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4,700 | Clinical correlates of elevated plasma natriuretic peptides and Big endothelin-1 in a population of ambulatory patients with heart failure. A substudy of the Italian Network on Congestive Heart Failure (IN-CHF) registry. IN-CHF Investigators. | Activation of neuroendocrine factors plays a major role in the pathophysiology and progression of heart failure. The aim of the present study was 1) to assess the clinical correlates of elevated plasma natriuretic peptides [atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)] and Big endothelin-1 in a population of 180 ambulatory patients from the Italian registry of heart failure (Italian Network on Congestive Heart Failure, IN-CHF) in 22 clinical centers, 2) to assess the within-patient variability of plasma BNP concentration, and 3) to evaluate the analytical agreement for BNP determination between a core laboratory and local sites.</AbstractText>ANP and BNP were measured with specific immunoradiometric methods, Big endothelin-1 with an enzyme immunoassay.</AbstractText>Elevated BNP was associated with severe mitral valve regurgitation (odds ratio 8.546, 95% confidence interval 1.879-38.510, p = 0.0052); high circulating concentrations of ANP and BNP were found in older patients, and in patients with higher NYHA functional class or reduced left ventricular ejection fraction. Elevated plasma concentration of Big endothelin-1 was a strong and independent predictor of atrial fibrillation (odds ratio 4.001, 95% confidence interval 1.531-10.454, p = 0.0047). Plasma concentration of BNP was reasonably stable at 3-month interval in patients with mild-to-moderate heart failure (mean between-visit difference -1.5+/-45 pg/ml, n = 96). There was a satisfactory analytical agreement between the central laboratory and sites, over a broad range of concentrations (2-1133 pg/ml, n = 283) with a slope for the best line fitted by linear regression of 1.09 (r2 = 0.96).</AbstractText>BNP assay may become an appropriate tool for routine clinical practice in patients with congestive heart failure.</AbstractText> |
4,701 | Doppler-derived acceleration rate of right ventricular early filling reliably predicts mean right atrial pressure at baseline and after loading manipulations in patients with chronic heart failure. | We investigated whether Doppler-derived variables of tricuspid flow could estimate mean right atrial pressure and monitor its changes after loading manipulations in patients with chronic heart failure.</AbstractText>Simultaneous mean right atrial pressure (Swan-Ganz catheterization) and tricuspid Doppler recordings were initially evaluated in 136 patients (23 with atrial fibrillation) with chronic heart failure and severe left ventricular systolic dysfunction, and then were repeated in 18 patients after unloading (sodium nitroprusside infusion) and in 13 patients after overloading (active leg elevation) manipulations.</AbstractText>A significant correlation was observed between mean right atrial pressure and peak E velocity (r = 0.70), early deceleration time (r = -0.72) and acceleration time (r = -0.75). However, the best correlation found was between the acceleration rate of early flow and mean right atrial pressure, and it was identical in patients in sinus rhythm or with atrial fibrillation (r = 0.98). Moreover, after acute effective unloading or overloading manipulations, although all Doppler tricuspid variables changed significantly, the acceleration rate of early flow still emerged as the strongest independent predictor of mean right atrial pressure (r = 0.95 and 0.99, respectively).</AbstractText>Doppler-derived acceleration rate of early diastolic tricuspid flow is a powerful tool to predict mean right atrial pressure and to monitor its changes after loading manipulations.</AbstractText> |
4,702 | The risk of contrast media-induced ventricular fibrillation is low in canine coronary arteriography with ioxilan. | Previous studies have proposed that sodium supplement to nonionic contrast media (CM) can decrease the risk of ventricular fibrillation (VF). This study was designed to compare the occurence of VF induced by ioxilan (containing 9 mmol/LNa+) with other nonionic CMs. After wedging a catheter in the right coronary artery, test solutions including ioxilan, ioversol, iomeprol, and iopromide were infused for 30 sec at the rate of 0.4 ml/sec or until VF occurred. Then, incidence of VF, contact time (i.e. the time required to produce VF), and QTc were measured. Also, the CMs other than ioxilan were investigated at sodium levels adjusted to 9 and 20 mmol/L Na+. The incidence of VF with ioxilan (0%) was the lowest of all. In the other CMs, the incidence decreased in accordance with increase of sodium. Iomeprol and iopromide showed significant reduction of VF incidence at the sodium level of 20 mmol/L. The higher sodium supplements also prolonged the contact times. The increase of QTc was the greatest in ioxilan. Ioxilan has the least arrythmogenic property among the current low-osmolality nonionic CMs. This property might be attributable to an optimal sodium concentration of 9 mmol/L in the CM. |
4,703 | Inhibition of the Na(+)/H(+) exchanger attenuates phase 1b ischemic arrhythmias and reperfusion-induced ventricular fibrillation. | The sodium-hydrogen exchanger-isotype 1 (NHE-1) plays a critical role in myocardial ischemia-reperfusion injury. While studies employing less selective sodium-hydrogen inhibitors have demonstrated antiarrhythmic activity, only one study has examined the in vivo efficacy of selective NHE-1 inhibition in a canine model of ischemia-reperfusion-induced arrhythmia. In the present study, the antiarrhythmic activity of Benzamide, N-(aminoiminomethyl)-4-¿4-(2-furanylcarbonyl)-1-piperazinyl -3-(methy lsulfonyl), methanesulfonate (BIIB 513), a novel NHE-1 inhibitor, was examined. An in vivo canine model of myocardial ischemia-reperfusion injury in which 60 min of left anterior descending coronary artery (LAD) occlusion followed by 3 h of reperfusion was employed. BIIB 513 was infused either prior to ischemia or prior to reperfusion. Arrhythmias were quantified by single lead electrocardiogram. Infarct size, determined by triphenyltetrazolium staining, was expressed as a percent of the area-at-risk. In vivo, NHE-1 inhibition did not affect phase 1a arrhythmias, which occur within the first 10 min of occlusion, however, BIIB 513 significantly reduced the incidence of ischemia-induced phase 1b arrhythmias which occur between 10 and 30 min following occlusion and the incidence of reperfusion-induced ventricular fibrillation. Furthermore, NHE-1 inhibition significantly reduced infarct size, when the drug was administered either prior to ischemia or prior to reperfusion. NHE-1 inhibition selectively reduces both ischemia-induced phase 1b arrhythmias and reperfusion-induced ventricular fibrillation, and also markedly reduces myocardial infarct size when the drug is administered prior to ischemia or prior to reperfusion. |
4,704 | Atrial fibrillation: nonpharmacologic approaches. | Various nonpharmacologic interventions are available for patients with atrial fibrillation (AF) who are refractory to standard drug therapy. Atrioventricular junctional ablation and permanent pacing is a very effective therapy for patients with AF and a poorly controlled ventricular response. The surgical MAZE procedure has been performed on small numbers of patients but is remarkably successful in restoring and maintaining sinus rhythm. The role of permanent pacing as treatment for paroxysmal AF is undergoing evaluation and dual-site atrial pacing appears particularly promising in reducing the number of episodes of paroxysmal AF. Certainly the most exciting frontier in the treatment of AF is radiofrequency catheter ablation procedures. Our understanding of the mechanisms of paroxysmal AF and chronic AF has expanded enormously in the past 5 years. Radiofrequency lesions in pulmonary veins using standard technology will cure many cases of paroxysmal AF. However, catheter systems under development offer a great promise of treating most paroxysmal and chronic AF within the next few years. These developments will revolutionize our approach to this ever more prevalent clinical problem. |
4,705 | Drug choices in the treatment of atrial fibrillation. | When considering therapy for atrial fibrillation (AF), the dominant issues are rate control, anticoagulation, rhythm control, and treatment of any underlying disorder. Drug choices for rate control include beta-blockers, verapamil and diltiazem, and digitalis as first-line agents, with consideration of other sympatholytics, amiodarone, or nonpharmacologic approaches in resistant cases. Anticoagulation may be accomplished with aspirin or warfarin, with the latter preferred in all older or high-risk patients. Antiarrhythmic drug therapy may be used (1) to produce cardioversion (most effective with ibutilide or class IC agents in recent onset AF); (2) to facilitate electrical conversion (class III agents); (3) to prevent early reversion after cardioversion; (4) to maintain sinus rhythm during chronic therapy; and/or (5) to facilitate conversion of fibrillation to flutter, which may then be amenable to termination or prevention with antitachypacing or ablative techniques. Antiarrhythmic drug selection for AF is guided by efficacy considerations (most drugs are similar), by convenience, cost, and discontinuation considerations; and, most importantly, by safety considerations. When possible, agents with serious organ toxicity potential and proarrhythmic risk should be avoided as first-line choices. In structurally normal hearts, class IC antiarrhythmic drugs are least proarrhythmic and least organ toxic (when considered together). In normal hearts, sotalol, dofetilide, and potentially azimilide also appear to have attractive profiles. Amiodarone has low proarrhythmic risk but can produce bradyarrhythmias and toxicity. In hypertrophied hearts, the risk of torsade de pointes with class III/IA agents is enhanced, whereas in ischemia or conditions with impaired cell contact, whether functionally (as by ischemia) or anatomically (as by fibrosis, infiltration, etc), proarrhythmic risk with class I antiarrhythmic drugs (sustained ventricular fibrillation/flutter) is greatly increased. The class I drugs should be avoided in these circumstances. Additional issues to consider are where to initiate therapy (in- or outpatient), what follow-up protocols to use, and whether to limit therapy to proprietary drugs or to allow generic formulation substitution. Each of these considerations is detailed in this article. |
4,706 | Management of atrial fibrillation: therapeutic options and clinical decisions. | Atrial fibrillation (AF) is the most common, sustained tachyarrhythmia seen in clinical practice. Although it is not immediately life threatening, AF can cause troublesome symptoms and poses a risk of stroke. The patient's clinical status is often complicated by the presence of other cardiovascular or concomitant diseases. As a result, management of the patient with AF involves many questions and choices, all of which must be individualized. There are 3 general strategies for the management of patients with AF, including (1) restoration and maintenance of sinus rhythm, (2) control of ventricular rate, and (3) prevention of stroke. More than 1 strategy may be appropriate in some patients. Furthermore, either pharmacologic or nonpharmacologic options can be chosen in certain situations. Although some data from randomized clinical trials are available to aid in clinical decision-making, only the benefits of anticoagulation are supported by substantial evidence. This article explores practical approaches to several management issues and scenarios for which there are limited relevant clinical data. These include: (1) patient selection for ventricular rate control and assessment of treatment, (2) choice of antiarrhythmic drug for maintenance of sinus rhythm, (3) inpatient versus outpatient initiation of therapy, (4) definition of antiarrhythmic drug success, (5) methods of transthoracic direct cardioversion, and (6) prediction and prevention of AF after cardiac surgery. |
4,707 | Mechanism of ventricular defibrillation. The role of tissue geometry in the changes in transmembrane potential in patterned myocyte cultures. | The geometry of the myocardium may influence changes in transmembrane potential (DeltaVm) during defibrillation. To test this hypothesis, specific nonlinear structures (bifurcations, expansions, and curved strands or "bends") were created in patterned cultures of neonatal rat myocytes.</AbstractText>Extracellular field stimuli (EFS; 7 to 11 V/cm field strength) were applied parallel to the strands. Changes in Vm were measured with microscopic resolution using optical mapping techniques. In bifurcations, EFS produced 2 DeltaVm maxima (so-called secondary sources) at the shoulder of each limb that were separated by a decrease of either hyperpolarization or depolarization at the insertion of the stem strand. In expansions, EFS produced a significant decrease in DeltaVm at the insertion site of the expansion compared with the DeltaVm maxima measured at the lateral borders. In 50% of experiments, tertiary sources of opposite polarity appeared in the strand due to local electrotonic currents. New action potentials were propagated from the sites of DeltaVm maxima located at the lateral borders of the expansions. In bends, the strand oriented in parallel to the field dominated electrotonically and partially cancelled the sources produced by the perpendicular segment.</AbstractText>In electrically well-coupled nonlinear structures, EFS produced changes in Vm at resistive boundaries that were determined by the electrotonic interaction between sources of different, direction-dependent strength. In addition, the interaction between localized secondary sources at nonlinear boundaries generated local current circuits, which gave rise to further changes in Vm (tertiary sources).</AbstractText> |
4,708 | Effects of HNS-32, a novel antiarrhythmic drug, on ventricular arrhythmias induced by coronary artery occlusion and reperfusion in anesthetized rats. | HNS-32 (N1,N1-dimethyl-N2-(2-pyridylmethyl)-5-isopropyl-3, 8-dimethylazulene-1-carboxamidine: CAS 186086-10-2) is a newly synthesized compound, and possesses antiarrhythmic properties with vasodilator action in dog hearts. The aim of this study was to investigate the dose-dependent effects of HNS-32 on ischemia- and/or reperfusion-induced ventricular arrhythmias in anesthetized rats in vivo and compared with those of mexiletine. Saline or drugs were administered intravenously 5 min prior to coronary artery occlusion. On the ischemia-induced ventricular arrhythmias, HNS-32 showed dose-dependent reduction of total number of premature ventricular complexes (PVC) from 2091+/-225 to 656+/-116 and 286+/-69 beats/30 min (p < 0.05), the ventricular tachycardia (VT) duration from 183+/-33 to 28+/-9 and 4+/-2 sec (p < 0.05), the incidence of VT from 100 to 90 (n.s.) and 40% (p < 0.05), and the incidence of ventricular fibrillation (VF) from 50 to 0 and 0% (p < 0.05) with 3 and 5 mg/kg, respectively. Mexiletine also reduced these parameters to 936+/-159 beats/30 min (p < 0.05), 39+/-22 sec (p < 0.05), 90% (n.s.) and 10% (n.s.), respectively. HNS-32 completely suppressed the late reperfusion-induced arrhythmias, however mexiletine did not affect them. On the early reperfusion-induced ventricular arrhythmias, HNS-32 showed dose-dependent reduction of VT duration from 126+/-34 to 37+/-12 and 3+/-2 sec (p < 0.05), incidence of VT from 100 to 90 (n.s.) and 40% (p < 0.05), incidence of VF from 100 to 10 and 0% (p < 0.05), and mortality rate from 90 to 0 and 0% (p < 0.05), with 3 and 5 mg/kg, respectively. Mexiletine also reduced these parameters to 16+/-9 sec (p < 0.05), 80 (n.s.), 50 (p < 0.05), and 10% (p < 0.05), respectively. HNS-32 significantly reduced the heart rate in a dose-dependent manner, from 399+/-14 to 350+/-8 and 299+/-10 beats/min (p < 0.05) with 3 and 5 mg/kg, respectively. The antiarrhythmic effects of HNS-32 were more potent than that of the similar dose of mexiletine against occlusion-induced and reperfusion-induced arrhythmias in in vivo rats. |
4,709 | The management of hyperkalaemia in the emergency department. | Life threatening hyperkalaemia (> 7.0 mmol/l) is commonly associated with acute renal failure. Moderate hyperkalaemia (6.1-6.9 mmol/l) is also common and well tolerated in patients with chronic renal failure. Renal failure is the most common cause of hyperkalaemia although other causes to consider include drugs (potassium sparing diuretics, angiotensin converting enzyme inhibitors), hyperglycaemia, rhabdomyolysis and adrenal insufficiency. Hyperkalaemia affects the cardiac conducting tissue and can cause serious arrhythmias including ventricular fibrillation and asystolic arrest. Therefore it is important to treat hyperkalaemia promptly in the emergency department. This paper evaluates the therapeutic options available for treatment of hyperkalaemia. |
4,710 | Selective coronary angiography in pediatric patients. | Selective coronary angiography (SCA) is an important diagnostic tool in pediatric cardiology; however, there are few reports on its feasibility and safety in young patients. We reviewed our experience with SCA from July 1, 1993 to December 31, 1997. There were 158 cardiac catheterizations that included SCA in patients whose ages ranged from 2 days to 46 years (median, 5.3 years). The most common indication was surveillance for coronary vasculopathy after heart transplantation. A retrograde approach was used in all patients through the femoral artery (n = 157) or umbilical artery (n = 1). Preformed coronary catheters were used and the Judkins left (JL) and Judkins right (JR) were the most common catheters, with the catheter curve size correlating with patient height (R(2) =.76 for JL, R(2) =. 673 for JR). Complications during SCA included brief ST-T wave changes (11%), bradycardia (2.5%), and ventricular fibrillation (0. 6%). Complications of vascular access were transient pulse loss (6%), hematoma (5%), and rebleeding (0.6%). Only one case of femoral artery occlusion was encountered on subsequent cath. In conclusion, complications of SCA were infrequent and serious complications were rare. SCA can be safely performed in pediatric patients at any age including neonates. |
4,711 | Electrocardiography and 24-hour electrocardiographic ambulatory recording (Holter monitor) studies in children infected with human immunodeficiency virus type 1. The Pediatric Pulmonary and Cardiac Complications of Vertically Transmitted HIV-1 Infection Study Group. | Limited data are available on the electrocardiogram and ambulatory electrocardiogram recording (Holter) in children infected with the human immunodeficiency virus type 1 (HIV-1). The purpose of this study was to estimate the prevalence and cumulative incidence of rhythm and conduction abnormalities in HIV-1-infected children. Electrocardiograms and Holter monitoring studies were performed annually on 205 HIV-1-infected children enrolled after 28 days of life (group I), 93 HIV-1-infected infants enrolled during pregnancy or during the first 28 days of life (group IIa), and 463 HIV-1-uninfected infants enrolled during pregnancy or during the first 28 days of life (group IIb). The 5-year cumulative incidence in the group I children of second-degree atrioventricular block or supraventricular or ventricular tachycardia was 13.4%, and the 5-year incidence was higher for the older infected group I children (16.8% for children > or =4 years old at first study and 11.4% for children <4 years, p = 0.04). The mean corrected QT interval was also longer for the older infected group I children (p = 0.002) and prolonged in the HIV-1-infected compared to the HIV-1-uninfected group II children (p = 0.02). None of the children had atrial fibrillation or flutter. Arrhythmias are uncommon in children infected with HIV-1 and in children of HIV-1-infected mothers and the arrhythmias identified tend to be benign. Therefore, routine Holter monitoring does not appear to be indicated in asymptomatic children. |
