle protein, PV, to examine whether Ca(2+) buffering alone can mitigate ventricular arrhythmias. During the first hour after I/R, the rate of nonsustained VT plus VF was 16 +/- 5 episodes per h (n = 6) in the Ad.beta gal group, 22 +/- 6 in the Ad.PV group, and 4 +/- 2(n = 6, P < 0.01) in the Ad.SERCA2a group. The decrease in VT plus VF in the Ad.SERCA2a group was consistent throughout the 48 h of monitoring. These results show that improving intracellular Ca(2+) handling by overexpression of SERCA2a restores contractile function and reduces ventricular arrhythmias during I/R. |
1,767 | Delta-opioid receptor agonist reduces severity of postresuscitation myocardial dysfunction. | Postresuscitation myocardial dysfunction is recognized as a leading cause of early death after initially successful cardiopulmonary resuscitation (CPR). In the present study, we hypothesized that a delta-opioid receptor agonist would decrease the severity of postresuscitation myocardial dysfunction and improve survival. Fifteen Sprague-Dawley rats, fasted overnight with access to water, were anesthetized by an injection of 45 mg/kg ip pentobarbital sodium. Additional doses of 10 mg/kg were administered at hourly intervals but not within 30 min before induced ventricular fibrillation (VF). Either the delta-opioid receptor agonist pentazocine (300 microg/kg), pentazocine pretreated with the opioid receptor-blocking agent naloxone (1 mg/kg), or saline placebo was injected into the right atrium after 5 min of untreated VF and 3 min before initiation of CPR. After an additional 8 min of CPR administration, defibrillation was attempted. All animals were successfully resuscitated. Left ventricular rate of pressure increase at 40 mmHg and cardiac index values were significantly improved in pentazocine-treated animals, which also had significantly longer survival times (60 +/- 11 vs. 16 +/- 7 h; P < 0.01). Except for ease of defibrillation, the beneficial effects of pentazocine were completely abolished by pretreatment with naloxone. The concept of pharmacological hibernation employing a delta-opioid receptor agonist is a novel and promising intervention for minimizing global ischemic injury during CPR and postresuscitation myocardial dysfunction. |
1,768 | Mibefradil is more effective than verapamil for restoring post-ischemic function of isolated hearts of guinea pigs with acute renal failure. | The deleterious intracellular Ca(2+) overload in the ischemic-reperfusion injury of the heart can be even more expressed in subjects with acute renal failure in whom maintenance of intracellular Ca(2+) has already been disturbed in normoxia. To study the influence of acute renal failure in ischemic-reperfusion injury on the heart, we used isolated Langendorff's hearts of guinea pigs with gentamicin-induced acute renal failure. We examined arrhythmias, heart contractility and myocardial cell damage during reperfusion. Two specific Ca(2+) channel antagonists, mibefradil (0.1 and 1 microM) and verapamil (0.1 microM), were used to test the possible involvement of T-type and L-type Ca(2+) channels in these processes. We exposed hearts to 50 min of zero-flow global ischemia and 60 min of reperfusion. During reperfusion, unrecoverable ventricular fibrillation appeared more often in hearts of animals with acute renal failure than in control hearts (80% vs. 0%, respectively). Mibefradil, but not verapamil, applied either pre- or post-ischemically, terminated ventricular fibrillation in all hearts of animals with acute renal failure. Mibefradil (0.1 microM only) improved contractility in hearts of animals with acute renal failure during reperfusion by 30%. During reperfusion, lactate dehydrogenase (LDH) release rate increased less in hearts of guinea pigs with acute renal failure than in control hearts and only verapamil decreased it additionally. Thus, our results suggest a more important role of T- than of L-type Ca(2+) channels in ischemic-reperfusion injury in isolated guinea pig hearts with acute renal failure. |
1,769 | Radiofrequency applications in congenital heart disease. | The relatively recent application of radiofrequency technologies in the treatment of congenital heart defects has provided a safe and effective alternative to conventional therapies in establishing endovascular patency for a variety of lesions. Radiofrequency, with typically used frequencies of approximately 500 kHz, does not cause pain and is unlikely to induce atrial or ventricular fibrillation. It can be used either to ablate (higher power (35-50 W); longer duration of application (90-120 sec); lower voltage (30-50 V)) or to perforate (lower power (5-10 W) shorter duration of application (1-5 sec), higher voltage (150-280 V)). In the past, perforating radiofrequency has been applied to establish right ventricular outflow tract patency in pulmonary atresia with intact septum and with ventricular septal defect. More recently radiofrequency has been shown to be effective at recanalizing central and peripheral vasculature and has also been applied in establishing percutaneous left heart access. A new radiofrequency catheter, dedicated to transseptal left atrial cannulation, has been demonstrated to be safe and effective in an animal model and is now ready for clinical trials. |
1,770 | Effects of sasanquasaponin on ischemia and reperfusion injury in mouse hearts. | We investigated effects of sasanquasaponin (SQS), a traditional Chinese herb's effective component, on ischemia and reperfusion injury in mouse hearts and the possible role of intracellular Cl- homeostasis on SQS's protective effects during ischemia and reperfusion. An in vivo experimental ischemia model was made in mice (weight 27-45 g) using ligation of left anterior descending coronary artery, and in vitro models were made in perfused hearts by stopping flow or in isolated ventricular myocytes by hypoxia. The in vivo results showed that SQS inhibited cardiac arrhythmias during ischemia and reperfusion. Incidence of arrhythmias during ischemia and reperfusion, including ventricular premature beats and ventricular fibrillation, was significantly decreased in the SQS-pretreated group (P<0.05). Results in perfused hearts showed that SQS suppressed the arrhythmias, prevented against ischemia-induced decrease in contract force and promoted the force recovery from reperfusion. Furthermore, intracellular Cl- concentrations ([Cl-]i) were measured using a MQAE fluorescence method in isolated ventricular myocytes in vitro. SQS slightly decreased [Cl-]i in non-hypoxic myocytes and delayed the hypoxia/reoxygenation-induced increase in [Cl-]i during ischemia and reperfusion (P<0.05). Our results showed that SQS protected against ischemia/reperfusion-induced cardiac injury in mouse hearts and that modulation of intracellular Cl- homeostasis by SQS would play a role in its anti-arrhythmia effects during ischemia and reperfusion. |
