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2,600 | Real-time cardiac catheter navigation on three-dimensional CT images. | Targets for ablation of atrial fibrillation, atrial flutter, and non-idiopathic ventricular tachycardia are increasingly being selected based on anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures, and is associated with radiation risk, other approaches to mapping may be beneficial.</AbstractText>The spatial and temporal information of an electromagnetic catheter tip position sensing system (Magellan, Biosense Inc.) was superimposed on a three-dimensional (3D) CT of the chest in swine using fiducial markers for image registration. Position and orientation of a 6 French catheter with an electromagnetic sensor was displayed in real-time on a corresponding 3D-CT. Catheter navigation within the heart and the great vessels was guided by detailed knowledge about catheter location in relation to cardiac anatomy.</AbstractText>Anatomic structures including the atrial septum, pulmonary veins, and valvular apparatus were easily identified and used to direct catheter navigation. During the right heart examination, the catheter was navigated through the superior and inferior vena cava to predetermined anatomic locations in right atrium, right ventricle and pulmonary artery. The ablation catheter was also navigated successfully from the aorta through the aortic valve in the left ventricle. No complication was encountered during the experiments. The accuracy and precision of this novel approach to mapping was 4.69 +/- 1.70 mm and 2.22 +/- 0.69 mm, respectively.</AbstractText>Real-time display of catheter position and orientation on 3D-CT scans allows accurate and precise catheter navigation in the heart. The detailed anatomic information may improve anatomically based procedures like pulmonary vein ablation and has the potential to decrease radiation times.</AbstractText> |
2,601 | Factors determining the duration of tracheal intubation in cardiac surgery: a single-centre sequential patient audit. | The study was designed to identify those factors associated with early tracheal extubation following cardiac surgery. Previous studies have tended to concentrate on surgery for coronary artery bypass or on other selected cohorts.</AbstractText>Sequential cohort analysis of 296 unselected adult cardiac surgery patients was performed over 3 months.</AbstractText>In total, 39% of all patients were extubated within 6 h, 89% within 24 h and 95% within 48 h. Delayed extubation (>6 h after surgery) appeared unrelated to age, gender, body mass index, a previous pattern of angina or myocardial infarction, diabetes, preoperative atrial fibrillation, and preoperative cardiovascular assessment, as well as other factors. Delayed tracheal extubation was associated with poor left ventricular, renal and pulmonary function, a high Euroscore, as well as the type, duration and urgency of surgery. Early extubation (<6 h) was not associated with a reduced length of stay in either the intensive care unit or in hospital compared with patients who were extubated between 6 and 24 h. In these groups, it is presumed that organizational and not clinical factors appear to be responsible for a delay in discharge from intensive care. Patients who were extubated after 24 h had a longer duration of hospital stay and a greater incidence of postoperative complications. Postoperative complications were not adversely affected by early tracheal extubation.</AbstractText>In an unselected sequential cohort, both patient- and surgery-specific factors may be influential in determining the duration of postoperative ventilation of the lungs following cardiac surgery. In view of the changing nature of the surgical population, regular re-evaluation is useful in reassessing performance.</AbstractText> |
2,602 | Effects of rolipram, pimobendan and zaprinast on ischaemia-induced dysrhythmias and on ventricular cyclic nucleotide content in the anaesthetized rat. | This study was designed to compare the haemodynamic, electrophysiological and pharmacodynamic effects of three selective inhibitors of the different isoenzyme forms of phosphodiesterase (PDE) on ischaemia-induced dysrhythmias in the anaesthetized rat. The drugs used were pimobendan, a selective PDE III inhibitor, rolipram, a selective PDE IV inhibitor, and zaprinast, a selective PDE V inhibitor.</AbstractText>The coronary artery was occluded 15 min after commencing drug administration, and myocardial ischaemia was maintained for 30 min during which the heart rate and mean arterial pressure were recorded. cAMP and cGMP were determined by radioimmunoassay.</AbstractText>Pretreatment with rolipram decreased the duration of ventricular tachycardia without any change in the incidences of dysrhythmias or the mortality rate. This drug did not modify ventricular content of adenosine 3',5'-cyclic monophosphate (cAMP) or guanosine 3',5'-cyclic monophosphate (cGMP). Pimobendan (1 mg kg(-1) + 0.1 mg kg(-1) min) decreased the duration of ventricular tachycardia. This dose of pimobendan and zaprinast (1 mg kg(-1) + 0.1 mg kg(-1) min(-1)) increased the incidence rate of ventricular fibrillation following coronary artery ligation and the mortality rate. Moreover, both drugs increased cGMP in the ventricle.</AbstractText>The results demonstrated that pimobendan and zaprinast increased the incidence of dysrhythmias and the mortality rate, which was accompanied by an increase in the ventricular content of cGMP. Rolipram decreased the duration of ventricular tachycardia without a change in the cyclic nucleotide content or in the mortality rate.</AbstractText> |
2,603 | [Long-term efficacy of combination therapy using antiarrhythmic agents and angiotensin converting enzyme inhibitor in patients with paroxysmal and persistent atrial fibrillation: importance of the timing of administration]. | This study examined the long-term efficacy of combination therapy using antiarrhythmic agents and angiotensin converting enzyme inhibitor (ACE-I) to maintain sinus rhythm in patients with paroxysmal and persistent atrial fibrillation (Paf). There were 246 patients (176 men, 70 women, mean age 67.3 +/- 11.7 years, mean follow-up period 48.9 +/- 29.3 months) divided into two groups: the ACE-I(+) group (n = 74) and the ACE-I(-) group (n = 172).</AbstractText>The incidence of hypertension and underlying heart disease in the ACE-I(+) group (85.1% and 34.3%, respectively) was significantly higher than those in the ACE-I(-) group (37.8% and 25.0%, respectively) (both p < 0.01). Left ventricular ejection fraction in the ACE-I(+) group (65.6 +/- 12.5%) was significantly lower than that in the ACE-I(-) group (71.9 +/- 8.9%) (p < 0.01). The actuarial rate of the maintenance of sinus rhythm at 48 months in the ACE-I(+) group (86.5%) was similar to that in the ACE-I(-) group (83.1%). Among the 104 patients who had suffered from Paf for < 3 months after the first episode, the actuarial rate of maintenance of sinus rhythm at 48 months in the ACE-I(+) group (97.1%, n = 35) was significantly higher than that in the ACE-I(-) group (82.6%, n = 65), and the period of maintenance of sinus rhythm in the ACE-I(+) group (54.8 +/- 30.8 months) was significantly longer than that in the ACE-I(-) group (28.4 +/- 20.5 months) (both p < 0.05).</AbstractText>ACE-I must be additionally administered within 3 months of the first Paf episode to maintain normal sinus rhythm in patients with Paf.</AbstractText> |
2,604 | Clinical relevance of atrial fibrillation/flutter, stroke, pacemaker implant, and heart failure in Emery-Dreifuss muscular dystrophy: a long-term longitudinal study. | Emery-Dreifuss muscular dystrophy (EDMD) is a rare inherited disorder associated with cardiac involvement. We investigated the spectrum and relevance of the cardiac manifestations of EDMD, focusing on bradyarrhythmias and tachyarrhythmias (including atrial fibrillation/flutter), embolic stroke, and heart failure.</AbstractText>Eighteen patients (age 42.8+/-19.6 years) with genetically confirmed X-linked (n=10, including 3 carriers) or autosomal dominant (n=8) EDMD were followed for a period ranging from 1 to 30 years in a research center for neuromuscular diseases and in a university cardiological department. Pacemakers were required by 10 of 18 (56%) patients for bradyarrhythmia, and related complications occurred in 3 of 10 (30%) cases. Atrial fibrillation/flutter developed in 11 of 18 (61%) patients, with atrial standstill subsequently occurring in 5 of 11 (45%) cases and embolic stroke (most often disabling) in 4 of 11 (36%). Heart failure requiring transplantation occurred in 1 of 18 (6%) patients, and asymptomatic left ventricular dysfunction in a further 3 (17%). No relationship was evident between neuromuscular impairment and cardiac involvement.</AbstractText>Both X-linked and autosomal dominant EDMD patients risk not only bradyarrhythmia (requiring pacemaker implant) but also atrial fibrillation/flutter, which often anticipates atrial standstill and can cause disabling embolic stroke at a relatively young age. Antithromboembolic prophylaxis has to be recommended in EDMD patients with atrial fibrillation/flutter or atrial standstill. With careful monitoring, survival after pacemaker implant may be long. Heart failure, which seems to occur only in a minority of patients, may be severe.</AbstractText> |
2,605 | Amiodarone-induced postrepolarization refractoriness suppresses induction of ventricular fibrillation. | It is still incompletely understood why amiodarone is such a potent antiarrhythmic drug. We hypothesized that chronic amiodarone treatment produces postrepolarization refractoriness (PRR) without conduction slowing and that PRR modifies the induction of ventricular arrhythmias. In this study, the hearts of 15 amiodarone-pretreated (50 mg/kg p.o. for 6 weeks) rabbits and 13 controls were isolated and eight monophasic action potentials were simultaneously recorded from the epicardium and endocardium of both ventricles. Steady-state action potential duration (APD), conduction times, refractory periods, and dispersion of action potential durations were determined during programmed stimulation and during 50-Hz burst stimuli, and related to arrhythmia inducibility. Amiodarone prolonged APD by 12 to 15 ms at pacing cycle lengths of 300 to 600 ms (p < 0.05) but did not significantly increase conduction times or dispersion of APD. Amiodarone prolonged refractoriness more than action potential duration, resulting in PRR (refractory period - APD at 90% repolarization, 14 +/- 10 ms, p < 0.05 versus controls). PRR curtailed the initial sloped part of the APD restitution curve by 20%. During burst stimulation, pronounced amiodarone-induced PRR (40 +/- 15 ms, p < 0.05 versus controls) reduced the inducibility of ventricular arrhythmias (p < 0.05 versus controls). Furthermore, in 35% of bursts only monomorphic ventricular tachycardias and no longer ventricular fibrillation were inducible in amiodarone-treated hearts (p < 0.05 versus controls). Chronic amiodarone treatment prevents ventricular tachycardias by inducing PRR without much conduction slowing, thereby curtailing the initial part of APD restitution. PRR without conduction slowing is a desirable feature of drugs designed to prevent ventricular arrhythmias. |
2,606 | [Torsades de pointes ventricular tachycardia induced by intravenous amiodarone]. | The authors report on the case history of a 61 year old woman with hyperthyroidism induced atrial fibrillation, tachycardiomyopathy and congestive heart failure, in whom life threatening ventricular proarrhythmia (torsades de pointes) developed in response to intravenous amiodarone. The patient in a septic state was resuscitated because of ventricular fibrillation. The atrial fibrillation complicated by a high ventricular frequency was slowed down with intravenous amiodarone; additionally, the iodine-containing antiarrhythmic drug was expected to counter thyrotoxicosis. In response to amiodarone (2 x 300 mg), the sinus rhythm was restored, but the excessive post-cardioversion bradycardia led to the development of extreme QT interval prolongation and torsades de pointes ventricular tachycardias that often degenerated into ventricular fibrillation. In connection with this case, the authors survey those electropharmacological and pathophysiological factors which may have played a role in the emergence of ventricular proarrhythmia based on a lengthening of repolarization through the exhaustion of the repolarization reserve. |
2,607 | Older patients fare better with the Ross operation. | The Ross operation has an established position in young patients. We address the question of whether any age group profits most from the Ross operation, and we compare the results in various ages.</AbstractText>From February 1995 to August 2001 we performed 250 Ross operations. Group 1 consisted of 46 patients, ages 2 to 25 years (median age, 15 years). Group 2 consisted of 123 patients, ages 26 to 49 years (median age, 39 years). Group 3 consisted of 81 patients, ages 50 to 67 years (median age, 55 years). Echocardiography was performed perioperatively, at 2 to 6 months, and then yearly.</AbstractText>Mean follow-up for the three groups was 32, 31, and 28 months, respectively (p = 0.36). One patient from group 2 died after 25 months caused by suppurative pneumonia and 3 patients from group 3 died (1 from suspected acute thoracic aorta dissection at 40 months, 1 from ventricular fibrillation after 25 months, and 1 from an undiagnosed sudden death at 5 months). Autograft replacement was necessary for 3 patients from group 2 and 1 from group 3. Autograft repair was necessary for 1 patient from group 2, and pulmonary homograft reoperation was necessary for 1 patient from group 1. All other autografts currently have physiologic gradients and clinically insignificant regurgitation. Median peak gradient across the right ventricular outflow tract was 23.6 +/- 18 mm Hg for group 1, 14.6 +/- 8 mm Hg for group 2, and 11.5 +/- 7 mm Hg, which was significantly lower for group 3 patients (p < 0.001). Eleven patients are under close follow-up for right ventricular outflow tract gradients > or = 40 mm Hg; eight of these patients are from group 1, 3 are from group 2, and there are none from group 3.</AbstractText>Although the Ross operation provides excellent results in all age groups, the problem of right ventricular outflow tract stenosis has not been seen in patients older than 50 years, which implies that it offers superior results for aortic valve disease in middle aged and older patients.</AbstractText> |
2,608 | Improved neurohormonal markers of ventricular function after restoring sinus rhythm by the Maze procedure. | Clinical results of the Maze procedure for treatment of atrial fibrillation (AF) are excellent, suggesting improved ventricular function after restoring sinus rhythm. However, long-term corresponding effects on the release of cardiac natriuretic peptides and other vasoactive hormones are incompletely investigated after isolated Maze surgery.</AbstractText>Plasma levels of brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), antidiuretic hormone, aldosterone, and angiotensin II were measured in 15 patients (mean age, 52 +/- 11 years) undergoing isolated surgical Maze (III) procedures for medically refractory AF, preoperatively and 6 months postoperatively. At the time of blood sampling, hemodynamic correlates were obtained at baseline and after 6 and 12 minutes of rapid ventricular pacing at 150 stimulations/minute.</AbstractText>All patients were free of AF at 6-month follow-up. The measured plasma levels of BNP, ANP, and angiotensin II were all significantly lower (p = 0.03) late after the isolated Maze procedure. Cardiac output was significantly higher postoperatively (p < 0.01). Other hemodynamic values and left atrial size were unchanged after surgery. Ventricular pacing caused almost identical hemodynamic changes in atrial pressures before and late after surgery, but the associated plasma ANP response was significantly attenuated postoperatively (p < 0.001).</AbstractText>Levels of cardiac natriuretic peptides and angiotensin II as markers of ventricular function are improved in the long term after clinically successful isolated Maze procedures. ANP response to hemodynamic challenge by ventricular pacing was attenuated postoperatively, possibly due to atrial scarring.</AbstractText> |
2,609 | [Out-of-hospital cardiac arrest. Mechanisms and treatment with automated external defibrillator]. | In Denmark, approximately 4500 persons suffer yearly from an out-of-hospital cardiac arrest with mortality close to 100%. The principal arrhythmia is ventricular fibrillation, which can only be treated effectively with prompt external defibrillation. Automatic external defibrillators (AED) are small, portable, easily operated devices. They have documented high specificity and sensitivity. Moreover, biphasic automatic external defibrillators are at least as effective as traditional monophasic defibrillators. Survival rates with good neurological status as high as 60% have been reported. Better survival of out-of-hospital cardiac arrest victims requires, however, improvements throughout the chain of survival, not only more automatic external defibrillators. Therefore, the health care system has to discuss thoroughly and solve important questions regarding organisation, logistics, education, and legal aspects in order to improve survival for out-of-hospital cardiac arrest victims. |
2,610 | Angiotensin II subtype AT1 receptor blockade prevents hypertension and renal insufficiency induced by chronic NO-synthase inhibition in rats. | Aim of the present study was to investigate the influence of the angiotensin II (ANG II) subtype 1 (AT(1)) receptor blockers fonsartan and losartan on blood pressure, cardiac -dynamics and -metabolism as well as functional and morphological changes in the kidney of rats after long-term inhibition of the nitric oxide (NO) synthase by N(G)-nitro-L-arginine methyl ester (L-NAME). Oral chronic treatment with L-NAME in a dose of 25 mg/kg/d over 6 weeks caused a significant increase in systolic blood pressure (198+/-13 mmHg) when compared to untreated rats (144+/-4 mmHg). Animals receiving simultaneously L-NAME and fonsartan (10 mg/kg/d) or losartan (30 mg/kg/d) were protected against blood pressure increase. L-NAME treatment caused a significant decrease in glomerular filtration rate (GFR) from 4.52+/-0.81 to 1.34+/-0.26 ml/kg(-1)/min(-1) and renal plasma flow (RPF) from 10.52+/-1.29 ml/kg(-1)/min(-1) to 5.66+/-1.06 ml/kg(-1)/min(-1). Co-treatment with fonsartan and losartan prevented L-NAME-induced reduction in GFR and RPF. There was no difference in urine, sodium and potassium excretion in groups under investigation. Plasma renin activity (PRA) was further stimulated by fonsartan and losartan treatment. L-NAME produced a significant elevation in urinary protein excretion which was antagonised by both AT(1) blockers. Isolated hearts from animals treated with L-NAME showed a significant prolongation in the duration of ventricular fibrillation and a significant decrease in coronary flow as compared to control hearts. Treatment with fonsartan and losartan significantly decreased the duration of ventricular fibrillation as compared to L-NAME group. In addition, both AT(1) blockers given alone significantly reduced the duration of ventricular fibrillation as compared to hearts from untreated controls. During ischemia the cytosolic enzymes lactate dehydrogenase and creatine kinase as well as lactate in the coronary effluent were significantly increased in the L-NAME group. Myocardial tissue values of glycogen, ATP, and creatine phosphate were decreased, whereas lactate was increased. Fonsartan and losartan treatment totally abolished these effects. Histological examination of kidneys revealed that simultaneous administration of fonsartan and losartan with L-NAME abolished L-NAME-induced arteriolar hyalinosis, segmental sclerosis of glomerular capillaries and focal tubular atrophies. In conclusion, long-term blockade of ANG II subtype AT(1) receptors by fonsartan and losartan prevented L-NAME-induced hypertension, renal insufficiency, as well as cardio-dynamic, cardio-metabolic, and morphological deteriorations. |
2,611 | [Reversible thyrotoxic cardiomyopathy--report of three cases]. | Three patients with thyrotoxicosis, atrial tachyarrhythmia and congestive heart failure despite successful treatment of hyperthyroidism revealed atrial fibrillation/flagellation and left ventricular systolic dysfunction. Congestive heart failure resolved and left ventricular systolic function normalized only after successful cardioversion to sinus rhythm. In some patients treated for hyperthyroidism, achievement of euthyroid state is not by itself sufficient to reverse left ventricular failure. Improvement after successful reversion of atrial tachyarrhythmia suggest its essential role in pathogenesis of thyrotoxic cardiomyopathy. |
2,612 | Physiologic predictors of survival in post-traumatic arrest. | Traumatic cardiac or pulmonary arrest is often associated with a dismal outcome and is considered by many to be an example of medical futility and inappropriate use of resources. This study aimed to identify the predictors of survival in patients experiencing traumatic cardiac arrest. We retrospectively reviewed all trauma patients undergoing cardiopulmonary resuscitation on arrival to the Emergency Department (ED) at an American College of Surgeons-designated Level I trauma center over 4 years. ED survival, hospital survival, and neurologic outcomes on discharge were the primary outcomes. Survival rates were examined in relation to demographics, mechanism of injury, airway management, cardiac electrical rhythm, and pupil size and reactivity. Statistical analyses used chi-square and t tests, P < 0.05 was considered significant. A total of 195 patients arrived in the ED with traumatic cardiac arrest; 34 were pronounced dead on arrival (no signs of life), and no resuscitation efforts were initiated. Of the remaining 161 patients 53 (33%) survived to leave the ED, and only 15 (9%) left the hospital alive. Demographic features were similar in survivors and nonsurvivors. The setting of intubation (prehospital vs ED) did not influence survival (P = 0.36). Penetrating trauma adversely affected survival in the ED (P = 0.01); however, this only approached significance in the final outcome of hospital survival (P = 0.06). The presence of sinus rhythm and nondilated reactive pupils was highly significant in predicting ED and hospital survival (P = 0.001). No patient with agonal rhythm or ventricular fibrillation/tachycardia survived, and 14 of the 15 hospital survivors had reactive pupils on arrival to the ED. We conclude that sinus rhythm and pupil size and reactivity are important physiologic variables that predict potential survival and may be used to guide continuation of resuscitative efforts in patients with traumatic cardiac arrest. |