4,712 | Left atrial appendage function in patients with different pacing modes. | Many studies suggest that patients who receive a ventricular pacemaker have a higher incidence of systemic thromboembolism compared to patients receiving a physiological pacemaker. However, the exact mechanism regarding the etiology of thromboembolism remains unclear. We evaluated the left atrial appendage (LAA) functions, using multiplane transesophageal echocardiography (TEE), in patients with different pacing modes. In order to evaluate the ejection fraction (EF), peak emptying (V(E)) and filling (V(F)) flow velocities of the LAA by TEE, we studied 31 patients (mean age 63+/-18.5 years) who had been paced for 5.0+/-2.9 years. Patients with atrial fibrillation, left ventricular dysfunction and mitral valve disease were excluded. The pacing indications were complete atrioventricular block (AVB) in 19 patients (9 VVI, 10 VDD or DDD) and sick sinus syndrome (SSS) in 12 patients (5 VVI, 7 DDD). Mean EF, V(E) and V(F) of the LAA were significantly lower in all patients with ventricular pacing (25.5+/-15.6%, 30.4+/-15.6 cm/s and 29. 1+/-19.2 cm/s, respectively) compared to those with physiologic pacing (48.5+/-16.9%, 59.6+/-16.3 cm/s, 57.9+/-18.5 cm/s, respectively) (P<0.01 in all). When patients were further classified with respect to underlying heart disease whether they had SSS or AVB, all measurements of the LAA (EF, V(E) and V(F)) in both subgroup of patients with SSS and AVB were found significantly lower in those with ventricular pacing than in those with physiologic pacing (Tables 3 and 4). This decrease, especially in LAA flow, was much greater in those with SSS (Mean V(E) and V(F) <20 cm/s). In a patient paced with VVI for SSS, a thrombus was detected within the LAA cavity. In conclusion, these results suggest that the pacing modality appeared to influence the LAA functions in paced patients. Patients with asynchronous ventricular pacing modes had a significantly higher incidence of depressed LAA functions than did patients with physiological pacing, especially more marked in patients with sick sinus syndrome. This may be a factor responsible for increased risk of thrombus formation and thromboembolic events in this patient population. |
4,713 | [Role of antiarrhythmics in the post-infarction period]. | In the thrombolytic era, the mortality of myocardial infarction has been considerably reduced. The prognosis has also improved due to early treatment and the correction of residual ischaemia. Betablockers are valuable antiarrhythmic agents, both in the acute and chronic phases of infarction. Irrespective of the size of the infarct scar, a better prognosis is observed in patients taking betablockers. Class I antiarrhythmics, though, should be proscribed after the results of the CAST studies: these antiarrhythmics are effective on ventricular arrhythmias but do not improve the prognosis because of their proarrhythmic effects aggravated by ischaemia or left ventricular dysfunction. Of the Class III antiarrhythmics, amiodarone has been shown to reduce the incidence of sudden death in the post-infarction period in patients with ventricular hyperexcitability or severe left ventricular dysfunction. At present, classical antiarrhythmic therapy is opposed to the implantation of an automatic defibrillator in cases of serious arrhythmias after myocardial infarction. |
4,714 | [Electrophysiologic and anatomic atrial remodeling: an atrial rhythmic cardiomyopathy]. | In 1995, Wijffels and Alessie, using a curious goat model of atrial fibrillation, introduced the concept of atrial remodelling. The classical atrial substrate (anatomopathological-dilatation and hypokinesis-, and electrophysiological-short refractory periods and decreased conduction-), appeared not only to be one of the causes of atrial fibrillation but also the consequence of atrial fibrillation itself, the mechanism being a vicious circle. In addition to ventricular rhythmic cardiomyopathy, responsible for cardiac failure, the concept of atrial rhythmic cardiomyopathy with the same mechanical and electrophysiological consequences, has developed. These changes, characterised mainly by calcium overload associated with cellular hibernation and differentiation, have not been totally elucidated but have already renewed the physiopathology of atrial fibrillation. |
4,715 | [Present concepts of congenital long QT syndrome]. | The congenital long QT syndrome is characterised by the presence of syncopes due to torsades de pointe which may degenerate to ventricular fibrillation and cause sudden death. These syncopes occur in young subjects with electrocardiographic abnormalities and prolongation of the QT interval. Patients with the autosomally dominant transmitted Romano-Ward syndrome with normal audition are classically opposed to those with the Jervell and Lange-Nielsen autosomally recessive syndrome who have bilateral total deafness. Our understanding of the congenital long QT syndrome has improved in recent years with respect to the physiopathology, diagnosis and treatment, due to research in the fields of genetics, electrocardiography and electrophysiology. The diagnosis is based on analysis of the phenotype and genotypes. A family enquiry is always necessary to detect unrecognised forms. Five culprit genes have been identified for the Romano-Ward syndrome. All code for subunits of sodium or potassium channels: two a subunits of the potassium channels (QVLQT1 for LQT1, HERG for LQT2), the a subunit of the sodium channel INa (SCN5A for LQT3), and two regulatory subunits of potassium channels (KCNE1 for LQT5 regulating the KvLQT1 channel and MiRP1 regulating HERG). The concept of genetic heterogeneity of the congenital long QT syndrome may thus be understood: different genes may be responsible for the same phenotype. Except for specific cases, the usual treatment is life-long betablocker therapy and the avoidance of a large number of drugs, the list of which is continually updated. A multicentre trial is underway to validate betablocker therapy for the prevention of cardiac events in a LQT1 genotype population. Prospective studies will be necessary to assess gene-specific treatments. |
4,716 | Non-pharmacological treatments for atrial fibrillation. A critical perspective on the status quo. | In a proportion of patients with atrial fibrillation, antiarrhythmic drugs are either ineffective, unsafe, or poorly tolerated. Accordingly, a variety of non-pharmacological treatments have been developed. This article critically reviews these modalities. (i) For ventricular rate control, catheter ablation of the atrioventricular node with pacemaker implantation is commonplace. An alternative is atrioventricular node modulation using a procedure similar to "slow pathway" ablation. (ii) For restoration of sinus rhythm, internal cardioversion using low energy shocks is highly effective; this has prompted the development of atrial and dual chamber defibrillators. (iii) To eliminate the atrial fibrillation substrate, a number of surgical procedures have been developed, of which the most effective is the "Maze" operation. The efficacy of this operation cannot be reproduced by conventional catheter ablation, and current research is concentrating on simplified procedures using new catheter designs for linear ablation. (iv) Finally, pacemakers and catheter ablation may be used to suppress the triggers for atrial fibrillation episodes. A number of atrial algorithms are under investigation for overdrive suppression of ectopy, and the use of multisite atrial pacing to alter the atrial response to ectopy has shown promising results. Catheter ablation has shown considerable success in preventing "focal" atrial fibrillation that is triggered or driven by ectopy arising usually from the pulmonary veins. To date, there are few data regarding the long-term efficacy and safety of these techniques, and their effects on quality of life. However, ongoing multicentre trials addressing these issues are expected to report over the next few years. |
4,717 | [Recurrent ventricular fibrillation during a febrile illness in a patient with the Brugada syndrome]. | Different situations have been involved in the origin of ventricular arrhythmic events in patients with the Brugada syndrome such as bradycardia, alcohol consumption and mental stress. We present a 30 year old male with recurrent ventricular fibrillation due to a febrile illness with intense sweating. He had been previously studied at our Unit in 1995 because of an episode of resuscitated cardiac arrest due to ventricular fibrillation. The twelve-lead electrocardiogram showed the typical characteristics of a patient with the Brugada syndrome. Different invasive and non-invasive tests performed were normal. He received a defibrillator and had no recurrences during 4 years of follow up. In March,1999, after an upper respiratory tract infection he had high fever treated with paracetamol but at down he had sweating and chills, followed by 3 defibrillator shocks. Late interrogation showed 5 episodes of ventricular fibrillation, two of them non-sustained, and the rest adequately treated by the defibrillator. Activation and inactivation kinetics for early INa are twofold faster at higher temperature, and shift activation and steady-state inactivation. This may explain the role of the temperature as a trigger for ventricular arrhythmias in our patient. |
4,718 | Atrial septal defect in adults. Thirty-eight-year follow-up of a surgically and a conservatively managed group. | This report describes the long-term (up to 38 years) outcome, in terms of mortality and cardiovascular morbidity, in a non-randomized clinical observation study of a surgically and a conservatively managed group of adult patients with shunt lesions at atrial level. Haemodynamic status was assessed at baseline and at repeat examination. Twelve patients underwent surgical repair of the lesion between these two heart catheterizations, resulting in a marked reduction in heart size and right ventricular systolic pressure. These changes were associated with improvement in functional class and a trend towards less risk of cerebrovascular incidents, but not atrial fibrillation, during follow-up. Among 12 patients not operated on between catheterizations, symptomatic deterioration was common, often necessitating later surgical repair. The results support the assumption that early surgery should be recommended for adults with a haemodynamically significant lesion, to reduce the risk of mortality and prevent symptomatic deterioration. |
4,719 | [Guidelines for cardiopulmonary resuscitation of children]. | In this article the European Resuscitation Council's guidelines for basic and advanced resuscitation of children are presented. There are some changes from the previous guidelines. Children are divided in three age categories (in addition to the newly born): children up to one year old, one to eight years old, and more than eight years old. In Norway, but not in the rest of Europe, evaluation of the circulation by pulse check has been eliminated in basic, but not in advanced resuscitation. This is due to reports that pulse checks by lay rescuers require much time with poor specificity and sensitivity. In evaluating the patient's own ventilation, the differentiation between agonal gasps and regular breaths is stressed. ECG monitoring provides the link between paediatric basic life support and advanced life support. The algorithm for the latter closely resembles that proposed for adults. While there were previously three separate algorithms for ventricular fibrillation/ventricular tachycardia, asystole and electromechanical dissociation, there is now only one algorithm. Ventilation and chest compressions should be performed for one-minute periods with ventricular fibrillation/ventricular tachycardia, for three-minute periods with other rhythms. |
4,720 | [Heart arrest caused by ventricular fibrillation in acute biliary pancreatitis: a case report and etiopathogenetic hypothesis]. | Acute pancreatitis and/or gallbladder disease precipitating angina pectoris, or producing arrhythmias or ST-T wave changes on electrocardiography in the absence of coronary artery disease, have frequently been mentioned. Many attempts have been made to explain the etiology of these findings. To the authors' knowledge, this report is the most dramatic expression of pathogenetic mechanisms which are still considered hypothetical. |
4,721 | Pumpless extracorporeal lung assist - experience with the first 20 cases. | Long-term extracorporeal lung assist is limited by a significant mechanical blood trauma resulting in bleeding and hemolysis. To reduce the drawbacks of extracorporeal lung assist a new technique has been developed, by which the driving force for the extracorporeal circuit derives from the patients arterio-venous pressure gradient (pumpless extracorporeal lung assist). The aim of this clinical study was to test the feasibilty and effectiveness of pumpless extracorporeal lung assist in patients with acute respiratory distress syndrome.</AbstractText>Twenty patients (41+/-16 years) with acute respiratory distress syndrome of various causes and failing respirator therapy were enrolled. The minimum hemodynamic requirements included a cardiac output (CO) >6 l/min and mean arterial pressure (MAP) >70 mmHg. Pumpless extracorporeal lung assist was established using a short circuit arterio-venous shunt including a special designed low-resistance membrane oxygenator which was placed between the patients legs.</AbstractText>At the time of inclusion FiO(2) in all patients was 1.0 (paO(2) 45.9+/-7 mmHg, paCO(2) 58.9+/-17 mmHg). After 24 h of pumpless extracorporeal lung assist FiO(2) was reduced to 0.8+/-0.1. A significant improvement in oxygenation (paO(2) 84.1+/-21 mmHg, P<0.05) and CO(2) removal (paCO(2) 32.7+/-5 mmHg, P<0.05) was notable. The mean extracorporeal flow was 2.6+/-0.6 l/min, which represented approximately 25% of the patients mean CO (10.8+/-2 l/min). The median assist time was 12+/-8 (1-32) days. Fifteen out of twenty patients were weaned off pumpless extracorporeal lung assist. Five out of twenty patients died while on the system (four sepsis, one ventricular fibrillation). Three out of twenty patients died after successful weaning on day 8, 30, and 50, respectively. Twelve out of twenty patients were discharged in a healthy state (overall survival 60%). Technical problems included thrombosis of the venous cannula (n=5), thrombus formation within the membrane oxygenator (n=2), membrane oxygenator plasma leakage (n=2), and membrane oxygenator contamination with Candida albicans. No bleeding complication was observed.</AbstractText>Pumpless extracorporeal lung assist is feasible and effective in a selected group of patients with acute respiratory distress syndrome but preserved hemodynamic function. By eliminating the pump and reducing the tubing length blood trauma can be minimized. Being very simple the system entails fewer risks of technical complications and also facilitates nursing care.</AbstractText> |
4,722 | Mitral valve surgery and atrial fibrillation: is atrial fibrillation surgery also needed? | Atrial fibrillation (AF) persisting after mitral valve surgery reduces survival due to heart failure and thrombo-embolisms, and impairs quality of life. Arrhythmia surgery for AF shows today very satisfying results and therefore mitral valve surgery with AF surgery appears appealing. This study explores whether combined surgery in view of today's results of mitral valve surgery is indicated.</AbstractText>An outcome analysis of the arrhythmia outcome of patients undergoing exclusive mitral valve surgery with or without tricuspid repair was done. Preoperative baseline characteristics including arrhythmia pattern, surgical methods and follow-up findings were reviewed. Postoperative management of AF was not protocolized. Between 1990 and 1993, 162 consecutive patients underwent mitral valve surgery; follow-up was a mean of 3.3+/-1.9 years. In-hospital and late mortality were 1 and 9%, respectively. Sinus rhythm was preserved in 40 of 57 (70%) patients with preoperative sinus rhythm whereas AF persisted in 58 of 68 (85%) of patients with preoperative chronic AF (>1 year present). Sinus rhythm without AF was observed in 10 of 29 (34%) patients with preoperative paroxysmal AF. The 4-year Kaplan-Meier survival did not differ between patients with preoperative sinus rhythm (95.2%), paroxysmal AF (89.2%) and chronic AF (82.9%) but AF persisting after surgery tended to determine survival (P=0.05). Gender, age and right ventricular pressure and tricuspid valve repair were risk factors for postoperative recurrence of AF in patients with sinus rhythm at discharge, relative risk 0.35, 1.06, 1. 04 and 2.9, respectively.</AbstractText>Current mitral valve surgery with or without tricuspid valve repair does not eliminate preoperative paroxysmal or chronic AF. Secondly, because preoperative AF did not determine survival after mitral valve surgery, whereas postoperatively persisting AF was weakly associated with survival, atrial arrhythmia surgery primarily aims to reduce morbidity due to AF. Some characteristics can identify patients with increased propensity for persisting AF after surgery. Randomized studies of AF surgery are needed to identify suitable candidates for combined surgery.</AbstractText> |
4,723 | E 047/1: a new class III antiarrhythmic agent. | The efficacy, pharmacokinetics, safety, and tolerability of E 047/1, an amiodarone derivative, were evaluated in patients with acute supraventricular or ventricular arrhythmia. In an open, nonrandomized prospective multicenter trial, 20 patients were treated with three different i.v. dosage regimens of E 047/1. Arrhythmia termination indicated efficacy. Pharmacokinetics were determined by measurements of drug plasma levels. Safety was judged by changes of blood pressure, heart rate, ECG parameters, and appearance of adverse events. For local tolerability, effects at the site of infusion were assessed. In patients with atrial fibrillation and/or atrial flutter, drug plasma levels and prolongation of QT interval were correlated with efficacy. In 10 (50%) patients, therapeutic intervention with E 047/1 was successful. Drug plasma levels rapidly decreased within 1 h after administration. Blood pressure values and ECG parameters stayed constant during the observation period. Proarrhythmic effects were not observed. As adverse events, vertigo, vomiting, and nausea in three (15%) and hypotension in one (5%) patient, respectively, occurred in the high-dose bolus regimen only. At the site of infusion, no adverse effects were found. No dependency between drug plasma levels and arrhythmia termination was found. E 047/1 has proven to be efficient and safe in the treatment of arrhythmia. E 047/1 is characterized by rapid plasma elimination, absence of proarrhythmic or cardiodepressive effects, mild adverse events, and excellent local tolerability. For further investigation, we recommend a combined bolus- and weight-adapted infusion regimen. |