1,771 | Is female sex associated with increased survival after out-of-hospital cardiac arrest? | To evaluate survival after out-of-hospital cardiac arrest in relation to sex.</AbstractText>All patients with out-of-hospital cardiac arrest included in the Swedish Cardiac Arrest Registry between 1990 and 2000 in whom cardiopulmonary resuscitation (CPR) was attempted and who did not have a crew witnessed arrest were included. The registry covers 85% of the inhabitants of Sweden (approximately 8 million inhabitants). P-values were adjusted to differences in age. Survival was defined as patients being hospitalised alive and being alive one month after cardiac arrest. In all, 23,797 patients participated in the survey of which 27.9% were women.</AbstractText>Among women 16.4% were hospitalised alive versus 13.2% among men ( P<0.001). After one month 3.0% among women were alive versus 3.4% among men (NS). In a multivariate analysis considering differences in age and various factors at resuscitation female sex was an independent predictor for patients being hospitalised alive (odds ratio 1.66; 95% confidence limits 1.49-1.84) and for being alive after one month (odds ratio 1.27; 95% confidence limits 1.03-1.56). Women differed from men as they were older ( P<0.001 ), had a lower prevalence of witnessed cardiac arrest ( P=0.01), a lower occurrence of bystander CPR (P<0.001), a lower occurrence of ventricular fibrillation as initial arrhythmia (P<0.001) and a lower occurrence of cardiac disease judged to be the cause of cardiac arrest ( P<0.0001 ). On the other hand they had a cardiac arrest at home more frequently ( P<0.001 ).</AbstractText>Among patients suffering out-of-hospital cardiac arrest in Sweden which was not crew witnessed and in whom resuscitation efforts were attempted, female sex was associated with an increased survival.</AbstractText> |
1,772 | Long-term subjective memory function in ventricular fibrillation out-of-hospital cardiac arrest survivors resuscitated by early defibrillation. | Brain injury after a cardiac arrest remains a major cause of morbidity. Programs focusing on early defibrillation have yielded improved survival of patients after hospital discharge following ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA). Early defibrillation that promptly restores a circulating rhythm should decrease the hypoxic period and subsequent organ injury. Therefore this study was designed to determine if long-term memory complaints persist in VF OHCA survivors resuscitated in an early defibrillation program when compared with a healthy control population not experiencing cardiac arrest.</AbstractText>All patients with an OHCA between November 1990 and January 2001 who received defibrillation by emergency medical services personnel in Olmsted County, MN, USA, were included. The memory function questionnaire (MFQ), a 64-item, 7-point Likert-scaled instrument to evaluate the perception of everyday memory functioning was sent to all survivors. The MFQ comprises four scales: general frequency of forgetting (rates general forgetting), retrospective functioning (compares current memory with past ability), seriousness of forgetting (rates how memory impairment impacts daily life), and mnemonics usage (measures adaptation). The MFQ is scaled so that high scores reflect less severe memory complaints. The comparison population comprised members of the Mayo Older Americans Normative Studies (MOANS) cohort. Quality of life was ascertained with a short form (SF)-36 survey.</AbstractText>Seventy-nine of the 200 VF OHCA patients (40%) were discharged. Twenty-two patients have died since dismissal, with an overall average length of follow-up of 4.9+/-3.0 years. Thirty-eight (67%) of the survivors completed the MFQ. Compared with the normal, there was a significant decrease in the general frequency of forgetting score of 144.2+/-37.4 versus 168.1+/-27.3 ( P<0.001) and the seriousness of forgetting score of 84.8 +/-26.7 versus 95.2+/-19.7 (P=0.004). The retrospective function-scale scores were not significantly different ( 18.4+/-6.8 versus 18.7+/- 5.0 (P=0.74). Younger patients (lesser than 65 years of age) reported an increase in general forgetting and the seriousness of forgetting compared with older survivors. A comparison with SF-36 scores suggested an association between general forgetting and decreased vitality (P=0.03) and the seriousness of forgetting with a decreased general health (P=0.005), mental health (P=0.009), physical functioning ( P=0.02 ), and vitality ( P=0.05).</AbstractText>In a cohort of VF OHCA patients, survivors report more memory complaints in comparison with a general healthy older population. There were more long-term-memory complaints in younger patients. Patients with higher long-term quality-of-life score have fewer memory complaints.</AbstractText> |
1,773 | Improving the rate of return of spontaneous circulation for out-of-hospital cardiac arrests with a formal, structured emergency resuscitation team. | To assess the impact of a formal, structured resuscitation team in the emergency department (ED) on the success rate of cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) patients.</AbstractText>This is a "three-phase" (organized, transitional, and re-organized), prospective study in which medical records of all OHCA patients who needed resuscitation in the ED during the three 6-month periods were reviewed and data were coded in out-of-hospital Utstein style formats. An organized resuscitation team existed in the organized and re-organized phases but not in the transitional phase. The study population consisted of adult patients with non-traumatic cardiac arrest (>18 years of age).</AbstractText>The rates of return of spontaneous circulation (ROSC) were 51.3% for the organized phase, 31.0% for the transitional phase, and 53.1% for the re-organized phase ( P=0.013 ). The rates of ROSC from pulseless electrical activity (PEA)/asystole were significantly higher in periods with organized and re-organized teams ( P=0.007 ). The rates of ROSC for the ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) sub-groups were not significantly different in all three periods ( P=0.406 ). The chance of survival-to-discharge was 9.2% in the organized period, 11.2% in the transitional period, and 15.6% in the re-organized period ( P=0.496 ). The existence of a formal, structured emergency resuscitation team in the ED (odds ratio: 2.56, 95% confidence interval: 1.35-4.80) and witness at the scene (odds ratio: 2.45, 95% confidence interval: 1.34-4.45) were the only independent predictors of successful ROSC of OHCA patients by multiple logistic regression analysis.</AbstractText>The establishment of a formal and structured emergency resuscitation team in the ED is associated with an increased rate of ROSC for OHCA patients.</AbstractText> |
1,774 | [The efficiency of nifekalant hydrochloride for the prevention of ventricular tachycardia during cardiac surgery]. | Many cases have been successfully treated by us with experimented nifekalant hydrocholoride to prevent ventricular tachycardia (VT) during cardiac surgery. The 13 patients who underwent cardiac surgery at our hospital from 1999 to 2002 were retroactively given nifekalant hydrocholoride against VT. Lidocaine hydrochloride was not effective for VT, and it was difficult for 3 patients to be weaned for cardio-pulmonary bypass, while 6 patients needed aortic balloon pumping or percutaneous cardio-pulmonary support. Nifekalant hydrochloride suppressed VT induction in 9 patients (69.2%). Blood pressure and heart rate did not change, but QTc intervals were significantly increased with nifekalant hydrochloride (p < 0.005). Proarrhythmic events (Torsades de pointes) occurred in 2 patients, but none of the cases showed drug-induced worsening of cardiac function. Nifekalant hydrochloride is a class III antiarrhythmic drug that has been found to be effective against VT and ventricular fibrillation. While class I antiarrhythmic drugs are usually ineffective and induce severe heart failure, nifekalant hydrochloride can be effective. |