2,613 | Coronary surgery with non-cardioplegic methods in patients with advanced left ventricular dysfunction: immediate and long term results. | To evaluate perioperative results and long term survival in patients with severe left ventricular (LV) dysfunction undergoing coronary artery bypass grafting (CABG) using non-cardioplegic methods.</AbstractText>From April 1990 through December 1999, 4100 consecutive patients underwent isolated CABG using hypothermic ventricular fibrillation. Of these, 141 (3.4%) had severe LV dysfunction (ejection fraction < 30%). Mean age was 58.3 (9.6) years. 64 patients (45.4%) were in Canadian Cardiovascular Society class III or IV and 16 (11.3%) were subjected to urgent or emergent surgery. A previous myocardial infarction was recorded in 127 (90.1%). The majority (89.4%) had triple vessel and 26 (18.4%) had left main disease. The mean number of grafts per patient was 3.1. At least one internal thoracic artery was used in all patients and 21 (14.8%) had bilateral internal thoracic artery grafts (1.2 arterial grafts per patient).</AbstractText>Perioperative mortality was 2.8% (4 patients) and the incidence of acute myocardial infarction 2.8%. 50 (35.5%) patients required inotropes but only 16 (11.3%) required it for longer than 24 hours; 5 patients (3.5%) needed mechanical support. The incidence of renal failure was 3.5%. Mean duration of hospital stay was 9.6 (8.3) days. Follow up was 95% complete and extended for a mean of 57 (30) months. Late mortality was 11.5%. Actuarial survival rates at 1, 3, and 5 years were 96%, 91%, and 86%, respectively.</AbstractText>Non-cardioplegic techniques are safe and effective in preserving the myocardium during CABG in patients with coronary artery disease and poor LV function, with low operative mortality and morbidity, and encouraging medium to long term survival rates.</AbstractText> |
2,614 | Nucleotide changes in the translated region of SCN5A from Japanese patients with Brugada syndrome and control subjects. | The mutations of the SCN5A gene have been implicated to play a pathogenetic role in Brugada syndrome, which causes ventricular fibrillation. To determine the Brugada-associated mutations in Japanese patients, facilitate pre-symptomatic diagnosis, and allow genotype-phenotype studies, we screened unrelated patients with Brugada syndrome for mutations. DNAs from 6 Japanese patients were obtained and the sequence in the translated region of SCN5A was determined. We could not find the mutations reported previously, but found 17 sites of nucleotide change, consisting of 7 synonymous and 10 non-synonymous nucleotide changes in our patients. Among them, two non-synonymous nucleotide changes (G1663A and G5227A) are specific to our patients and these changes were not found in 53 healthy controls. In 4 patients out of 6, no specific nucleotide change for Brugada syndrome could be detected. Our findings demonstrating no patient-specific change in the translated region of the SCN5A gene among two thirds of the small number of patients examined here imply that another gene other than the SCN5A may be associated with this disease, supporting previous investigations in Japan and other countries. |
2,615 | Implantable cardioverter defibrillators in primary and secondary prevention: a systematic review of randomized, controlled trials. | Sudden cardiac death is common in persons with cardiovascular disease.</AbstractText>To assess the efficacy of implantable cardioverter defibrillators (ICDs) in persons at increased risk for sudden cardiac death.</AbstractText>MEDLINE (1980-2002), EMBASE (1980-2002), Cochrane Controlled Clinical Trial Registry (2002, Volume 3), other databases, and conference proceedings. Primary study authors and device manufacturers were contacted, and bibliographies of relevant papers were hand searched.</AbstractText>Randomized, controlled clinical trials evaluating ICDs versus usual care were selected.</AbstractText>Two reviewers extracted data independently.</AbstractText>Eight trials were included in the final analysis (4909 patients, 1154 deaths). Compared with usual care (most commonly amiodarone therapy), ICDs significantly reduced sudden cardiac death (relative risk [RR], 0.43 [95% CI, 0.35 to 0.53]) and all-cause mortality (RR, 0.74 [CI, 0.67 to 0.82]). The included trials were divided a priori into two categories: secondary prevention (involving patients resuscitated after cardiac arrest or unstable ventricular tachycardia or ventricular fibrillation [ n = 1963]) and primary prevention (involving patients at increased risk for sudden cardiac death but without documented cardiac arrest, ventricular fibrillation, or ventricular tachycardia [ n = 2946]). Regardless of baseline risk, ICDs were equally efficacious in preventing sudden cardiac death in both types of trials (RR, 0.50 [CI, 0.38 to 0.66] for secondary prevention vs. 0.37 [CI, 0.27 to 0.50] for primary prevention). However, the magnitude of benefit in total mortality varied within the primary prevention trials depending on baseline risk for sudden cardiac death.</AbstractText>Implantable cardioverter defibrillators prevent sudden cardiac death regardless of baseline risk. However, their impact on total mortality is sensitive to baseline risk for arrhythmic death. Decisions about resource allocation for ICDs depend on accurate stratification of patients according to risk.</AbstractText> |
2,616 | Off-pump coronary artery bypass grafting and transmyocardial laser revascularization via a left thoracotomy. | Off-pump coronary artery bypass grafting may be combined with adjunctive transmyocardial laser revascularization to optimize revascularization. This approach may be advantageous for high-risk patients, particularly those having undergone previous sternotomies. From October 2000 through May 2001, 17 patients (9 women and 8 men) underwent off-pump coronary artery bypass grafting and transmyocardial laser revascularization via a left thoracotomy. The patients had a mean age of 63 years and a mean ejection fraction of 0.33. All but 1 patient had undergone previous coronary surgery. In each patient, the heart was approached via a left thoracotomy through the 5th intercostal space, and 37 transmural channels, 1 mm in diameter, were each created with a single pulse of the carbon dioxide laser. Coronary artery bypass grafting was then performed with left internal thoracic artery or saphenous vein grafts. The follow-up period ranged from 2.1 to 9.3 months (mean, 6.2 months). The patients received 28 bypass grafts (mean, 1.6 grafts). Postoperatively, 2 patients required inotropic support. On day 8, 1 patient died of ventricular fibrillation. After a mean hospitalization of 7.7 days, the remaining patients were discharged, free of angina. At follow-up examination after a mean of 6 months (range, 2-9 months), 15 patients remained free of angina and one had mild angina. None had required further hospitalization. Performed via a left thoracotomy, off-pump coronary artery bypass grafting plus transmyocardial laser revascularization yielded an acceptable mortality rate, no major morbidity, and substantial angina relief in this carefully selected group of challenging, high-risk patients. |
2,617 | Delaying defibrillation to give basic cardiopulmonary resuscitation to patients with out-of-hospital ventricular fibrillation: a randomized trial. | Defibrillation as soon as possible is standard treatment for patients with ventricular fibrillation. A nonrandomized study indicates that after a few minutes of ventricular fibrillation, delaying defibrillation to give cardiopulmonary resuscitation (CPR) first might improve the outcome.</AbstractText>To determine the effects of CPR before defibrillation on outcome in patients with ventricular fibrillation and with response times either up to or longer than 5 minutes.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PATIENTS" NlmCategory="METHODS">Randomized trial of 200 patients with out-of-hospital ventricular fibrillation in Oslo, Norway, between June 1998 and May 2001. Patients received either standard care with immediate defibrillation (n = 96) or CPR first with 3 minutes of basic CPR by ambulance personnel prior to defibrillation (n = 104). If initial defibrillation was unsuccessful, the standard group received 1 minute of CPR before additional defibrillation attempts compared with 3 minutes in the CPR first group.</AbstractText>Primary end point was survival to hospital discharge. Secondary end points were hospital admission with return of spontaneous circulation (ROSC), 1-year survival, and neurological outcome. A prespecified analysis examined subgroups with response times either up to or longer than 5 minutes.</AbstractText>In the standard group, 14 (15%) of 96 patients survived to hospital discharge vs 23 (22%) of 104 in the CPR first group (P =.17). There were no differences in ROSC rates between the standard group (56% [58/104]) and the CPR first group (46% [44/96]; P =.16); or in 1-year survival (20% [21/104] and 15% [14/96], respectively; P =.30). In subgroup analysis for patients with ambulance response times of either up to 5 minutes or shorter, there were no differences in any outcome variables between the CPR first group (n = 40) and the standard group (n = 41). For patients with response intervals of longer than 5 minutes, more patients achieved ROSC in the CPR first group (58% [37/64]) compared with the standard group (38% [21/55]; odds ratio [OR], 2.22; 95% confidence interval [CI], 1.06-4.63; P =.04); survival to hospital discharge (22% [14/64] vs 4% [2/55]; OR, 7.42; 95% CI, 1.61-34.3; P =.006); and 1-year survival (20% [13/64] vs 4% [2/55]; OR, 6.76; 95% CI, 1.42-31.4; P =.01). Thirty-three (89%) of 37 patients who survived to hospital discharge had no or minor reductions in neurological status with no difference between the groups.</AbstractText>Compared with standard care for ventricular fibrillation, CPR first prior to defibrillation offered no advantage in improving outcomes for this entire study population or for patients with ambulance response times shorter than 5 minutes. However, the patients with ventricular fibrillation and ambulance response intervals longer than 5 minutes had better outcomes with CPR first before defibrillation was attempted. These results require confirmation in additional randomized trials.</AbstractText> |
2,618 | Remodelling after surgical repair of atrial septal defects within the oval fossa. | In a retrospective study, we analysed the data from 101 adults with echocardiographic follow-up after surgical repair of defects within the oval fossa at a mean age of 35 +/- 17 years; 56% of the cohort being above the age of 30 years. Mean age at follow-up was 44 +/- 18 years, and length of follow-up was up to 40 years (11 +/- 12 years). At follow-up, atrial fibrillation or flutter was present in one quarter. Dilation of the right atrium, found in 64%, of the left atrium, found in 44%, and of the right ventricle, found in 29%, were also frequent, as well as pulmonary arterial hypertension, which was found in 30%. Diminished right ventricular ejection fraction, in contrast, was very rare, found only in 1%, and abnormal left ventricular ejection fraction was not encountered. By multivariate analysis, predictors for right or left atrial, or right ventricular, dilation were age at follow-up, degree of tricuspid regurgitation, pulmonary hypertension, and/or atrial fibrillation. In a subset of 21 patients in sinus rhythm, we correlated prospectively the diastolic and systolic function of both ventricles with levels of brain natriuretic peptide, comparing values to those of 20 age-matched controls with a mean age of 46 +/- 14 years. Levels of brain natriuretic peptide were significantly higher in patients than in controls (p = 0.006), and correlated significantly with diastolic dysfunction (p = 0.007) and left atrial size (p < 0.0001). In the long-term follow-up after surgical repair of defect within the oval fossa, therefore, complete normalization of heart size and function is rare. Despite preserved systolic function, persistent diastolic dysfunction is common and is associated with elevated levels of brain natriuretic peptide, which may explain the late occurrence of atrial arrhythmias. |
2,619 | [Staging and diagnosis in accidental hypothermia]. | Core body temperature below 35 degrees C is defining arbitrarily hypothermia. There is no worldwide consensus concerning the staging and resuscitation strategies in such a vital emergency, not even in rewarming strategy. Accidental hypothermia has its own "survival chain", modifying some steps or the timing in the common cardiopulmonary resuscitation protocol, according to some particularities of the metabolism in such an accident. Taking into account the two major events during hypothermic conditions (ventricular fibrillation and coma), we have proposed a better borderline between the three severity classes, based on clinical, paraclinical and prognostic arguments. The interest in this special environmental emergency situation is coming not only from its incidence, but especially from its particular long time period in which the resuscitation maneuvers could be effective, so that a literature review mixed with our practical observations may be of didactical and legal benefit also. |
2,620 | Antiarrhythmic therapy in heart failure. | Heart failure is the term used for a cardiovascular syndrome whose definition lacks uniform criteria. It is associated with a very high mortality rate. Approximately 50% of deaths in patients with heart failure are sudden, mostly due to ventricular tachycardia (VT). In severe heart failure, death may also occur due to bradyarrhythmias. Other arrhythmias complicating heart failure include atrial and ventricular extrasystoles, atrial fibrillation, and sustained or non-sustained VT. Depending on the etiology of heart failure, different preconditions, including ischemia or structural alterations (such as fibrosis) may be prominent. Re-entrant mechanisms around scar tissue, afterdepolarizations, and triggered activity due to changes in calcium metabolism significantly contribute to arrhythmogenesis. The treatment of the underlying disease process and optimal management of heart failure is of major importance. Revascularization, beta-blocker therapy, and angiotensin converting enzyme inhibitors are all essential to appropriate therapy. Treatment of arrhythmias is performed either because patients are symptomatic or to reduce the risk of sudden cardiac death. The implantable cardioverter-defibrillator (ICD) is the best available therapy to prevent sudden cardiac death from VT. Devices with back-up pacing also offer protection against bradyarrhythmias. There is evidence that patients with sustained VT or a history of resuscitation have the best outcome with ICD therapy regardless of the degree of heart failure. Many of these patients require additional antiarrhythmic therapy (e.g. amiodarone) because of atrial fibrillation or non-sustained VT that may activate the device. |
2,621 | Short and long-term single-centre experience with an S-shaped unipolar lead for left ventricular pacing. | Left ventricular-based pacing is an established method for treatment of congestive heart failure in patients with ventricular dyssynchrony. The transvenous epicardial approach is the method of choice to pace the left ventricle.</AbstractText>To evaluate short and long-term stability and pacing and sensing performance of an S-shaped non-steroid unipolar lead.</AbstractText>Forty-eight procedures were performed in 43 consecutive patients (mean age: 70+/-8 years, 32 males) with severe congestive heart failure. The left ventricular lead was placed into a coronary sinus tributary. Pacing and sensing thresholds and pacing impedance were measured at implant, 1 and 6 months.</AbstractText>The mean procedure time was 90.0+/-35.5 min. Pacing thresholds at implant, 1 and 6 months were 1.1+/-0.8 V, 1.9+/-1.3 V and 1.9+/-1.5 V respectively. In 7 patients, lead implantation was unsuccessful. One of them had a successful second attempt. Lead revision was performed in 5 patients for loss of capture.</AbstractText>The S-shaped unipolar lead evaluated in this study provides stable long-term position and pacing thresholds. Recent improvement of this S-shaped lead model will hopefully reduce the rate of implantation failures and acute dislodgements.</AbstractText>Copyright 2003 The European Society of Cardiology. Published by Elsevier Science Ltd.</CopyrightInformation> |
2,622 | The DDDR closed loop stimulation for the prevention of vasovagal syncope: results from the INVASY prospective feasibility registry. | The contraction dynamics of the ventricular myocardium are affected before and during vasovagal fainting suggesting that the Closed Loop Stimulation (CLS) pacemaker could be useful for the treatment of these patients. CLS is a new concept of heart rate modulation in cardiac pacing. The pacemaker INOS(2) CLS (Biotronik, Germany) derives its information for heart rate optimization from myocardial contraction dynamics, by measuring right ventricular intracardiac impedance. The pacemaker becomes an integral part of the circulatory regulation and, therefore, reacts appropriately to different cardiovascular demands.</AbstractText>In a prospective registry, 34 patients with a history of recurrent vasovagal syncopal events were implanted with INOS(2) DDDR CLS pacemakers. The aim of the study was to evaluate both long term clinical outcome, including the first recurrence of syncope, with DDDR-CLS pacing and acute precipitation of vasovagal fainting with DDDR-CLS mode compared with DDD during head up tilt testing.</AbstractText>During a follow up period of 12-50 months, 30 patients experienced no further syncopal events in daily life; 1 patient had no syncope but night palpitations, which were eliminated by pacemaker reprogramming; 2 patients had presyncopal episodes but not syncopes; 3 syncopal recurrences occurred in one patient in chronic atrial fibrillation, possibly not an ideal candidate for implantation.</AbstractText>Further studies for detailed understanding of the preventive mechanism of DDDR-CLS pacing in vasovagal syncope are warranted. A randomized multicentre prospective new study (INotropy controlled pacing in VAsovagal SYncope: INVASY) is now in progress to confirm the beneficial effect of DDDR-CLS pacing in a larger group of patients with recurrent vasovagal syncope.</AbstractText>Copyright 2003 The European Society of Cardiology. Published by Elsevier Science Ltd.</CopyrightInformation> |
2,623 | Transjugular liver biopsy in patients with hematologic malignancy and severe thrombocytopenia. | The purposes of this study are to report experience with transjugular liver biopsy (TJLB) in patients with hematologic malignancy and severe thrombocytopenia and to determine the incidence of hemorrhage-related complications in patients with prebiopsy and pretransfusion platelet counts of 30 x 10(9) /L or lower to propose a threshold platelet count above which TJLB can be safely performed without transfusion.</AbstractText>Medical records and laboratory reports of 50 patients with severe thrombocytopenia who had undergone 51 TJLB procedures and prebiopsy platelet transfusions between August 1999 and September 2001 were retrospectively reviewed. Biopsy success and procedural complications were recorded.</AbstractText>TJLB was technically successful in 49 of 51 procedures (96%). The mean prebiopsy, pretransfusion platelet count was 17 x 10(9)/L (range, 3-30 x 10(9)/L) and a mean of 11 U (range, 6-32 U) of platelets per patient were transfused. The overall mean postbiopsy platelet count was 38 x 10(9)/L (range, 5-105 x 10(9)/L), but it remained 30 x 10(9)/L or lower in 24 TJLB procedures. No hemorrhage-related complications were encountered, but ventricular fibrillation occurred in one patient during the procedure.</AbstractText>A threshold platelet count for safe TJLB resides below 30 x 10(9)/L. A prospective study is necessary to better define a lower threshold above which TJLB can be performed without platelet transfusion.</AbstractText> |
2,624 | Thrombolytic therapy with recombinant streptokinase for prosthetic valve thrombosis. | Thrombosis is a serious complication of prosthetic heart valves, and management is often difficult. Thrombolytic therapy is a promising alternative to valve re-operation in the prosthetic valve thrombosis.</AbstractText>Fifteen consecutive patients with prosthetic heart valve thrombosis (10 mitral, 3 aortic, 2 tricuspid) were treated with intravenous recombinant streptokinase: 250,000 UI given over 30 minutes followed by an infusion an 100,000 UI per hour, always with clinical monitoring and echocardiographic examinations repeated at 24, 48, and 72 hours after starting thrombolytic therapy. Doppler echocardiography was the primary method use for diagnosis and was also used to follow the response to therapy</AbstractText>Fibrinolytic treatment was successful in 14 (93.3%) patients. Total response was achieved in 13 (86.6%)patients and partial response in 1 (6.7%) patient; one patient died of ventricular fibrillation. No major hemorrhagic events were observed, peripheral embolism occurred in two cases, and one case of minor peripheral bleeding occurred in another. Some patients experienced fever and chills.</AbstractText>The present study demonstrates the feasibility, safety and efficacy of thrombolytic therapy, which may be considered as first-line therapy for prosthetic heart valve thrombosis.</AbstractText> |