4,724 | Preventing ventricular fibrillation by flattening cardiac restitution. | Ventricular fibrillation is the leading cause of sudden cardiac death. In fibrillation, fragmented electrical waves meander erratically through the heart muscle, creating disordered and ineffective contraction. Theoretical and computer studies, as well as recent experimental evidence, have suggested that fibrillation is created and sustained by the property of restitution of the cardiac action potential duration (that is, its dependence on the previous diastolic interval). The restitution hypothesis states that steeply sloped restitution curves create unstable wave propagation that results in wave break, the event that is necessary for fibrillation. Here we present experimental evidence supporting this idea. In particular, we identify the action of the drug bretylium as a prototype for the future development of effective restitution-based antifibrillatory agents. We show that bretylium acts in accord with the restitution hypothesis: by flattening restitution curves, it prevents wave break and thus prevents fibrillation. It even converts existing fibrillation, either to a periodic state (ventricular tachycardia, which is much more easily controlled) or to quiescent healthy tissue. |
4,725 | [Atrial defibrillator]. | Atrial fibrillation (AF) is a frequent and costly health care problem representing the most common arrhythmia resulting in hospital admission. Total mortality and cardiovascular mortality are significantly increased in patients with AF compared to controls. In addition to symptoms of palpitations, patients with AF have an increased risk of stroke and may also develop decreased exercise tolerance and left ventricular dysfunction. All of these problems may be reversed with restoration and maintenance of sinus rhythm. External electrical cardioversion has been a remarkably effective and safe method for termination of this arrhythmia. Originally described by Lown et al. in 1963, it has been a well accepted mode of acute therapy. However, this technique requires general anesthesia or heavy sedation. Internal atrial defibrillation has been evaluated as an alternative approach to the external technique for over 2 decades. Recent studies have shown that low-energy internal atrial defibrillation using biphasic shocks is an effective and safe means in restoring sinus rhythm in patients with AF and should be considered especially in patients in whom external cardioversion attempts have failed. Implantable Atrial Defibrillator: Recently, a stand alone IAD, the Metrix System (models 3000 and 3020), has entered clinical investigation. Atrial defibrillation is accomplished by a shock delivered between electrodes in the right atrium and the coronary sinus. The right atrium lead has an active fixation in the right atrium. The coronary sinus lead has a natural spiral configuration for retention in the coronary sinus, and can be straightened with a stylet. Both leads are 7 French in diameter and the defibrillation coils are each 6 cm in length. The electrodes may be placed using separate leads, or very soon by using a single bipolar lead. A separate bipolar right ventricular lead is used for R wave synchronization and post shock pacing. The Metrix defibrillator can be used to induce AF by using R wave synchronous shocks and can store intracardiac electrograms (EGMs) for up to 2 minutes from the most recent 6 AF episodes. The device can be programmed into one of the following operating modes: fully automatic, patient activated, monitor mode, bradycardia pacing only, and off. As AF is not life-threatening, in the automatic mode the device is only intermittently active in detecting and treating AF, and this "sleep wake-up" cycle interval is programmable. The device employs extensive processing both for detection and R wave synchronization. In April 1996, the phase I Metrix multicenter clinical trial was started. As of May 1997, a total of 51 Metrix systems had been implanted as part of the phase I multicenter clinical trial. Preliminary data suggest that both defibrillation thresholds and electrograms are stable over time (implant to 3 months). Detection accuracy has been excellent (100% specificity, 92.3% sensitivity) and there have been no errors of R wave selection for synchronization. No proarrhythmias have resulted from over 3700 shocks delivered. The device is effective in electrically converting 96% of the spontaneous episodes of AF. In 27% of episodes several shocks were required because of early recurrence of AF. In 5 patients, the atrial defibrillator was removed: 2 infections, 1 cardiac tamponade, 1 permanent loss of telemetry, 1 patient required His-Bundle ablation because of frequent episodes of drug refractory AF with rapid ventricular response. Initial clinical experience under controlled conditions with the Metrix system suggests that the implantable atrial defibrillator may offer a therapeutic alternative for a subgroup of patients with drug refractory, symptomatic, long lasting, and infrequent episodes of AF. Further efforts must be undertaken to reduce the patient discomfort associated with internal atrial defibrillation in an attempt to make this new therapy acceptable to a larger patient population with AF. (ABSTRACT TRUNCATED) |
4,726 | [Non-contact mapping: a simultaneous spatial detection in the diagnosis of arrhythmias]. | The non-contact mapping device (Ensite, Endocardial Solution) enables a simultaneous, spatial detection of the myocardial depolarization. An isopotential map is visualized in the 3D reconstruction of the cardiac chamber. The analysis of focal premature beats, of unstable arrhythmias and of macro reentry mechanisms is possible. The current article demonstrates the use of the non-contact mapping device for analysis and ablation of atrial flutter, premature beat associated atrial fibrillation and of ventricular tachycardias. |
4,727 | [Non-drug treatment methods in ventricular rate control in atrial fibrillation: high-frequency catheter ablation and catheter modification of the AV node]. | AV nodal ablation with pacemaker implantation nor AV nodal modification is the therapy of the choice in patients with permanent or paroxysmal atrial tachyarrhythmias. Both methods of treatment are limited to patients with drug refractory atrial tachyarrhythmias. Therapy indication requires the complete knowledge of the current clinical status and medical history of the patient regarding the time course of the disease and the results of previous treatments. Both methods are effective and palliative treatments which may not modify the underlying arrhythmias. Neither treatment showed an improvement in patients prognosis; therefore a restrictive indication is mandatory. |
4,728 | [Microvolt level T wave alternans: a new marker for noninvasive risk stratification]. | Prospective identification of patients with structural heart disease who could profit from prophylactic ICD therapy is hampered by the low predictive power of the currently available risk stratification parameters. Microvolt T wave alternans measured noninvasively is a new promising parameter to assess impaired ventricular repolarization which has been associated with an increased incidence of ventricular tachyarrhythmias. T wave alternans is rate-dependent; to induce alternans, heart rate may be increased by atrial stimulation during invasive EP testing or noninvasively by exercise stress testing. The first clinical validation with respect to prediction of inducibility of ventricular tachyarrhythmias and of arrhythmic events during follow-up in patients undergoing invasive EP testing was reported in 1994. Subsequently, a good concordance between the results of invasive and noninvasive assessment of T wave alternans was demonstrated by our group. The first prospective evaluation of the noninvasive alternans measurement using submaximal exercise testing was performed in patients surviving prehospital ventricular fibrillation or sustained ventricular tachycardia referred to our institution. The occurrence of T wave alternans in this patient population was predictive of future tachyarrhythmic events with subsequent appropriate ICD therapy. The results of the currently performed prospective trials in various patient populations will help to establish the utility of T wave alternans assessment as a risk stratifier in clinical practice. |
4,729 | Baroreflex sensitivity as a new marker for risk stratification. | As the arterial baroreflex importantly contributes to modulation of the autonomic influences on the heart and thereby arrhythmogenesis, baroreflex sensitivity has been used as a measure of the interaction between sympathetic and parasympathetic activities at the cardiac level. The most widely applied technique both in the experimental and clinical setting is the measurement of the heart rate slowing in response to a blood pressure rise induced by small intravenous boluses of phenylephrine. Baroreflex sensitivity is expressed as ms/mmHg and prevailing vagal reflexes are reflected by the wider R-R interval lengthening. The experimental evidence that the occurrence of ventricular fibrillation was inversely related to baroreflex sensitivity, opened the way to clinical studies. The ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) trial has definitely demonstrated not only that a depressed baroreflex sensitivity (< 3 ms/mmHg) is a strong risk factor for cardiac death, but also that the information gained by the analysis of autonomic markers adds to the information obtained by better recognized measures of cardiovascular outcome such as left ventricular function and ventricular arrhythmias. The value of a depressed baroreflex sensitivity as a risk stratifier is meaningful in patients below age 65 in combination of a simultaneously depressed left ventricular ejection fraction. In these patients, the analysis of autonomic activity might be of value in the identification of patients who may need an implantable automatic defibrillator for primary prevention of sudden cardiac death. |
4,730 | [Acute myocardial ischemia and ventricular arrhythmias in the pathogenesis of sudden cardiac death in coronary disease]. | There is increasing evidence for a fatal interaction of myocardial ischemia, ventricular arrhythmias and sudden cardiac death in some patients with coronary artery disease. Evidence comes from autopsy studies, from the evaluation of patients who survived an episode of sudden cardiac death, from follow-up data of these patients either treated or not by revascularization therapy and/or an implantable cardioverter-defibrillator and indicate that reducing the individual ischemic burden will be beneficial to reduce the incidence of sudden cardiac death. Studies in patients with stable and especially with unstable angina using Holter monitoring could demonstrate that there is a close and causal relationship between myocardial ischemia inducing or aggravating life-threatening ventricular arrhythmias and sudden cardiac death particularly in patients with unstable and postinfarction status. This review summarizes some of our clinical knowledge on this topic and indicates that preventive strategies for myocardial ischemia are the antiarrhythmic treatment of choice in patients with severe coronary artery disease and patients with evidence or at risk for ischemic proarrhythmia. |
4,731 | [Ion channels and arrhythmias]. | Changes in ionic currents through ion channels of the myocardial cell membrane have to be regarded as main cause of cardiac arrhythmias. Three basic arrhythmogenic mechanisms are responsible for the initiation of tachyarrhythmias: 1. The disturbance of normal automaticity in cardiac pacemaker cells dependent on the currents If, ICa-L, ICa-T or IK-ACh,Ado and the occurrence of abnormal automaticity in atrial and ventricular working myocardium based on the currents ICa-L, INa, IK, IK1 or IK-ACh,Ado. 2. Triggered activity which may be recognized by the appearance of early (EAD) or late afterdepolarizations (LAD). EAD are mainly due to inhibition of the outward currents IKr and IKs and are favoured by an increase in the inward currents INa and ICa-L, respectively. Typical arrhythmias are torsade de pointes occurring during treatment with K(+)-channel inhibitors (e.g. sotalol) or in patients with QT-syndrome. LAD may be observed during Ca(2+)-overload of the myocardial cell (digitalis intoxication, catecholamines) and are based on the transient inward current Iti, which is build up by the participation of the currents INa/Ca, INS and ICa-L. 3. Reentry mechanisms are the most frequent cause of tachyarrhythmias. They originate in an anatomically defined excitation circle with unidirectional block. Na(+)- and Ca(2+)-channel dependent disturbances of conduction with long excitable gap may be distinguished from Na(+)-channel dependent disturbances of conduction and refractory period with short excitable gap. Interruption of reentry is possible in the first case by depression of conduction and excitability (Na(+)- or Ca(2+)-channel blockers), in the second case by increase in refractory period (K(+)- or Na(+)-channel blockers). |
4,732 | [Genetic aspects of the etiology of arrhythmia]. | Cardiac arrhythmias are common causes of morbidity and mortality in clinical medicine. Much has been learned about cellular mechanisms of arrhythmogenesis in the past but genetic components have only recently been recognized for some heritable forms of arrhythmias. The long QT syndrome and the Brugada syndrome are both caused by molecular defects in ion channel proteins. Cardiac arrhythmias can also be associated with structural heart diseases. For example, sinus node dysfunction or AV-block can precede some forms of inherited dilated cardiomyopathy. A distinct genetic form of hypertrophic cardiomyopathy is associated with the Wolff-Parkinson-White syndrome and maps to chromosome 7q35. Arrhythmogenic right ventricular cardiomyopathy has a strong genetic basis and often manifests with ventricular tachycardia. Atrial fibrillation can also occur as familial disease and may be allelic with dilated cardiomyopathy as both diseases can be closely linked to chromosome 10q2. |
4,733 | Molecular genetics of arrhythmias--a new paradigm. | The molecular genetic background of inherited cardiac arrhythmias has only recently been uncovered. This late development in comparison to other inherited cardiac disorders has partly been due to the high mortality and early disease onset of these arrhythmias resulting in mostly small nucleus families. Thus, traditional genetic linkage studies, which are based on the genetic information obtained from large multi-generation families, were made difficult. Inherited arrhythmogenic disorders can be divided into 'primary electrical disorders' (e.g., long-QT [LQT] syndrome) in which a detectable, organic heart disease is not evident, and into inherited diseases of the myocardial structure (e.g., hypertrophic cardiomyopathies) in which the arrhythmias occur combined with the structural alterations. To date, all inherited arrhythmogenic disorders in which the causative genes have been identified turned out to be channelopathies, since the genes encode channel subunits that regulate important ion currents that tune the cardiac action potential. The discovery of the genetic bases of the LQT syndrome became a new methodologic paradigm; because with the use of 'classical' genetic linkage strategies (named [positional] candidate strategies) not only the causative genes have been found, but moreover, functional components with a previously unknown but fundamental role for a normal repolarization process were discovered. Disease mutations turned out to be not only a family-specific event with a distinct phenotype and the potential of an additional diagnostic tool, but also, when expressed in heterologous expression systems, characterize the defective ion channel in a topological way and lead to a more specific understanding of ion channel function. Most, if not all, primary electrical cardiac disorders show a high genetic diversity. For the LQT syndromes, sixth disease loci and the responsible gene have been recently discovered (so-called locus or genetic heterogeneity). Within all disease genes, the mutations are spread over the entire gene (allelic heterogeneity); in addition, more than one disease mutation may be present. This complexity requires, at least, complete mutation analysis of all LQT genes before medical advice should be given. Meanwhile, genotype-phenotype correlations in large families are being used to evaluate intergene, interfamilial and intrafamilial differences in the clinical phenotype, reflecting gene specific, gene-site specific and individual consequences of a given mutation. A widespread phenotypic heterogeneity even within mutation carriers in the same family raises the importance of modifying factors and genes that are mostly unknown to date. The reduced penetrance and variable expressivity associated with the LQT mutations remain still to be explained. First insights into the complex actions of mutations are being extracted, from expression data; these preliminary results may lead to potential implications for a specific (gene-site directed) therapy. This paper discusses the current data on molecular genetics and genotype-phenotype correlations in LQT syndrome and related disorders and the potential implications for diagnosis and treatment. |
4,734 | Inhibition of Na,K-ATPase by external electrical cardioversion in a sheep model of atrial fibrillation. | Electrical external cardioversion commonly used to treat atrial fibrillation (AF) is associated with myocardial membrane damage and disturbances in ionic homeostasis (hemodynamically unstable). The present study was designed to investigate whether alterations in ionic homeostasis observed were due in part to changes in the myocardial activity of Na,K-ATPase.</AbstractText>AF was induced by pacing in ten anesthetized sheep divided into two groups. Group I (n = 4) received a single external countershock of 360 J after three episodes of AF lasting 10 minutes. Group II (n = 6) served as controls. Activity, responsiveness to ouabain, and membrane expression of catalytic alpha and beta subunits of Na,K-ATPase in sarcolemmal myocardial membrane fractions were investigated. Membrane fluidity and fatty acid composition, and plasma levels of atrial natriuretic factor (ANF) also were measured. One shock after episodes of AF significantly decreased ventricular Na,K-ATPase activity up to 50% (P < 0.001) without modification of atrial activity at the membrane level. Sites with low affinity to ouabain showed a fivefold lower affinity for ouabain in the cardioversion group than in the control group (IC50 = 7.9 micromol/L vs 40 micromol/L ouabain, P < 0.05). Plasma levels of ANF were significantly increased in the cardioversion group compared with the control group. These changes were independent of membrane modulation in terms of expression of Na,K-ATPase, membrane fluidity, and fatty acid composition.</AbstractText>This study suggests that left ventricular perturbation of ionic homeostasis subsequent to transthoracic cardioversion could result from inactivation of Na,K-ATPase activity.</AbstractText> |