1,775 | Myocardial ischaemia in children with sickle cell disease. | The heart may be involved in children affected with sickle cell disease (SCD) via several mechanisms. Principally, chronic anaemia increases cardiac output and may cause left ventricular enlargement and cardiac insufficiency.</AbstractText>To investigate whether the heart also suffers from ischaemia in SCD, as has already been shown for other organs (bone, brain, etc), and to look for risk factors predisposing to this complication.</AbstractText>Twenty two children with SCD, and chest pain or ECG or echocardiographic signs (left ventricle dilation or hypokinesis) suggesting myocardial ischaemia were subjected to thallium-201 (201Tl) single photon emission computed tomography (SPECT).</AbstractText>Eight children had a normal SPECT, 14 an abnormal one. Myocardial perfusion defects were reversible in nine, fixed in five. Patients with perfusion defects tended to be older and have more severe disease. Five had had cardiac symptoms (episodes of cardiac failure in three, ventricular fibrillation in one, angina in one). Myocardial perfusion was reassessed after six months of hydroxyurea treatment in three patients, and was found to be improved.</AbstractText>Myocardial perfusion defects are present in children with SCD and may be demonstrated using SPECT. Hydroxyurea improved perfusion in three patients.</AbstractText> |
1,776 | [Intraoperative ventricular fibrillation in a patient with chronic cocaine abuse--a case report]. | With increasing drug abuse of cocaine, the chances are growing that an anaesthetist comes into contact with an acutely intoxicated patient or chronic cocaine user while on call or during his daily routine. In South America chewing coca leaves is daily practise, while in the industrialised world the drug is sniffed, smoked or injected intravenously. Clinically, cocaine is used topically in ENT and ophthalmology due to its local analgesic and strong vasoconstrictive properties. Cocaine has a similar effect on the CNS as amphetamines and produces euphoria and hallucinations. Cocaine acts indirectly on sympathetic stimulation, release of dopamine and inhibition of catecholamine metabolism. It is metabolised in the liver and by serum esterases. Intoxication with cocaine leads to respiratory depression, arrhythmias, ventricular fibrillation and death. If an emergency operation during acute cocaine intoxication is necessary, all sympathomimetic anaesthetic drugs must be avoided. A deep anaesthesia must be provided to reduce the risk of cardiovascular complications. In the literature, anaesthesia is regarded as safe for patients with chronic cocaine misuse after abstinence of 24 hours. This case report shows that, even without acute intoxication, severe cardiovascular problems are possible in patients with chronic cocaine abuse. Hence, we recommend a cocaine-free interval of at least one week before elective surgical procedures. |
1,777 | Direction-dependent conduction abnormalities in a canine model of atrial fibrillation due to chronic atrial dilatation. | Chronic rapid atrial pacing (RAP) leads to changes that perpetuate atrial fibrillation (AF). Chronic atrial dilatation due to mitral regurgitation (MR) also increases AF inducibility, but it is not clear whether the underlying mechanism is similar. Therefore, we have investigated atrial electrophysiology in a canine MR model (mitral valve avulsion, 1 mo) using high-resolution optical mapping and compared it with control dogs and with the canine RAP model (6-8 wk of atrial pacing at 600 beats/min, atrioventricular block, and ventricular pacing at 100 beats/min). At followup, optical action potentials were recorded using a 16 x 16 photodiode array from 2 x 2-cm left atrial (LA) and right atrial (RA) areas in perfused preparations, with pacing electrodes around the field of view to study direction dependency of conduction. Action potential duration at 80% repolarization (APD(80)) was not different between control and MR but was reduced in RAP atria. Conduction velocities during normal pacing were not different between groups. However, the MR LA showed increased conduction heterogeneity during pacing at short cycle lengths and during premature extrastimuli, which frequently caused pronounced regional conduction slowing. Conduction in the MR LA during extrastimulation also displayed a marked dependence on propagation direction. These phenomena were not observed in the MR RA and in control and RAP atria. Thus both models form distinctly different AF substrates; in RAP dogs, the decrease in APD(80) may stabilize reentry. In MR dogs, regional LA conduction slowing and increased directional dependency, allowing unidirectional conduction block and preferential paths of conduction, may account for increased AF inducibility. |
1,778 | EEG and ECG in sudden unexplained death in epilepsy. | Sudden unexpected death in epilepsy (SUDEP) is a major cause of mortality for patients with epilepsy. Cardiac factors may be involved and were evaluated in this study.</AbstractText>EEG and ECG data for 21 patients with definite (n = 6) or probable (n = 15) SUDEP were compared with data from a group of 43 patients with refractory partial epilepsy. ECG abnormalities and heart rate (HR) changes were correlated with clinical data.</AbstractText>Fourteen patients died in their sleep; two were awake. Ictal maximal HR (90 seizures from 16 of 21 patients) was significantly higher in SUDEP (mean, 149 beats/min, BPM) than in comparison patients (mean, 126 BPM; p < 0.001). Greater increases in HR were associated with seizures arising from sleep (78 BPM increase) than from wakefulness (47 BPM; p < 0.001) in SUDEP, as compared with the non-SUDEP group (52 BPM in sleep, 43 BPM in wakefulness; p = 0.27). Ictal cardiac repolarization and rhythm abnormalities occurred in 56% of SUDEP (including two atrial fibrillation, two ventricular premature depolarizations, two marked sinus arrhythmia, two atrial premature depolarizations, one junctional escape, one ST-segment elevation), and 39% of comparison patients (p = 0.39). No specific seizure onset (laterality or lobe) was associated with SUDEP.</AbstractText>This study reveals, for the first time, evidence of increased autonomic stimulation (as measured by HR) associated with seizures, particularly in sleep, in patients with SUDEP, as compared with a clinically similar group of patients with refractory epilepsy.</AbstractText> |