2,625 | Hypertonic saline improves myocardial blood flow during CPR, but is not enhanced further by the addition of hydroxy ethyl starch. | To evaluate the effects of hypertonic saline (HS) and/or hydroxy ethyl starch (HES) on myocardial perfusion pressure (MPP) and blood flow (MBF), and cardiac index (CI) during and after cardiopulmonary resuscitation (CPR).</AbstractText>In 32 domestic swine (13-23.5 kg) open chest CPR was initiated after 8 min of ventricular fibrillation. With the onset of CPR animals randomly received 2 ml/kg per 10 min of either HS (7.2% NaCl) or hypertonic HES saline (HHS) (6% HES 200000/0.5 in 7.2% NaCl) or HES (6% HES 200000/0.5 in 0.9% NaCl) or normal saline (NS) (0.9% NaCl). Haemodynamic variables were monitored continuously, and coloured microspheres were used to measure MBF and CI before cardiac arrest, during CPR, and 20, 90 and 240 min after restoration of spontaneous circulation.</AbstractText>During CPR HS and HHS significantly increased MBF in comparison to HES and NS (P<0.05, respectively, MANOVA). MPP and CI were not different between the groups. HS and HHS significantly increased resuscitation success and the 240 min survival rate. 14/15 animals receiving HS or HHS and 8/17 after HES-or NS -infusion survived the observation period (P<0.05, chi(2)-test). No negative side effects of HS with or without the addition of HES were observed.</AbstractText>Hypertonic solutions (HS and HHS) applied during internal cardiac massage enhanced MBF and significantly increased resuscitation success and survival rate. Addition of HES to HS did not further improve the positive haemodynamic effects of HS alone.</AbstractText> |
2,626 | Evaluation of the in-hospital Utstein template in cardiopulmonary resuscitation in secondary hospitals. | The in-hospital Utstein template for cardiopulmonary resuscitation (CPR) was assessed in four secondary hospitals (334-441 beds) which did not have systematic data collection.</AbstractText>The reports and outcome over a period of 12 months during the years 2000-2001 were evaluated.</AbstractText>Of a total of 1690 patients that had a cardiac arrest (CA), 204 (12%) were resuscitated. Information on the collected Utstein parameters were available as follows: initial rhythm in 91%, time interval from collapse to defibrillation (in case of ventricular fibrillation or ventricular tachycardia as initial rhythm) in 90%, time interval to return of spontaneous circulation (ROSC) in 83% and duration of resuscitation in 83%. ROSC was achieved in 69 patients (34%, CI 27-41%) and 34 (17%, CI 11-23%) survived to hospital discharge. Twenty patients showed satisfactory neurological recovery (10%, CI 6-14%). Eighteen (9%, CI 5-13%) patients were alive at 12 months from the event. Factors associated with survival to hospital discharge were VF/VT (P=0.007) as the initial rhythm and shorter interval to defibrillation (P=0.046).</AbstractText>The in-hospital Utstein template was logical but laborious and it provided tools for resuscitation management evaluation in the study hospitals. For continuous use, a slightly compressed model may be warranted. In the present material, the overall survival rate to hospital discharge was in line with previous reports but there were somewhat less neurologically satisfactory survivors. There is an evident need to improve the outcome of patients suffering CA on the wards. An important step is to reduce the time interval to defibrillation.</AbstractText> |
2,627 | Molecular mechanisms of cardioprotection by a novel grape seed proanthocyanidin extract. | Free radicals and oxidative stress play a crucial role in the pathophysiology of a broad spectrum of cardiovascular diseases including congestive heart failure, valvular heart disease, cardiomyopathy, hypertrophy, atherosclerosis and ischemic heart disease. We have demonstrated that IH636 grape seed proanthocyanidin extract (GSPE) provides superior antioxidant efficacy as compared to Vitamins C, E and beta-carotene. A series of studies were conducted using GSPE to demonstrate its cardioprotective ability in animals and humans. GSPE supplementation improved cardiac functional assessment including post-ischemic left ventricular function, reduced myocardial infarct size, reduced ventricular fibrillation (VF) and tachycardia, decreased the amount of reactive oxygen species (ROS) as detected by ESR spectroscopy and reduced malondialdehyde (MDA) formation in the heart perfusate. Cardiomyocyte apoptosis detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining. In concert, the proapoptotic signals mediated by JNK-l and c-fos proteins were also reduced suggesting that the novel cardioprotective properties of GSPE may be at least partially attributed to its ability to block anti-death signaling mediated through the proapoptotic transcription factors and genes such as JNK-1 and c-JUN. In a separate study, GSPE pretreatment significantly inhibited doxorubicin-induced cardiotoxicity as demonstrated by reduced serum creatine kinase (CK) activity, DNA damage and histopathological changes in the cardiac tissue of mice. Concentration-dependent efficacy of GSPE was also assessed in a hamster atherosclerosis model. Approximately 49 and 63% reduction in foam cells, a biomarker of early stage atherosclerosis, were observed following supplementation of 50 and 100 mg GSPE/kg body weight, respectively. A human clinical trial was conducted on hypercholesterolemic subjects. GSPE supplementation significantly reduced oxidized LDL, a biomarker of cardiovascular diseases. Finally, a cDNA microarray study demonstrated significant inhibition of inducible endothelial CD36 expression, a novel cardioregulatory gene, by GSPE. These results demonstrate that GSPE may serve as a potential therapeutic tool in promoting cardiovascular health via a number of novel mechanisms. |
2,628 | Treatment of arrhythmias during pregnancy. | During pregnancy, significant changes occur in the hormonal and hemodynamic state of women that make arrhythmias more likely to occur. Palpitations are frequently reported, but are usually found to be associated with sinus tachycardia. The incidence of paroxysmal supraventricular tachycardia is increased during pregnancy, whereas atrial fibrillation and ventricular tachycardia are rarely seen. Women with long QT syndrome experience significantly more cardiac events in the postpartum period, making beta-blocker therapy most important during this time. Acute treatment of arrhythmias for pregnant women is much the same as that for nonpregnant patients. However, chronic drug therapy during pregnancy should be reserved for only the frequent, hemodynamically significant arrhythmia episodes. |
2,629 | [First onset of panic disorder and agoraphobia induced by a series of inappropriate shocks of an implanted cardioverter/defibrillator]. | We report on a 61-year-old patient with an implanted defibrillator due to malignant arrhythmia after myocardial infarction. After several years of appropriate function, the patient suffered a cluster of 16 shocks due to a defect in the defibrillator. Soon the patient developed a panic disorder with agoraphobia which was successfully treated with cognitive-behavioral therapy. Possible cognitive-behavioral mechanisms of panic disorder and special issues of behavioral therapy of patients with serious organic diseases are discussed. |
2,630 | Leukotriene-mediated coronary vasoconstriction and loss of myocardial contractility evoked by low doses of Escherichia coli hemolysin in perfused rat hearts. | hemolysin has been implicated as an important pathogenic factor in extraintestinal infections including sepsis. We investigated the effects of coronary administration of hemolysin on cardiac function in isolated rat hearts perfused at constant flow.</AbstractText>Prospective, experimental study.</AbstractText>Research laboratory at a university hospital.</AbstractText>Isolated hearts from male Wistar rats.</AbstractText>Isolated hearts were perfused with purified hemolysin for 60 min.</AbstractText>Low concentrations of the toxin in the perfusate (0.1-0.2 hemolytic units/mL) caused a dose-dependent coronary vasoconstriction with a marked increase in coronary perfusion pressure, which was paralleled by a decrease in left ventricular developed pressure (and the maximum rate of left ventricular pressure increase). Moreover, 0.2 hemolytic units/mL hemolysin evoked ventricular fibrillation within 10 mins of toxin application. These events were accompanied by the liberation of leukotrienes (LTC4, LTD4, LTE4, and LTB4), thromboxane A2, prostaglandin I2, and the cell necrosis markers lactate dehydrogenase and creatine kinase into the recirculating perfusate. The lipoxygenase inhibitor MK-886 fully blocked the toxin-induced coronary vasoconstrictor response and the loss of myocardial contractility and reduced the release of lactate dehydrogenase and creatine kinase. In contrast to this, the cyclooxygenase inhibitor indomethacin was entirely ineffective. In addition, hemolysin elicited an increase in heart weight and left ventricular end-diastolic pressure, the latter again being suppressed by MK-886.</AbstractText>Low doses of hemolysin cause strong coronary vasoconstriction, linked with loss of myocardial performance, release of cell injury enzymes, and electrical instability, with all events being largely attributable to toxin-elicited leukotriene generation in the coronary vasculature. Bacterial exotoxins such as hemolysin thus may be implicated in the cardiac abnormalities encountered in septic shock.</AbstractText> |
2,631 | Failing atrial myocardium: energetic deficits accompany structural remodeling and electrical instability. | The failing ventricular myocardium is characterized by reduction of high-energy phosphates and reduced activity of the phosphotransfer enzymes creatine kinase (CK) and adenylate kinase (AK), which are responsible for transfer of high-energy phosphoryls from sites of production to sites of utilization, thereby compromising excitation-contraction coupling. In humans with chronic atrial fibrillation (AF) unassociated with congestive heart failure (CHF), impairment of atrial myofibrillar energetics linked to oxidative modification of myofibrillar CK has been observed. However, the bioenergetic status of the failing atrial myocardium and its potential contribution to atrial electrical instability in CHF have not been determined. Dogs with (n = 6) and without (n = 6) rapid pacing-induced CHF underwent echocardiography (conscious) and electrophysiological (under anesthesia) studies. CHF dogs had more pronounced mitral regurgitation, higher atrial pressure, larger atrial area, and increased atrial fibrosis. An enhanced propensity to sustain AF was observed in CHF, despite significant increases in atrial effective refractory period and wavelength. Profound deficits in atrial bioenergetics were present with reduced activities of the phosphotransfer enzymes CK and AK, depletion of high-energy phosphates (ATP and creatine phosphate), and reduction of cellular energetic potential (ATP-to-ADP and creatine phosphate-to-Cr ratios). AF duration correlated with left atrial area (r = 0.73, P = 0.01) and inversely with atrial ATP concentration (r = -0.75, P = 0.005), CK activity (r = -0.57, P = 0.054), and AK activity (r = -0.64, P = 0.02). Atrial levels of malondialdehyde, a marker of oxidative stress, were significantly increased in CHF. Myocardial bioenergetic deficits are a conserved feature of dysfunctional atrial and ventricular myocardium in CHF and may constitute a component of the substrate for AF in CHF. |
2,632 | Automated external defibrillator arrhythmia detection in a model of cardiac arrest due to commotio cordis. | Cardiac arrest due to chest wall blows (commotio cordis) has been reported with increasing frequency in children, and only about 15% of victims survive. Automated external defibrillators (AEDs) have been shown to be life saving in adults with cardiac arrest, but data on their use in children are limited. In a swine model of commotio cordis designed to be most relevant to young children, we assessed the efficacy of a commercially available AED for recognition and termination of ventricular fibrillation.</AbstractText>Ventricular fibrillation was produced in anesthetized juvenile swine by precordial impact from a baseball under controlled conditions. Animals were randomized to defibrillation after 1, 2, 4, or 6 minutes of ventricular fibrillation. Twenty-six swine underwent 50 ventricular fibrillation inductions. Sensitivity of the AED for recognition of ventricular fibrillation was 98%, and specificity for nonshockable episodes was 100%. All episodes of ventricular fibrillation were successfully terminated by the AED.</AbstractText>In this experimental model of commotio cordis, the AED proved to be highly sensitive and specific for recognition of ventricular fibrillation and effective in terminating the arrhythmia and restoring sinus rhythm. These findings suggest that early defibrillation with the AED could save young lives on the athletic field.</AbstractText> |
2,633 | Delayed afterdepolarization inhibitor: a potential pharmacologic intervention to improve defibrillation efficacy. | Electrical and optical mapping studies of defibrillation have demonstrated that following shocks of strength near the defibrillation threshold (DFT), the first several postshock cycles always arise focally. No immediate postshock reentry was observed. Delayed afterdepolarizations (DADs) have been suggested as a possible cause of this rapid repetitive postshock activity. The aim of this study was to test the hypothesis that DFT is decreased by application of a DAD inhibitor.</AbstractText>Six pigs (30-35 kg) were studied. First, control DFT was determined using a three-reversal up/down protocol. Each shock (RV-SVC, biphasic, 6/4 msec) was delivered after 10 seconds of ventricular fibrillation (VF). Then, flunarizine (a DAD inhibitor) was injected intravenously (2 mg/kg bolus and 4 mg/kg/hour maintenance) and the DFT was again determined. A third DFT was determined 50 minutes after drug infusion was terminated to allow the drug to wash out. DFT after flunarizine application (520 +/- 90 V, 14 +/- 3 J) was significantly lower than control DFT (663 +/- 133 V, 23 +/- 4 J). After the drug washed out, DFT (653 +/- 107 V, 22 +/- 4 J) returned to the control DFT value (P = 0.6). Flunarizine reduced the DFT approximately 22% by leading-edge voltage and approximately 40% by energy.</AbstractText>Flunarizine, a DAD inhibitor, significantly improved defibrillation efficacy. This finding suggests that DADs could be the source of the rapid repetitive focal activation cycles arising after failed near-DFT shocks before degeneration back into VF. Future studies are needed to investigate the cause of the earliest postshock activation and to determine if the DADs are responsible.</AbstractText> |
2,634 | Three-dimensional mapping of earliest activation after near-threshold ventricular defibrillation shocks. | Following shocks with a 50% defibrillation success (DFT50) delivered from electrodes at the right ventricular (RV) apex and superior vena cava (SVC), the earliest epicardial postshock activation always appears focally in the left ventricular (LV) apex for both successful and failed shocks. Because the heart is a three-dimensional (3D) structure, questions remain whether this activation truly arises from a focus or the focal pattern represents epicardial breakthrough resulting from intramural reentry. To answer these questions, 3D electrical mapping was performed.</AbstractText>In six pigs, 60 to 84 epoxy fiberglass needles (0.7-mm-diameter), each containing six electrodes 2 mm apart, were inserted into the LV with 3- to 5-mm spacing around the apex and 5- to 10-mm spacing near the base. Ten DFT50 shocks (RV-->SVC, biphasic, 6/4 msec) were delivered after 10 seconds of fibrillation in each animal. The first five activations after each shock were mapped. Of 60 DFT50 shocks, 31 were successful, of which the first postshock cycle was a sinus beat in 13. In the other 18 successful shock episodes, the first postshock activation was detected 63 +/- 16 msec after the shock, which was not significantly different from the 58 +/- 23 msec postshock interval for the 29 failed shock episodes. In these 47 successful and failed shock episodes, the earliest postshock activation always arose focally from the LV apex. Its origin was in the subepicardium in 76% +/- 17%, midmyocardium in 16% +/- 12%, and subendocardium in 8% +/- 6% of cases.</AbstractText>Following near-DFT50 shocks, the first postshock cycles did not arise by macroreentry. Instead, they originated from a true focus or microreentry, most commonly near the epicardium.</AbstractText> |
2,635 | Transvenous defibrillation leads: high incidence of failure during long-term follow-up. | Patients with implantable cardioverter defibrillators (ICD) critically depend on correct functioning of their system. The aim of this study was to determine the incidence and clinical presentation of transvenous ICD lead failures during long-term follow-up.</AbstractText>The study group consisted of 261 consecutive patients who received Medtronic right ventricular polyurethane transvenous leads (models 6884, 6966, 6936) between 1990 and 1998 as part of an abdominal (n = 70) or pectoral (n = 191) ICD system. During mean follow-up of 4.0 +/- 2.6 years, 31 patients (12%) developed a lead-related sensing failure with oversensing of artifacts. All failures except two were compatible with an insulation defect and occurred late after ICD placement (6.0 +/- 1.8 years after implant). Lead survival decreased from 98% at 4-year follow-up to only 62% at 8-year follow-up. Lead survival was not related to patient age, sex, venous lead implantation route, or device implantation site. In 26 (87%) of 31 patients, a sensing defect resulted in inappropriate detection of ventricular fibrillation and subsequent delivery of 3 +/- 3 (range 1-11) inappropriate shocks in 19 (61%) of 31 patients. Device interrogation showed artifacts classified as nonsustained ventricular tachycardia in 21 patients, 40 +/- 43 days before clinically relevant failure of the system. One patient with a subclavian crush syndrome required resuscitation because of undersensing of true ventricular fibrillation.</AbstractText>Transvenous polyurethane ICD leads showed a high rate of lead insulation failure late after implantation with frequent inappropriate shock deliveries. Close follow-up is mandatory in patients with these leads. Automated device control features with patient alert function integrated into new devices may contribute to early detection of lead failure.</AbstractText> |
2,636 | Effect of coronary sinus electrode on the optimal atrial defibrillation pathway for an atrioventricular defibrillator. | Previous studies have demonstrated significant failure in converting atrial fibrillation (AF) using a conventional ventricular pathway. The aim of this study was to assess the benefit of incorporating a coronary sinus (CS) lead into the atrial defibrillation pathway in atrial defibrillation threshold (ADFT) reduction in patients with persistent AF.</AbstractText>This study was a prospective, randomized assessment of shock configuration on ADFT in 18 patients undergoing elective internal cardioversion for persistent AF (mean AF duration: 8 +/- 9 months). The lead system included a dual-coil defibrillation lead (Endotak DSP, Guidant) with a distal right ventricular (RV) electrode and a proximal superior vena cava (SVC) electrode, a CS lead (Perimeter, Guidant), and a left pectoral cutaneous electrode (Can). In each patient, dual step-up ADFTs were determined for each of three vectors: (1) RV --> SVC+Can; (2) CS --> SVC+Can; and (3) RV --> CS+SVC+Can (group 1, n = 8) or RV+CS --> SVC+Can (group 2, n = 10), using R wave-synchronized biphasic shocks. Successful defibrillation was achieved in all patients without any ventricular proarrhythmia. ADFT of CS --> SVC+Can (11.8 +/- 5.6 J) was significantly lower than ADFT of RV --> SVC+Can (16.5 +/- 7.8 J, P = 0.021). ADFT of CS --> SVC+Can was similar to RV --> CS+SVC+Can (group 1: 12.0 +/- 6.5 J vs 17.4 +/- 4.8 J, P = 0.16), but it was significantly higher than RV+CS --> SVC+Can (group 2: 9.0 +/- 3.9 J vs 11.6 +/- 5.0 J, P = 0.049).</AbstractText>Patients with persistent AF of substantial duration can be reliably cardioverted using a conventional implantable cardioverter defibrillator (ICD) lead set; however, the incorporation of a CS lead to the conventional ICD lead configuration significantly lowered ADFT. The optimal shock vector that incorporates a CS lead for atrial defibrillation requires future studies.</AbstractText> |
2,637 | Regional gap junction inhibition increases defibrillation thresholds. | It is clear that ischemia inhibits successful defibrillation by altering regional electro-physiology. However, the exact mechanisms are unclear. This study investigated whether regional gap junction inhibition increases biphasic shock defibrillation thresholds (DFT). Sixteen swine were instrumented with a mid-left anterior descending (LAD) perfusion catheter for regional infusion of 0.5 mM/h heptanol (n = 8) or saline (n = 8). DFT values and effective refractory periods (ERP) at five myocardial sites were determined. Regional conduction velocity (CV) was determined in an LAD drug-perfused and nondrug-perfused region in an additional seven swine. Regional heptanol infusion increased 50% DFT values by 33% (P = 0.01) and slowed CV by 42-59% (P < 0.01) but did not affect ERP. Regional heptanol also increased CV dispersion by approximately 270% (P < 0.05) but did not change ERP dispersion. Regional placebo did not alter any of these parameters. Furthermore, regional heptanol infusion induced spontaneous ventricular fibrillation in eight of eight animals. Increasing spatial conduction velocity dispersion by impairing regional gap junction conductance increased DFT values. Dispersion in conduction velocity slowing during regional ischemia may be an important determinant of defibrillation efficacy. |