4,735 | Specific up-regulation of mitochondrial F0F1-ATPase activity after short episodes of atrial fibrillation in sheep. | Ventricular fibrillation induced by either digitalis intoxication or electrical stimulation is reported to alter myocardial energy by impairing the sarcolemmal Na,K-ATPase or the receptor for digitalis and the mitochondrial ATPase synthase or F0F1-ATPase. However, little is known about these membrane functions during atrial fibrillation (AF).</AbstractText>We analyzed the effects of electrically induced AF on biochemical activities of atrial F0F1-ATPase and Na,K-ATPase in sheep. A group of six sheep was subjected to direct short electrical stimulation of the right atrium to induce AF. Sham-operated sheep served as a control group. Microsomal and mitochondrial membranes of atrial muscle were isolated and tested for enzymatic activity. All paced sheep developed multiple episodes of sustained AF, with a mean total duration of 110 minutes over a 2-hour period. Data showed that short-term pacing-induced AF significantly activated membrane F0F1-ATPase activity (P < 0.05) without changes in cytochrome-c oxidase activity, Na,K-ATPase activity, ouabain sensitivity, and alpha1-subunit expression.</AbstractText>Specific activation of F0F1-ATPase activity is an early molecular consequence of sustained AF in sheep.</AbstractText> |
4,736 | Body surface distribution and response to drugs of ST segment elevation in Brugada syndrome: clinical implication of eighty-seven-lead body surface potential mapping and its application to twelve-lead electrocardiograms. | Body surface distribution and magnitude of ST segment elevation and their reflection in 12-lead ECGs have not been clarified in Brugada syndrome.</AbstractText>Eighty-seven-lead body surface potential mapping and 12-lead ECGs were recorded simultaneously in 25 patients with Brugada syndrome and 40 control patients. The amplitude of the ST segment 20 msec after the end of QRS (ST20) was measured from all 87 leads, and an ST isopotential map was constructed. The maximum ST elevation (maxST20) was distributed in an area of the right ventricular outflow tract in all Brugada patients, and it was larger than that in control patients (0.37 +/- 0.13 vs 0.12 +/- 0.04 mV; P < 0.0005). The maximum was observed on the level of the parasternal fourth intercostal space, on which the V1 and V2 leads of the standard 12-lead ECG were located, in 18 of the 25 Brugada patients in whom typical coved- or saddleback-type ST elevation was seen in leads V1 and V2. The maximum was located on the second intercostal space in the remaining seven Brugada patients in whom only a mild saddleback-type ST elevation was seen in leads V1 and V2 of the 12-lead ECG. Typical ST segment elevation was recognized in leads V1 and V2, which were recorded on the second or third intercostal space. ST elevation in Brugada patients was dramatically normalized by isoproterenol, a beta-adrenergic agonist (maxST20 = 0.17 +/- 0.08 mV; P < 0.0005 vs control conditions), and accentuated by disopyramide, an Na+ channel blocker (maxST20 = 0.50 +/- 0.15 mV; P < 0.0005 vs control conditions), without any change in the location of the maxST20.</AbstractText>Our data indicate that recordings of leads V1-V3 of the 12-lead ECG on the parasternal second or third intercostal space would be helpful in diagnosing suspected patients with Brugada syndrome. The data suggest that Na+ channel blockers are capable of accentuating ST elevation in leads V1-V3.</AbstractText> |
4,737 | Effect of phased chest and abdominal compression-decompression cardiopulmonary resuscitation on myocardial and cerebral blood flow in pigs. | This study was designed to assess the effects of a phased chest and abdominal compression-decompression cardiopulmonary resuscitation (CPR) device, Lifestick, vs. standard CPR on vital organ blood flow in a porcine CPR model.</AbstractText>Prospective, randomized laboratory investigation using an established porcine model with instrumentation for measurement of hemodynamic variables, vital organ blood flow, blood gases, and return of spontaneous circulation.</AbstractText>University hospital research laboratory.</AbstractText>Twelve domestic pigs.</AbstractText>After 4 mins of untreated ventricular fibrillation, either the Lifestick CPR device (n = 6) or standard CPR (n = 6) was started and maintained for an additional interval of 6 mins before attempting defibrillation.</AbstractText>During CPR, but before epinephrine, use of the Lifestick CPR device resulted in significantly higher (p < .05) mean (+/- SD) coronary perfusion pressure (23+/-9 vs. 10+/-7 mm Hg), cerebral perfusion pressure (29+/-11 vs. 18+/-10 mm Hg), mean arterial pressure (49+/-10 vs. 36+/-13 mm Hg), end-tidal carbon dioxide (32+/-11 vs. 20+/-7 mm Hg), left ventricular myocardial blood flow (44+/-19 vs. 19+/-12 mL x min(-1) x 100 g(-1)), and total cerebral blood flow (29+/-10 vs. 14+/-12 mL x min(-1) x 100 g(-1)). After 45 microg/kg epinephrine, hemodynamic and vital organ blood flow variables increased to comparable levels in both groups.</AbstractText>Compared with standard CPR, the Lifestick CPR device increased significantly hemodynamic variables and vital organ blood flow during CPR before epinephrine administration.</AbstractText> |
4,738 | [Quality of life two years after myocardial infarction. 2. Examination of affecting factors]. | This study aimed at determining these factors--ventricular fibrillation (VF) in acute phase of myocardial infarction MI), thrombolytic therapy, beta-blockers after MI, cardiac rehabilitation--affect quality of life (QOL) during the follow-up. The study involved 100 patients (mean age 45.5 years), on the average 2 years after MI, MI has complicated VF in 50 patients. Questionnaire of QOL after MI developed internally, taking into account 26 features (clinical, emotional and social status), and estimating anxiety level (STAI) were used. Computer medical diagnostics "SyntMED" (Krefft's method) was used. In both groups after MI (complicated and not complicated VF) beneficial effect of: thrombolytic treatments in acute phase MI (0.65 vs conventional 0.45, p > 0.05), use of beta-blockers after MI (0.56 vs 0.41 p < 0.05), and cardiac rehabilitation (0.64 vs 0.44 p < 0.05) on value QOL were noted. Patients after MI complicated VF had higher level of anxiety. Patients who returned to work had higher index QOL (0.62 vs 0.39). Ventricular fibrillation complicated the acute phase of MI had no significant effect on follow-up QL. |
4,739 | [Quality of life two years after myocardial infarction. 1. Examination questionnaires]. | The purpose of the present study was to assess the quality of life (QOL) and factors influencing QOL in patients 2 years after myocardial infarction (MI). The study was performed in 100 pts (mean age 45.5) mean 2 years after MI. 50 pts of studied group (mean age 42.5) were resuscitated from ventricular fibrillation (VF) complicating acute phase of MI. The control group consisted of 100 healthy subjects persons (mean age 53.5). The QOL index was assessed with the use of 2 types questionnaires: "Quality of Well-Being Scale" (QWB) and questionnaires of QOL including 26 factors in terms of: pain, dyspnoea, anxiety, depression, energy, sleep, emotions, mobility, social isolation, sexual activity, hobby, subjective emotional, distress, functional and social state and return to work. The QOL index was assessed using mathematical Krefft method. The average value of QOL index in patients 2 years following MI was significantly lower when compared with control group. The mathematical method of Krefft showed, that out of 26 features the most important diagnostic power factor for the QOL index were: self estimation of physical performance, return to work, the lifestyle and presence of stenocardial pain and dyspnoea. The pts resuscitated from VF revealed the higher level of anxiety. |
4,740 | Transient left ventricular aneurysm and hypertrophy accompanied by polymorphic ventricular tachycardia in a patient suspected of acute myocarditis. | A 75-year-old woman presented with recurrent ventricular tachycardia (VT) compatible with torsades de pointes (TdP) based on sinus bradycardia and QT prolongation. Previously she had received pirmenol, at a serum concentration within therapeutic range, for her paroxysmal atrial fibrillation. Emergent cardiac catheterization identified a ventricular aneurysm of the anteroapical and inferior wall along with angiographically normal coronary arteries. A right ventricular endomyocardial biopsy revealed postmyocarditic change. The left ventricular contraction improved after 5 weeks of conservative treatment. A follow-up echocardiogram revealed transient thickening of partial left ventricular wall consistent with the segment of the aneurysm. Several months later, almost all abnormal findings had improved except for sustained deep negative T waves in precordial leads. Acute myocarditis was primarily suspected as the cause of her clinical presentation. |
4,741 | Predictors of congestive heart failure in the elderly: the Cardiovascular Health Study. | We sought to characterize the predictors of incident congestive heart failure (CHF), as determined by central adjudication, in a community-based elderly population.</AbstractText>The elderly constitute a growing proportion of patients admitted to the hospital with CHF, and CHF is a leading source of morbidity and mortality in this group. Elderly patients differ from younger individuals diagnosed with CHF in terms of biologic characteristics.</AbstractText>We analyzed data from the Cardiovascular Health Study, a prospective population-based study of 5,888 elderly people >65 years old (average 73 +/- 5, range 65 to 100) at four locations. Multiple laboratory measures of cardiovascular structure and function, blood chemistries and functional assessments were obtained.</AbstractText>During an average follow-up of 5.5 years (median 6.3), 597 participants developed incident CHF (rate 19.3/1,000 person-years). The incidence of CHF increased progressively across age groups and was greater in men than in women. On multivariate analysis, other independent predictors included prevalent coronary heart disease, stroke or transient ischemic attack at baseline, diabetes, systolic blood pressure (BP), forced expiratory volume 1 s, creatinine >1.4 mg/dl, C-reactive protein, ankle-arm index <0.9, atrial fibrillation, electrocardiographic (ECG) left ventricular (LV) mass, ECG ST-T segment abnormality, internal carotid artery wall thickness and decreased LV systolic function. Population-attributable risk, determined from predictors of risk and prevalence, was relatively high for prevalent coronary heart disease (13.1%), systolic BP > or =140 mm Hg (12.8%) and a high level of C-reactive protein (9.7%), but was low for subnormal LV function (4.1%) and atrial fibrillation (2.2%).</AbstractText>The incidence of CHF is high in the elderly and is related mainly to age, gender, clinical and subclinical coronary heart disease, systolic BP and inflammation. Despite the high relative risk of subnormal systolic LV function and atrial fibrillation, the actual population risk of these for CHF is small because of their relatively low prevalence in community-dwelling elderly people.</AbstractText> |
4,742 | Atrial pacing for the prevention of atrial fibrillation after cardiovascular surgery. | The purpose of this study was to determine the efficacy of atrial pacing in the prevention of atrial fibrillation following cardiovascular surgery.</AbstractText>Although pharmacologic therapy has been used to help prevent postoperative atrial fibrillation, it suffers from limited efficacy and adverse effects. In the nonoperative setting, novel pacing strategies have been shown to reduce recurrences of atrial fibrillation and prolong arrhythmia-free periods in patients with paroxysmal atrial arrhythmias.</AbstractText>A total of 154 patients (115 men; mean age, 65 +/- 10 years; ejection fraction, 53 +/- 10%) undergoing cardiac surgery (coronary artery bypass surgery, 88.3%; aortic valve replacement, 4.5%; coronary bypass + aortic valve replacement, 7.1%) had right and left atrial epicardial pacing electrodes placed at the time of surgery. Patients were randomized to either no pacing, right atrial (RAP), left atrial (LAP) or biatrial pacing (BAP) for 72 h after surgery. Beta-adrenergic blocking agents were administered concurrently to all patients following surgery.</AbstractText>There was a reduction in the incidence of postoperative atrial fibrillation from 37.5% in patients receiving no postoperative pacing to 17% (p < 0.005) in patients assigned to one of the three pacing strategies. The length of hospital stay was reduced by 22% from 7.8 +/- 3.7 days to 6.1 +/- 2.3 days (p = 0.003) in patients assigned to postoperative atrial pacing. The incidence of atrial fibrillation was lower in each of the paced groups (RAP, 8%; LAP, 20%; BAP, 26%) compared with patients who did not receive postoperative pacing (37.5%).</AbstractText>Postoperative atrial pacing, in conjunction with beta-blockade, significantly reduced both the incidence of atrial fibrillation and the length of hospital stay following cardiovascular surgery. Additional studies are needed to determine the most effective anatomic pacing site.</AbstractText> |
4,743 | Effective prevention of atrial fibrillation by continuous atrial overdrive pacing after coronary artery bypass surgery. | The present study was aimed to evaluate the efficacy of a specific algorithm with continuous atrial dynamic overdrive pacing to prevent atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery.</AbstractText>Atrial fibrillation occurs in 30% to 40% of patients after cardiac surgery with a peak incidence on the second day. It still represents a challenge for postoperative prevention and treatment and may have medical and cost implications.</AbstractText>Ninety-six consecutive patients undergoing CABG for severe coronary artery disease and in sinus rhythm without antiarrhythmic therapy on the second postoperative day were randomized to have or not 24 h of atrial pacing through temporary epicardial wires using a permanent dynamic overdrive algorithm. Holter ECGs recorded the same day in both groups were analyzed to detect AF occurrence.</AbstractText>No difference was observed in baseline data between the two study groups, particularly for age, male gender, history of AF, ventricular function, severity of coronary artery disease, preoperative beta-adrenergic blocking agent therapy or P-wave duration. The incidence of AF was significantly lower (p = 0.036) in the paced group (10%) compared with control subjects (27%). Multivariate analysis showed AF incidence to increase with age (p = 0.051) but not in patients with pacing (p = 0.078). It decreased with a better left ventricular ejection fraction only in conjunction with atrial pacing (p = 0.018).</AbstractText>We conclude that continuous atrial pacing with an algorithm for dynamic overdrive reduces significantly incidence of AF the second day after CABG surgery, particularly in patients with preserved left ventricular function.</AbstractText> |
4,744 | Should interventional cardiac catheterization procedures take place at the time of diagnostic procedures? | In many cardiac catheterization laboratories interventional procedures are performed at a date later than the diagnostic study, causing increased hospital days and costs. Few data exist which compare procedural success, complications, and costs between procedures performed at the time of diagnostic study and those performed later.</AbstractText>The purpose of this study was to evaluate the safety and success of same-day interventional procedures and to quantitate hospital cost savings with this strategy.</AbstractText>In all, 357 consecutive patients who underwent an elective interventional procedure of a native coronary artery either at the time of diagnostic study (same day, n = 244) or later (delayed, n = 113) were reviewed. Procedural success [< 30% residual lesion post-percutaneous transluminal coronary angioplasty (PTCA) or 0% residual lesion post-stent], major complications [death, emergent coronary artery bypass grafting (CABG), myocardial infarction, and ventricular fibrillation], hospital days, and costs were analyzed. Procedural expense, including the diagnostic and interventional procedure in the cardiac catheterization laboratory, and hospital expense were analyzed.</AbstractText>Both groups were similar in terms of age, gender, coronary risk factors, indications (myocardial infarction, unstable angina, abnormal stress test), the culprit coronary artery, type of intervention (PTCA, stent), and lesion complexity (type A, B, C). The average hospital stay for the two groups was 4.37 +/- 2 and 6.55 +/- 2.4 days, respectively (p < 0.0001). The procedural charges were $8,207.99 and 10,581.87, respectively (p < 0.0001).</AbstractText>Catheter intervention performed at the same time as the diagnostic cardiac catheterization procedure is as successful and as safe as that performed at a later date. Hospital stay and costs, as well as procedural expenses are significantly reduced by this practice.</AbstractText> |
4,745 | The implantable cardioverter-defibrillator. | Ventricular arrhythmias remain a major cause of cardiovascular mortality. Therapy for serious ventricular arrhythmias has evolved over the past decade, from treatment primarily with antiarrhythmic drugs to implanted devices. The implantable cardioverter-defibrillator (ICD) is the best therapy for patients who have experienced an episode of ventricular fibrillation not accompanied by an acute myocardial infarction or other transient or reversible cause. It is also superior therapy in patients with sustained ventricular tachycardia (VT) causing syncope or hemodynamic compromise. Controlled clinical trials have confirmed the utility of these devices. As primary prevention, the ICD is superior to conventional antiarrhythmic drug therapy in patients who have survived a myocardial infarction and who have spontaneous, nonsustained ventricular tachycardia, a low ejection fraction, inducible VT at electrophysiologic study, and whose VT is not suppressed by procainamide. The effect of the ICD on survival of other patient populations remains to be proven. The device is costly, but its price is generally accepted to be reasonable. The ICD has been a major advance in the treatment of ventricular arrhythmias. |
4,746 | Atrial fibrillation and the risk of cerebral white matter lesions. | Cerebral white matter lesions are often observed on MRI scans of elderly nondemented and demented persons. Their pathogenesis is not fully understood but cerebral hypoperfusion may be involved. Atrial fibrillation is a common finding in elderly subjects and may lead to a reduced cardiac output with cerebral hypoperfusion. The authors investigated the association between atrial fibrillation and the presence of white matter lesions.</AbstractText>From 1995 through 1996, the authors randomly sampled 1077 subjects from two ongoing prospective population-based studies. From each participant, an electrocardiogram (ECG) was recorded; atrial fibrillation and left ventricular hypertrophy were diagnosed with a computer program. For one of the two groups (553 subjects), earlier ECGs were available (mean follow-up 4.7 years). All subjects underwent 1.5-T MRI scanning; white matter lesions were separately rated for the periventricular and subcortical regions.</AbstractText>The prevalence of atrial fibrillation was 1.9% among subjects younger than 75 years and 5.5% in subjects older than 75 years. The total number of subjects with atrial fibrillation was 28. Subjects with atrial fibrillation had severe periventricular white matter lesions more than twice as often as subjects who did not (RR 2.2; 95% CI 1.0 to 5.2) but had no increased risk of subcortical white matter lesions (RR 1.1; 95% CI 0.4 to 2.6). For seven subjects with atrial fibrillation both at baseline and at follow up, these relative risks were 6.3 (95% CI 1.1 to 37.1) and 0.7 (95% CI 0.1 to 3.7).</AbstractText>Atrial fibrillation is associated with periventricular white matter lesions, but not with subcortical white matter lesions.</AbstractText> |
