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3,000 | Cost effectiveness of implantable cardioverter defibrillator therapy versus drug therapy for patients at high risk of sudden cardiac death. | The implantable cardioverter defibrillator (ICD) is a therapy for patients at risk of sudden cardiac death due to ventricular tachycardia (VT) or ventricular fibrillation (VF). But the apparent high cost of ICD therapy relative to antiarrhythmic drugs such as amiodarone has raised questions about the cost effectiveness of ICD therapy versus drug therapy. To inform this debate we reviewed the literature on ICD cost effectiveness. An electronic and manual search was conducted for articles published since 1980 reporting original data on the cost effectiveness of ICD versus drug therapy for patients at risk of VT/VF. Data on costs and life-years gained were abstracted and studies were grouped into those that used decision-analysis models and those that were trial-based analyses. Cost-effectiveness ratios were inflated to 2001 US dollars. Nine studies were included in the review; five studies were modelling studies and four were part of randomised trials of ICD therapy. Studies varied in time horizon, but all except one indicated that ICD therapy was more costly than drug therapy. Early decision models assumed larger survival benefits than those observed in subsequent trials and therefore had attractive incremental cost-effectiveness ratios in the range of dollars US 27000 to dollars US 60000 per life-year gained. Trial-based studies, with the exception of one small trial, indicated cost per life-year gained in the range dollars US 44000 to dollars US 144000. Stratified analysis shows clearly that patients with a greater risk of mortality due to structural heart disease (e.g. left ventricular ejection fraction < or =35%) benefit more from ICD therapy and therefore have a more attractive cost effectiveness ratio than patients at lower risk. ICD therapy is still evolving over time with implant costs declining and device technology improving. Current evidence is that, in selected patients who are at high risk of VT/VF, ICD therapy can be a cost-effective option. Future research should focus on (i) patient selection to optimise benefits for available resources; and (ii) more comprehensive outcome measures to include health-related quality of life. |
3,001 | Time-dependent cardioprotection with calcium antagonism and experimental studies with clevidipine in ischemic-reperfused pig hearts: part II. | The intracellular calcium level is increased during ischemia and early reperfusion. The aim of this study was to study the role of the calcium influx in the development of myocardial ischemic and reperfusion injury during the early and late phases of ischemia and during early reperfusion. An ultrashort-acting calcium antagonist, clevidipine, was used as a tool for this investigation. Pentobarbital-anesthetized pigs were subjected to 45 minutes of LAD occlusion followed by 240 minutes of reperfusion. In the first set of experiments, clevidipine (0.3 nmol/kg per minute) was infused over 5 minutes into the ischemic myocardium via a catheter in the LAD, starting at 5, 35, or 44 minutes following the onset of ischemia (n = 6 in each group). The area at risk and the infarct size were determined after 240 minutes of reperfusion by staining with Evans blue dye and triphenyl tetrazolium chloride (TTC), respectively. In a second set of experiments, two groups of animals (n = 6 in each) were subjected to the same periods of ischemia and reperfusion; one group received no infusion during ischemia, whereas the other group received vehicle infusion during a 5-minute period between 5 and 10 minutes of ischemia. In the first set of experiments, there were no significant differences between the groups with regard to hemodynamic variables. The area at risk expressed as a percentage of the left ventricle was of similar magnitude in all three clevidipine-treated groups (about 18%). The infarct size, expressed as a percentage of the area at risk, was significantly smaller in pigs given clevidipine after 5 minutes (58 +/- 17%; p < 0.01) and after 44 minutes (42 +/- 6%; p < 0.01) of ischemia than in pigs receiving clevidipine after 35 minutes of ischemia (85 +/- 4%). The difference in infarct size between pigs given clevidipine after 5 or 44 minutes of ischemia was not significant. In the second set of experiments, there was a similar area at risk and no significant difference in infarct size between the noninfusion group and the 5-minute vehicle infusion group, indicating that the LAD infusion per se did not affect infarct size. The present results demonstrate that blockade of calcium influx by the short-acting dihydropyridine calcium antagonist clevidipine during the early phase of ischemia and at the time of reperfusion, but not during a late phase of ischemia, limits infarct size induced by ischemia and reperfusion. This indicates that the pathophysiological importance of calcium influx varies according to the different phases of myocardial ischemia and reperfusion. |