2,638 | [Value of NTproBNP concentration in an out-of-hospital adult population]. | The diagnosis of chronic heart failure (CHF) is based on demonstrating the cardiac origin of clinical manifestations. Echocardiography is the method of choice for the detection of left ventricular systolic dysfunction (LVSD). Brain natriuretic peptide (BNP) rises during LVSD.</AbstractText>To analyze the plasma concentration of N-terminal brain natriuretic propeptide (NTproBNP) in a general adult population in relation to different spontaneous circumstances and to study its capacity for identifying patients with LVSD.Methods. A cardiological examination was made and plasma NTproBNP levels were measured in a randomized group of 203 people (49-81 years old) from the Community of Valencia.</AbstractText>The average NTproBNP concentration was 52.2 98.2 pmol/l. NTproBNP levels varied with age, gender and functional stage (NYHA). The highest NTproBNP values were observed in people who had previously suffered from acute pulmonary edema or who had an ejection fraction (EF) of less than 40%. There was also a significant elevation in patients with nocturnal dyspnea, orthopnea, atrial fibrillation, EF < or = 50%, angina, and ankle edema. The best concentration of NTproBNP for differentiating EF < or = 50% was 37.7 pmol/l, with 92% sensitivity and 68% specificity.</AbstractText>The elevation of NTproBNP concentration indicates the cardiac origin of clinical manifestations and serves to select patients for echocardiographic examination. Low NTproBNP concentrations help to rule out LVSD.</AbstractText> |
2,639 | Effect of cervical vagal nerve stimulation on defibrillation energy: a possible adjunct to efficient defibrillation. | The efficacy of electrical defibrillation is considered to be related to the autonomic status. In search of a possible adjunct to enhance the therapeutic performance of an implantable cardioverter-defibrillator. we investigated whether parasympathetic manipulation by cervical vagal nerve stimulation (VNS) increases defibrillation efficacy. The effects of VNS on transcardiac defibrillation threshold (DFT) were assessed in 55 anesthetized dogs. In neurally intact dogs, right and left unilateral VNS at 10 mA for 7 seconds significantly decreased the DFT after 10 seconds of ventricular fibrillation (control: 3.1 +/- 0.9 J, right: 2.1 +/- 0.9 J [delta-35 +/- 12%, P < 0.0001], left: 2.2 +/- 0.8 J [delta-31 +/- 11%, P < 0.0005]), while bilateral VNS did not (2.8 +/- 1.0 J). In dogs with decentralized vagus nerves, both unilateral and bilateral VNS decreased the DFT. The extent of the VNS-induced decrease in DFT was dependent on the current and the duration of stimulation. We conclude that unilateral VNS decreases the DFT, while bilateral VNS paradoxically has no effect on the DFT unless the vagi are decentralized. |
2,640 | [Pathogenesis and clinical significance of atrial fibrillation]. | The authors review the current knowledge relating to the epidemiology, classification and pathogenesis of atrial fibrillation, and then discuss those cardiac electrophysiological changes that play roles in the initiation and/or maintenance of atrial fibrillation. They draw attention to the fact that atrial fibrillation is the most common cardiac arrhythmia in humans, its prevalence increasing continuously with the increase in average lifespan of the population. Atrial fibrillation doubles all-cause mortality, it gives rise to considerable haemodynamic alterations and clinical symptoms, and it is responsible for almost half of the cases of hospitalizations attributable to arrhythmia. Because of the great pathogenetic variety, the most important diagnostic task is to establish the nature of the underlying disease, the arrhythmia substrate, and the predisposing and triggering factors; this permits selection of the therapeutic procedure that is optimum for the given patient. The results of the most recent prospective randomized clinical trials indicate that, in certain groups of patients, it will no longer be absolutely necessary in the future to strive to restore and maintain sinus rhythm: effective oral anticoagulant treatment in combination with pharmacological ventricular rate control ensures the same survival chances and the same quality of life for the patient as those achieved in earlier years with the preferred sinus rhythm-preserving treatment strategy based on pharmacological and/or electrical cardioversions and prophylactic antiarrhythmic drug therapy. |
2,641 | Atrial fibrillation after ondansetron for the prevention and treatment of postoperative nausea and vomiting: a case report. | Even though clinical safety has been established in large studies, ondansetron has been reported to cause adverse cardiovascular events. We present a case of atrial fibrillation in association with ondansetron in the postoperative period.</AbstractText>A 47-yr-old, 81 kg female presented with a benign lump in her left breast for lumpectomy. Her past medical history was unremarkable. Physically she was very active, non-smoker and had no allergies. She underwent the procedure under general anesthesia. She received 4 mg of ondansetron intravenously for postoperative nausea and vomiting prophylaxis at the end of the procedure and an additional 4 mg in the recovery room for nausea. Within 15 min after the second dose she was noted to be in atrial fibrillation that required admission to the hospital and procainamide infusion for conversion to normal sinus rhythm. She did not have any evidence of myocardial ischemia, valvular abnormality or pulmonary embolism.</AbstractText>The 5-hydroxytryptamine 3 receptor (5-HT(3)) antagonist ondansetron has been reported to cause myocardial ischemia, supraventricular and ventricular tachycardia. Postulated mechanism includes inhibition of Bezold-Zarisch cardiac reflex and coronary vasoconstriction. Inhibition of 5-HT(3) receptors in the heart could lead to unopposed action of other serotonin receptors leading to atrial fibrillation or other tachyarrhythmias described in the literature.</AbstractText> |
2,642 | Involvement of tyrosine kinase in peroxynitrite-induced preconditioning in rat isolated heart. | We have investigated the role of tyrosine kinase in the antiarrhythmic effects of peroxynitrite preconditioning in rat isolated heart by using a tyrosine phosphatase inhibitor, sodium orthovanadate, and tyrosine kinase inhibitors, genistein and tyrphostin. Rat hearts were preconditioned by peroxynitrite administration at 1 microM for 3 min, which was followed by 10-min washout and 30 min of ischemia. None of the hearts had ventricular fibrillation in the peroxynitrite preconditioning group (from 64%, n=11, to 0%, n=11). Neither sodium orthovanadate (10 microM) nor genistein (50 microM) or tyrphostin (100 microM) alone showed any effects on arrhythmias. Peroxynitrite preserved its beneficial effects on arrhythmias (to 0% ventricular fibrillation, n=7) during sodium orthovanadate infusion (for 23 min) prior to 30 min of an ischemic period. On the other hand, genistein or tyrphostin treatment significantly reversed the protective effects of the peroxynitrite preconditioning (to 71% ventricular fibrillation, n=14, genistein and, to 75% ventricular fibrillation, n=8, tyrphostin). These results suggest that the tyrosine kinase pathway plays a significant role in peroxynitrite-induced preconditioning in rat isolated heart. |
2,643 | Amiodarone and bretylium in the treatment of hypothermic ventricular fibrillation in a canine model. | Refractory ventricular fibrillation (VF) is a complication of severe hypothermia. Despite mixed experimental data, some authors view bretylium as the drug of choice in hypothermic VF. Bretylium was removed from Advanced Cardiac Life Support guidelines, and, to date, efficacy of amiodarone in hypothermia is unknown.</AbstractText>To compare defibrillation rates from hypothermic VF after drug therapy with amiodarone, bretylium, and placebo.</AbstractText>This was a randomized, blinded, and placebo-controlled laboratory experiment. Thirty anesthetized dogs were mechanically ventilated and instrumented to monitor coronary perfusion pressure (CPP), rectal core temperature, and electrocardiogram (ECG). Animals were cooled to 22 degrees C or the onset of spontaneous VF. Ventricular fibrillation was induced as needed with a transthoracic AC current. Cardiopulmonary resuscitation (CPR) was initiated and animals were randomized (n = 10 each group) to receive amiodarone 10 mg/kg (A), bretylium 5 mg/kg (B), or placebo (P) intravenously. CPR was continued while monitoring for chemical defibrillation. Rewarming was limited to removal from the cold environment. After 10 minutes, up to three escalating defibrillatory shocks were administered. Hemodynamic monitoring continued after resuscitation. Return of spontaneous circulation (ROSC) was defined as a sustainable ECG rhythm generating a corresponding arterial pressure tracing lasting a minimum of 15 minutes. Sample size permitted 80% power to detect a 60% difference in conversion rate between groups.</AbstractText>CPR was adequate based on CPP > 15 mm Hg in all animals. Mean (+/-SD) CPP was 35.3 +/- 18.8 mm Hg with an overall lower trend in the amiodarone group (p = 0.06). Baseline variables were similar between groups. No instance of chemical defibrillation was noted. There was no significant difference in ROSC rates between groups. Resuscitation rates were: amiodarone = 1/10, bretylium = 4/10, and placebo = 3/10 (p = 0.45).</AbstractText>In this model of severe hypothermic VF, neither amiodarone nor bretylium was significantly better than placebo in improving the resuscitation rate.</AbstractText> |
2,644 | Factors associated with cardiac rhythm disturbances in the early post-pneumonectomy period: a study on 259 pneumonectomies. | To identify predisposing factors associated with cardiac rhythm disturbances during the early post-pneumonectomy period (first 7 postoperative days).</AbstractText>During the study period (1995-1999), 259 pneumonectomies were performed for malignant (244 cases) or benign disease (15 cases). Postoperative monitoring of patients included continuous arterial pressure - rhythm monitoring and pulse oximetry. Cardiac rhythm disturbances during the intensive care unit stay were detected on the monitor screen and recorded with a 12-lead electrocardiogram. Cardiac rhythm disturbances associated with electrolytes or fluid balance abnormality, mediastinal deviation or surgical postoperative complications were excluded from the study. Age of patients, preexisting cardiac disease, side of pneumonectomy, intrapericardial procedures, stage of the malignant disease, expected postoperative FEV(1)<1200 ml, intraoperative transfusions of packed red cells, elevated right heart pressures, low postoperative serum magnesium levels and long operative times were considered as predisposing factors for the development of post-pneumonectomy cardiac rhythm disturbances. Statistical analysis has been made using logistic regression analysis, Student t-test and chi-square test.</AbstractText>Cardiac rhythm disturbances were detected in 49 patients (18.91%). Atrial fibrillation/flutter (31 cases), supraventricular tachycardia (14 cases), and premature ventricular contractions (four cases) were the observed rhythm disturbances. Right pneumonectomy versus left pneumonectomy (P<0.0001) and intrapericardial pneumonectomy versus standard pneumonectomy (P<0.0001) were identified as strong predisposing factors for the establishment of post-pneumonectomy cardiac rhythm disturbances. Patients who established post-pneumonectomy cardiac rhythm disturbances had significantly higher (P=0.024) right ventricular systolic pressure (42.50+/-15.50 mmHg) when compared with patients who had postoperative sinus rhythm (29.07+/-7.71 mmHg) and had also longer operative times than patients who did not develop rhythm disturbances (P=0.015). Mortality rate in patients who developed post-pneumonectomy rhythm disturbances was 20.40%.</AbstractText>Cardiac rhythm disturbances observed early after pneumonectomy are mainly of supraventricular origin, complicating right and intrapericardial pneumonectomies, patients with elevated right heart pressures and long operative times, and are associated with high mortality rates.</AbstractText> |
2,645 | Predictors of cerebrovascular events in patients subjected to isolated coronary surgery. The importance of aortic cross-clamping. | Stroke is a major complication after coronary surgery, occurring in 1-4% of the patients. In this study, we evaluate the incidence and pre- and intraoperative risk factors for the development of a cerebrovascular accident (CVA) and the impact of such an event on perioperative mortality and on hospital length of stay.</AbstractText>Data from 4567 patients submitted to isolated coronary artery bypass grafting (CABG) with hypothermic ventricular fibrillation between 1992 and 2001 were entered prospectively into a dedicated computerized database and analyzed retrospectively at this time. Univariate and multivariate analyses were performed where appropriate.</AbstractText>The incidence of postoperative CVA was 2.5% (116 patients). Multivariable logistic regression identified the following variables to be independent predictors of a postoperative CVA: cerebrovascular disease (P<0.001; odds ratio (OR), 2.66), peripheral vascular disease (P<0.001; OR, 2.33), number of periods of aortic cross-clamping (P=0.019; OR, 1.31 per each period of aortic cross-clamping), LV dysfunction (P=0.012; OR, 1.82) and age (P=0.008; OR, 1.28 per each 10 years). Non-elective surgery showed a marginal significance (P=0.08; OR 1.83). The 30-day mortality for patients who experienced a CVA was 16.4% versus 0.6% for patients who did not (P<0.001). Postoperative CVA increased the length of hospital stay threefold to 20.3+/-28.3 days as compared with patients who did not have a postoperative CVA (7.6+/-4.2 days; P<0.001).</AbstractText>Postoperative CVA dramatically increases the mortality and length of stay after CABG. Identification of predisposing factors permits preoperative risk stratification and may facilitate improved patient selection or optimization. Our study adds evidence to the superiority of the fibrillation technique over intermittent cross-clamping of the aorta, among non-cardioplegic techniques, in terms of neurological protection.</AbstractText> |
2,646 | Postinfarction ventricular septal defect closure with Amplatzer occluders. | Postinfarction ventricular septal defect (PIVSD) is a rare and life-threatening complication with high risk of both surgical and medical treatment. Another option available now is transcatheter closure. The purpose of this paper is to report the results of such treatment with Amplatzer occluders.</AbstractText>Seven patients aged from 51 to 71 years were included. The procedure was performed between 2 and 10 weeks after myocardial infarction. One patient had double residual VSD (2 months after previous surgery) and another, coexisting critical stenosis of right coronary artery (RCA). All patients were in III/IV NYHA class, on intropes, one patient on aortic balloon counterpulsation. Venous jugular approach was used to close the VSD in six patients, venous transfemoral in one patient. Implantation of six Ampaltzer atrial septal occluders (ASO) and one muscular Amplatzer VSD occluder (VSO) were performed.</AbstractText>All procedures but two were finished successfully. In one patient, the defect could not be entered neither from the venous nor the arterial side due to unusual oblique course (which was confirmed during subsequent operation). In the second patient (2 weeks after MI), the reason was unstable position of 24 mm ASO (probably due to necrotic borders of VSD). Immediate significant clinical improvement was achieved in all patients, in whom PIVSD was closed with Amplatzer occluders. In one postsurgical patient, two ASO were used; in another patient, prior to VSD closure, PTCA and stent implantation to RCA was performed. The stretched diameter of PIVSD ranged from 8 to 22 mm, the size of implanted Amplatzer occluders from 12 to 24 mm. Fluoroscopy time was 60 min (18-120). During the procedure, ventricular fibrillation requiring defibrillation was observed in three patients. One patient died 1 week after the procedure because of multiorgan failure and increasing mitral incompetence (MI).</AbstractText>Despite some technical problems, implantation of Amplatzer occluders, is an attractive option of treatment of patients with subacute PIVSD.</AbstractText> |
2,647 | [The best of valvular heart disease in 2002]. | For AS, besides a very thorough update by Carabello on their management, new experimental work confirms that the pathophysiology of the condition is closer to atherosclerotic and inflammatory processes than pure degeneration. Moreover this year brings a batch of long term post-operative results, one of which is an important series relating to 2194 bioprostheses followed up for 15 years. The choice of valvular substitute between 60 and 70 years old is the subject for several studies. A series of 259 re-operations for bioprosthesis deterioration allows quantification of the operative risk to which those with this substitute are subjected in case of degeneration. Finally, the strategy to adopt in a patient with an indication for aortocoronary bypass but also with a not-tight AS is discussed (abstention, decalcification, or "preventive" valvular replacement?). For aortic insufficiency (AI) some new results for the Ross operation have been published and the first publications reporting on the attempts of experimental positioning of bioprostheses via the percutaneous route in animals are appearing. As for mitral valvulopathies, MI has carved a privileged place. Much work this year relates amongst other things to functional MI in dilated cardiomyopathies with dilatation of the ring, to the natural history of mitral valvular prolapse detailed in an important series of 833 patients, and to the evolutive risk of atrial fibrillation (AF) with MI and its treatment during plasty or mitral valvular replacement procedures. Anticoagulant treatment for mechanical prostheses is the subject of much work drawn from a large German prospective study (GELIA) confirming the general tendency for alleviation of intensity in aortic especially but also mitral valvulopathies, stressing the advantages of autocontrol. Finally, the Valvulopathy Working Group of the European Society of Cardiology publishes its recommendations for asymptomatic valvulopathies, recalling the echographic criteria of dilatation and left ventricular function to be retained for operative indications, emphasising furthermore the significance of the stress test in the follow up of asymptomatic AS. |
2,648 | [The best of arrhythmias in 2002]. | In the era of evidence based medicine the year 2002 will be remembered principally for having brought the results of two large trials in areas of daily preoccupation for rhythmologists: those of atrial fibrillation and of prevention of rhythmic sudden death. The Atrial Fibrillation Following Investigation of Rhythm Management (AFFIRM) study compared strategies for controlling frequency and rhythm in atrial fibrillation for subjects aged over 65 years or having at least one risk factor for cerebral vascular accident. In an unexpected fashion, although in accordance with other recent results, the two strategies are equivalent in terms of mortality. It also underlined the necessity of continuing anticoagulation with an INR > 2. even when it is proposed to maintain the rhythm. In the matter of primary prevention of sudden coronary death, the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) had the originality of evaluating patients with no other risk factor than a severe alteration in left ventricular ejection fraction (30% Pounds). This "simple" selection of patients at risk allowed a mortality reduction of 30% to be demonstrated by the placement of a ventricular defibrillator, in addition to that brought about by optimal conventional treatment. In the chapter on syncope, the Framingham study delivers information in terms of incidence and long term prognosis, in a non selected population. Even if these results are difficult to compare with those recent studies using notably the inclination test, they remind us of the poor prognosis of cardiac origin syncope and the absence of excess mortality in patients affected by vagal syncope. The significance of these very wide series does not preclude drawing the greatest attention to the work by the Bordeaux team who have been able to provide evidence, in 27 patients with relapsing idiopathic ventricular fibrillation, of the initiator role of extra-systoles originating from the distal Purkinje network. A medium term cure was obtainable by ablation of these extra-systoles. This work of course allows the prospect of application to other types of malign ventricular arrhythmias. |