4,747 | EKG abnormalities during partial seizures in refractory epilepsy. | This study assessed the frequency and character of ictal cardiac rhythm and conduction abnormalities in intractable epilepsy. Sudden unexpected death in epilepsy (SUDEP) is a major cause of excess mortality in people with refractory epilepsy, and cardiac arrhythmias during seizures may be responsible. The frequency of cardiac abnormalities during seizures in patients with refractory epilepsy must be determined.</AbstractText>Fifty-one seizures in 43 patients with intractable partial epilepsy were analyzed prospectively from CCTV-EEG monitoring with one ECG channel. Arrhythmias, repolarization abnormalities, and PR and QTc intervals were determined for preictal (3 min), ictal, and postictal (3 min) periods for one or more seizures per patient. Parametric statistics were used for continuous variables, and nonparametric statistics were used for categoric variables.</AbstractText>Of the patients, 39% had one or more abnormalities of rhythm and/or repolarization during or immediately after seizures. Abnormalities included asystole (one), atrial fibrillation (one), marked or moderate sinus arrhythmia (six), supraventricular tachycardia (one), atrial premature depolarizations (APDs; eight), ventricular premature depolarizations (VPDs; two), and bundle-branch block (three). Mean seizure duration was longer in patients with abnormalities than in those without (204 vs. 71 s; p < 0.001). Generalized tonic-clonic seizures were also associated with increased occurrence of ictal ECG abnormalities (p = 0.006) as compared with complex partial seizures. There were no clinically significant differences in mean preictal and ictal/postictal PR and QTc intervals.</AbstractText>Cardiac rhythm and conduction abnormalities are common during seizures, particularly if they are prolonged or generalized, in intractable epilepsy. These abnormalities may contribute to SUDEP.</AbstractText> |
4,748 | Switch from a BIVAD to a LVAD in a boy with Kawasaki disease. | A 9-year-old boy with Kawasaki disease survived after two severe myocardial infarctions. Thereafter pharmacologically untreatable ventricular arrhythmia and rapidly deteriorating heart failure developed in the patient. After 19 days of biventricular and a further 27 days of left univentricular mechanical circulatory support with the Berlin Heart (Cardiotechnica, Berlin, Germany) assist device the boy successfully underwent heart transplantation. At a follow-up of 54 months, the boy is leading an active and unrestricted life. |
4,749 | Dissection of the coronary sinus secondary to pacemaker lead manipulation. | We report a 64-year-old man with atrial fibrillation and impaired left ventricular function in whom pacemaker lead manipulation during biatrial pacemaker lead removal and biventricular pacemaker lead insertion caused coronary sinus dissection. After further manipulation of the biventricular pacing lead, the true lumen of the coronary sinus could be entered and satisfactory left ventricular pacing undertaken. The dissection was managed conservatively without long-term sequelae. |
4,750 | Effect of rates of perfusion on dominant frequency and defibrillation energy in isolated fibrillating hearts. | This study assessed the influence of rates of reperfusion on excitability of the myocardium using dominant frequency (DF) (in Hz) of VF and the relationship of DF to the minimum defibrillation energy (MDE) (in J). Our hypothesis was that increasing flow during reperfusion increases DF that raises MDE. Initially, six Langendorff perfused swine hearts were serially fibrillated and perfusion arrested for 4 minutes followed by reperfusion and defibrillation to establish reproducibility of the model. The epicardial ECG was analyzed for DF. In subsequent studies (n = 8), no flow VF was followed by 1-minute reperfusion at normal flow or 10% flow (low flow) and shocked with increasing energy via epicardial pads until defibrillation. The DF at onset of no flow VF was 9.5 +/- 1.4 and decreased to 3.6 +/- 1.4 after 4 minutes. Reperfusion at normal flow increased the DF of VF compared to low flow after 1 minute (10.8 +/- 1.1 vs 4.5 +/- 1.1 Hz, P = 0.0002) and was associated with increased defibrillation energy requirements (13.5 +/- 5.0 vs 7.3 +/- 6.2 J, P = 0.047). In summary, defibrillation energy requirements are lower when myocardial excitability is reduced during low flow reperfusion. |
4,751 | The relation between ejection fraction and mitral annulus motion before and after direct-current electrical cardioversion. | Mitral annulus motion (MAM) and the relation between left ventricular ejection fraction (EF) and MAM has been shown to differ between patients with sinus rhythm and patients with atrial fibrillation. However, it has not been investigated how the relation between EF and MAM changes on direct-current (DC) electrical cardioversion to sinus rhythm. Therefore, 31 consecutive patients on the waiting list for DC electrical cardioversion were examined by echocardiography before DC electrical cardioversion, and those who maintained sinus rhythm (13 patients) were examined again 4-8 weeks after cardioversion. The conversion factor (CF) (ratio EF/MAM) decreased from 8.4 +/- 1.7 before to 5.8 +/- 0.8 SD after cardioversion (P<0.001). The EF increased slightly (P<0.05) but the MAM had a much greater increase (P<0.001), resulting in the decrease in CF. There was no significant difference in CF between patients after cardioversion and age- and gender-matched control patients with sinus rhythm, indicating that CF is normalized or almost normalized 4-8 weeks after cardioversion. This indicates that when MAM is used for investigation of the left ventricular function, and the function is expressed as EF, the same CF as in other patients with sinus rhythm can be used 4-8 weeks after DC electrical cardioversion. |
4,752 | Endothelin-1 vasoconstriction during swine cardiopulmonary resuscitation improves coronary perfusion pressures but worsens postresuscitation outcome. | Vasoconstriction during cardiopulmonary resuscitation (CPR) improves coronary perfusion pressure (CPP) and thereby outcome. The combination of endothelin-1 (ET-1) plus epinephrine improved CPP during CPR compared with epinephrine alone in a canine cardiac arrest model. The effect of the combination on outcome variables, such as successful resuscitation and survival, has not been investigated.</AbstractText>Twenty-seven swine were randomly provided with 1 mg epinephrine (Epi group) or 1 mg epinephrine plus 0.1 mg ET-1 (ET-1 group) during a prolonged ventricular fibrillatory cardiac arrest. ET-1 resulted in substantially superior aortic relaxation pressure and CPP during CPR. These hemodynamic improvements tended to increase initial rates of restoration of spontaneous circulation (8 of 10 versus 8 of 17, P=0.12). However, continued intense vasoconstriction from ET-1 led to higher aortic diastolic pressure and very narrow pulse pressure after resuscitation. The mean pulse pressure 1 hour after resuscitation was 7+/-8 mm Hg with ET-1 versus 24+/-1 mm Hg with Epi, P<0.01. Most importantly, the postresuscitation mortality was dramatically higher in the ET-1 group (6 of 8 versus 0 of 8 in the Epi group, P<0.01).</AbstractText>These data establish that administration of ET-1 during CPR can result in worse postresuscitation outcome. The intense vasoconstriction from ET-1 improved CPP during CPR but had detrimental effects in the postresuscitation period.</AbstractText> |
4,753 | Dobutamine stress echocardiography: safety in diagnosing coronary artery disease. | Dobutamine stress echocardiography is considered a relatively well-tolerated diagnostic modality, effective in the management of patients with known or suspected coronary artery disease. Adverse effects during testing are relatively frequent, precluding the achievement of a diagnostic end-point in about 5 to 10% of tests. These adverse effects, mostly tachyarrhythmias and arterial hypotension, are usually minor and self limiting. However, severe life-threatening complications, as well as death, also occur. By analysing Medline-quoted literature up to March 1999, we found 35 original studies from a single institution with more than 100 patients, as well as 2 multicentre studies, concerning the feasibility and safety of dobutamine stress echocardiography. In a cumulative total of 26438 tests performed, 79 life-threatening complications (such as acute myocardial infarction, asystole, ventricular fibrillation, sustained ventricular tachycardia or severe symptomatic hypotension) have been reported, giving an incidence of 1 severe adverse reaction per every 335 examinations. In addition, 29 isolated case reports have been published describing life-threatening complications during dobutamine echocardiography. In case reports, 2 deaths have been described, both due to acute cardiac rupture in patients with recent inferior myocardial infarction. Severe adverse reactions during dobutamine echocardiography can be ischaemia independent, and are independent of operator experience and are unpredictable; some complications can be late occurring and long lasting. As a consequence, the procedure must be clearly indicated, written informed consent has to be obtained from the patient, an attending physician must be present during testing, and long term observation of outpatients is useful in order to manage late complications. In conclusion, while the safety of dobutamine stress echocardiography was reported to be outstanding in early reports, further experience presents a substantially more worrying picture. This must be taken into account by both physicians and patients when assessing the risk-benefit profile of the procedure. |
4,754 | Clinical study to investigate the predictive parameters for the onset of atrial fibrillation in patients with essential hypertension. | The risk factors involved in the onset of atrial fibrillation (AF) are well known, but the predictive clinical and paraclinical parameters for the onset of AF in hypertensive patients have not been investigated specifically.</AbstractText>We retrospectively analyzed 97 consecutive patients with hypertension and no known history of AF or cardiovascular events who attended the cardiology outpatient clinic. The analysis was based on clinical data, the noninvasive ambulatory 24-hour measurement of blood pressure (AMBP), a standard 12-lead electrocardiogram, and a Doppler echocardiogram. After a mean follow-up of 25 +/- 3 months, 19 (19. 5%) patients had AF, 3 (15.8%) of whom had a cerebrovascular accident. The patients with AF were older than the others and their AMBP showed higher mean systolic diurnal and nocturnal blood pressures, though no differences in the clinical blood pressure readings were present. On the electrocardiogram, the maximum duration of the P wave and its dispersion were more prolonged in the patients with AF. On the Doppler echocardiogram, left ventricular mass and left atrial dimension were higher in the patients with AF, and the A-wave velocity of diastolic mitral flow was reduced in these patients. In the multivariate analysis, age (odds ratio 3.28, P <.001), diurnal systolic blood pressure (odds ratio 1.35, P <.01) and nocturnal systolic blood pressure (odds ratio 1.16, P <.01), maximum duration of the P wave (odds ratio 2.09, P <.01), dispersion of the P wave (odds ratio 2.52, P <.001), echocardiographic left ventricular mass (odds ratio 1.43, P <.01), left atrial dimension (odds ratio 2.81, P <.001), and velocity of the A wave (odds ratio 2. 24, P <.01) were independent predictors for the onset of AF. After correction for age, maximum duration of the P wave (odds ratio 1.34, P <.01), dispersion of the P wave (odds ratio 1.63, P <.001), and the velocity of the A wave (odds ratio 1.42, P <.01) remained independent predictors for the onset of AF.</AbstractText>In patients with hypertension, age and the level of diurnal and nocturnal systolic blood pressures measured by 24-hour AMBP are important independent predictors for the onset of AF. Independent of age, increases in left atrial dimension and left ventricular mass, prolongation of the maximum duration and dispersion of the P wave and reduced A-wave velocity are also predictors for the onset of AF.</AbstractText> |
4,755 | Determinants of outcome in patients with sustained ventricular tachyarrhythmias: the antiarrhythmics versus implantable defibrillators (AVID) study registry. | The prognosis of patients with sustained ventricular tachyarrhythmias varies according to clinical characteristics. We sought to identify predictors of survival in a large population of patients with documented sustained ventricular tachyarrhythmias not related to reversible or correctable causes included in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Registry.</AbstractText>We analyzed the impact of 36 demographic, clinical, and discharge treatment variables on the outcome for 3559 patients. Survival status was assessed with the use of the National Death Index. Multivariate analyses were performed with the use of the Cox proportional hazards model. After a mean follow-up of 17 +/- 12 months, 631 patients died. Actuarial survival was 0.86 (95% confidence interval [CI] 0.85 to 0.88), 0.79 (95% CI 0.78 to 0.81), and 0.72 (95% CI 0.70 to 0.74) at 1, 2, and 3 years. Multivariate predictors of worse survival included older age, severe left ventricular dysfunction, lower systolic blood pressure, history of congestive heart failure, diabetes, smoking or atrial fibrillation, and preexistent pacemaker. The hemodynamic impact of the qualifying arrhythmia was not a predictor of outcome. Defibrillator implantation and hospital discharge while the patient was taking a beta-blocker or an angiotensin-converting enzyme inhibitor were associated with better prognosis.</AbstractText>Despite therapeutic advances, the mortality rates of patients with sustained ventricular tachyarrhythmias remain high. Prognosis depends on the severity of underlying heart disease, as reflected by the extent of left ventricular dysfunction and the presence of heart failure. Well-tolerated ventricular tachycardia in patients with structural heart disease does not carry a significantly better prognosis than ventricular tachyarrhythmia with more severe hemodynamic consequences.</AbstractText> |
4,756 | Inappropriate therapy from atrial fibrillation and sinus tachycardia in automated implantable cardioverter defibrillators. | Inappropriate therapy from supraventricular tachyarrhythmias (atrial fibrillation [AF] and sinus tachycardia [ST]) in patients with implanted cardioverter defibrillators is a major challenge. We tested the performance of stability algorithms from 3 manufacturers for episodes of inappropriate therapy delivered because of AF and an onset algorithm for all episodes of inappropriate therapy caused by ST.</AbstractText>Therapy was classified as caused by ventricular tachycardia (VT), ST, or AF from review of stored intracardiac electrograms, history, clinical information, and R-R data before study inception. By using 30 to 60 R-R intervals before therapy, sensitivity and specificity for a family of stability values and percentage of onset values were calculated for each manufacturer and receiver operating characteristic curves generated.</AbstractText>Of the 217 patients monitored, 62 (29%) received inappropriate therapy, and 40 had complete R-R information available. Of the 40 patients, 21 patients received therapy for AF, 19 for ST, and 1 patient for noise; 15 (38%) also received appropriate therapy for VT. We analyzed 83 episodes of VT from 18 patients, 94 episodes of AF from 21 patients, and 56 episodes of ST from 19 patients. Specificity, in the clinically relevant sensitivity range of >/=95%, was comparable across manufacturers at about 40%. An onset value of 80% was associated with 91% sensitivity and 95% specificity for the specific algorithm tested.</AbstractText>Inappropriate therapy is a common problem in implantable cardiac defibrillators. The performance of the stability algorithms used to differentiate AF from VT was less than ideal, though comparable across manufacturers. The onset algorithm accurately differentiates ST from VT.</AbstractText> |
4,757 | A low amplitude His-bundle potential predicts failure of the right-sided approach for atrioventricular junction ablation. | In 30 patients with drug refractory atrial fibrillation-flutter who underwent radiofrequency (RF) ablation of the atrioventricular (AV) junction, 23 were successfully ablated using the conventional right-sided approach (group A). Seven patients required a left-sided approach (group B) after multiple applications from the conventional right-sided approach failed to produce complete AV block. The amplitude of the His-bundle potential recorded at the ablation site differed significantly between the 2 groups (0.23+/-0.11 mV in group A vs 0.12+/-0.04 mV in group B; p<0.005). Also, the amplitude of the His-bundle potential recorded in the standard position across the tricuspid annulus differed significantly between the 2 groups (0.27+/-0.35 mV in group A vs 0.11+/-0.44 mV in group B; p<0.007). There was no significant difference in the amplitude of the ventricular potential between the 2 groups. The probability of successful ablation of the AV junction with a conventional right-sided approach was 6 out of 12 patients (50%) if the His amplitude was <0.12mV, and 17 out of 18 patients (94%) if the His amplitude was >0.12mV (p<0.005). Patients in group B had a mean of 20.5+/-13.0 failed right-sided RF applications (5-33 applications), but required a mean of only 2 subsequent RF applications for success on the left side (1-6 applications). The His-amplitude recorded from the left side using the same catheter was significantly greater than that on the corresponding right-side (0.22+/-0.09 mV on the left side vs 0.12+/-0.04 mV on the right side: p<0.05). Total mean fluoroscopic time was 62+/-12min for group B and 20+/-13min for group A patients. In patients that underwent RF ablation of the AV junction, a maximum His amplitude <0.12 mV predicted a success rate of approximately 50% in the present study. An early switch to a left-sided approach may avoid multiple RF applications and prolonged fluoroscopic time in patients with a low amplitude His-bundle potential. |
4,758 | Termination of resuscitation in the prehospital setting for adult patients suffering nontraumatic cardiac arrest. National Association of EMS Physicians Standards and Clinical Practice Committee. | The National Association of EMS Physicians (NAEMSP) supports out-of-hospital termination of resuscitation for adult, nontraumatic cardiac arrest patients who have not responded to full resuscitative efforts. The following factors should be considered in establishing termination of resuscitation protocols: 1) Termination of resuscitation may be considered for any adult patient who suffers sudden cardiac death that is likely to be medical. 2) Unwitnessed cardiac arrest with delayed initiation of cardiopulmonary resuscitation (CPR) beyond 6 minutes and delayed defibrillation beyond 8 minutes has a poor prognosis. 3) In the absence of "do not resuscitate" or advanced directives, a full resuscitative effort including CPR, definitive airway management, medication administration, defibrillation if necessary, and at least 20 minutes of treatment following Advanced Cardiac Life Support (ACLS) guidelines should be performed prior to declaring the patient dead. 4) A patient whose rhythm changes to, or remains in, ventricular fibrillation or ventricular tachycardia should have continued resuscitative efforts. Patients in asystole or pulseless electrical activity should be strongly considered for out-of-hospital termination of resuscitation. 5) Logistic factors should be considered, such as collapse in a public place, family wishes, and safety of the crew and public. 6) Online medical direction should be established prior to termination of resuscitation. The decision to terminate efforts should be a consensus between the on-scene paramedic and the online physician. 7) The on-scene providers and family should have access to resources, such as clergy, crisis workers, and social workers. 8) Quality review is necessary to ensure appropriate application of the termination protocol, law enforcement notification, medical examiner or coroner involvement, and family counseling. |