1,779 | Linkage between mechanical and electrical alternans in patients with chronic heart failure. | Progressive heart failure and ventricular fibrillation are major causes of death in patients with chronic heart failure. Mechanical alternans (pulsus alternans) has been observed in patients with severe congestive heart failure. Visible T wave alternans occasionally is a precursor of ventricular fibrillation. We investigated the occurrence of both cardiac alternans in 94 patients with chronic heart failure.</AbstractText>Mean left ventricular ejection fraction (LVEF) of the study population was 35 +/- 10%. Mechanical alternans was detected in left ventricular pressure during diagnostic cardiac catheterization. Only sustained mechanical alternans was included in the study. Visible T wave alternans, not microvolt alternans, was noted on standard surface ECG. Cardiac alternans was examined at rest, during physiologic tachycardia, and during stepwise dobutamine loading (2-4-8 microg/kg/min). Prevalences of mechanical and electrical alternans were 19.1% and 4.4% at rest, 45.5% and 8.0% during physiologic tachycardia, and 62.1% and 9.5% under dobutamine loading. Overall, 70 patients (74.5%) showed mechanical alternans and 10 patients (10.6%) showed T wave alternans. T wave alternans always appeared with large mechanical alternans. Among patients with mechanical alternans, cases with T wave alternans showed lower LVEF than those without (27.5 +/- 4.4 and 35.1 +/- 10.2, P < 0.002).</AbstractText>Visible T wave alternans was detectable in patients with chronic heart failure, especially under tachycardia or catecholamine exposure. Investigating mechanical and mechanoelectrical alternans may bring new insights into the management of patients with chronic heart failure.</AbstractText> |
1,780 | Do patients accept implantable atrial defibrillation therapy? Results from the Patient Atrial Shock Survey of Acceptance and Tolerance (PASSAT) Study. | The Medtronic Jewel AF 7250 is an implantable cardioverter defibrillator with atrial and ventricular therapies (ICD-AT). The ICD-AT is effective in managing atrial tachyarrhythmias (atrial fibrillation [AF]), but patient acceptance remains an issue. This aim of this study was to measure ICD-AT acceptance.</AbstractText>ICD-AT acceptance was evaluated in 96 patients enrolled in the "Jewel AF-AF-Only Study" for > or =3 months of follow-up (mean 19 months). Patients were mostly men (72%; age 65 +/- 12 years). Clinical data and a written survey (75% response rate) were used to quantify demographics, AF frequency and symptoms, atrial defibrillation therapy, quality of life (QOL), psychosocial distress, and ICD-AT therapy acceptance. From implant to survey, AF symptom and severity scores decreased by 18% (P < or = 0.05), and QOL (SF-36) scores increased by 15% to 50% (P < or = 0.05). ICD-AT therapy acceptance was high, with 71.3% of patients scoring in the 75th percentile on the Florida Patient Acceptance Survey. ICD-AT acceptance was correlated with the Physical Component Scale and Mental Health Component Scale scores of the SF-36 (r = 0.28 and 0.35, respectively). ICD-AT acceptance was negatively correlated with depressive symptomatology (r =-0.59), trait anxiety (r =-0.48), illness intrusiveness (r =-0.55), and AF symptom and severity scores (r =-0.26). ICD-AT acceptance did not correlate with preimplant cardioversions, number of atrial shocks, AF episodes detected by the device, or device implant duration.</AbstractText>Most patients accepted ICD-AT therapy. Patients were more likely to accept ICD-AT if they had less psychosocial distress, greater QOL, and lower AF symptom burden.</AbstractText> |
1,781 | Advanced life support therapy on out-of-hospital cardiac arrest patients: an engineering perspective. | In the USA alone, several hundred thousand people die of sudden cardiac arrests each year. Basic life support, defined as chest compressions and ventilations, and early defibrillation are the only factors proven to increase the survival of patients with out-of-hospital cardiac arrest and are key elements in the chain of survival defined by the American Heart Association. The current cardiopulmonary resuscitation guidelines treat all patients the same but studies show a need for more individualization of treatment. This review focusses on ideas on how to strengthen the weak parts of the chain of survival including the ability to measure the effects of therapy, improve time efficiency and optimize the sequence and quality of the various components of cardiopulmonary resuscitation. |
1,782 | Can antiarrhythmic drugs save lives in patients with congestive heart failure? | Although arrhythmic death is a common cause of death in patients with congestive heart failure (CHF), numerous trials involving prophylactic antiarrhythmic drug treatment have yielded few gains. To date, only beta-blockers have shown a distinct mortality-reducing effect and despite the antiarrythmic effect of gamma-blockers, results point towards causes other than the antiarrhythmic effect in obtaining this beneficial effect. Atrial fibrillation is an often-encountered arrhythmia in patients with CHF and recent trials have cast doubt on the present treatment strategy of persistently striving to obtain sinus rhythm. This paper outlines the results of the large clinical trials dealing with antiarrhythmic drug treatment in CHF patients with or without atrial fibrillation and certain subgroup analysis and future treatment possibilities are discussed. |
1,783 | [Correction of rate and structure of ventricular rhythm in permanent atrial fibrillation: a novel pathogenetic approach]. | To analyze action of digoxin and some non-digitalis drugs (beta-blockers, verapamil, amiodarone, d,l-sotalol) and their combinations on electrical activity of atria, frequency and structure of ventricular rhythm in patients with permanent atrial fibrillation.</AbstractText>One hundred patients with permanent atrial fibrillation and heart rate at rest above 80 bpm were divided into 9 treatment groups. High-resolution orthogonal Frank lead ECG was recorded before and after allocated treatment. Analysis included construction of ff-waves periodograms, histograms of RR interval, cardiointervalograms and application of autocorrelation function.</AbstractText>It was demonstrated that frequency and form (structure) of ventricular rhythm was determined not only by the state of AV conduction but also by value of basic period of ff-waves. The mechanisms of ventricular rate deceleration by investigated drugs were not identical. beta-blockers and verapamil directly slowed AV conduction without changing parameters of ff-waves and differed from each other only in action on parameters of concealed conduction in AV node. Action of digoxin in patients with ff-waves period equal to or exceeding 0,15 s was biphasic. During phase I shortening of ff-wave period (by 0.025+/-0.012 s) occurred. This was associated with increase of their concealed conduction through AV node. The latter phenomenon represented independent mechanism of ventricular rhythm deceleration. During phase II of digoxin action direct inhibition of AV conduction took place. Amiodarone and d,l-sotalol increased basic ff-waves period. This facilitated their conduction through AV node. Greater heart rate slowing effect of d,l-sotalol was attributed to its ability to augment concealed conduction. Due to their antiarrhythmic qualities amiodarone and d,l-sotalol slowed heart rate in patients with peak RR duration in the region of 0.28-0.46 s. These patients often had bi- and tri-modal structure of interval RR histogram. Changes of ventricular rhythm structure during use of various drugs were different. Action of digoxin was most whilst that of beta-blockers least favorable.</AbstractText>Choice of a drug for treatment of permanent atrial fibrillation should be conducted with consideration of ff-waves periodicity, parameters of RR interval histogram, and characteristics of ventricular rhythm structure.</AbstractText> |