2,649 | Experimental evidence of regional myocardial ischemia during beating heart coronary bypass: prevention with temporary intraluminal shunts.<Pagination><StartPage>10</StartPage><EndPage>18</EndPage><MedlinePgn>10-8</MedlinePgn></Pagination><Abstract><AbstractText Label="BACKGROUND" NlmCategory="BACKGROUND">Our center has been performing beating heart coronary artery bypass grafting with a temporary intraluminal shunt since 1983. Based on our clinical observations of more than 846 surgical cases, we believe that a temporary intraluminal shunt (TIS) greatly reduces the risk of the patient developing regional myocardial ischemia during clamping of the coronary artery. To seek evidence in support of our clinical observations, we evaluated the effects of coronary clamping with and without TIS in a porcine experimental model.</AbstractText><AbstractText Label="METHODS" NlmCategory="METHODS">We compared 2 groups of healthy Landrace pigs that underwent the same period of coronary occlusion but differed only in whether a TIS was used. The shunt device was a straight flow-through silicone tube that has been described in detail in previous publications. Ischemic changes during the test period were detected via analysis of monophasic action potential (MAP) recordings. MAPs were recorded with the contact electrode technique, which has been shown to be specific for ischemia. In group I (no shunt) animals (n = 25), MAPs were monitored during a single 15-minute occlusion of the left anterior descending (LAD) coronary artery without any form of distal perfusion. In group II (shunted) animals (n = 15), MAPs were sampled over the same intervals after the LAD was snared and opened and the TIS was introduced within the first 2 minutes. Infarct analysis using biochemical end points (serum lactate dehydrogenase [LDH] and creatine phosphokinase-myocardial band [CPK-MB]) was performed with standard serologic assays.</AbstractText><AbstractText Label="RESULTS" NlmCategory="RESULTS">Confirming the presence of regional ischemia in group I (no shunt) were significant changes from baseline in measurements of mean action potential duration, upstroke velocity (dV/dt), and total MAP area (millivolts milliseconds). The presence of ischemia in group I was also confirmed by significant elevations in serum LDH and CPK-MB levels. Furthermore, the use of lidocaine was greater in group I (no shunt) animals than in group II (shunted) animals because of the greater frequency of ventricular arrhythmias in group I (P =.001). Six animals (24%) in group I and no animals in group II developed ventricular fibrillation during the 15 minutes of occlusion (P =.046). Ischemic changes in the MAP were found only prior to shunt insertion in Group II animals, and the MAP then promptly returned to normal a few minutes after TIS flow was established. Statistical analysis revealed significant differences between group I and group II in MAP duration, dV/dt, total area, lidocaine requirements, incidence of ventricular fibrillation, and serum LDH levels.</AbstractText><AbstractText Label="CONCLUSIONS" NlmCategory="CONCLUSIONS">There has been controversy about the relative effectiveness of temporary intraluminal shunting for reducing the risk of regional myocardial ischemia during beating heart coronary artery bypass grafting. At least in this porcine model, we could demonstrate a positive effect of shunting, which parallels our clinical experience using TIS in hundreds of patients for the past 2 decades. In the animal model, we demonstrated preservation of the MAP, as well as a reduction in both the incidence of ventricular arrhythmias and the serum levels of ischemic by-products, when temporary intraluminal shunting was used. It is our conclusion that intraluminal shunts do protect the vulnerable myocardium from regional ischemia during the period of temporary coronary occlusion necessary for construction of a bypass graft on the beating heart. Temporary intraluminal shunting is a costeffective adjunct that can increase safety and reliability in offpump coronary artery bypass grafting.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Gandra</LastName><ForeName>Sylvio M A</ForeName><Initials>SM</Initials><AffiliationInfo><Affiliation>Department of Cardiovascular Surgery, Faculdade de Ciencias Medicas da Santa Casa de Sao Paulo, Sao Paulo, Brazil. [email protected]</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Rivetti</LastName><ForeName>Luiz A</ForeName><Initials>LA</Initials></Author></AuthorList><Language>eng</Language><PublicationTypeList><PublicationType UI="D003160">Comparative Study</PublicationType><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList></Article><MedlineJournalInfo><Country>United States</Country><MedlineTA>Heart Surg Forum</MedlineTA><NlmUniqueID>100891112</NlmUniqueID><ISSNLinking>1098-3511</ISSNLinking></MedlineJournalInfo><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D000200" MajorTopicYN="N">Action Potentials</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D000818" MajorTopicYN="N">Animals</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D019540" MajorTopicYN="N">Area Under Curve</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D001145" MajorTopicYN="N">Arrhythmias, Cardiac</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="N">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002315" MajorTopicYN="N">Cardiopulmonary Bypass</DescriptorName><QualifierName UI="Q000009" MajorTopicYN="N">adverse effects</QualifierName><QualifierName UI="Q000295" MajorTopicYN="N">instrumentation</QualifierName><QualifierName UI="Q000379" MajorTopicYN="Y">methods</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D003250" MajorTopicYN="N">Constriction</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005260" MajorTopicYN="N">Female</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D007431" MajorTopicYN="N">Intraoperative Complications</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="Y">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D008297" MajorTopicYN="N">Male</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D023421" MajorTopicYN="N">Models, Animal</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D009200" MajorTopicYN="Y">Myocardial Contraction</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D017202" MajorTopicYN="N">Myocardial Ischemia</DescriptorName><QualifierName UI="Q000209" MajorTopicYN="N">etiology</QualifierName><QualifierName UI="Q000517" MajorTopicYN="Y">prevention & control</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D013552" MajorTopicYN="N">Swine</DescriptorName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="received"><Year>2002</Year><Month>10</Month><Day>20</Day></PubMedPubDate><PubMedPubDate PubStatus="accepted"><Year>2002</Year><Month>10</Month><Day>31</Day></PubMedPubDate><PubMedPubDate PubStatus="pubmed"><Year>2003</Year><Month>3</Month><Day>4</Day><Hour>4</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>2003</Year><Month>4</Month><Day>23</Day><Hour>5</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2003</Year><Month>3</Month><Day>4</Day><Hour>4</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">12611726</ArticleId><ArticleId IdType="doi">10.1532/hsf.869</ArticleId></ArticleIdList></PubmedData></PubmedArticle><PubmedArticle><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">12611162</PMID><DateCompleted><Year>2003</Year><Month>06</Month><Day>16</Day></DateCompleted><DateRevised><Year>2006</Year><Month>11</Month><Day>15</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0201-7563</ISSN><JournalIssue CitedMedium="Print"><Issue>6</Issue><PubDate><Year>2002</Year><Season>Nov-Dec</Season></PubDate></JournalIssue><Title>Anesteziologiia i reanimatologiia</Title><ISOAbbreviation>Anesteziol Reanimatol</ISOAbbreviation></Journal>[The shape of high-voltage impulse and the effect of defibrillation]. | The paper discusses how to choose the optimum shape of a pulse for electric defibrillation of the heart. The authors' data are given on the values of an induced field in the contracting myocardial structure when a defibrillator evokes pulses. Mono- and bipolar pulse-induced changes of the transmembranous potential on the hyper- and depolarized sides of a cell are calculated. Mechanisms of defibrillation in the use of pulses of different shapes are considered. |
2,650 | Mitral regurgitation of degenerative etiology: should the timing of surgery be changed in the mitral valve repair era? | The timing of surgery in patients with chronic mitral regurgitation is a controversial issue. Left ventricular dysfunction progresses silently and is partly predictable; depressed left ventricular contractility sometimes accompanies a normal ejection fraction. Severe symptoms remain a clear recommendation for surgery. However several factors suggest that surgery should not be delayed until severe symptoms appear: impact on survival of ejection fraction < 60%, preoperative symptoms, and atrial fibrillation. Early surgery is justified in patients with degenerative mitral regurgitation independently of the type of lesion (prolapse of posterior, anterior or both the leaflets), because the addition of new techniques to the surgical armamentarium has neutralized prolapse of the anterior leaflet as an incremental risk factor for reoperation. In conclusion, early surgery is a reasonable treatment for low-risk patients with repairable valves and should be considered in asymptomatic patients with ejection fraction approaching the lower limit of normal, history of paroxysmal atrial fibrillation or pulmonary hypertension during exercise. |
2,651 | [Atrial flutter with 1/1 nodo-ventricular conduction with amiodarone. From physiopathology to diagnosis]. | Atrial flutter with 1/1 nodo-ventricular conduction is a classical complication of Vaughan-Williams's Class I antiarrhythmic drugs. The increase of the flutter cycle and weak action of the antiarrhythmic on the atrioventricular node leads to 1/1 conduction of atrial depolarisation to the ventricles. In view of their marked action on the atrioventricular node, this type of pro-arrhythmic effect is very unexpected with Class III antiarrhythmics. The authors report 7 cases of 1/1 atrial flutter with oral amiodarone observed between 1994 and 2001. The patients were 6 men and 1 woman with an average age of 58 +/- 14 years. Four of them had underlying cardiac disease; none were hyperthyroid. The initial arrhythmia was 2/1 atrial flutter (n = 4), 1/1 atrial flutter (n = 2) and atrial fibrillation (n = 1). Treatment was preventive with doses of 400 mg/day associated with carvedilol in one patient and 200 mg/day in another. The other five patients all received loading doses of 9200 +/- 2400 mg over 10 +/- 4 days. The symptoms were palpitations (n = 2) associated in one patient with hypotension, one syncope, one near syncope and one cardiogenic shock. The ventricular cycle of the 1/1 flutter was 287 +/- 33 ms. The QRS duration was 136 +/- 35 ms with ventricular tachycardia-like appearances in 3 cases. An adrenergic trigger factor was noted in 5 patients. One patient required emergency cardioversion. The authors discuss the physiopathology of 1/1 flutter and theoretical diagnostic methods are proposed. In conclusion, amiodarone does not always prevent the occurrence of 1/1 nodo-ventricular conduction in atrial flutter. |
2,652 | Behaviour of the adrenergic cardiovascular drive in atrial fibrillation and cardiac arrhythmias. | Animal studies have conclusively shown that the sympathetic nervous system plays a major role not only in regulating sinus node activity but also in promoting cardiac rhythm alterations. Less univocal and often circumstantial have been the evidences collected on this issue in humans. However, the introduction of the microneurographic technique in clinical research has allowed to gain new important insights on the role of neuroadrenergic factors in the pathophysiology of cardiac arrhythmias.</AbstractText>The present paper will review the results of microneurographic studies performed by our group and others in the field of cardiac rhythm disturbances by addressing three specific issues. First it will examine the relationships between heart rate and muscle sympathetic neural outflow in a variety of cardiovascular diseases characterized by sympathetic activation. This will be followed by an analysis of the behaviour of the sympathetic nerve traffic responses to paroxysmal atrial fibrillation. Finally, the sympathetic adjustments to spontaneously occurring or artificially induced pre-mature ventricular contractions will be highlighted.</AbstractText> |
2,653 | [Holter EKG for the hypertensive heart disease]. | During chronic mechanical overload induced by hypertension, left ventricular hypertrophy predisposes to atrial and ventricular arrhythmias. Atrial arrhythmias, mainly atrial fibrillation, decrease cardiac output and increase the risk of embolism whereas ventricular arrhythmias remain the major cause of sudden death. In hypertensive patients, Holter EKG recordings frequently detect atrial or ventricular premature beats and more rarely atrial or ventricular tachycardia. In these patients, the presence of non-sustained ventricular tachycardia is considered as an independent predictor of mortality. Moreover, this non invasive method through the assessment of heart rate variability allows the study of the autonomic control of the heart, known to modulate occurrence of arrhythmias. |
2,654 | Combination of QT variability and signal-averaged electrocardiography in association with ventricular tachycardia in postinfarction patients. | The authors investigate incidence of ventricular tachycardia/ventricular fibrillation (VT/VF) in relationship with combination of noninvasive arrhythmia risk markers as left ventricular ejection fraction (LVEF), late potentials (LP), and QT variability index (QTVI) and compare the utility of their combination in association with sustained ventricular arrhythmias in patients after myocardial infarction (MI). Fifty-four patients with old MI, among them 27 with documented spontaneous sustained VT/VF entered the study. All of them underwent evaluation for arrhythmias and noninvasive risk stratification. Logistic regression analysis demonstrated that the highest association with ventricular tachyarrhythmia had combination of LP and increased QTVI (13.8, P<.0002), followed then by combination of LVEF and LP (12.2, P<.0005), LP alone (P<.001), QTVI (P<.002) and LVEF (P<.003) alone and age (P<.01). After stepwise regression analysis showed that the model including association of LP and QTVI, age and EF is the best one for delineating patients having the risk of ventricular tachyarrhythmia development. In conclusion, patients with combination of positive LP and increased QTVI after MI have high likelihood for development of serious sustained arrhythmia. |
2,655 | Frequent ventricular ectopy after exercise as a predictor of death. | Exercise-induced ventricular ectopy predicts an increased risk of death in population-based cohorts. We sought to examine in a clinical cohort the prognostic importance of ventricular ectopy immediately after exercise, when reactivation of parasympathetic activity occurs. We hypothesized that ventricular ectopy after exercise (i.e., during the recovery phase) would predict an increased risk of death better than ventricular ectopy during exercise.</AbstractText>We studied 29,244 patients (mean [+/-SD] age, 56+/-11 years; 70 percent men) who had been referred for symptom-limited exercise testing without a history of heart failure, valve disease, or arrhythmia. Frequent ventricular ectopy was defined by the presence of seven or more ventricular premature beats per minute, ventricular bigeminy or trigeminy, ventricular couplets or triplets, ventricular tachycardia, ventricular flutter, torsade de pointes, or ventricular fibrillation.</AbstractText>Frequent ventricular ectopy occurred only during exercise in 945 patients (3 percent), only during recovery in 589 (2 percent), and during both exercise and recovery in 491 (2 percent). There were 1862 deaths during a mean of 5.3 years of follow-up. Frequent ventricular ectopy during exercise predicted an increased risk of death (five-year death rate, 9 percent, vs. 5 percent among patients without frequent ventricular ectopy during exercise; hazard ratio, 1.8; 95 percent confidence interval, 1.5 to 2.1; P<0.001), but frequent ventricular ectopy during recovery was a stronger predictor (11 percent vs. 5 percent; hazard ratio, 2.4; 95 percent confidence interval, 2.0 to 2.9; P<0.001). After propensity matching for confounding variables, frequent ventricular ectopy during recovery predicted an increased risk of death (adjusted hazard ratio, 1.5; 95 percent confidence interval, 1.1 to 1.9; P=0.003), but frequent ventricular ectopy during exercise did not (adjusted hazard ratio, 1.1; 95 percent confidence interval, 0.9 to 1.3; P=0.53).</AbstractText>Frequent ventricular ectopy during recovery after exercise is a better predictor of an increased risk of death than ventricular ectopy occurring only during exercise.</AbstractText>Copyright 2003 Massachusetts Medical Society</CopyrightInformation> |
2,656 | Comparison of cardioprotective efficacy of two thromboxane A2 receptor antagonists. | The purpose of the current study was to compare the efficacy of two structurally unrelated thromboxane A (TXA ) receptor antagonists, KT2-962 and daltroban (BM 13.505), in a dog model of myocardial ischemia/reperfusion injury. Pentobarbital-anesthetized dogs were subjected to left circumflex coronary artery occlusion for 90 minutes followed by 5 hours of reperfusion. Vehicle, KT2-962 (10 mg/kg), or daltroban (10 mg/kg) were administered as intravenous boluses 10 minutes before coronary occlusion. Systemic hemodynamics were measured throughout the experiments and regional myocardial blood flow was measured by the radioactive microsphere technique. At the end of the reperfusion period, myocardial infarct size was quantified by staining with triphenyltetrazolium chloride. Neither KT2-962 nor daltroban significantly altered heart rate, mean arterial blood pressure, or regional myocardial blood flow. The content of myeloperoxidase activity in the ischemic/reperfused tissue, an index of neutrophil infiltration, was not significantly different among the three treatment groups. However, administration of KT2-962, but not daltroban, significantly reduced the incidence of ventricular fibrillation during the ischemic period and significantly reduced myocardial infarct size expressed as a percentage of the risk region (approximately 40%). Subsequent in-vitro assays using electron spin resonance spectroscopy demonstrated that KT2-962 inhibited the formation of hydroxyl radicals, whereas daltroban had no effect. These results suggest that the beneficial effects of KT2-962 may be due to its direct free radical scavenging properties rather than its ability to block TXA receptors.(2) (2) (2) |
2,657 | Decreased left atrial appendage flow velocity with atrial fibrillation caused by negative inotropic agents: report of two cases. | Although pharmacological agents are frequently used to control ventricular rate or restore sinus rhythm of patients with atrial fibrillation (AF), there are no reports of the relationship between those agents and left atrial appendage (LAA) function. Two cases of a decrease in LAA blood flow velocity caused by negative inotropic agents are presented as an indication that negative inotropic agents are a risk factor for systemic thromboembolism with AF. |
2,658 | A giant aneurysm of the circumflex coronary artery with fistulous connection to the coronary sinus: a case report. | Non-atherosclerotic coronary artery aneurysms are rare and most of them remain asymptomatic. We report a case who has a giant circumflex coronary artery aneurysm with fistulisation into the coronary sinus. The patient presents with dyspnea and palpitation due to atrial fibrillation with rapid ventricular response. The diagnostic contributions of echocardiography, coronary angiography are discussed. The hemodynamic effects of this anomaly are reviewed. |
2,659 | His electrogram alternans reveal dual atrioventricular nodal pathway conduction during atrial fibrillation: the role of slow-pathway modification. | Traditional tools to study dual-pathway atrioventricular nodal (AVN) electrophysiology are not applicable in subjects with permanent atrial fibrillation (AF). The presence of fast-pathway (FP) and slow-pathway (SP) wavefronts and their possible modification remain uncertain in this condition. We demonstrated previously that His electrogram (HE) alternans can determine whether the FP or the SP reaches the His bundle on a beat-by-beat basis. We have now applied this novel index to monitor dual-pathway conduction and the effects of SP modification during AF.</AbstractText>In 12 rabbit AVN preparations, HE alternans were confirmed during a standard A(1)A(2) pacing protocol. During AF, in 9 of the 12 hearts, HE alternans indicated the presence of dual pathways. Successful SP modification guided by the HE alternans eliminated the SP, resulting in a predominantly FP conduction during AF in all hearts. This increased the average His-His interval (204+/-14 versus 276+/-51 ms, P<0.001). Morphological studies revealed that SP modification damaged only the posterior extension of the AVN.</AbstractText>We have demonstrated for the first time in rabbits that HE alternans permit "visualization" of dual-pathway electrophysiology and confirmed the presence of both FP and SP wavefronts during AF. This novel index has been used in a selective SP ablation that resulted in a significant slowing of the ventricular rate. HE alternans provide a new insight into the mechanisms of AVN conduction and could guide AVN modification for ventricular rate control in AF clinically.</AbstractText> |