4,759 | [Multi-recurrent cardiac arrest: when to discontinue cardiopulmonary resuscitation?]. | A 52-year-old man developed an out-of-hospital cardiac arrest complicating a myocardial infarction. After prolonged cardiopulmonary resuscitation, he was admitted to an intensive care unit, where 25 episodes of cardiac arrests occurred within a few hours. Finally the outcome was favourable. This case raises the question of the duration a cardiopulmonary resuscitation in case of out-of-hospital and in-hospital cardiac arrest. The question is to determine how long resuscitation efforts must be prolonged after recurrent cardiac arrests. |
4,760 | The effects of repeated doses of vasopressin or epinephrine on ventricular fibrillation in a porcine model of prolonged cardiopulmonary resuscitation. | This study evaluated ventricular fibrillation mean frequency and amplitude to predict defibrillation success in a porcine cardiopulmonary resuscitation (CPR) model using repeated administration of vasopressin or epinephrine. After 4 min of cardiac arrest and 3 min of CPR, 10 pigs were randomly assigned to receive either vasopressin (early vasopressin: 0.4, 0.4, and 0.8 units/kg, respectively, n = 5) or epinephrine (early epinephrine: 45, 45, and 200 microg/kg, respectively, n = 5). Another 11 animals were randomly allocated after 4 min of cardiac arrest and 8 min of CPR to receive every 5 min either vasopressin (late vasopressin: 0.4 and 0. 8 units/kg, respectively, n = 5) or epinephrine (late epinephrine: 45 and 200 microg/kg, n = 6). Ventricular fibrillation mean frequency and amplitude on defibrillation were significantly higher in the vasopressin groups than in the epinephrine groups, respectively. In vasopressin versus epinephrine animals, mean frequency immediately before defibrillation was 9.6 +/- 1.5 Hz vs 7. 0 +/- 0.7 Hz (P < 0.001), mean amplitude was 0.65 +/- 0.26 mV vs 0. 21 +/- 0.14 mV (P < 0.001, and coronary perfusion pressure was 27 +/- 9 mm Hg vs 8 +/- 4 mm Hg (P < 0.00001), respectively. In contrast to no epinephrine animals, all vasopressin animals were successfully defibrillated and survived 1 h (P < 0.05). Mean fibrillation frequency and amplitude predicted successful defibrillation and may serve as noninvasive markers to monitor continuing CPR efforts. Furthermore, vasopressin was superior to epinephrine in maintaining these variables above a threshold necessary for successful defibrillation. |
4,761 | Transoesophageal low-energy cardioversion of atrial fibrillation. Results with the oesophageal-right atrial lead configuration. | Low energy internal cardioversion is a safe and effective procedure to restore sinus rhythm in patients with atrial fibrillation refractory to external cardioversion. However the procedure is invasive and fluoroscopy is mandatory. Aim of the study To assess the efficacy, safety and tolerability of a new simplified procedure of low energy internal cardioversion.</AbstractText>Twenty-five consecutive patients (19 males and 6 females) with persistent atrial fibrillation were submitted to low energy internal cardioversion using a step-up protocol (in steps of 50 V, starting from 300 V). A large surface area lead (cathode) was positioned in the oesophagus, 45 cm from the nasal orifice. A second large surface area lead (anode) was positioned in the right atrium. A quadripolar lead was positioned at the right ventricular apex to achieve ventricular synchronization and back-up pacing. Oesophageal endoscopy was performed within 24 h of the end of the procedure and repeated after 48 h, if injury to the oesophageal mucosa had occurred.</AbstractText>Sinus rhythm was restored in 23 patients (92%) with a mean delivered energy of 15.74 J (range 5-27) and a mean impedance of 48 Omega. In two patients, endoscopy revealed that small burns had occurred in the oesophageal mucosa. Such lesions spontaneously healed after 48 h.</AbstractText>This new technique of performing low energy internal cardioversion is effective and safe and avoids the positioning of a lead in the coronary sinus or in the left pulmonary artery, thereby simplifying the procedure.</AbstractText>Copyright 2000 The European Society of Cardiology.</CopyrightInformation> |
4,762 | Transoesophageal echocardiography-guided cardioversion of atrial fibrillation or flutter. Selection of a low-risk group for immediate cardioversion. | Despite exclusion of left atrial thrombi by transoesophageal echocardiography, cardioversion-related thromboembolism has been reported in atrial fibrillation or flutter. To define a low-risk group for cardioversion without previous anticoagulation, patients were selected for immediate cardioversion if there were no thrombi, no echo spontaneous contrast and the outflow velocity of the left atrial appendage was greater than 0.25 m. s(-1)on transoesophageal echocardiography.</AbstractText>Two hundred and forty-two consecutive patients referred for cardioversion of atrial fibrillation or flutter with a duration of more than 2 days and no anticoagulation therapy were examined with transoesophageal echocardiography. After the transoesophageal echocardiography examination, patients who were eligible for immediate cardioversion were anticoagulated with low molecular weight heparin (dalteparin) subcutaneously, together with warfarin prior to cardioversion. Dalteparin treatment was continued until the patient had reached therapeutic prothrombin values. Based on the transoesophageal echocardiographic findings the patients were divided into two groups: immediate cardioversion, group A, with a mean age of 62+/-13 years (n=162); or conventional warfarin treatment before cardioversion, group B, with a mean age of 67+/-10 years (P<0.05) (n=80). In group A, lone atrial fibrillation or flutter was more common (53%; 95% CI: 45-61) compared to group B (34%; 95% CI: 23-44, P<0.05), while heart disease was more common in group B (45%; 95% CI: 34-56) compared to group A (31%; 95% CI: 24-39, P<0.05). Echocardiography revealed thrombi in 5% (95% CI: 2.6-8) of the patients, left atrial size was larger, fractional shortening lower, and a higher proportion had impaired left ventricular function in group B. No thromboembolic event occurred at or after cardioversion in any of the patients; however, before planned cardioversion one transitory ischaemic attack, one lethal stroke and one cardiac death occurred in three of the patients with thrombi despite warfarin therapy. One-month follow-up maintenance of sinus rhythm was 75% in group A compared to 45% in group B (P<0.01).</AbstractText>After using our transoesophageal echocardiographic exclusion criteria (no thrombi, no spontaneous echo contrast and left atrial appendage outflow velocity > or = 25 m. s(-1)) cardioversion can safely be performed in 2/3 of patients with atrial fibrillation or flutter without previous anticoagulation therapy. These patients maintained sinus rhythm significantly better after 1 month compared to patients with prolonged warfarin therapy before cardioversion.</AbstractText>Copyright 2000</CopyrightInformation> |
4,763 | Gamma-linolenic acid provides additional protection against ventricular fibrillation in aged rats fed linoleic acid rich diets. | Ligation of the coronary artery in rats produces severe ventricular fibrillation (VF) and malignant cardiac arrhythmia. Mortality increases with the age of the animal. Diets rich in saturated fatty acids (SF) but low in linoleic acid (LA) increase, but diets high in LA and low in SF decrease the severity of VF and mortality in older animals. The effects of an LA enriched diet can be blocked by inhibition of cyclooxygenase suggesting that conversion of LA to eicosanoids is central to the development of VF. Conversion of LA to gamma-linolenic acid (GLA) via delta-6 desaturase is the first step in the process. The activity of delta-6 desaturase declines with age. Thus inclusion of GLA in the diet of older animals may provide an additional benefit over LA alone. Dietary supplements of evening primrose oil (EPO) to one year old rats reduced ischaemic VF more than a supplement of sunflower seed oil (SSO) without GLA. Substitution of borage oil (more GLA than EPO but less LA than either EPO or SSO) was without additional benefit. |
4,764 | Myocardial ischemia-reperfusion injury in estrogen receptor-alpha knockout and wild-type mice. | We investigated the function of estrogen receptor-alpha in global myocardial ischemia and reperfusion injury in male estrogen receptor-alpha knockout (ERKO) and wild-type mice. Mouse hearts were subjected to 45 min of global ischemia followed by 180 min of reperfusion. The hearts were excised, cannulated, and maintained in a chilled (4 degrees C) cardioplegia solution until warm (37 degrees C) oxygenated Krebs-Henseleit bicarbonate buffer was perfused through the coronary arteries. ERKO hearts started beating later and had a higher incidence of ventricular fibrillation and/or tachycardia than control hearts. Coronary flow rate was significantly lower in ERKO hearts during the 90- and 120-min periods of reperfusion. Ca(2+) accumulation was significantly greater following 30, 90, 120, 150, and 180 min of reperfusion in ERKO hearts. Nitrite production was significantly less in ERKO hearts following 90, 120, and 150 min of reperfusion. Myocardial reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was significantly lower in experimental ERKO hearts. Marked interstitial edema and contraction bands were seen in hematoxylin-eosin-stained sections of ischemia-reperfused ERKO hearts but not in control tissues. Hematoxylin-basic fuchsin-picric acid-stained sections from experimental ERKO hearts had fewer viable myocytes compared with controls. Transmission electron microscopy revealed swollen and fragmented mitochondria with amorphous and granular bodies, loss of matrix, and rupture of cristae in experimental ERKO hearts. This is the first demonstration that estrogen receptor-alpha plays a cardioprotective role in ischemia-reperfusion injury in males. |
4,765 | [Cardiothyreosis: retrospective study of 32 cases in the cardiology and internal medicine department at Ouagadougou, Burkina Faso (1993-1998)]. | Cardiothyreosis is a relatively frequent condition in Sub-Saharan Africa and represents 1.7% of cardiac admissions in Ouagadougou. In this retrospective study, our aim has been to describe clinical characteristics of the disease and its cross-disciplinary management. Over a period of six years (1993-1998), we observed 32 cases of cardiothyreosis at the Centre Hospitalier Yalgado Ouedraogo. Average age was 43.3 +/- 14.7, with a clear majority of women (78.1%). Systolic blood pressure was on average 136 +/- 5 mmHg and mean diastolic blood pressure was 78 +/- 16 mmHg. Mean heart frequency was measured at 125 +/- 27 beats/minute and we detected 13 cases (41%) of atrial fibrillation. Heart failure occurred in 22 cases (69%). Underlying mitral valvulopathy was found in 5 cases. Arrhythmia was reduced in 53% of the cases, after treating with betablocker or cibenzoline (4 cases). Eighteen out of 25 patients presented anaemia (72%), 64% had hypocalcemia, and 50%--hypokaliemia. The average cardio-thoracic index was 0.63 +/- 0.09 with extremes of 0.75 and 0.40. An echocardiogramme was conducted for 10 patients and showed atrial dilation in 4 cases and ventricular dilation in one case. This turned out to be Basedow illness in 62.5% of the cases and multinodular goitre in 37.5%. Mean hospitalisation was 18.3 +/- 12.7 days. Antithyroidian treatment led to a positive evolution in 97% of the cases (only one death occurred through refractory heart failure). |
4,766 | Cardiac arrest due to succinylcholine-induced hyperkalemia in a patient with wound botulism. | Cardiac arrest due to hyperkalemia is a known complication of succinylcholine administration in patients with neuromuscular disease, extensive burns, and prolonged immobility. We report a case of hyperkalemic cardiac arrest following the administration of succinylcholine in a patient suffering from wound botulism. |
4,767 | Using an artificial neural network to detect activations during ventricular fibrillation. | Ventricular fibrillation is a cardiac arrhythmia that can result in sudden death. Understanding and treatment of this disorder would be improved if patterns of electrical activation could be accurately identified and studied during fibrillation. A feedforward artificial neural network using backpropagation was trained with the Rule-Based Method and the Current Source Density Method to identify cardiac tissue activation during fibrillation. Another feedforward artificial neural network that used backpropagation was trained with data preprocessed by those methods and the Transmembrane Current Method. Staged training, a new method that uses different sets of training examples in different stages, was used to improve the ability of the artificial neural networks to detect activation. Both artificial neural networks were able to correctly classify more than 92% of new test examples. The performance of both artificial neural networks improved when staged training was used. Thus, artificial neural networks may beuseful for identifying activation during ventricular fibrillation. |
4,768 | Idiopathic annular dilation: a rare cause of isolated severe tricuspid regurgitation. | The management of patients with severe tricuspid regurgitation (TR) requires the clinician to clarify the mechanism of regurgitation. Primary disorders of the tricuspid valve, either congenital or acquired, may be readily identified by echocardiography. Severe TR most often results from left-sided heart disease and secondary pulmonary hypertension. Cardiomyopathic processes may also cause right ventricular failure and functional TR. We report three patients with severe TR due to idiopathic annular dilation. The tricuspid valves were otherwise normal on surgical inspection, and the pulmonary pressures were not significantly elevated. Each patient was aged over 65 years and had chronic atrial fibrillation with preserved left ventricular systolic function. Surgical treatment was associated with marked clinical improvement. Clinicians should recognize this unusual but treatable cause of right-sided congestive heart failure. |
4,769 | Worsening of mitral regurgitation secondary to ventricular pacing. | A 68-year-old woman was admitted to hospital for possible mitral valve surgery for severe mitral regurgitation (MR). Six months before admission, a DDD pacemaker was implanted for symptomatic bradycardia. She developed atrial fibrillation and the pacer was changed to a VVI mode. At cardiac catheterization, the pulmonary artery and wedge pressures were elevated; coronary angiography showed non-obstructive coronary artery disease. 2-D echocardiography confirmed preserved left ventricular function, severe MR and moderate tricuspid regurgitation. The change in pacing had a dramatic effect on MR severity; ventricular pacing was associated with a MR jet that occupied a larger area of the left atrium than with the unpaced rhythm, the continuous-wave mitral regurgitant Doppler profile was 'dagger'-shaped, and the signal intensity stronger compared with the unpaced rhythm. These findings are consistent with severe MR. The pacer was reprogrammed to reduce the pacing rate from 70 to 45 beats/min, allowing an unpaced rhythm for the most part. The patient improved and was discharged two days later. Six months later she was asymptomatic; repeat echocardiography confirmed mild to moderate MR. |
4,770 | Cardiac arrest outcomes at the Melbourne Cricket Ground and shrine of remembrance using a tiered response strategy-a forerunner to public access defibrillation. | The provision of medical, paramedical and first aid services at major public events is an important concern for pre-hospital emergency medical care providers. Patient outcomes of a cardiac arrest response strategy employed at the Melbourne Cricket Ground (MCG) and the Shrine of Remembrance by St John Ambulance Australia volunteers are reported. Twenty-eight consecutive events occurring between December 1989 and December 1997 have been analysed. Included are three cardiac arrests managed at ANZAC day parades utilising the same response strategy by the same unit. The incidence of cardiac arrest at the MCG was 1:500000 attendances. Of the 28 patients, 24 (86%) left the venue alive and 20 (71%) were discharged home from hospital. In all cases the initial rhythm was ventricular fibrillation (VF). All 26 patients (93%) who were defibrillated by St John teams had this intervention within 5 min from the documented time of collapse. One patient in VF spontaneously reverted during CPR. Of the eight fatalities, four died at the scene. At major public venues and events, a co-ordinated emergency life support provision strategy, tailor made for the venue, is necessary for the delivery of prompt CPR, timely defibrillation and advanced life support. |
4,771 | Atrial function during cardiac arrest caused by ventricular fibrillation. | To report observations on preserved regular atrial electrical and mechanical systole during ventricular fibrillation (VF) and to quantitate blood flow generated by atrial contractions in this setting.</AbstractText>In 10 rats, right atrial pressure pulses were continuously recorded before and for an interval of 8 min after inducing VF. In 3 isolated, perfused rat hearts, epicardial right atrial electrograms were recorded after inducing VF. In 15 pigs, transesophageal echo-Doppler measurements were obtained with pulsed and color-Doppler visualization of flow across the mitral valve after onset of VF.</AbstractText>In each rat, regular right atrial pressure pulses were documented during VF. These persisted over an average interval of 7.5 min. In isolated, perfused hearts, right atrial contractions were accompanied by regular atrial depolarizations. In pigs, regular atrial contractions generated atrial stroke volumes of approximately 12 mL, or 25% of prearrest values during the first minute after onset of VF, but those declined to approximately 6 mL after 10 min of untreated cardiac arrest. Blood flow from the left atrium into the left ventricle failed to advance significantly into the systemic circuit. During atrial diastole, we observed reversal of flow into the left atrium.</AbstractText>Atrial contractions are preserved during the initial 8 min or more after cardiac arrest due to VF. Substantial forward flow into the left ventricle failed to advance through the outflow tract but regurgitated into the atrium during atrial diastole.</AbstractText> |