1,784 | Left ventricular mechanics during right ventricular apical or left ventricular-based pacing in patients with chronic atrial fibrillation after atrioventricular junction ablation. | The aim of the study was to evaluate whether left ventricular (LV) mechanics are better under LV-based pacing than under right ventricular (RV) apical pacing in patients with permanent atrial fibrillation (AF) after atrioventricular junction (AVJ) ablation.</AbstractText>"Ablate and pace" is an acceptable therapy for drug-refractory AF. However, the RV apical stimulation commonly used seems to interfere with the beneficial hemodynamic effect of regularization of heart rhythm.</AbstractText>The study included 12 patients (5 men, mean age 62 +/- 8.3 years), 6 with impaired and 6 with normal LV systolic function. All of them had a biventricular pacemaker system implanted and underwent atrioventricular node ablation for drug-refractory chronic AF. Using a conductance catheter, we analyzed LV pressure-volume loops during routine coronary angiography in order to evaluate short-term changes in LV mechanics during RV apical and LV-based (LV free wall or biventricular) pacing.</AbstractText>Compared with RV pacing, LV-based pacing significantly improved the indexes of LV systolic function (i.e., end-systolic pressure and volume, cardiac index, stroke work, preload recruitable stroke work, maximal rate of rise of LV pressure [dP/dt(max)], LV ejection fraction, and end-systolic elastance). The LV diastolic filling indexes, end-diastolic pressure and volume, were better during LV-based pacing, whereas LV diastolic function indexes, -dP/dt(max), passive diastolic chamber stiffness, and time constant of LV isovolumic relaxation showed no clear change.</AbstractText>In the short term, LV-based pacing is superior to RV apical pacing in terms of contractile function and LV filling after AVJ ablation for drug-refractory AF.</AbstractText> |
1,785 | Pulmonary vein isolation for the treatment of atrial fibrillation in patients with impaired systolic function. | We aimed to determine the safety and efficacy of pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients with impaired left ventricular (LV) systolic function.</AbstractText>To date, PVI has been performed primarily in patients with normal LV function. Yet, many AF patients have impaired LV systolic function. The outcomes of PVI in patients with impaired LV systolic function are unknown.</AbstractText>We included 377 consecutive patients undergoing PVI between December 2000 and January 2003. Ninety-four patients had impaired LV function (ejection fraction [EF] <40%), and they comprised the study group. The control group was the remaining 283 patients who had a normal EF. End points included AF recurrence and changes in EF and quality of life (QoL).</AbstractText>Mean EF was 36% in our study group, compared with 54% in controls. After initial PVI, 73% of patients with impaired EF and 87% of patients with normal EF were free of AF recurrence at 14 +/- 6 months (p = 0.03). In the study group, there was a nonsignificant increase in EF of 4.6% and significant improvement in QoL. Complication rates were low and included a 1% risk of pulmonary vein stenosis.</AbstractText>Although the AF recurrence rate after initial PVI in impaired EF patients was higher than in normal EF subjects, nearly three-fourths of patients with impaired EF remained AF-free. Although our sample size was nonrandomized, our results suggest PVI may be a feasible therapeutic option in AF patients with impaired EF. Randomized studies with more patients and longer follow-up are warranted.</AbstractText> |
1,786 | Catheter ablation of frequently recurring ventricular fibrillation in a patient after aortic valve repair. | It has been demonstrated that idiopathic ventricular fibrillation (VF) can be triggered by ventricular premature beats (VPBs) arising from the Purkinje fibers. Eliminating these VPBs by radiofrequency catheter ablation prevented VF recurrences. Whether the same pathophysiology and the same treatment option exist in patients with structural heart disease is unknown. Recurrent VF was observed in a 17-year-old patient after aortic valve repair of a perforated noncoronary cusp with resulting severe aortic regurgitation. VF recurred despite therapy with various antiarrhythmic drugs. A maximum of 14 external defibrillations was necessary during a 24-hour period to stabilize the patient. Due to increasing hemodynamic instability as a result of this electrical storm, the patient was referred for invasive diagnostics. During electrophysiologic study, frequent short runs of VF initiated by VPB with a narrow QRS complex were observed. After extensive mapping of the right and left ventricles, two distinct sources of VPBs originating from anteroseptal and inferoseptal areas of the left ventricle could be successfully ablated. VPBs were preceded by distinct Purkinje potentials with intervals from the Purkinje potential to QRS onset of VPB of 68 ms and 30 ms at effective sites, respectively. During short-term follow-up of 2 months, there was no VF recurrence. VPB originating from the Purkinje system may be one possibility for VF initiation in patients with structural heart disease. Eliminating these sources of VPBs by catheter ablation can prevent recurrent VF in such patients. |
1,787 | Shock-induced epicardial and endocardial virtual electrodes leading to ventricular fibrillation via reentry, graded responses, and transmural activation. | The mechanism of ventricular fibrillation (VF) induction by T wave shocks has been attributed to reentry, propagated graded responses (PGR), and triggered activity. The limitation of recording transmembrane potential (V(m)) from only a single surface has hampered efforts to elucidate the relative role of these phenomena and their relationship to shock-induced virtual electrodes.</AbstractText>V(m) patterns from epicardial and endocardial surfaces of isolated sheep right ventricles were recorded with two CCD cameras for monophasic (M) and biphasic (B) shocks delivered at various coupling intervals (CI) from a unipolar mesh electrode on the epicardium. VF was induced via (1) the formation of reentry following make or break excitation; (2) propagated graded responses during apparent isoelectric window; and (3) breakthrough activation patterns coincident with endocardial-to-epicardial gradients in V(m). M shocks depolarized both surfaces at long CIs and polarized epicardial and endocardial surfaces oppositely at short CIs. At intermediate CIs, postshock V(m) patterns could lead to reentry on one surface or endocardial-to-epicardial gradients resulting in breakthrough. B induced VF less than M for short and intermediate CIs due to more homogeneous end-shock V(m) patterns. However, at long CIs these homogeneous patterns resulted in more VF induction because B left the tissue closer to the V(m) threshold for propagation.</AbstractText>Postshock activity occurred either immediately via epicardial or endocardial reentry, or after a delay caused by transmural propagation or propagated graded responses. These findings could explain the isoelectric window and focal activation patterns observed on the epicardium following VF induction shocks.</AbstractText> |