2,660 | Sustained reentry in the left ventricle of fibrillating pig hearts. | It has been proposed that ventricular fibrillation (VF) is driven by sustained reentry. However, mapping studies have not detected such "mother rotors" in large mammalian hearts. We mapped VF from three 21x12 unipolar electrode arrays in 6 pigs. Two of the arrays were adjacent to each other on the left-ventricular epicardium. Electrode spacing was 2 mm. The third array consisted of 21 needles (0.5-mm diameter, 12 electrodes, 1-mm spacing) inserted in a row (2-mm spacing) between the epicardial arrays. A total of 88 5-second VF epochs were analyzed with automatic reentry detection algorithms. Although intramural reentry was sporadically present (29 total occurrences), it was always short-lived with a mean life span of 127+/-57 ms. However, in 3 of the 6 animals, sustained epicardial reentry (ie, reentry persisting for more than a few cycles) was consistently present, often lasting for several seconds. For each epoch, we computed indices characterizing (1) the relative duration of reentry on the two epicardial arrays (R), (2) the flow of wavefronts between epicardial arrays (W), and (3) the relative activation rates of the two epicardial arrays (F). R did not correlate with either W or F indicating that rotor-containing regions did not produce a net outflow of wavefronts and were not faster than neighboring regions. Thus, sustained epicardial, but not intramural, rotors were consistently present in some large animal hearts during VF. However, we found no evidence that these rotors were responsible for sustaining VF through the mechanisms outlined in the mother rotor hypothesis. |
2,661 | Wavebreak formation during ventricular fibrillation in the isolated, regionally ischemic pig heart. | Both fixed and dynamic heterogeneities were implicated in the mechanism of wavebreak (WB) generation during ventricular fibrillation (VF). However, their relative roles remain unclear. We hypothesized that during ischemic VF, the WBs are produced primarily because of a fixed heterogeneity; namely, the gradient of refractoriness across the ischemic border zone (BZ). Ischemia was induced in 15 isolated blood-perfused hearts by occluding the left anterior descending coronary artery. Simultaneous video imaging (approximately 32x32 mm2) of Di-4-ANEPPS fluorescence in the ischemic zone (IZ), the BZ, and the nonischemic zone (NIZ) was performed. Dominant-frequency maps were constructed to assess gradients of refractoriness during VF. We used singularity points analysis to quantify the incidence of WBs per square centimeter per second. During preischemic VF, the distribution of WBs was relatively uniform. Ischemia caused an increase of WBs in the BZ (from 6.2+/-2.8 to 10.8+/-4.0) and a decrease of WBs in the IZ (from 5.8+/-2.8 to 2.8+/-1.4), without a significant change in NIZ (from 6.4+/-2.3 to 4.1+/-1.7). This finding is fully consistent with the dominant-frequency distribution during ischemic VF: the average dominant frequency was significantly slower in IZ than in NIZ (7.8+/-0.7 versus 10.1+/-1.0 Hz), suggesting a large gradient in refractory periods across the BZ. We concluded that acute regional ischemia plays a dual role in the maintenance of VF, decreasing the incidence of WB in the IZ while increasing it in the BZ. This suggests a predominant role of fixed heterogeneities in the formation of WB during VF in acute regional ischemia. |
2,662 | Increased vulnerability to ischemia/reperfusion-induced ventricular tachyarrhythmias by pre-ischemic inhibition of nitric oxide synthase in isolated rat hearts. | The relationship between vulnerability to reperfusion-induced ventricular tachyarrhythmias, such as ventricular tachycardia (VT) and fibrillation (VF), and the endogenous activity of nitric oxide synthase (NOS) has not been well documented. The objective of the present study was to clarify whether the vulnerability to reperfusion-induced VT/VF changes with preishemic, sustained inhibition of NOS.</AbstractText>The experiments were performed using Langendorff-perfused isolated rat hearts, in which left ventricular pressure (LVP) and left ventricular cardiomyograms (LVCMGs) were measured.</AbstractText>A pre-ischemic, sustained inhibition of NOS resulted in an increased vulnerability to reperfusion-induced VT/VF, and the increase was markedly attenuated by co-treatment with L-arginine or by post-ischemic treatment with 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of tetrahydrobiopterin (BH(4)) synthesis. We then tried to elucidate whether nitric oxide (NO) and superoxide were produced during reperfusion, and ATP-sensitive potassium channels (K(ATP)), especially mitochondrial ATP-sensitive potassium channels (mitoK(ATP)), are involved in the increased vulnerability. Post-ischemic inhibition of NOS and treatment with a NO scavenger attenuated the increased vulnerability to reperfusion-induced VT/VF, but post-ischemic treatment with a superoxide scavenger did not. In addition, post-ischemic treatment with S-nitroso-N-acetyl-DL-penicillamine (SNAP), a NO donor, or with diazoxide, a selective opener of mitoK(ATP), increased the VT/VF duration during reperfusion. The increased vulnerability to VT/VF was attenuated by the treatment with a selective mitoK(ATP) blocker.</AbstractText>The results suggest that a pre-ischemic, sustained inhibition of NOS increases the vulnerability to reperfusion-induced VT/VF, and the NO-mitoK(ATP) pathway is one of the possible factors contributing to the increased vulnerability to VT/VF.</AbstractText> |
2,663 | Zoniporide: a potent and selective inhibitor of the human sodium-hydrogen exchanger isoform 1 (NHE-1). | The sodium-hydrogen exchanger isoform-1 (NHE-1) plays an important role in the myocardial response to ischemia-reperfusion; inhibition of this exchanger protects against ischemic injury, including reduction in infarct size. Herein we describe a novel, potent, and highly selective NHE-1 inhibitor, zoniporide (CP-597,396; [1-(quinolin-5-yl)-5-cyclopropyl-1H-pyrazole-4-carbonyl] guanidine). Zoniporide inhibits human NHE-1 with an IC(50) of 14 nM, has >150-fold selectivity vs. other NHE isoforms, and potently inhibits ex vivo NHE-1-dependent swelling of human platelets. This compound is well tolerated in preclinical animal models, exhibits moderate plasma protein binding, has a t(1/2) of 1.5 h in monkeys, and has one major active metabolite. In both in vitro and in vivo rabbit models of myocardial ischemia-reperfusion injury, zoniporide markedly reduced infarct size without adversely affecting hemodynamics or cardiac function. In the isolated heart (Langendorff), zoniporide elicited a concentration-dependent reduction in infarct size (EC(50) = 0.25 nM). At 50 nM it reduced infarct size by 83%. This compound was 2.5-20-fold more potent than either eniporide or cariporide (EC(50)s of 0.69 and 5.11 nM, respectively), and reduced infarct size to a greater extent than eniporide. In open chest, anesthetized rabbits, zoniporide also elicited a dose-dependent reduction in infarct size (ED(50) = 0.45 mg/kg/h) and inhibited NHE-1-mediated platelet swelling (93% inhibition at 4 mg/kg/h). Furthermore, zoniporide attenuated postischemic cardiac contractile dysfunction in conscious primates, and reduced both the incidence and duration of ischemia-reperfusion-induced ventricular fibrillation in rats. Zoniporide represents a novel class of potent and selective human NHE-1 inhibitors with potential utility for providing cardioprotection in a clinical setting. |
2,664 | Relation between heart rate, heart rhythm, and reverse left ventricular remodelling in response to carvedilol in patients with chronic heart failure: a single centre, observational study. | To determine whether the process of reverse left ventricular remodelling in response to carvedilol is dependent on baseline heart rate (BHR), heart rhythm, or heart rate reduction (HRR) in response to carvedilol.</AbstractText>Retrospective analysis of serial echocardiograms in 257 patients with chronic systolic heart failure at baseline and at 12-18 months after starting carvedilol. Reverse left ventricular remodelling was determined by changes in left ventricular end diastolic dimension (LVEDD), end systolic dimension (LVESD), and fractional shortening (LVFS).</AbstractText>Heart failure clinic within a university teaching hospital.</AbstractText>Changes in LVEDD, LVESD, and LVFS.</AbstractText>LVEDD and LVESD decreased by 2.6 (0.4) mm and 4.9 (0.5) mm, respectively (mean (SEM)), and LVFS increased by 4.3 (0.5)% (all p < 0.0001 v baseline). Simple regression revealed no significant relation between BHR or HRR and the changes in LVEDD, LVESD, or LVFS. Stratification of patients into high and low BHR groups (above and below the mean) or according to the baseline heart rhythm (sinus rhythm v atrial fibrillation) showed no differences between groups in the extent of reverse left ventricular remodelling. Improvements in left ventricular function and dimensions were associated with significant improvements in New York Heart Association functional class.</AbstractText>The benefits of carvedilol in terms of reverse left ventricular remodelling and symptomatic improvement in patients with chronic heart failure are independent of BHR, heart rhythm, and the HRR that occurs in response to carvedilol.</AbstractText> |
2,665 | Effects of vasopressin on adrenal gland regional perfusion during experimental cardiopulmonary resuscitation. | Despite the important role of the adrenal gland during cardiac arrest, little is known about changes in the adrenal medullary or cortical blood flow in this setting. This study was designed to assess regional adrenal gland perfusion in the medulla and cortex during cardiopulmonary resuscitation (CPR), and after administration of adrenaline (epinephrine) versus vasopressin versus saline placebo.</AbstractText>After 4 min of untreated ventricular fibrillation, and 3 min of basic life support CPR, 19 animals were randomly assigned to receive either vasopressin (0.4 U/kg; n=7), adrenaline (45 microg/kg; n=6) or saline placebo (n=6), respectively. Haemodynamic variables, adrenal, and renal blood flow were measured after 90 s of CPR, and 90 s and 5 min after drug administration.</AbstractText>All values are given as mean+/-S.E.M. Blood flow in the adrenal medulla was significantly higher 90 s after adrenaline when compared with saline placebo in the right adrenal medulla (210+/-14 vs. 102+/-5 ml/min per 100 mg), and in the left adrenal medulla (218+/-14 vs. 96+/-3 ml/min per 100 mg). Blood flow in the adrenal medulla was significantly higher 90 s and 5 min after vasopressin when compared with adrenaline in the right (326+/-22 mg vs. 210+/-14 ml/min per 100 mg, and 297+/-17 vs. 103+/-5 ml/min per 100 mg), and in the left medulla (333+/-25 vs. 218+/-14 ml/min per 100 mg, and 295+/-14 vs. 111+/-7 ml/min per 100 mg). Ninety seconds and five minutes after vasopressin, and 90 s after adrenaline, adrenal cortex blood flow was significantly higher when compared with saline placebo. After 12 min of cardiac arrest, including 8 min of CPR, seven of seven pigs in the vasopressin group, one of six pigs in the adrenaline group, but none of six placebo were successfully defibrillated.</AbstractText>Both vasopressin and adrenaline produced significantly higher medullary and cortical adrenal gland perfusion during CPR than did a saline placebo; but vasopressin resulted in significantly higher medullary adrenal gland blood flow when compared with adrenaline.</AbstractText> |
2,666 | Survival and normal neurological outcome after CPR with periodic Gz acceleration and vasopressin. | We showed previously that whole body periodic acceleration along the spinal axis (pGz) is a novel method of cardiopulmonary resuscitation (CPR). The ultimate assessment of the value of any CPR technique is the neurological outcome after using such a technique. In this study, we determined the neurological outcome in pigs after prolonged pGz-CPR, with administration of vasopressin immediately prior to defibrillation. Neurological outcome after pGz-CPR was compared to a control group where no intervention occurred for the same time period (C-NoInterv).</AbstractText>Ventricular Fibrillation (VFIB) was induced in 12 animals. After a 3 min non-interventional interval, the animals received either pGz-CPR (n=7), or C-NoInterv (n=5) for 15 min. After 18 min of VFIB, a single dose of vasopressin (0.8 U/kg) was administered along with sodium bicarbonate and bretylium, and defibrillation was attempted. All animals in the pGz-CPR group had return of spontaneous circulation (ROSC) and normal neurological assessment at 24 h. Neurologic outcome remained normal at 48 h. In contrast, none of the animals in the C-NoInterv had ROSC.</AbstractText>Prolonged pGz-CPR, with administration of vasopressin immediately prior to defibrillation results in normal neurological outcomes at 24 h.</AbstractText> |
2,667 | 'Event tree' analysis of out-of-hospital cardiac arrest data: confirming the importance of bystander CPR. | The British National Service Framework (NSF) for heart disease commended the 'Utstein style' for auditing out-of-hospital cardiac arrests. The NSF also set standards for pre-hospital treatment and response times. To increase the flexibility of Utstein, an 'event tree' technique is proposed as an audit tool. Event trees consist of nodes and branches on which numbers, percentages or probability values are entered.</AbstractText>Using the London Ambulance Service's (LAS) 1997 database on 3,759 out-of-hospital cardiac arrests, 2,772 arrests witnessed by lay bystanders or unwitnessed were analysed focusing on bystander cardiopulmonary resuscitation (BCPR) and response times.</AbstractText>The Utstein template showed that witnessed arrests in ventricular fibrillation (VF) or ventricular tachycardia (VT) who had received BCPR achieved a return of spontaneous circulation (ROSC) in the field significantly more often than non-BCPR recipients-26 versus 16% (P=0.006). But the likelihood of being admitted to a hospital bed, and discharged alive, was only marginally better for BCPR recipients. To examine the influence of BCPR on the presenting rhythm an event tree showed that in 48% of witnessed BCPR cases the presenting rhythm was VF/VT, whereas, for witnessed non-BCPR cases, 27% were in VF/VT (P<0.0001). With unwitnessed arrests, 31% of BCPR cases were in VF/VT compared with 18% for non-BCPR cases (P<0.0001). Call to scene time was less than 8 min for 66% of all VF/VT arrests.</AbstractText>The event trees, when combined with the Utstein template, demonstrated the importance of examining comprehensively datasets for both witnessed and unwitnessed cardiac arrests when monitoring performance standards. The analyses also emphasised the relevance of community programmes in Greater London for teaching basic life saving skills.</AbstractText> |
2,668 | Evaluation of a defibrillator-basic cardiopulmonary resuscitation programme for non medical personnel. | To improve the outcome for out-of-hospital patients with ventricular fibrillation/pulseless ventricular tachycardia (VF/VT), the use of automated external defibrillators (AEDs) by first responders including non-medical personnel with a duty to respond to an emergency is recommended. A special CPR-AED course has been developed. We wanted to test the results (quality and speed of operating an AED and CPR) after completion of such a course and retention after approximately 1-year. At the same time we wanted to see if personnel could use an AED after receiving written information without having attended the course. Study subjects were divided randomly into groups, and tested pre-course (n=54), post-course (n=50), and unannounced 10+/-3 months after the course (retention group, n=61). For statistical analysis two sample tests for binomial proportions and Wilcoxon-Mann-Whitney test was used as appropriate. Fifteen of the 27 pairs (56%) in the pre-course group with no previous exposure to an AED decided to use it. There was no difference between the groups in electrode pad positioning, and all stayed clear of the manikin during the process of AED charging and shock delivery. The post-course group had a higher rate of checking for responsiveness (vs. pre-course), not to check for a pulse (vs. both other groups), the shortest time interval from arrival on scene to start of CPR and shock delivery, and in parallel the shortest hands-off interval (without chest compressions and ventilations) before shock delivery. The quality of chest compressions was improved by the course but decreased to a similar standard as in the pre-course when tested 10+/-3 months later, except for correct depth which was similar to post course. Most ventilation attempts in all groups were scored as incorrect due to the high incidence of excessively rapid inflations. The retention group had a lower frequency of correct inflations than the pre-course group, and the post-course group the highest number of correct ventilations per minute. These findings suggest that use of an AED by untrained laypersons may be feasible and that complex and time-consuming training programmes may not be necessary. The present study also supports the need for annual training and recertification. |
2,669 | Public access defibrillation in Helsinki--costs and potential benefits from a community-based pilot study. | In cardiac arrest the interval between the collapse and defibrillation may be shortened by teaching lay people to use defibrillators. We conducted a 3-year prospective, community-based study on public access defibrillation (PAD) in an urban emergency medical services system. All public sites with a cardiac arrest incidence of at least one per year were equipped with automated external defibrillators. Twenty cardiac arrest patients were enrolled, seven in PAD and 13 in control group. Defibrillation was accomplished significantly earlier (P=0.01) in the PAD group. The direct costs were 110,270 Eur and only 13.5-16% of this figure would be related to the cost of defibrillators during their 8 years lifespan. This study showed that a community based model of PAD shortens the time to CPR and defibrillation significantly in an urban environment but various challenges have to be solved before wider implementation of PAD. In future projects the nature of the costs especially should be considered. |
2,670 | Electrical injury as a possible cause of sick sinus syndrome. | Electrical injury is a serious public health problem. Heart is one of the most frequently affected organs. Electrical injury can cause life-threatening cardiac complications such as asystole, ventricular fibrillation, and myocardial rupture. In this case report, we present a 20-yr-old male patient with sick sinus syndrome that developed years after electrical injury. |
2,671 | Quality of life after use of the patient activated atrial defibrillator. | The aim of the study was to evaluate the effects of long-term use of the patient-activated atrial defibrillator for recurrent persistent atrial fibrillation (AF) on quality of life (QOL). Fifteen patients were implanted with the Medtronic Jewel AF 7250 device (dual chamber atrial and ventricular defibrillator) for AF only. AF recurrences were treated by out-of-hospital patient-activated atrial defibrillation shocks following the self-administration of oral sedation. QOL was assessed at pre-implant and up to one year with SF36, symptom checklist and HADS questionnaires. A total of 238 (median 10) out-of-hospital patient-activated atrial defibrillation shocks were performed. The SF36 demonstrated a trend toward improvement over the 12-month period compared with baseline values. There was no significant change in the symptom frequency or severity scores. Pre-implant levels of both anxiety and depression were within the predefined range of normality (6 +/- 3 and 3 +/- 2, respectively) and no significant change was seen at 6 months (5 +/- 4 and 3 +/- 3) or 12 months post implant (5 +/- 4 and 2 +/- 2, respectively). After one year of follow-up, 13 (87%) patients said they would have the device implanted again (two were undecided). The study demonstrates that patient-activated atrial defibrillation is a well tolerated therapeutic strategy for maintaining sinus rhythm. |
2,672 | Effectiveness of percutaneous mechanical mitral commissurotomy using the metallic commissurotome in patients with restenosis after balloon or previous surgical commissurotomy. | Balloon mitral valvuloplasty has been reported to give equal or less positive results after previous commissurotomy than after a first procedure. Percutaneous mechanical mitral commissurotomy (PMMC) is a new technique that has not yet been evaluated in this subset of patients. Of 1,175 PMMC procedures (1,175 patients), 173 patients (14.7%) had previous commissurotomy; patients were older (40 vs 35 years of age, p <0.0001) and more often in atrial fibrillation (34% vs 21%, p = 0.0016) than were patients who had not undergone previous commissurotomy. The baseline transmitral gradient was lower (17 +/- 8 vs 19 +/- 8 mm Hg, p <0.002) and the echocardiographic Wilkins score was higher (8.7 +/- 1.9 vs 7.6 +/- 1.8, p <0.0001) for patients who underwent previous commissurotomy. Baseline mitral valve area was comparable between the 2 groups (0.96 +/- 0.21 vs 0.93 +/- 0.24 cm(2)). Immediate results were satisfactory, although slightly less favorable after previous commissurotomy, with a final mitral valve area of 2.01 +/- 0.30 versus 2.12 +/- 0.36 cm(2) (p <0.0001), and a residual transvalvular gradient of 5.0 +/- 3.6 versus 4.2 +/- 4.1 mm Hg (p = 0.003). The rates of procedural success (93%) and severe complications (4.7%) were comparable between the 2 groups. Thus, PMMC is an effective and safe technique for the treatment of mitral restenosis after previous commissurotomy. |