4,772 | Nerve sprouting and sudden cardiac death. | The factors that contribute to the occurrence of sudden cardiac death (SCD) in patients with chronic myocardial infarction (MI) are not entirely clear. The present study tests the hypothesis that augmented sympathetic nerve regeneration (nerve sprouting) increases the probability of ventricular tachycardia (VT), ventricular fibrillation (VF), and SCD in chronic MI. In dogs with MI and complete atrioventricular (AV) block, we induced cardiac sympathetic nerve sprouting by infusing nerve growth factor (NGF) to the left stellate ganglion (experimental group, n=9). Another 6 dogs with MI and complete AV block but without NGF infusion served as controls (n=6). Immunocytochemical staining revealed a greater magnitude of sympathetic nerve sprouting in the experimental group than in the control group. After MI, all dogs showed spontaneous VT that persisted for 5.8+/-2.0 days (phase 1 VT). Spontaneous VT reappeared 13.1+/-6.0 days after surgery (phase 2 VT). The frequency of phase 2 VT was 10-fold higher in the experimental group (2.0+/-2.0/d) than in the control group (0.2+/-0.2/d, P<0.05). Four dogs in the experimental group but none in the control group died suddenly of spontaneous VF. We conclude that MI results in sympathetic nerve sprouting. NGF infusion to the left stellate ganglion in dogs with chronic MI and AV block augments sympathetic nerve sprouting and creates a high-yield model of spontaneous VT, VF, and SCD. The magnitude of sympathetic nerve sprouting may be an important determinant of SCD in chronic MI. |
4,773 | High-output heart failure resulting from a remote traumatic aorto-caval fistula: diagnosis by echocardiography. | Congestive heart failure (CHF) due to high output states is known to occur in a variety of systemic illnesses and in patients with arterial-venous fistulas. This paper reports the case of a 45-year-old man admitted to the emergency room with a diagnosis of new onset atrial fibrillation and CHF, whose past medical history was not significant except for a gunshot wound to his abdomen 22 years previously. The etiology of his CHF together with the cardiomegaly and hyperdynamic left ventricular systolic function was unknown. A subcostal view routinely done during transthoracic echocardiography revealed a severely dilated inferior vena cava and the presence of an aorto-caval fistula by color doppler. The patient underwent successful corrective repair with dramatic improvement in symptoms and resolution of the atrial fibrillation, and cardiac size returned to normal. This rare case emphasizes that patients with refractory CHF must be closely examined with particular attention to palpation and auscultation over all scars, irrespective of the duration since any traumatic or surgical event. |
4,774 | Acute management of atrial fibrillation and atrial flutter in the critical care unit: should it be ibutilide? | Ibutilide is currently indicated for the rapid conversion of atrial fibrillation (Afb) or atrial flutter (Afl) of recent onset but limited to patients who are hemodynamically stable and without symptomatic cardiovascular conditions.</AbstractText>The study was undertaken to assess the efficacy and safety of ibutilide in patients with Afb or Afl associated with acute cardiovascular-medical disorders and in patients receiving prior selective antiarrhythmic drug therapy.</AbstractText>The study included 34 patients, mean age 75 +/- 16.3 years, with Afb (n = 25) or Afl (n = 9) having a variety of disorders, for example, congestive heart failure, unstable angina, borderline hypotension, respiratory failure, and chronic renal failure. Prior antiarrhythmic drugs consisted of propafenone (n = 5) or amiodarone (n = 3). Eligibility for cardioversion was established with appropriate anticoagulation or transesophageal echocardiography findings. Ibutilide was given as up to two 10 min infusions of 1 mg separated by 10 min.</AbstractText>The overall conversion rate after ibutilide was 79.4% (27/34 patients): 80% for Afb and 78% for Afl. More than 90% converted within 1 h of treatment. A high conversion rate of 92% resulted in those with an arrhythmia duration of < or = 1 week. All eight patients with prior antiarrhythmic therapy converted to sinus rhythm. The average baseline QTc interval for all patients increased 17.1% (397 +/- 63.3 to 465 +/- 60.2 ms) at 30 min. For eight patients (including four who received prior antiarrhythmic drugs), QTc interval prolongation > or = 500 ms was associated with nearly half the entire incidence of arrhythmic events. Proarrhythmia, the exclusive adverse effect, consisted of ventricular extrasystoles (n = 10) and nonsustained monomorphic ventricular tachycardia (VT) (n = 2) managed with intravenous MgSO4, and sustained polymorphic VT (n = 1) requiring electrical cardioversion.</AbstractText>Ibutilide is an effective and well tolerated drug for the rapid termination of Afb or Afl of recent onset associated with symptomatic and/or hemodynamically unstable disorders, and it is most efficacious (> or = 90%) when the atrial arrhythmia is < or = 1 week in duration. Proarrhythmic events are readily manageable in a monitored unit with access to appropriate treatment.</AbstractText> |
4,775 | Atrial fibrillation independently prolongs hospital stay after coronary artery bypass surgery. | Atrial fibrillation (AF) is the most common arrhythmia occurring in patients after coronary artery bypass surgery (CABG).</AbstractText>The purpose of this study was to determine whether AF independently prolonged postoperative length of stay (LOS).</AbstractText>Consecutive patients undergoing elective CABG were identified. Baseline clinical variables, postoperative course including the development of AF, and postoperative LOS were recorded.</AbstractText>In all, 216 patients (aged 61 +/- 13 years) were examined. Postoperative LOS was 11.3 +/- 6.4 days (median LOS = 9 days). Fifty-five patients (25%) developed AF. Among 16 variables examined, the univariate predictors of LOS included age (p < 0.001), preoperative left ventricular ejection fraction (p < 0.001), absence of a prior smoking history (p < 0.05), bypass limited to venous conduits (p < 0.001), postoperative AF (p < 0.001), and the occurrence of a postoperative event (p < 0.001). Length of stay for patients who developed AF was significantly longer than that for patients who did not (15.1 +/- 9.0 vs. 10.0 +/- 4.6 days, p < 0.001). After adjusting for other significant variables, the occurrence of AF after CABG independently prolonged LOS: patients who developed AF stayed 3.2 +/- 1.7 days longer than patients who did not (p < 0.001).</AbstractText>Atrial fibrillation lengthens hospital stay after CABG, and its effect is independent of other important variables. Identification of patients who are at risk for AF and successful treatment to prevent AF will likely contribute to major reductions in consumption of health care resources in patients with CABG.</AbstractText> |
4,776 | Echocardiography of the coronary sinus in adults. | The coronary sinus (CS) is a small tubular structure just above the posterior left atrioventricular junction. The CS can be imaged in several different echocardiographic views. Using zoom M-mode recordings of the CS in apical two-chamber view, CS caliber can be sharply imaged and easily measured during different phases of the cardiac cycle. We have recently shown that the CS narrows during atrial contraction in persons with sinus rhythm, but does not narrow at all if atrial fibrillation is present. Attenuation of CS narrowing occurs in patients with congestive heart failure and inferior vena cava plethora. Maximal CS caliber occurs during ventricular systole. Patients with poor left ventricular systolic function show mild CS dilatation. Greater CS dilatation is present in patients with persistent left superior vena cava, and huge dilatation when this anomaly is accompanied by absence of a right superior vena cava. Injection of sonicated saline into a left and then a right arm vein is diagnostically useful in confirming these two venous anomalies. Pulsed-wave Doppler of the CS can be recorded in the parasternal right heart inflow view. From this and from the CS cross-section area it may be possible to estimate coronary blood flow. |
4,777 | Natriuretic peptide levels in atrial fibrillation: a prospective hormonal and Doppler-echocardiographic study. | The objective was to determine the independent association between atrial fibrillation (A-Fib) and activation of natriuretic peptides.</AbstractText>The association of A-Fib with activation of N-terminal atrial and brain natriuretic peptides (N-ANPs and BNPs, respectively) is uncertain but of great importance for the diagnostic utilization of natriuretic peptides. This uncertainty is related to the lack of appropriate controls, with left ventricular (LV) and atrial overload similar to A-Fib.</AbstractText>We prospectively measured N-terminal atrial and BNPs and endothelin-1 levels in 100 patients and 14 age- and gender-matched control subjects. The 32 patients with A-Fib were compared with 68 patients in sinus rhythm and similar LV and atrial overload (due to mitral regurgitation or LV dysfunction) measured simultaneously with hormonal levels with comprehensive Doppler echocardiography.</AbstractText>Patients with A-Fib compared with those in sinus rhythm had similar symptoms, comorbid conditions, cardioactive medications, pulmonary pressure, left atrial volume, and LV ejection fraction and filling characteristics but demonstrated higher N-ANP levels (2,613 +/- 1,681 vs. 1,654 +/- 1,323 pg/ml, p = 0.007) even after adjustment for the underlying cardiac disease (p < 0.0001). Conversely, BNP levels were similar in both groups (165 +/- 163 vs. 160 +/- 269 pg/ml, p = 0.9). In multivariate analysis, a higher N-ANP level was associated with A-Fib (p = 0.0003), symptom class (p < 0.0001) and endothelin-1 level (p = 0.032) independently of left atrial volume and LV ejection fraction. Conversely, BNP showed no independent association with and was most strongly associated with LV ejection fraction (p < 0.0001).</AbstractText>Atrial fibrillation is an independent determinant of higher N-ANP levels and blurs its association with LV dysfunction. Conversely, the BNP is not independently associated with A-Fib and is strongly determined by LV dysfunction, for which it is an independent marker.</AbstractText> |
4,778 | Synthesis and antifibrillatory activity of nibentan and its analogues. | A series of 1,5-diaminopentane derivatives, structurally related to nibentan, was synthesized and tested for antifibrillatory activity. Improved modifications of some known chemical syntheses were proposed. (+/-)-N-[5-(Diethylamino)-1-(4-nitrophenyl)pentyl]-benzamide hydrochloride, (+/-)-N-[5-(diethylamino)-1-(4-nitrophenyl)pentyl]-4-nitrobenzamide hydrochloride and (+/-)-N-[5-(diethylamino)-1-(4-hydroxyphenyl)pentyl]-4-nitrobenzamide hydrochloride were more potent than nibentan and possessed a longer duration of action (up to 5 h in comparison with 60-90 min for nibentan). The antifibrillatory activity of (+/-)-N-[5-(diethylamino)-1-(4-methoxyphenyl)pentyl]-4-nitrobenzamide hydrochloride was comparable to that of nibentan but exceeded the potency of D-sotalol and sematilide. |
4,779 | Predictive power of increased QT dispersion in ventricular extrasystoles and in sinus beats for risk stratification after myocardial infarction. | QT dispersion, commonly measured in sinus beats (QTd-S), can also be calculated in premature ventricular beats (QTd-V). To date, no studies have addressed the relation between these 2 variables.</AbstractText>In 148 patients with remote myocardial infarction and premature ventricular beats on a routine ECG, QT dispersion, defined as the difference between the maximum and the minimum QT interval across the 12-lead ECG, was calculated separately for the ventricular extrasystole and the preceding sinus beat. In the total group of patients, QTd-V was greater than QTd-S (83+/-33 versus 74+/-34 ms, respectively; P=0.001). During a follow-up period of 35+/-17 months, arrhythmic events (sustained ventricular tachycardia, ventricular fibrillation, or sudden death) were noted in 30 patients. A QTd-V of >/=100 ms was a stronger univariate marker of arrhythmic events than was a QTd-S of >/=100 ms, and multivariate analysis selected only prolonged QTd-V (hazard ratio 3.81, 95% CI 2.2 to 11.2) and low ejection fraction (hazard ratio 3.05, 95% CI 1.6 to 7.6) as independent predictors of arrhythmic events.</AbstractText>The magnitude of QTd-V was greater than that of QTd-S in the total group of patients. Prolonged QTd-V is associated with a significantly increased risk for arrhythmic events in postinfarction patients, and the prognostic significance of QTd-V exceeds that of QTd-S.</AbstractText> |
4,780 | Identification of patients most likely to benefit from implantable cardioverter-defibrillator therapy: the Canadian Implantable Defibrillator Study. | Patients with resuscitated ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation) benefit from implantable cardioverter-defibrillators (ICDs) compared with medical therapy. We hypothesized that the patients who benefit most from an ICD are those at greatest risk of death.</AbstractText>In the Canadian Implantable Defibrillator Study (CIDS), 659 patients with resuscitated ventricular tachyarrhythmias were randomly assigned to receive an ICD or amiodarone and were then followed for a mean of 3 years. There were 98 and 83 deaths in the amiodarone and ICD groups, respectively. We used multivariate Cox analysis to assess the impact of baseline parameters on the mortality in the amiodarone group. Reduced left ventricular ejection fraction, advanced age, and poor NYHA status identified high-risk patients (P=0.0001 to 0.0009). Quartiles of risk were constructed, and the mortality reduction associated with ICD treatment in each quartile was assessed. There was a significant interaction between risk quartile and the ICD treatment effect (P=0.011). In the highest risk quartile, there was a 50% relative risk reduction (95% CI 21% to 68%) of death in the ICD group, whereas in the 3 lower quartiles, there was no benefit. Patients who are most likely to benefit from an ICD can be identified with a simple risk score (>/=2 of the following factors: age >/=70 years, left ventricular ejection fraction </=35%, and NYHA class III or IV). Thirteen of 15 deaths that were prevented by the ICD occurred in patients with >/=2 risk factors.</AbstractText>In CIDS, patients at highest risk of death benefited most from ICD therapy. These can be identified easily on the basis of age, poor ventricular function, and poor functional status.</AbstractText> |
4,781 | Stroke prevention: cardiac and carotid-related stroke. | The aim of this article is to discuss cardiac sources of stroke as well as the management of symptomatic and asymptomatic carotid stenosis. The authors detail the risks of cardioembolic stroke in the following conditions: aortic arch atheroma, atrial fibrillation, atrial myxoma, atrial septal aneurysm, dilated cardiomyopathy, infective endocarditis, left ventricular thrombus, mitral annular calcification, mitral valve prolapse, patent foramen ovale, prosthetic heart valves, valvular strands, and the optimal medical management for these conditions. The indications for carotid endarterectomy, angioplasty, and stenting are also outlined. |
4,782 | Arrhythmia prophylaxis after coronary artery bypass grafting: regimens of magnesium sulfate administration. | Arrhythmias are common after open heart surgery and may be related to hypomagnesaemia due to cardiopulmonary bypass. Although perioperative prophylactic Mg2+ administration may prevent arrhythmias after coronary artery bypass grafting (CABG), clear indications as well as the timing of Mg2+ substitution and dose regimen need to be clarified. Aim of this study was to evaluate the antiarrhythmic effects of Mg2+ infusion in patients who underwent elective CABG.</AbstractText>Ninety-seven patients who underwent elective CABG were divided in four Groups. In Group A 1 g of magnesium sulfate was added to the pump prime, Group B received 1 g in the pump prime plus 5 mmol/L in the cardioplegic solution, Group C received 5 mmol/L in the cardioplegic solution, and Group D was a placebo control Group. Groups A, B, and C also received 24 h continuous infusion of magnesium sulfate at 10 mmol/L. Three-channel electrocardiogram (II-V5-V6) continuous monitoring was performed 12 hours preoperatively and 48 hours postoperatively. Blood samples were taken for subsequent Serum magnesium measurements, at five different time points before, during and after CBP.</AbstractText>In all Groups serum Mg2+ levels were reduced during CPB (Time 2) and statistically significant differences from pre-anaesthesia levels (Time 1) were noted (p <0.05). In Groups A, B, and C Serum Mg2+ levels increased progressively from Time 3 to Time 5; in Group D serum Mg2+ levels were still much lower at Time 5. Significant differences (p<0.05) were noted for Groups B and C vs Groups A and D in atrial ectopics, atrial fibrillation, and ventricular arrhythmic events.</AbstractText>Our results demonstrate that Mg2+ sulfate administration regimens used in Group B and C reduce postoperative arrhythmic events in patients undergoing CABG.</AbstractText> |
4,783 | Patients with implantable cardioverter defibrillators: transition to home. | Implantable cardioverter defibrillators (ICD) are highly effective in the identification and termination of malignant ventricular tachycardia and fibrillation. It is anticipated that the number of patients receiving this device will increase because of major advancements in technology and the results of prospective controlled clinical trials. Major life changes occur after implantation of the device. Continued research is needed to identify concerns and needs of patients with ICDs and their families. Specific interventions must be tested to determine efficacy. Nurses must be able to provide education and psychologic support to assist patients in their successful transition to home. |
4,784 | Opposing effects on infarction of delta and kappa opioid receptor activation in the isolated rat heart: implications for ischemic preconditioning. | Delta-opioid receptors are known to participate in the protection found following ischemic preconditioning (IPC), but the role of kappa-receptors in IPC is currently controversial. Langendorff-perfused rat hearts received 35 min regional ischemia and 2 h reperfusion. PC (2 cycles 5 min global ischemia) substantially reduced infarct size. Pharmacological PC with the delta-agonist DADLE (10 nmol/L) had similar protective effects. However, higher dose DADLE (1 micromol/L) had a less beneficial effect, and in conjunction with the delta-antagonist naltrindole unexpectedly increased infarct size (61.5 +/- 2.0%, p<0.05 v 45.9 +/- 2.4% in controls) suggesting a non-delta effect. The universal kappa-opioid agonist bremazocine (30 nmol/L) increased infarct size (61.3 +/- 1.6%, p<0.05 v controls), an effect abrogated by the selective kappa1-antagonist nor-binaltorphimine (BNI). Since opiates are known to have anti-adrenergic effects, which hypothetically may help to mediate IPC, cyclic AMP levels were measured in DADLE and in bremazocine-treated hearts. Decreased levels of cyclic AMP at the start of the regional ischemic period were found in low dose DADLE hearts (0.485 +/- 0/020, n = 8, vs controls, 0.654 +/- 0.025 nmol/g wet weight, p<0.001), but not in high dose DADLE nor in bremazocine treated hearts. Thus, in the isolated rat heart kappa1-opioid receptor activation exacerbates infarct size through an as yet unknown mechanism, suggesting that there could be an "antipreconditioned state". In contrast, delta-activity mediates protection which may be associated with a reduction of tissue cyclic AMP levels. |