1,788 | Repolarization abnormality in idiopathic ventricular fibrillation: assessment using 24-hour QT-RR and QaT-RR relationships. | We evaluated the characteristics of QT-RR and QaT (apex of T wave)-RR relationships in patients with idiopathic ventricular fibrillation (IVF) compared with control subjects. We hypothesized that IVF patients have unique repolarization dynamics related to a reduced fast Na current and a prominent transient outward current.</AbstractText>The study group consisted of 9 men (age 47 +/- 10 years) with IVF (6 with Brugada type and 3 with non-Brugada type) who had experienced nocturnal episodes of VF. The control group consisted of 28 healthy age-matched men (age 44 +/- 12 years). The relationships between QT and RR intervals and between QaT and RR intervals were analyzed from 24-hour Holter ECG data using an automatic measurement system. Both QT and QaT at RR intervals of 0.6, 1.0, and 1.2 seconds were determined from QT-RR and QaT-RR linear regression lines. Both QT-RR and QaT-RR slopes were lower in the IVF group than in the control group (QT-RR: 0.092 +/- 0.023 vs 0.137 +/- 0.031, P < 0.001; QaT-RR: 0.109 +/- 0.025 vs 0.153 +/- 0.028, P < 0.001). QT at an RR interval of 0.6 second did not differ between two groups, but QT at RR intervals of either 1.0 or 1.2 seconds was significantly shorter in the IVF group than in the control group (RR 1.0 s: 0.384 +/- 0.018 vs 0.399 +/- 0.017, P < 0.05; RR 1.2 s: 0.402 +/- 0.019 vs 0.426 +/- 0.020, P < 0.01). QaT at RR intervals of either 1.0 or 1.2 seconds also was shorter in the IVF group (RR 1.0 s: 0.289 +/- 0.022 vs 0.312 +/- 0.021, P < 0.01; RR 1.2 s: 0.311 +/- 0.024 vs 0.343 +/- 0.024, P < 0.01). In four patients, oral administration of disopyramide (300 mg/day) was effective in suppressing VF episodes and increased slopes of QT-RR and QaT-RR relationships.</AbstractText>IVF patients had lower slopes of QT-RR and QaT-RR regression lines and impaired prolongation of QT and QaT at longer RR intervals compared with control subjects. These unique repolarization dynamics may be related to the frequent occurrence of VF episodes at night.</AbstractText> |
1,789 | Incidence of nonsustained and sustained ventricular tachyarrhythmias in patients with an implantable cardioverter defibrillator. | Nonsustained ventricular tachycardia (NSVT) is a frequent phenomenon in some patients with heart disease, but its association with sustained ventricular tachycardias (ventricular tachycardia [VT]/ventricular fibrillation [VF]) is still not clear. The aim of this study was to determine whether NSVT incidence was associated with sustained VT/VF in patients with an implantable cardioverter defibrillator (ICD).</AbstractText>Retrospective data analysis was conducted in 923 ICD patients with a mean follow-up of 4 months. NSVT and sustained VT/VF were defined as device-detected tachycardias. The incidence rates of NSVT and sustained VT/VF as well as ICD therapies were determined as episodes per patient. The NSVT index was defined as the product of NSVT episodes/day times the mean number of beats per episode, i.e., total beats/day. The NSVT index peak was defined as the highest value on or prior to the day with sustained VT/VF episodes. Patients (n = 393) with NSVT experienced a higher incidence of sustained VT/VF (17.2 +/- 63.0 episodes/patient) and ICD therapies (15.2 +/- 61.4 episodes/patient) than patients (n = 530) without NSVT (sustained VT/VF: 0.5 +/- 6.6 and therapies: 0.5 +/- 5.6; P < 0.0001). Approximately 74% of NSVT index peaks occurred on the same day or <3 days prior to sustained VT/VF episodes. The index was higher for peaks < or =3 days prior to the day with sustained VT/VF (94.3 +/- 140.1 total beats/day) than for peaks >3 days prior to the day with sustained VT/VF (32.7 +/- 55.9 total beats/day; P < 0.0001).</AbstractText>ICD patients with NSVT represent a population more likely to experience sustained VT/VF episodes with a temporal association between an NSVT surge and sustained VT/VF occurrence.</AbstractText> |
1,790 | Functional genomic study on atrial fibrillation using cDNA microarray and two-dimensional protein electrophoresis techniques and identification of the myosin regulatory light chain isoform reprogramming in atrial fibrillation. | Functional and structural changes of atrial tissue occur during the natural course of atrial fibrillation (AF), and these changes may contribute to further AF. We investigated the changes in AF tissue using cDNA microarray and two-dimensional protein electrophoresis techniques.</AbstractText>We established a porcine model of AF by rapid right atrial appendage pacing at a rate of 600/min. Atrial tissue was obtained after rapid atrial depolarization for 6 weeks. Microarrays containing 6,035 cDNA clones were used to evaluate the alterations of mRNA. Two-dimensional protein electrophoresis was performed to compare protein patterns. In cDNA microarray studies, we identified 387 genes with significant change in the left atrium and 81 genes in the right atrium. Among the genes, the ventricular isoform of the myosin regulatory light chain (MLC-2V) showed the greatest fold of change (9.4 and 7.3 in the left and right atrium, respectively). In protein electrophoresis, the expression levels of three protein spots spanning from 18 to 20 kDa in the acidic region (PI 4.5-5.0) were specifically elevated in the AF group. Interestingly, through tandem mass spectrometric analysis, these three spots were identified as MLC-2V. Thus, MLC-2V expression at the mRNA and protein levels corresponded well, and both indicated a significant increase in AF.</AbstractText>Both cDNA microarray and two-dimensional polyacrylamide protein electrophoresis studies revealed characteristic changes in AF tissue. We demonstrated the reprogramming of myosin regulatory light chain isoform composition, with a significant increase of its ventricular isoform (MLC-2V).</AbstractText> |
1,791 | Impact of catheter ablation on pulmonary vein morphology and mechanical function. | Previous reports have documented that radiofrequency catheter ablation of pulmonary veins induces a significant increase in the peak velocity of transvenous blood flow. Although the magnitude of the increase infers a state of pulmonary vein stenosis, there have been no reports of direct visualization of the ablation zone.</AbstractText>In each of 23 subjects, the myocardium investing one or more pulmonary veins (total of 42 veins) was electrically isolated by applying a confluent circumferential ablation lesion to the atrial side of the venoatrial junction. Doppler measurements of transvenous flow velocity were made before and after ablation using phased-array intracardiac echocardiography. Direct visualization of the ablation zone was performed using rotating intracardiac echocardiography, permitting assessment of shape, cross-sectional area, phasic variation in cross-sectional area, and wall thickness. In a subset of 5 subjects, a more detailed assessment of the ablation and contiguous regions was performed using three-dimensional echocardiography (rotating transducer). Prior to ablation, venoatrial junctions demonstrated noncircular shape and marked phasic variation in cross-sectional area. There was a trivial transvenous pressure gradient. After ablation, there was a significant increase in both anterograde and retrograde flow velocities and pressure gradient, the magnitudes of which were inversely proportional to the preablation and postablation areas. Direct visualization of the ablation zone revealed circumferential wall swelling, reduced cross-sectional area, and diminishment in phasic variation in cross-sectional area. Similar observations were made at contiguous nonablated sites, diminishing in magnitude as a function of distance.</AbstractText>Pulmonary vein ablation induces significant acute changes in morphology and mechanical function that extend beyond the ablation zone.</AbstractText> |