2,673 | Cardiac resynchronization and death from progressive heart failure: a meta-analysis of randomized controlled trials. | Progressive heart failure is the most common mechanism of death among patients with advanced heart failure. Cardiac resynchronization, a pacemaker-based therapy for heart failure, enhances cardiac performance and quality of life, but its effect on mortality is uncertain.</AbstractText>To determine whether cardiac resynchronization reduces mortality from progressive heart failure.</AbstractText>MEDLINE (1966-2002), EMBASE (1980-2002), the Cochrane Controlled Trials Register (Second Quarter, 2002), The National Institutes of Health ClinicalTrials.gov database, the US Food and Drug Administration Web site, and reports presented at scientific meetings (1994-2002). Search terms included pacemaker, pacing, heart failure, dual-site, multisite, biventricular, resynchronization, and left ventricular preexcitation.</AbstractText>Eligible studies were randomized controlled trials of cardiac resynchronization for the treatment of chronic symptomatic left ventricular dysfunction. Eligible studies reported death, hospitalization for heart failure, or ventricular arrhythmia as outcomes. Of the 6883 potentially relevant reports initially identified, 11 reports of 4 randomized trials with 1634 total patients were included in the meta-analysis.</AbstractText>Trial reports were reviewed independently by 2 investigators in an unblinded standardized manner.</AbstractText>Follow-up in the included trials ranged from 3 to 6 months. Pooled data from the 4 selected studies showed that cardiac resynchronization reduced death from progressive heart failure by 51% relative to controls (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.25-0.93). Progressive heart failure mortality was 1.7% for cardiac resynchronization patients and 3.5% for controls. Cardiac resynchronization also reduced heart failure hospitalization by 29% (OR, 0.71; 95% CI, 0.53-0.96) and showed a trend toward reducing all-cause mortality (OR, 0.77; 95% CI, 0.51-1.18). Cardiac resynchronization was not associated with a statistically significant effect on non-heart failure mortality (OR, 1.15; 95% CI, 0.65-2.02). Among patients with implantable cardioverter defibrillators, cardiac resynchronization had no clear impact on ventricular tachycardia or ventricular fibrillation (OR, 0.92; 95% CI, 0.67-1.27).</AbstractText>Cardiac resynchronization reduces mortality from progressive heart failure in patients with symptomatic left ventricular dysfunction. This finding suggests that cardiac resynchronization may have a substantial impact on the most common mechanism of death among patients with advanced heart failure. Cardiac resynchronization also reduces heart failure hospitalization and shows a trend toward reducing all-cause mortality.</AbstractText> |
2,674 | [Arrhythmogenic right ventricular dysplasia as a cause of "sudden cardiac death" with survival]. | A 42 year old woman was resuscitated from ventricular fibrillation. 5 months previously she had a syncope. Her nephew had died of sudden cardiac death at the age of 25 years.</AbstractText>There was no evidence for ST segment elevation, myocardial infarction or pulmonary embolism. The ECG showed right precordial T wave inversion. Coronary artery disease was excluded angiographically. Echocardiography and angiography revealed inferior wall akinesia of the right ventricle with normal left ventricular function and chamber size. Ventricular fibrillation could not be reproduced by programmed stimulation of the right ventricle during an electrophysiologic study. Results of endomyocardial biopsy of the right ventricle showed a focal fibrous infiltration of the myocardium. Magnetic resonance imaging confirmed inferior wall abnormalities of the right ventricle without typical fatty infiltration in the right ventricular myocardium.</AbstractText>The patient recovered rapidly without neurologic deficits. Arrhythmogenic right ventricular dysplasia was suspected, and a cardioverter defibrillator (ICD) was implanted. Within 6 months after implantation the ICD memory showed no evidence of ventricular fibrillation.</AbstractText>Arrhythmogenic right ventricular dysplasia is an important cause of ventricular fibrillation with a potential risk of sudden cardiac death in young persons. Concealed arrhythmogenesis as an early manifestation of right ventricular dysplasia is difficult to detect.</AbstractText> |
2,675 | Prognostic and clinical significance of newly acquired complete right bundle branch block in Japan Airline pilots. | The purpose of this study was to evaluate the prognostic and clinical significance of newly acquired complete right bundle branch block (CRBBB) in airline pilots.</AbstractText>This study included pilots with acquired CRBBB, identified from a group of over 2,700 Japan Airline pilots. When the pilots applied for employment, a past medical history, physical examination, electrocardiogram, and chest radiograph were obtained. The pilots with ECG abnormality including CRBBB were not included in the study because of hiring requirements.</AbstractText>Thirty-six pilots with CRBBB were identified between 1983 and 2002. All pilots with CRBBB were evaluated for the presence of ischemic heart disease by treadmill exercise testing, echocardiogram and exercise thallium scintigraphy. Twelve individuals underwent coronary angiography. The mean age of pilots was 44.4 +/- 5.8 years. The mean observation period was 10.9 +/- 5.7 years. For each of the 36 study subjects, Holter electrocardiogram and echocardiogram were obtained every 6 months after the CRBBB was detected. Exercise stress testing was performed every year. Exercise thallium scintigraphy was performed every 2 years to detect ischemic heart disease. During the observation period, two pilots stopped flying temporarily because of frequent ventricular premature beats and one pilot stopped flying permanentaly because of atrial fibrillation. During the follow-up period, no cardiovascular events were observed in pilots with CRBBB who had no underlying ischemic heart disease.</AbstractText>Acquired CRBBB does not confer a poor prognosis, particularly in young men working as a pilot if there is no evidence of ischemia on exercise stress testing, echocardiography and exercise thallium scintigraphy.</AbstractText> |
2,676 | [Analysis and detection of abnormal ECG signal: ventricular tachycardia and fibrillation]. | This paper, utilizing signal power spectrum and L-Z complexity measure, analyzes the abnormal ECG: ventricular tachycardia (VT) and ventricular fibrillation (VF). And on the base of linear and nonlinear dynamics, the paper forwards a new definition of information complexity rate, deduces some relative properties and applies it to complexity analysis in irregular ECG. By means of biological experiments and computer simulations, the reasonability of information complexity and complexity rate is confirmed. At last, objective analysis and explanations of the mechanism of VT and VF are reported. The results indicate: with the help of power spectrum, complexity measure and complexity rate, the recognition of VT and VF can attain 100%. |
2,677 | [The development of a 64-channel epicardial potential mapping system]. | A 64-channel epicardial potential mapping system was developed in order to study the mechanics of arrhythmia such as atrial fibrillation and ventricular fibrillation, and instruct the procedure of detecting and eliminating abnormal rhythm in experiment or clinic. The system was consist of electrode, amplifier, A/D card, computer and output device. The system's software include signal acquisition module, signal preprocessing module, character-point detecting module, isochrone-map construction module, output display and print module. The system could be used to detect the activation path of atrial fibrillation and ventricular fibrillation. |
2,678 | A novel approach to identifying antiarrhythmic drug targets. | Sudden cardiac death, secondary to ventricular fibrillation (VF), remains the leading cause of death in the USA. Recent experimental and theoretical studies suggest that VF could be caused by spiral wave re-entry. The initiation and subsequent break-up of spiral waves has been linked to electrical alternans, a phenomenon produced in cardiac tissue that has a steeply sloped restitution relation. Agents that reduce the slope of the restitution relation have been shown to suppress alternans and, presumably by that mechanism, terminate VF. These results suggest that electrical restitution could be a promising new target for antiarrhythmic therapies. |
2,679 | Effect of atrial fibrillation on the dynamics of mitral annular area. | The mitral annulus shows dynamic changes in shape and size during the cardiac cycle. A smaller size in end-diastole is attributed to the sphincteric action of atrial systole, and this may be important for functional integrity of the mitral valve. However, the effect of atrial fibrillation (AF) on dynamic changes in mitral annular size in humans is not known.</AbstractText>Mitral annular diameters in apical four- and two-chamber views were measured using echocardiography in 25 patients in atrial fibrillation, and in 37 subjects in normal sinus rhythm at mid-diastole, end-diastole and end-systole. Mitral annular area was computed assuming elliptical geometry.</AbstractText>Patients in sinus rhythm showed a significant increase in mitral annular area of 25.9 +/- 12.8% with ventricular systole compared to its area in end-diastole (p < 0.0001), and a 10.5 +/- 8.4% reduction with atrial systole compared to mid-diastole (p < 0.001). Patients in AF had larger mitral annuli which showed non-significant changes in size between these three phases of the cardiac cycle. Percent reduction in mitral annular area in the latter half of diastole correlated significantly with left atrial (LA) diameter (r = -0.54, p < 0.0001), LA volume (r = -0.50, p < 0.0001), left ventricular (LV) fractional shortening (r = 0.37, p = 0.0036), mitral annular area in mid-diastole (r = -0.41, p = 0.0011) and mitral annular area in end-diastole (r = -0.64, p < 0.0001). That is, atrial sphincteric action on the mitral annulus was less in the presence of larger left atrium or the mitral annulus. Stepwise multiple regression analysis showed rhythm and mitral annular size to be independent predictors of dynamic changes in mitral annular area.</AbstractText>It is concluded that AF blunts or eliminates the phasic changes in mitral annular size during the cardiac cycle with loss of its presystolic sphincteric action; this may have implications in the genesis and surgical correction of mitral regurgitation.</AbstractText> |
2,680 | [Clinical and experimental study of effect of yangxin fumai oral liquid in treating patients with extrasystole]. | To evaluate the therapeutic effect of Yangxin Fumai Oral Liquid (YFOL), a Chinese herbal medicine for nourishing heart and restoring pulse, in treating patients with extrasystole.</AbstractText>The effect of YFOL was observed in treating 30 patients with different kinds of extrasystole and compared with that in 30 patients treated by propafenone. The effect of YFOL on experimental arrhythmia was studied in animals as well.</AbstractText>Clinical observation showed that the effect of YFOL against extrasystole in the two groups was similar, but the YFOL group showed better effect in symptom improvement (P < 0.01) with no marked side-effects. Experimental study showed that YFOL could reduce the chloroform induced ventricular fibrillation occurrence in mice, delay the initiating time of ventricular extrasystole, tachycardia and fibrillation induced by aconitine, BaCl2 and coronary artery ligation in rats, or shorten the lasting time of arrhythmia, reduce the attacking rate of ventricular extrasystole. There was significant difference in comparing with the control group (P < 0.05, P < 0.01).</AbstractText>YFOL is a good and convenient Chinese herbal preparation for different kinds of extrasystole with low toxic and side-effects in clinical practice.</AbstractText> |
2,681 | Should vasopressin replace adrenaline for endotracheal drug administration? | Arginine vasopressin was established recently as a drug of choice in the treatment of cardiac arrest and in retractable ventricular fibrillation; however, the hemodynamic effect of vasopressin following endotracheal drug administration has not been fully elucidated. We compared the effects of endotracheally administered vasopressin vs. adrenaline on hemodynamic variables in a canine model, and we investigated whether vasopressin produces the same deleterious immediate blood pressure decrease as did endotracheal adrenaline in the canine model.</AbstractText>Prospective controlled study.</AbstractText>Animal laboratory in Tel-Aviv University, Israel.</AbstractText>Five adult mongrel dogs weighing 6.5-20 kg.</AbstractText>Dogs were anesthetized; each dog was intubated orally, and both femoral arteries were cannulated for the measurement of arterial pressure and for sampling blood gases. Each dog was studied four times, 1 wk apart, by using the same protocol for injection and anesthesia: endotracheal placebo (10 mL NaCl 0.9%,), endotracheal vasopressin (1 units/kg), endobronchial adrenaline (0.1 mg/kg), and endotracheal adrenaline (0.1 mg/kg). Following placebo, vasopressin, and adrenaline instillation, five forced manual ventilations were delivered with an Ambu bag. Each dog was its own control.</AbstractText>Following placebo or drug administration, heart electrocardiography and arterial pressures were continuously monitored with a polygraph recorder for 1 hr. Endotracheal vasopressin produced an immediate increase of diastolic blood pressure (from 83 +/- 10 mm Hg [baseline] to 110 +/- 5 mm Hg at 1 min postinjection). This response lasted >1 hr. In contrast, both endotracheal and endobronchial administration of adrenaline produced an early and significant (p <.05) decrease in diastolic and mean blood pressures. The diastolic blood pressure increase from 85 +/- 10 mm Hg to 110 +/- 10 mm Hg took an ill-afforded 55 secs following endotracheal adrenaline. Diastolic blood pressure was significantly (p <.05) higher following vasopressin compared with adrenaline administration in both routes.</AbstractText>Vasopressin accomplishes its hemodynamic effect, particularly on diastolic blood pressure, more rapidly, vigorously, and protractedly and to a significant degree compared with both endotracheal and endobronchial adrenaline. Evaluation of the effects of endotracheal vasopressin in a closed chest cardiopulmonary resuscitation model is recommended.</AbstractText> |
2,682 | Effectiveness of direct-current cardioversion for treatment of supraventricular tachyarrhythmias, in particular atrial fibrillation, in surgical intensive care patients. | To evaluate primary success rate and effectiveness of direct-current cardioversion in postoperative critically ill patients with new-onset supraventricular tachyarrhythmias.</AbstractText>Prospective intervention study.</AbstractText>Twelve-bed surgical intensive care unit in a university teaching hospital.</AbstractText>Thirty-seven consecutive, adult surgical intensive care unit patients with new-onset supraventricular tachyarrhythmias without previous history of tachyarrhythmias.</AbstractText>Direct-current cardioversion using a monophasic, damped sinus-wave defibrillator. Energy levels used were 50, 100, 200, and 300 J for regular supraventricular tachyarrhythmias (n = 6) and 100, 200, and 360 J for irregular supraventricular tachyarrhythmias (n = 31).</AbstractText>None of the patients was hypoxic, hypokalemic, or hypomagnesemic at onset of supraventricular tachyarrhythmia. Direct-current cardioversion restored sinus rhythm in 13 of 37 patients (35% primary responders). Most patients responded to the first or second direct-current cardioversion shock. Only one of 25 patients requiring more than two direct-current cardioversion shocks converted into sinus rhythm. Primary responders were significantly younger and demonstrated significant differences in arterial Po2 values at onset of supraventricular tachyarrhythmias compared with nonresponders. At 24 and 48 hrs, only six (16%) and five (13.5%) patients remained in sinus rhythm, respectively.</AbstractText>In contrast to recent literature, direct-current cardioversion proved to be an ineffective method for treatment of new-onset supraventricular tachyarrhythmias and, in particular, atrial fibrillation with a rapid ventricular response in surgical intensive care unit patients.</AbstractText> |
2,683 | Sudden cardiac death in dilated cardiomyopathy -- therapeutic options. | Despite routine use of angiotensin-converting enzyme (ACE) inhibitors, beta-blockers and spironolactone in patients with heart failure due to dilated cardiomyopathy (DCM), these patients still have a considerable annual mortality rate of 5-10%. Sudden unexpected death accounts for up to 50% of all deaths and is most often due to rapid ventricular tachycardia or ventricular fibrillation and less often due to bradyarrhythmias or asystole.</AbstractText>The use of beta-blockers in patients with heart failure has been shown to improve overall mortality considerably. This survival benefit has been demonstrated for bisoprolol, metoprolol and carvedilol. Therefore, one of these three beta-blocking agents should be administered routinely starting with low doses in all patients with New York Heart Association (NYHA) class II or III heart failure in addition to ACE inhibitors, unless there is a contraindication to beta-blocker use. In addition, NYHA class IV heart failure patients have been shown to benefit from carvedilol therapy, if tolerated. The conflicting results of GESICA and CHF-STAT studies do not support a strategy of "prophylactic" amiodarone therapy in patients with DCM in order to prevent sudden cardiac death. Despite growing evidence that implantable cardioverter defibrillator (ICD) therapy results in improved overall survival py preventing sudden cardiac death in patients at high risk for serious arrhythmic events, arrhythmia risk stratification with regard to prophylactic ICD implantation remains highly controversial in patients with DCM.</AbstractText>This review describes potential arrhythmia mechanisms in DCM and summarizes the results of antiarrhythmic drug trials and of prophylactic ICD trials in patients with heart failure as well as our knowledge concerning arrhythmia risk stratification in patients with DCM.</AbstractText> |
2,684 | Molecular mechanisms of inherited ventricular arrhythmias. | Inherited ventricular arrhythmias such as the long QT syndrome (LQTS), Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia (CPVT), idiopathic ventricular fibrillation (VF), and arrhythmogenic right ventricular cardiomyopathy (ARVC) account for a relevant proportion of sudden cardiac death cases in young patients cohorts. The detailed pathogenetic mechanisms of inherited ventricular arrhythmias are still poorly understood because systematic investigations are difficult to perform due to low patient numbers and the lack of appropriate experimental models. However, recent advances in research and science have identified a genetic background for many of these diseases.</AbstractText>In LQTS, various mutations in different genes encoding for cardiac potassium and sodium channel proteins have been identified ("channelopathy"), and initial progress in genotype-phenotype correlation is made. Mutations in the cardiac sodium channel gene have also been identified in a subset of patients with Brugada syndrome, whereas a genetic background has not yet been demonstrated in idiopathic VF and right ventricular outflow-tract tachycardia (RVO-VT). Very recently, mutations in the cardiac ryanodine receptor gene have been identified in CPVT and in a subgroup of patients with ARVC. Although several chromosomal loci were suggested, no other responsible genes or mutations have been found in autosomal dominant forms of ARVC. However, in Naxos disease, a recessive form of ARVC with coexpression of palmoplantar keratoderma and woolly hair, a mutation in the plakoglobin gene has recently been discovered, thus underscoring the potential role of genetic alterations in cytoskeletal proteins in ARVC.</AbstractText>In the next years, significant progress in the genetic diagnosis pathophysiologic understanding of disease mechanisms, genotype-phenotype correlation, and the development of gene- or target-directed treatment strategies can be expected in the field of inherited ventricular arrhythmias.</AbstractText>This review summarizes the current knowledge of the molecular mechanisms, including aspects of pathoanatomy, autonomic innervation, genetics, and genotype-phenotype correlations with their potential implications for diagnosis and treatment of inherited ventricular arrhythmias.</AbstractText> |
2,685 | Atrial fibrillation in hypertension: predictors and outcome. | Incidence, determinants, and outcome of atrial fibrillation in hypertensive subjects are incompletely known. We followed for up to 16 years 2482 initially untreated subjects with essential hypertension. At entry, all subjects were in sinus rhythm. Subjects with valvular heart disease, coronary artery disease, preexcitation syndrome, thyroid disorders, or lung disease were excluded. During follow-up, a first episode of atrial fibrillation occurred in 61 subjects at a rate of 0.46 per 100 person-years. At entry, subjects with future atrial fibrillation differed (all P<0.05) from those without by age (59 versus 51 years), office, and 24-hour systolic blood pressure (165 and 144 versus 157 and 137 mm Hg, respectively), left ventricular mass (58 versus 49 g/height[m](2.7)), and left atrial diameter (3.89 versus 3.56 cm). Age and left ventricular mass (both P<0.001) were the sole independent predictors of atrial fibrillation. For every 1 standard deviation increase in left ventricular mass, the risk of atrial fibrillation was increased 1.20 times (95% CI, 1.07 to 1.34). Atrial fibrillation became chronic in 33% of subjects. Age, left ventricular mass, and left atrial diameter (all P<0.01) were independent predictors of chronic atrial fibrillation. Ischemic stroke occurred at a rate of 2.7% and 4.6% per year, respectively, among subjects with paroxysmal and chronic atrial fibrillation. These data indicate that in hypertensive subjects with sinus rhythm and no other major predisposing conditions, risk of atrial fibrillation increases with age and left ventricular mass. Increased left atrial size predisposes to chronicization of atrial fibrillation. |