4,785 | [Myocardial revascularization in malignant ventricular tachyarrhythmia--prognostic significance]. | The survival of patients with chronic ischaemic heart disease and malignant ventricular tachyarrhythmia is influenced positively in some instances by revascularization of the heart muscle and implantation of a cardioverter-defibrillator. The objective of the submitted work was to evaluate by perspective follow-up of subjects with chronic ischaemic heart disease and malignant ventricular tachyarrhythmia: a) the effect of revascularization of the heart muscle on the prognosis, making use of programmed stimulation of the ventricles and testing the effectiveness of antiarrhythmic treatment; b) the importance of implantation of a cardioverter-defibrillator in revascularized and non-revascularized subjects for the prevention of sudden "arrhythmic" deaths.</AbstractText>The authors examined 37 patients (32 men and 5 women), age bracket 34 to 78 years (mean age 61 +/- 11) with IHD and spontaneous ventricular tachyarrhythmia after ruling out acute myocardial infarction. The group was divided into sub-groups without revascularization (21 subjects) and with revascularization (16 subjects). In both sub-groups programmed stimulation of the ventricles was implemented. During the diagnostic finding of programmed stimulation they tested antiarrhythmic drugs, most frequently amiodarone administered orally. A cardioverter-defibrillator was implanted to 10 patients. All patients were followed-up to death, the longest period being 24 months. They evaluated the frequency of cardiac deaths (death on cardiac grounds incl. sudden "arrhythmic" death) and sudden "arrhythmic" deaths (death within on hour after onset of symptoms or first recorded malignant ventricular tachyarrhythmia). In the sub-group without revascularization with diagnostic inducibility of the heart muscle in 85.7% of patients the authors described 9 cardiac deaths (42.9%) and 8 sden "arrhythmic" deaths (38.1%). Conversely in the sub-group with revascularization and with diagnostic programmed stimulation of the ventricles in half the subjects 5 clinical deaths were found (31.3%) and 3 sudden "arrhythmic" deaths (18.8%). Analysis of 11 sudden "arrhythmic" deaths revealed that no subjects with an implanted cardioverter-defibrillator (5) died (documented malignant ventricular tachyarrhythmia). Five of the six patients who died (all without a cardioverter-defibrillator) were not revascularized.</AbstractText>Revascularization of the heart muscle in patients with ischaemic heart disease (after elimination of acute cardiac infarction) and malignant ventricular tachyarrhythmia reduces the risk of relapse of this arrhythmia. The benefit of implantation of a cardioverter-defibrillator was recorded in all subjects regardless of the revascularization of the heart muscle.</AbstractText> |
4,786 | A fatal case of gun blue ingestion in a toddler. | Acute selenium poisoning occurs infrequently. The form of selenium encountered plays a great role in toxicity. Several fatalities have been reported and all but I involved ingestion of selenious acid or selenium dioxide. A healthy 22-mo-old male ingested up to 15 ml of Gun Blue solution (selenious acid). Initially he was pink, alert, and combative in the ambulance but his condition rapidly deteriorated. There was no measurable blood pressure, his oxygen saturation was 84% by pulse oximetry, and his mental status deteriorated to require hand ventilation. The child was cyanotic, unresponsive, and without palpable pulses upon presentation. Cardiopulmonary resuscitation was initiated unsuccessfully and was terminated after 35 minutes. |
4,787 | Unmasking effect of propafenone on the concealed form of the Brugada phenomenon. | A case report of a patient with frequent ventricular premature beats but with an otherwise normal ECG and no structural heart disease. Propafenone in therapeutical doses unmasked the ECG picture of the Brugada phenomenon. |
4,788 | ST segment and T wave alternans in a patient with Brugada syndrome. | We describe a patient with Brugada syndrome in whom J point and ST-segment elevation in leads V1 and V2 were augmented by atrial pacing and intravenous administration of propranolol or cibenzoline. Significant T wave alternans with a 2:1 appearance of terminal negative T wave was observed in the absence and presence of atrial pacing after the administration of cibenzoline. The cellular mechanism responsible for T wave alternans, beat-to-beat appearance of terminal negative T wave and augmented J point and ST-segment elevation is discussed. |
4,789 | Near fatal electrical storm in a patient equipped with an implantable cardioverter defibrillator for Brugada syndrome. | A patient with Brugada syndrome experienced incessant ventricular fibrillation 7 years after implantation of an ICD. General anesthesia, fast ventricular pacing, bretylium, and atenolol infusion were ineffective; amiodarone infusion was started. After 190 defibrillation shocks over 36 hours, the electrical storm stopped. A multiorgan failure occurred as a complication of the electrical storm and necessitated prolonged reanimation. Thorough cardiac evaluation revealed no structural abnormality and the patient, now on chronic oral amiodarone therapy, remains free of arrhythmia 1 year after the event. |
4,790 | Spontaneous sustained monomorphic ventricular tachycardia after administration of ajmaline in a patient with Brugada syndrome. | We present the case of a 13-year-old boy with an episode of aborted sudden death, absence of structural heart disease, and a characteristic ECG pattern of right bundle branch block with persistent ST-segment elevation in the right precordial leads, in whom a monomorphic sustained ventricular tachycardia developed spontaneously after the administration of ajmaline. This effect may be related to an increased inhomogeneity of repolarization mediated by the drug and demonstrates the arrhythmogenic potential of Class I antiarrhythmic drugs in patients with Brugada syndrome. |
4,791 | Brugada syndrome characterized by the appearance of J waves. | We describe a patient with Brugada syndrome. The ST-segment elevation in precordial leads was revealed during admission, but the appearance of J waves was characteristic before ventricular fibrillation (VF), rather than ST-segment elevation. J waves have been reported to be associated with the presence of an Ito-mediated prominent action potential notch in the epicardium. It is considered that one of the mechanisms of this VF is due to heterogeneous distribution of the refractory period according to changes in K+ channels including Ito. |
4,792 | Preliminary results with the simultaneous use of implantable cardioverter defibrillators and permanent biventricular pacemakers: implications for device interaction and development. | We report our preliminary experience with the combined use of implantable cardioverter defibrillators (ICD) and biventricular pacemakers in six patients with heart failure and malignant ventricular arrhythmia. Two patients underwent ICD implantation for malignant ventricular arrhythmia after previous biventricular pacemaker implantation. One patient underwent biventricular pacemaker insertion for NYHA Class III heart failure after previous ICD implantation. Two patients underwent single device implantation. In the sixth patient, a combined implantation failed due to an inability to obtain a satisfactory left ventricular pacemaker lead position. The potential for device interaction was explored during implantation. In two patients a potentially serious interaction was discovered. Subsequent alterations in device configuration and programming prevented these interactions with long-term use. No complication of combined device use has been demonstrated during a mean follow-up of 2 months (range 1-4 months). Satisfactory ICD and pacemaker function has also been demonstrated. We conclude that combined device implantation may be feasible with currently available pacing technology and that further prospective studies are required in this area. |
4,793 | Effect of 6-wk estrogen withdrawal or replacement on myocardial ischemic tolerance in rats. | Menopausal status is a risk factor for coronary artery disease death, but the mechanism underlying this association is uncertain. To test whether estrogen ameliorates the effects of acute myocardial ischemia in ways likely to translate into a mortality difference, we compared the response to brief (6-min) and prolonged (45-min) coronary occlusion in vivo in five groups (each n = 16) of rats: ovariectomized females; ovariectomized females after 6 wk 17beta-estradiol replacement; male rats supplemented with estradiol for 6 wk; normal males; and normal females. Coronary occlusion produced a uniform ischemic risk area averaging 53 +/- 3% of left ventricular volume. After a brief occlusion, reperfusion ventricular tachycardia/fibrillation occurred with >85% frequency in all groups. During a prolonged occlusion, ischemic ventricular tachycardia occurred in 100% and sustained tachycardia requiring cardioversion in >75% of rats in all groups. Myocardial infarct size averaged 52 +/- 4% of the ischemic risk area and was similarly unaffected by gender or estrogen status. We conclude that neither short-term estrogen withdrawal, replacement, nor supplementation significantly affects the potentially lethal outcomes from acute coronary occlusion in this species. |
4,794 | Virtual electrodes and deexcitation: new insights into fibrillation induction and defibrillation. | Previous models of fibrillation induction and defibrillation stressed the contribution of depolarization during the response of the heart to a shock. This article reviews recent evidence suggesting that comprehending the role of negative polarization (hyperpolarization) also is crucial for understanding the response to a shock. Negative polarization can "deexcite" cardiac cells, creating regions of excitable tissue through which wavefronts can propagate. These wavefronts can result in new reentrant circuits, inducing fibrillation or causing defibrillation to fail. In addition, deexcitation can lead to rapid propagation through newly excitable regions, resulting in the elimination of excitable gaps soon after the shock and causing defibrillation to succeed. |
4,795 | Ventricular tachyarrhythmias following coronary surgery: predisposing factors. | The perioperative factors potentially associated with post-coronary artery bypass grafting (CABG) ventricular tachyarrhythmias (VT) onset have not been deeply investigated. Monomorphic or polymorphic ventricular tachycardia and ventricular fibrillation represent the most dreadful arrhythmic events that can complicate the postoperative course of CABG. As a consequence, the aim of our paper was to identify which perioperative variables might predict post-CABG VT occurrence. One hundred and fifty-two consecutive patients who underwent CABG surgery at our Institution were included in the study. Post-CABG VT occurred in 13 out of 152 patients (8.5%, six cases of monomorphic ventricular tachycardia and seven cases of ventricular fibrillation). At univariate analysis, VT patients were significantly younger (54.8+/-6.6 vs. 60.1+/-8.8, P=0.038), exhibited a more severe coronary artery disease (CAD) (number of diseased vessels 2.92+/-0.3 vs. 2.45+/-0.7, P=0.023, and percentage of patients with three-vessel CAD 91.7% vs. 57.3%, P=0.043) and received a greater number of CABGs than those remaining in sinus rhythm (SR) (percentage of patients receiving three or more CABGs 76. 9% vs. 38.8%, P1000 76.9% vs. 38%, Pnormal range 72.7% vs. 30.7%, P=0.014), electrolyte derangement (84.6% vs. 45.6%, P=0.017) and a severe haemodynamic impairment (need for IABP 23% vs. 2.9%, P1000, postoperative electrolyte imbalance, the need for three or more CABGs and of IABP all were independent correlates for VT. In conclusion, post-CABG VT seem to be related to the preexistence of a severe underlying coronary artery disease along with perioperative triggering factors such as acute ischemia, electrolytic disorders and a sudden haemodynamic impairment. |
4,796 | Alteration of ventricular fibrillation by flecainide, verapamil, and sotalol: an experimental study. | The purpose of this study was to determine whether the myocardial electrophysiological properties are useful for predicting changes in the ventricular fibrillatory pattern.</AbstractText>Thirty-two Langendorff-perfused rabbit hearts were used to record ventricular fibrillatory activity with an epicardial multiple electrode. Under control conditions and after flecainide, verapamil, or d,l-sotalol, the dominant frequency (FrD), type of activation maps, conduction velocity, functional refractory period, and wavelength (WL) of excitation were determined during ventricular fibrillation (VF). Flecainide (1.9+/-0.3 versus 2.4+/-0.6 cm, P<0. 05) and sotalol (2.1+/-0.3 versus 2.5+/-0.5 cm, P<0.05) prolonged WL and diminished FrD during VF, whereas verapamil (2.0+/-0.2 versus 1. 7+/-0.2 cm, P<0.001) shortened WL and increased FrD. Simple linear regression revealed an inverse relation between FrD and the functional refractory period (r=0.66, P<0.0001), a direct relation with respect to conduction velocity (r=0.33, P<0.01), and an inverse relation with respect to WL estimated during VF (r=0.49, P<0.0001). By stepwise multiple regression, the functional refractory periods were the only predictors of FrD. Flecainide and sotalol increased the circuit size of the reentrant activations, whereas verapamil decreased it. The 3 drugs significantly reduced the percentages of more complex activation maps during VF.</AbstractText>The activation frequency is inversely related to WL during VF, although a closer relation is observed with the functional refractory period. Despite the diverging effects of verapamil versus flecainide and sotalol on the activation frequency, WL, and size of the reentrant circuits, all 3 drugs reduce activation pattern complexity during VF.</AbstractText> |
4,797 | A mechanism of transition from ventricular fibrillation to tachycardia : effect of calcium channel blockade on the dynamics of rotating waves. | Abbreviation of the action potential duration and/or effective refractory period (ERP) is thought to decrease the cycle length of reentrant arrhythmias. Verapamil, however, paradoxically converts ventricular fibrillation (VF) to ventricular tachycardia (VT), despite reducing the ERP. This mechanism remains unclear. We hypothesize that the size and the dynamics of the core of rotating waves, in addition to the ERP, influence the arrhythmia manifestation (ie, VF or VT). The objectives of this study were (1) to demonstrate functional reentry as a mechanism of VF and VT in the isolated Langendorff-perfused rabbit heart in the absence of an electromechanical uncoupler and (2) to elucidate the mechanism of verapamil-induced conversion of VF to VT. We used high-resolution video imaging with a fluorescent dye, ECG, frequency and 2-dimensional phase analysis, and computer simulations. Activation patterns in 10 hearts were studied during control, verapamil perfusion (2x10(-6) mol/L), and washout. The dominant frequency of VF decreased from 16.2+/-0.7 to 13.5+/-0.6 Hz at 20 minutes of verapamil perfusion (P<0.007). Concomitantly, phase analysis revealed that wavefront fragmentation was reduced, as demonstrated by a 3-fold reduction in the density of phase singularities (PSs) on the ventricular epicardial surface (PS density: control, 1.04+/-0.12 PSs/cm(2); verapamil, 0.32+/-0.06 PSs/cm(2) [P=0.0008]). On washout, the dominant frequency and the PS density increased, and the arrhythmia reverted to VF. The core area of transiently appearing rotors significantly increased during verapamil perfusion (control, 4.5+/-0.6 mm(2); verapamil, 9.2+/-0.5 mm(2) [P=0.0002]). In computer simulations, blockade of slow inward current also caused an increase in the core size. Rotating waves underlie VF and VT in the isolated rabbit heart. Verapamil-induced VF-to-VT conversion is most likely due to a reduction in the frequency of rotors and a decrease in wavefront fragmentation that lessens fibrillatory propagation away from the rotor. |
4,798 | Cox-Maze procedure for atrial fibrillation: Mayo Clinic experience. | The Cox-Maze procedure corrects atrial fibrillation in 90% of patients, and successful operation restores sinus rhythm, thereby reducing risks of thromboembolism and anticoagulant-associated hemorrhage. Symptoms such as palpitation and fatigability also improve with restoration of atrioventricular synchrony. At the Mayo Clinic, 221 Cox-Maze procedures were performed from March 1993 through March 1999. Over 75% of patients had associated cardiac disease and concomitant operations. Overall, early mortality was 1.4%, and the incidence of postoperative pacemaker implantation was 3.2%. Limiting incisions to the right atrium simplifies the operation for patients who primarily have tricuspid valve disease, and in early follow-up, outcome appeared to be as good as that achieved with biatrial incisions. The Cox-Maze procedure has proved particularly useful for patients with preoperative atrial fibrillation who require valvuloplasty for acquired mitral valve regurgitation; 87 patients have had this combined procedure, and there have been no early deaths. Further, our experience indicates that ventricular dysfunction is not a contraindication for operation and that restoration of sinus rhythm after the Cox-Maze procedure improves left ventricular ejection fraction in most patients. |
4,799 | [Cardiac pacemaker therapy for optimizing brain circulation. A possible prevention for cerebrovascular diseases?]. | A 78-year-old patient experienced dizziness, impairment of mnemic and cognitive function, chronic fatigue and recurrent syncope.</AbstractText>Hypertensive heart disease, reduced left ventricular function, and ventricular ectopia classification Lown IVb was documented. Computed tomography showed minimal brain atrophia. Stenoses of the brain supplying arteries and of other intracranial diseases were excluded. A distinct correlation between cardiac output and cerebral blood flow in correspondence to changes of heart rate were found (cardiac output 4.2 l/min during sinus rhythm, 7.4 l/min during temporary atrial pacing--AAI-Mode with a pacing rate of 90/min; 4.8 l/min--AAI-Mode with a pacing rate of 120/min; cerebral blood flow: 70, 74 and 62 ml/100 g per minute, respectively). Thus, impairment of cerebral blood flow autoregulation can be assumed.</AbstractText>After implantation of a permanent pacemaker the patient was without any complaints. The mnemic and cognitive function improved, dizziness and fatigue disappeared. Synopsis did not occur. 14 months later a sudden onset of complaints occurred caused by atrial fibrillation (heart rate 120/min). Cardiac output and cerebral blood flow were now 4.0 l/min and 35 ml/100 g per minute. After antiarrhythmic drug therapy and restoration of sinus rhythm cardiac output and cerebral blood flow increased and the complaints disappeared again.</AbstractText>In patients with impaired capacity of cerebral autoregulation a reduced cardiac function and output can induce a reduction of cerebral blood flow. Thus, impairment of mnemic and cognitive function as well as other unspecific neurological deficits can be caused. In these cases pacemaker therapy has to be discussed as an effective therapeutical concept.</AbstractText> |
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