1,792 | Prospective randomized study of mode switching in a clinical trial of pacemaker therapy for sinus node dysfunction. | Atrial fibrillation (AF) is common in pacemaker patients with sinus node dysfunction (SND) and may result in rapid ventricular pacing (RVP) in the DDDR mode. Mode switching (MS) reduces RVP, but its clinical benefit in patients with SND is unknown.</AbstractText>Two hundred two patients in the Mode Selection Trial (MOST; 2,010-patient, 6-year trial of DDDR vs VVIR pacing in SND) randomized to DDDR pacemakers with atrial high-rate episode (AHRE) storage capabilities were subrandomized to MS ON (N = 96) or MS OFF (N = 106). Cardiovascular symptoms, quality of life (QOL), reprogramming due to RVP, death, stroke, and heart failure hospitalization (HFH) were compared between groups. The treatment groups were similar with regard to AF history (59% MS ON vs 57% MS OFF). AHREs occurred in 49% patients during median follow-up of 2.2 years. Median AHRE duration (in min; MS ON 116 vs MS OFF 58, P = 0.29), frequency AHREs/week (MS ON 3.5 vs MS OFF 6.4, P = 0.23), and time spent in AHRE (min/week) (MS ON 450, MS OFF 268) were similar. Reprogramming due to any RVP during AHREs occurred more in MS OFF vs MS ON (13.2% vs 3.1%, P = 0.011) and marginally more for symptomatic RVP (8.5% vs 2.1%, P = 0.062). Cardiovascular symptoms occurred in 93.6% MS ON vs 90.2% MS OFF (P = 0.38). Median number of symptoms reported per visit was similar (MS ON 1.3 vs MS OFF 1.5, P = 0.62). Median symptom frequency/severity, summed and averaged over visits, was similar (MS ON 4.3 vs MS OFF 4.5, P = 0.74). QOL was not different between groups. Death, stroke, and HFH were not different between groups.</AbstractText>MS reduces pacemaker reprogramming due to RVP during AHREs in a small number of patients but does not improve QOL or cardiovascular symptoms overall among patients with SND.</AbstractText> |
1,793 | Renin-angiotensin system gene polymorphisms and atrial fibrillation. | The activated local atrial renin-angiotensin system (RAS) has been reported to play an important role in the pathogenesis of atrial fibrillation (AF). We hypothesized that RAS genes might be among the susceptibility genes of nonfamilial structural AF and conducted a genetic case-control study to demonstrate this.</AbstractText>A total of 250 patients with documented nonfamilial structural AF and 250 controls were selected. The controls were matched to cases on a 1-to-1 basis with regard to age, gender, presence of left ventricular dysfunction, and presence of significant valvular heart disease. The ACE gene insertion/deletion polymorphism, the T174M, M235T, G-6A, A-20C, G-152A, and G-217A polymorphisms of the angiotensinogen gene, and the A1166C polymorphism of the angiotensin II type I receptor gene were genotyped. In multilocus haplotype analysis, the angiotensinogen gene haplotype profile was significantly different between cases and controls (chi2=62.5, P=0.0002). In single-locus analysis, M235T, G-6A, and G-217A were significantly associated with AF. Frequencies of the M235, G-6, and G-217 alleles were significantly higher in cases than in controls (P=0.000, 0.005, and 0.002, respectively). The odds ratios for AF were 2.5 (95% CI 1.7 to 3.3) with M235/M235 plus M235/T235 genotype, 3.3 (95% CI 1.3 to 10.0) with G-6/G-6 genotype, and 2.0 (95% CI 1.3 to 2.5) with G-217/G-217 genotype. Furthermore, significant gene-gene interactions were detected by the multifactor-dimensionality reduction method and multilocus linkage disequilibrium tests.</AbstractText>This study demonstrates the association of RAS gene polymorphisms with nonfamilial structural AF and may provide the rationale for clinical trials to investigate the use of ACE inhibitor or angiotensin II antagonist in the treatment of structural AF.</AbstractText> |
1,794 | A trafficking defective, Brugada syndrome-causing SCN5A mutation rescued by drugs. | The human cardiac SCN5A gene encodes for the alpha subunit of the human cardiac voltage-dependent sodium channel hNav1.5 [Neuron 28 (2) (2000) 365] and carries inward Na current (INa). Mutations in SCN5A cause arrhythmia syndromes including Brugada syndrome (BrS) and congenital long QT syndrome subtype 3 (LQT3). Here, we report a trafficking defective BrS-causing SCN5A mutation that was drug-rescued.</AbstractText>A 14-year-old Caucasian male was diagnosed with BrS with typical ECG pattern for BrS and ventricular fibrillation was easily induced. He also had significant HV interval delay ( approximately 65 ms) and high (31 J) defibrillation thresholds (DFTs). Genomic analysis revealed the SCN5A mutation (G1743R). We engineered G1743R into the cardiac Na channel and transfected HEK-293 cells for functional studies. The mutant channel yielded nearly undetectable sodium channel currents. Coexpression with the beta1 subunit, or incubation at low temperature did not increase current density. However, mexiletine, a sodium channel blocker, increased current density 93-fold in G1743R, but only twofold in WT.</AbstractText>This study identifies an expression-defective BrS mutation in SCN5A with pharmacological rescue. The profoundly decreased sodium current associated with the G1743R suggests a molecular basis for the delayed His-Purkinje conduction and elevated DFTs observed in the proband. Whether the mutant channel may be rescued in vivo by mexiletine and normalize the patient's electrophysiologic parameters remains to be tested.</AbstractText> |
1,795 | [The calcified ascending aorta in aortocoronary bypass]. | Heavily calcified ascending aorta significantly increased morbidity and lethality during open-heart surgery. Cannulation and clamping (partial or total) of severely atherosclerotic ascending aorta can easily cause damage and rupture of aortic wall, with consequential distal (often fatal) embolization with atheromatous debris (brain, myocardium). From June 1998. until June 2000, 11 of 2,136 (0.5%) patients who underwent coronary artery bypass grafting were with the severe atheromatous ascending aorta. The site of cannulation was in the aortic arch in three patients (aorta was occluded with Foley catheter in one case, and single clamp technique was used in the other two cases). The femoral artery was the cannulation site in other five cases. Profound hypothermia, ventricular fibrillation, and circulatory arrest, with no cross-clamping or cardioplegia, were used in three patients. Two patients were operated on with extracorporeal circulation, one in normothermia, on the beating heart, the other in moderate hypothermia, on fibrillating heart. In three patients myocardial revascularization was performed on the beating heart, in normothermia, without extracorporeal circulation. Postoperative course was uneventful in all 11 patients. Neither atheroembolism in the peripheral organs, nor atheroembolism of the extremities occurred. The proposed surgical approaches have the potential to reduce the prevalence of stroke and systemic embolization associated with coronary artery bypass grafting in patients with heavily calcified ascending aorta. This result was achieved due to the applied modifications of standard cardiosurgical technique. |