2,686 | Upper and lower limits of vulnerability to sudden arrhythmic death with chest-wall impact (commotio cordis). | In an animal model of commotio cordis, sudden death with chest-wall impact, we sought to systematically evaluate the importance of impact velocity in the generation of ventricular fibrillation (VF) with baseball chest-wall impact.</AbstractText>Sudden cardiac death can occur with chest-wall blows in recreational and competitive sports (commotio cordis). Analyses of clinical events suggest that the energy of impact is often not of unusual force, although this has been difficult to quantify.</AbstractText>Juvenile swine (8 to 25 kg) were anesthetized, placed prone in a sling to receive chest-wall strikes during the vulnerable time window during repolarization for initiation of VF with a baseball propelled at 20 to 70 mph.</AbstractText>Impacts at 20 mph did not induce VF; incidence of VF increased incrementally from 7% with 25 mph impacts, to 68% with chest impact at 40 mph, and then diminished at >/=50 mph (p < 0.0001). Peak left ventricular pressure generated by the chest blow was related to the incidence of VF in a similar Gaussian relationship (p < 0.0001).</AbstractText>The energy of impact is an important variable in the generation of VF with chest-wall impacts. Impacts at 40 mph were more likely to produce VF than impacts with greater or lesser velocities, suggesting that the predilection for commotio cordis is related in a complex manner to the precise velocity of chest-wall impact.</AbstractText> |
2,687 | Mechanism of syncope in patients with positive adenosine triphosphate tests. | We prospectively evaluated the mechanism of syncope in patients with positive adenosine triphosphate (ATP) tests (defined as the induction of atrioventricular [AV] block with a ventricular pause >/=6 s after an intravenous bolus of 20 mg ATP).</AbstractText>Patients with unexplained syncope tend to have more positive ATP tests results than those without syncope.</AbstractText>An implantable loop recorder (ILR) was inserted in 36 ATP-positive patients (69 +/- 10 years; 22 women; median of 6 syncopal episodes); 15 of them also had a positive response to tilt testing.</AbstractText>During the follow-up of 18 +/- 9 months, 18 patients (50%) had syncopal recurrence and 16 (44%) had an electrocardiographically documented episode: AV block (n = 3: paroxysmal in 2 and permanent in 1), AV block followed by sinus arrest (n = 1), sinus arrest (n = 5), sinus bradycardia <40 beats/min (n = 2), normal sinus rhythm (n = 2), sinus tachycardia (n = 1), rapid atrial fibrillation (n = 1), and ectopic atrial tachycardia (n = 1). Bradycardia was documented in a total of 11 cases (69%), and a long ventricular pause (4 to 29 s) was present in eight cases (50%). All three patients with ILR-documented AV block had previously had a negative tilt test, whereas seven of eight with ILR-documented sinus bradycardia or sinus arrest had previously had a positive tilt test.</AbstractText>In patients with adenosine-sensitive syncope, the mechanism of syncope is heterogeneous, although bradycardia is the most frequent finding. Adenosine triphosphate-induced AV block predicts AV block as the mechanism of spontaneous syncope in only a few tilt-negative patients.</AbstractText> |
2,688 | Detection and management of an implantable cardioverter defibrillator lead failure: incidence and clinical implications. | This study evaluated the long-term reliability of an implantable cardioverter defibrillator (ICD) lead to determine the incidence, clinical presentation, and management of lead failure.</AbstractText>Despite recent advances in ICD technology, the long-term reliability of ICD leads remains a significant problem.</AbstractText>Concern about long-term reliability of coaxial polyurethane ICD leads caused us to systematically study all patients implanted with Medtronic (Minneapolis, Minnesota) 6936 lead at our institution. We performed follow-up of 74 patients with 76 ICD leads that were implanted from February 28, 1995 to September 8, 1997. Thirty-seven patients underwent routine clinical ICD follow-up testing and ventricular fibrillation induction to determine the status of their ICD lead after a mean follow-up of 68.6 +/- 8.2 months.</AbstractText>The lead survival analysis shows a cumulative failure probability of 37% (confidence interval, 24% to 54%) at 68.6 months. Six patients demonstrated a previously undescribed mode of ICD lead failure: prolonged oversensing immediately after shock therapy. The use of short interval counters to monitor nonphysiologic R-R intervals and the measurement of ring-to-coil impedance detected early lead failures in five patients.</AbstractText>This analysis shows: 1) problems with ICD leads may not become apparent until late during follow-up and may become a significant late problem, 2) a "signature" mode of lead failure for the 6936 consisting of oversensing of electrical noise following shocks, 3) early detection of lead failure with a short interval counter algorithm or measurement of ring-to-coil impedance may be clinically useful.</AbstractText> |
2,689 | Effect of regional differences in cardiac cellular electrophysiology on the stability of ventricular arrhythmias: a computational study. | Re-entry is an important mechanism of cardiac arrhythmias. During re-entry a wave of electrical activation repeatedly propagates into recovered tissue, rotating around a rod-like filament. Breakdown of a single re-entrant wave into multiple waves is believed to underlie the transition from ventricular tachycardia to ventricular fibrillation. Several mechanisms of breakup have been identified including the effect of anisotropic conduction in the ventricular wall. Cells in the inner and outer layers of the ventricular wall have different action potential durations (APD), and support re-entrant waves with different periods. The aim of this study was to use a computational approach to study twisting and breakdown in a transmural re-entrant wave spanning these regions, and examine the relative role of this effect and anisotropic conduction. We used a simplified model of action potential conduction in the ventricular wall that we modified so that it supported stable re-entry in an anisotropic model with uniform APD. We first examined the effect of regional differences on breakdown in an isotropic model with transmural differences in APD, and found that twisting of the re-entrant filament resulted in buckling and breakdown during the second cycle of re-entry. We found that breakdown was amplified in the anisotropic model, resulting in complex activation in the region of longest APD. This study shows that regional differences in cardiac electrophysiology are a potentially important mechanism for destabilizing re-entry and may act synergistically with other mechanisms to mediate the transition from ventricular tachycardia to ventricular fibrillation. |
2,690 | The influence of spontaneous termination of atrial fibrillation on P wave-triggered signal-averaged electrocardiogram. | Prolongation of total filtered P wave duration (Ad) and low root mean square voltages for the last 20 ms of the P wave (LP20) on a P wave-triggered signal-averaged electrocardiogram (PSAECG) are typically observed in paroxysmal atrial fibrillation (PAF) patients. A shortening of atrial refractoriness and intra-atrial conduction delay (atrial remodeling) have been shown to occur in response to PAF. We, therefore, investigated the effects of spontaneous termination of PAF on the parameters of PSAECG.</AbstractText>We measured the Ad, LP20 and left atrial (LA) diameter by ultrasonic echocardiography before, within 1 h after, and 3 and 12 months after PAF termination in patients with no structural heart disease (n=11).</AbstractText>The PAF duration was 16+/-5 h. The Ads before, within 1 h after, and 3 and 12 months after PAF were 137+/-4, 148+/-4, 137+/-6, and 135+/-7 ms, respectively. The Ad within 1 h after PAF was significantly (P<0.01) longer than at the other three acquisition points. Although the LP20 within 1 h after PAF termination was not significantly different from the other three points, the change in LP20 (within 1 h after PAF-before PAF, -1.1+/-0.4 microV) in the long PAF duration group was significantly (P<0.05) greater than that of the short PAF duration group. LA diameter was unchanged at all points.</AbstractText>These data suggest that PAF results in prolongation of Ad after termination of PAF.</AbstractText> |
2,691 | Effects of verapamil and metoprolol on recovery from atrial electrical remodeling after cardioversion of long-lasting atrial fibrillation. | The aim of this prospective, randomized study was to investigate the effect of pretreatment with two different intracellular calcium-lowering drugs (verapamil and metoprolol) on recovery from atrial effective refractory period (AERP) shortening after internal electrical cardioversion (EC) of persistent atrial fibrillation (AF) in patients on amiodarone. Twenty-one patients on amiodarone for at least 30 days were referred to our hospital for internal EC of a persistent AF refractory to external EC. They were randomized to receive only amiodarone (group AMI, n=7), or amiodarone and verapamil 240 mg/day (group VER, n=7), or amiodarone and metoprolol 100 mg/day (group MET, n=7). Left AERP was measured 10 min and 24 h after EC. AERP was also determined in 13 controls. The AERP after 10 min was significantly shorter in group AMI (201 (31) ms, P<0.02) and group MET (203 (34) ms, P<0.03) than in controls (249 (45) ms), but not in group VER (237 (51) ms, P=NS). The AERP after 24 h was still significantly shorter in group AMI (204 (38) ms, P<0.04) than in controls, but not in group MET (225 (52) ms, P=NS) or in group VER (290 (36) ms, P=NS). Pretreatment with amiodarone and verapamil prevents AERP shortening, while pretreatment with amiodarone and metoprolol only accelerated AERP recovery. |
2,692 | Oral loading single dose flecainide for pharmacological cardioversion of recent-onset atrial fibrillation. | The efficacy and safety of the single oral loading dose of flecainide for cardioversion of recent-onset atrial fibrillation was examined by reviewing the trials on the subject identified through a comprehensive literature search. Most of the trials used a single dose of 300 mg for oral loading. The success rate ranged from 57 to 68% at 2-4 h and 75 to 91% at 8 h after drug administration. The conversion time ranged from 110+/-82 to 190+/-147 min, depending on the duration of observation after drug administration, which in most trials was of 8 h. Single oral loading regimen of flecainide was significantly more efficacious than placebo, and was as efficacious as the single oral loading regimen of propafenone. Both the single oral loading and the intravenous loading regimens of flecainide were equally efficacious but the intravenous regimen resulted in an earlier conversion. Adverse effects reported were mild non-cardiac side effects, reversible QRS complex widening, transient arrhythmias and left ventricular decompensation. The transient arrhythmias were chiefly at the time of conversion and included appearance of atrial flutter and sinus pauses. No life-threatening ventricular arrhythmia or death was reported. The single dose oral loading regimen of flecainide appears to be effective for cardioversion of recent-onset atrial fibrillation with a relatively rapid effect within 2-4 h, and is free of serious complications in patients without structural heart disease. Patients with substantial structural heart disease were excluded from most of the trials. |
2,693 | The frequency of systolic versus diastolic heart failure in an Egyptian cohort. | All factors predisposing for congestive heart failure (CHF), such as coronary artery disease (CAD), hypertension and diabetes are increasing in prevalence in Egypt. Despite this, no data about CHF in our country are available.</AbstractText>To study the relative contribution of systolic vs. diastolic heart failure in Egyptians and the prevalence of risk factors in this population, as well as their prognosis.</AbstractText>This was a retrospective study of patients with a diagnosis of CHF over a 3.5-year period in a general cardiology clinic. Demographic, ECG and echocardiographic data for left ventricular systolic and diastolic function were collected. The differential effect of systolic versus diastolic CHF was analyzed regarding hospitalization and mortality.</AbstractText>After exclusion of valvular diseases, we found 155 patients diagnosed with heart failure, 102 patients (66%) had systolic heart failure, and 53 (34%) had diastolic heart failure. Mean age was 60+/-10 and 63+/-11 years, respectively (P=0.13). Systolic CHF patients had significantly more CAD, while those with diastolic failure were mostly hypertensives (P<0.01) for both. There was no significant difference in the incidence of diabetes mellitus, cerebrovascular accidents or atrial fibrillation between the two groups. Patients with systolic failure required more hospitalization, P<0.05, and had a mortality rate of 17.6% vs. 11.3% for patients with diastolic heart failure (P=0.3).</AbstractText>Diastolic heart failure is present in one-third of cases of CHF in Egyptians. Hypertension is very common in this group. These patients require less hospitalization but have a similar mortality rate.</AbstractText> |
2,694 | Blood compatibility of a newly developed trileaflet mechanical heart valve. | An ideal heart valve prosthesis, which has both the flow dynamic properties and blood compatibility of a tissue valve prosthesis and the durability of a mechanical prosthesis, does not exist. The Triflo trileaflet mechanical heart valve (MHV; Triflo Medical Inc., Irvine, CA) is a newly developed MHV prosthesis with the following design goals: central flow, minimal flow disturbance and stasis around the hinge region, and durability. The current study was conducted to evaluate the blood compatibility of a 29 mm Triflo MHV in the mitral position of eight calves for 5 months without any postoperative anticoagulation. Whole blood platelet aggregometry and the Xylum Clot Signature Analyzer (Xylum Corporation, Scarsdale, NY) were used to evaluate the postoperative changes in platelet and coagulation functions. Full autopsies, histological examinations of major internal organs, and scanning electron microscopy analyses of the explants were performed. Early termination occurred in two cases; one was because of valve thrombosis on the 25th day, and the other was killed because of a nonvalvular complication on the 105th day. The valve thrombosis was attributed to prolonged ventricular fibrillation at the time of valve replacement surgery. Whole blood platelet aggregometry and clot signature analyzer parameters did not show any sign of activation of platelets or the coagulation system. No hemolysis was observed. There was no macroscopic valve thrombosis or embolism observed in the remaining seven cases. Scanning electron microscopy analyses showed clean leaflet and valve ring surfaces, with only occasional minute platelet aggregations. Excellent blood compatibility of the Triflo MHV was demonstrated in this study. |
2,695 | Clinical characteristics of induced nonclinical ventricular tachycardia in nonischemic cardiomyopathy. | The clinical significance of induced nonclinical ventricular tachycardia (NCVT) in nonischemic dilated cardiomyopathy (DCM) remains controversial. Twenty-eight patients with sustained VT or ventricular fibrillation related to DCM underwent programmed ventricular stimulation (PVS) to induce VT. However, VT was not induced in four patients. Based on the morphology of induced ventricular arrhythmia, we classified the remaining 24 patients into NCVT (n = l1 ) and clinical VT (CVT) groups (n = 13), then evaluated the prognosis for a mean follow-up period of 22 months. The cycle length of induced NCVT was significantly shorter than that of induced CVT (277 +/- 38 ms vs 325 +/- 63 ms, P < 0.05). Appropriate antiarrhythmic agents were selected by serial PVS in 36% of the NCVT group and in 38% of the CVT group (4/11 vs 5/13). Among patients who had been treated by PVS guided drug therapy, arrhythmic events were observed in 75% of the NCVT group and 80% of the CVT group (3/4 vs 4/5). The total incidence of sudden death in the NCVT group was higher than that in the CVT group (5/11: 45% vs 4/13: 31%). In conclusion, induced NCVT and CVT are refractory to pharmacological therapy and both have an important characteristic value in DCM. |
2,696 | Long-term follow-up of pacemakers with an Autocapture pacing system. | The aim of this study was to evaluate the safety and performance of the Autocapture pacing system during a 5-year follow-up period. The study was conducted retrospectively between May 1996 and May 2001. Sixty consecutive patients who had undergone VVI pacemaker implantation using an Autocapture program with leads 1402T (n: 31) and 1452T (n: 29) were included in the study. Intraoperative measurements including a ventricular stimulation threshold test, sensing of intrinsic R wave (mV), and lead impedance (W) were done by a standard pacing system analyzer. Evoked responses (ER, mV) and polarization signals (PS, mV) were measured after the pocket was closed. Pacing thresholds by Autocapture (AC thrd, V) and Vario (Vario thrd, V), battery current (mA), and battery impedance (kW) were also repeated during predischarge and 1, 6, 12, 18, 24, 30, 40, 50, and 60 months after discharge. According to the ER and PS values an Autocapture algorithm could be activated in 49 patients (88%). The Autocapture algorithm remained active during the follow-up in all of these patients. In patients with inappropriate ER and PS values (11 patients, 12%), pacemakers were programmed to a VVIR pacing mode and Autocapture algorithm was inactivated. ER and PS values did not reach appropriate values to activate the Autocapture algorithm in any of these patients in consecutive follow-ups. Twenty-four-hour Holter monitoring could be conducted in 32 patients (53%). In all recordings, when the loss of capture occurred, it was confirmed that back-up pacing continued. When the first measurements recorded during implantation were compared to approximately the 5th year measurements; ER (9.2 mV vs 9.6 mV), PS signal (1.13 +/- 0.30 mV vs 1.15 +/- 0.72 mV), AC thrd (0.4 V vs 1.2 V), Vario thrd (0.7 V vs 1.3 V), and lead impedance (502 ohm vs 620 ohm) were not changed significantly. Battery impedance increased 1 kOhm between 30-40 months of the implantation. Seven deaths occurred during follow-up. Three patients had fatal myocardial infarction, one died due to a non-cardiac event, and the remaining three died due to progressive heart failure.</AbstractText>ER, R wave amplitude, and PS, which are the main parameters for the continuation of Autocapture function, did not change significantly during long-term follow-up. High output back up pacing provided additional safety for sudden rises in threshold. The Autocapture pacing algorithm was found to be effective and reliable during long-term follow-up.</AbstractText> |
2,697 | Hyperthyroidism: a "curable" cause of congestive heart failure--three case reports and a review of the literature. | With the increasing incidence of coronary artery disease and the aging population, the prevalence of congestive heart failure (CHF) is increasing. In the majority of these cases the etiology is underlying coronary artery disease. Other less common causes of CHF include valvular heart disease, hypertension, alcoholic cardiomyopathy, and dilated cardiomyopathy. In addition, there are rare causes, one of which is hyperthyroidism. Hyperthyroidism can affect the cardiovascular system in a variety of ways. The cardiovascular manifestations range from sinus tachycardia to atrial fibrillation and from a high cardiac output state to CHF due to systolic left ventricular dysfunction. If the underlying hyperthyroidism is recognized and treated early the CHF in such cases can be cured. The authors present three cases of CHF due to systolic left ventricular dysfunction secondary to hyperthyroidism, which showed considerable improvement in the left ventricular function once the hyperthyroidism was treated. |
2,698 | Post-cardiac catheterization access site complications and low-molecular -weight heparin following cardiac catheterization. | The low molecular weight heparin enoxaparin is often administered to patients on long-term anticoagulation regimens who temporarily discontinue warfarin prior to undergoing invasive procedures. The clinical outcome of all enoxaparin-treated patients who underwent cardiac catheterization or coronary artery interventional procedures (n = 119) was evaluated. A total of 5 patients (4.2%) requiring anticoagulation (3 with chronic atrial fibrillation and 2 with ventricular thrombi) developed severe late enoxaparin-associated hemorrhagic or vascular complications at the femoral arterial puncture site between 3 and 11 days post-procedure. Complications included development of femoral arterial pseudoaneurysm (n = 3), hypotension (systolic blood pressure < 90 mmHg) (n = 2), acute decrease in hemoglobin levels to < 8.5 mg/dl (n = 4) and cardiac arrest (n = 1). In patients receiving standard dose enoxaparin after percutaneous invasive cardiac procedures, there is the potential for delayed and severe access site hemorrhagic and vascular complications. |
2,699 | [Indications of automatic ventricular implantable defibrillator. Implications for daily practice]. | The authors were the redactors of the Guidelines of the French Society of Cardiology for the indications of the automatic implantable defibillator, derived from the available indication in USA, and from the ulteriorly performed controlled studies. Three Class-I indications were selected: 1) circulatory arrest due to ventricular tachycardia (VT) or fibrillation (VF) whithout acute curable aetiology. 2) sustained VT with underlying heart disease and contractile alterations. 3) non-sustained VT with prior myocardial infarction and LVEF < 35% with inductible despite maximal drug therapy. Class-II indications were also three: 1) inheritable disease with high risk of sudden death without known effective therapy. 2) Syncope in patients with underlying heart disease and inductible VT or VF during electrophysiologic study. 3) VT or VF in patients in list for heart transplant. |
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