1,796 | Long-term alcohol consumption and the risk of atrial fibrillation in the Framingham Study. | Atrial fibrillation (AF) is a major risk factor for stroke. Although acute alcohol intake has been associated with AF, it is not known whether long-term alcohol consumption in moderation is associated with an increased risk of AF. We used a risk set method to assess the relation of long-term alcohol consumption to the risk of AF among participants in the Framingham Study. For each case, up to 5 controls were selected and matched for age, age at baseline examination, sex, cohort, baseline history of hypertension, congestive heart failure, and myocardial infarction. Within each risk set, alcohol consumption was averaged from baseline until the examination preceding the index case of AF. Of the 1,055 cases of AF occurring during a follow-up of >50 years, 544 were men and 511 were women. In a conditional logistic regression with additional adjustment for systolic blood pressure, age at baseline examination, education, and cumulative history of myocardial infarction, congestive heart failure, diabetes mellitus, left ventricular hypertrophy, and valvular heart disease, the relative risks were 1.0 (reference), 0.97 (95% confidence interval [CI] 0.78 to 1.22), 1.06 (95% CI 0.80 to 1.38), 1.12 (95% CI 0.80 to 1.55), and 1.34 (95% CI 1.01 to 1.78) for alcohol categories of 0, 0.1 to 12, 12.1 to 24, 24.1 to 36, and >36 g/day, respectively. In conclusion, our data indicate little association between long-term moderate alcohol consumption and the risk of AF, but a significantly increased risk of AF among subjects consuming >36 g/day (approximatively >3 drinks/day). |
1,797 | Heart rate variability in atrial fibrillation related to left atrial size. | The purpose of this investigation was to determine whether heart rate variability (HRV) in atrial fibrillation (AF) can be related to any echocardiographic-derived measurements of cardiac dimensions or function. AF is characterized by marked HRV. Although HRV in normal sinus rhythm has been studied and shown to have important clinical implications, there have been relatively few published reports dealing with the phenomenon in AF. This study examines HRV in AF taking into account the influence of heart rate. HRV measurements were obtained in 38 patients with persistent AF who had undergone 24-hour ambulatory electrocardiographic monitoring. Taking into account a strong heart rate dependence of the HRV measurements, regressions were calculated. The relations were then re-examined using the differences (diff) in HRV from the expected for the average RR intervals. No significant correlations were found between unadjusted HRV measurements and any clinical features or echocardiographic variables. However, taking into account heart rate relations, with negative HRVdiff signifying less HRV than expected, reduced HRV correlated with increasing left atrial and left ventricular dimensions. On multivariate regression analysis, left atrial dimension emerged as an independent determinant of HRV. Also, HRV was greater in patients with lone AF than in those with cardiac disorders. HRV in AF is highly rate dependent. Unless this influence is taken into account, important relations may be obscured. When HRVdiff are related to echocardiographic measurements, increasing left atrial dimensions correlate with less HRV. |
1,798 | New insights into diastolic heart failure: role of diabetes mellitus. | Heart failure affects nearly 5 million people in the United States and is a major contributor to mortality, hospitalization, and medical costs. Approximately 40% of patients with heart failure have preserved left ventricular systolic function, thus exhibiting diastolic heart failure. More common in women and the elderly, this condition is associated with hypertension, coronary artery disease, and/or atrial fibrillation. With the exception of the Digitalis Investigation Group (DIG) and the Candesartin in Heart Failure: Assessment of Reduction in Mortality and Morbidity (CHARM)-Preserved trials, no completed large randomized clinical trial has addressed the management of such patients. Symptomatic treatment involves administration of diuretics and nitrates, but long-term management with angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, aldosterone antagonists, beta-blockers, and calcium channel blockers targets the underlying disorders. Recent studies found that diabetes mellitus produces functional, biochemical, and morphologic myocardial abnormalities independent of coronary atherosclerosis and hypertension. These abnormalities may result in impaired left ventricular diastolic function, contributing importantly to heart failure with normal systolic function. Although tight glycemic control decreases the risk of heart failure in patients with diabetes, the effects of different diabetic treatment regimens on heart failure with normal systolic function are unknown and remain subject to future investigation. |
1,799 | Radioiodine ablation of the thyroid to prevent recurrence of amiodarone-induced thyrotoxicosis in patients with resistant tachyarrhythmias. | Amiodarone-induced thyrotoxicosis (AIT) is a common complication of amiodarone therapy. Although permanent withdrawal of amiodarone is recommended due notably to the risk of worsening of tachyarrhythmias, some patients may require the reintroduction of amiodarone several months after normalizing their thyroid function. We, retrospectively, assessed the effects of (131)I therapy to prevent recurrence of AIT in euthyroid patients requiring reintroduction of amiodarone.</AbstractText>Amiodarone was required in 10 cases of recurrent symptomatic paroxysmal atrial fibrillation (AF) and in 5 cases of ventricular tachycardia (VT) (M = 12, F = 3, mean age: 63 +/- 14). The underlying heart disease was dilated cardiomyopathy (n = 4), ischaemic heart disease (n = 4), hypertensive heart disease (n = 2), arrhythmogenic right ventricular dysplasia (n = 27) and valvulopathy (n = 1). Two patients had idiopathic paroxysmal AF.</AbstractText>A mean (131)I dose of 579 +/- 183 MBq was administered 34 +/- 37 after the episode of AIT. Amiodarone was reintroduced in 14 of 15 patients after a mean interval of 103 +/- 261 d. Fourteen patients developed definite hypothyroidism necessitating l-thyroxine but we observed no late recurrence of AIT. After a mean follow-up of 22 +/- 16 months, tachyarrhythmias were controlled in 12 of 14 patients.</AbstractText>(131)I therapy appears to be an effective and safe approach to prevent the recurrence of AIT in a patient requiring the reintroduction of amiodarone for tachyarrhythmias.</AbstractText> |
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