3,002 | The prediction of defibrillation outcome using a new combination of mean frequency and amplitude in porcine models of cardiac arrest. | We estimated the predictive power with respect to defibrillation outcome of ventricular fibrillation (VF) mean frequency (FREQ), mean peak-to-trough amplitude (AMPL), and their combination. We examined VF electrocardiogram signals of 64 pigs from 4 different cardiac arrest models with different durations of untreated VF, different durations of cardiopulmonary resuscitation, and use of different drugs (epinephrine, vasopressin, N-nitro-L-arginine methyl ester, or saline placebo). The frequency domain was restricted to the range from 4.33 to 30 Hz. In the 10-s epoch between 20 and 10 s before the first defibrillation shock, FREQ and AMPL were estimated. We introduced the survival index (SI; 0.68 Hz(-1). FREQ + 12.69 mV(-1). AMPL) by use of multiple logistic regression. Kruskal-Wallis nonparametric one-way analysis was used to analyze the different porcine models for significant difference. The variables FREQ, AMPL, and SI were compared with defibrillation outcome by means of univariate logistic regression and receiver operating characteristic curves. SI increased predictive power compared with AMPL or FREQ alone, resulting in 89% sensitivity and 86% specificity. The probabilities of predicting defibrillation outcome for FREQ, AMPL, and SI were 0.85, 0.89 and 0.90, respectively. FREQ, AMPL, and SI values were not sensitive in regard to the four different cardiac arrest models but were significantly different for vasopressin and epinephrine animals.</AbstractText>We present a retrospective data analysis to evaluate the predictive power of different ventricular fibrillation electrocardiogram variables in pigs with respect to defibrillation outcome. We showed that our combination of variables leads to an improved forecast, which may help to reduce harmful unsuccessful defibrillation attempts.</AbstractText> |
3,003 | The incidence and outcome of ventricular arrhythmias after noncardiac thoracic surgery. | Atrial arrhythmias are common after thoracic surgery, but the incidence and significance of ventricular arrhythmias early after such surgery are not well established. Our goal was to determine the incidence and outcome of this complication from a continuing prospective database in 412 patients who had lobectomy (n = 243) or pneumonectomy (n = 169) and were continuously monitored with Holter recorders for 72-96 h postoperatively. The primary end point of the study was the occurrence of ventricular tachycardia (VT) defined as three or more consecutive wide complexes. Sixty-one of 412 patients (15%) developed 1 or more episode of VT. There were no episodes of sustained (>30 s) VT and no patient required treatment for hemodynamic compromise associated with any VT episode. Patients with VT had a more frequent incidence of a preoperative left bundle branch block (P = 0.01) but did not differ in other clinical characteristics, operative data, or core temperature on arrival to the postanesthesia care unit, when compared with those without VT. Patients who developed VT had significantly more atrial premature contractions (P < 0.001), ventricular premature contractions (P < 0.001), ventricular couplets (P < 0.001), and postoperative atrial fibrillation, 21 of 61 (34%) versus 58 of 351 (17%), P = 0.001, than those without VT, respectively. Multivariate logistic regression analysis revealed that only postoperative atrial fibrillation occurrence was independently associated with VT (relative risk 2.6, 95% confidence intervals 1.4 to 4.8, P = 0.002). We conclude that nonsustained VT after noncardiac thoracic surgery occurs frequently but is not associated with poor outcome. The strong association of atrial and ventricular arrhythmogenesis with VT suggests that vagal withdrawal and/or adrenergic hyperactivity may have a role in precipitating these events in the early postoperative period.</AbstractText>In 412 patients, we determined that the incidence of nonsustained ventricular tachycardia after major thoracic surgery is 15% and is not associated with poor outcome.</AbstractText> |
3,004 | Predictors of survival following in-hospital adult cardiopulmonary resuscitation. | This study was undertaken to provide up-to-date survival data for Canadian adult in-patients following attempted resuscitation from cardiac or respiratory arrest. We hope that objective data might encourage more meaningful dialogue between physicians, patients and their families regarding resuscitation wishes.</AbstractText>We reviewed all records of adult cardiopulmonary arrest that occurred between Jan. 1, 1997, and Jan. 31, 1999, at the 3 main teaching hospitals in Edmonton. We then abstracted data from the full inpatient medical records to describe patient characteristics, type of arrest and survival details. The family physicians of survivors were contacted to confirm the outcomes. We included only adults admitted to hospital but not to a critical care bed.</AbstractText>There were 247 arrests during the study period; 143 (57.9%) were witnessed, and 104 (42.1%) were unwitnessed). Of the patients whose arrests were witnessed, 48.3% (95% confidence interval [CI] 39.8%-56.8%) were able to be resuscitated, 22.4% (95% CI 1 5.8%-30.1%) survived to hospital discharge, and 18.9% (95% CI 12.8%-26.3%) were able to return home. Survival was highest after primary respiratory arrest and lowest after pulseless electrical activity or asystole. Of the patients with unwitnessed arrests, 21.2% (95% CI 13.8%-30.3%) were able to be resuscitated, but only 1 patient (1.0% [95% CI 0.0%-5.2%]) survived to hospital discharge and was able to return home. This patient survived an unwitnessed respiratory arrest. No patient who had an unwitnessed cardiac arrest survived to discharge. Most of the respiratory arrests were witnessed (93.1%), and most of the pulseless electrical activity or asystole arrests were unwitnessed (54.6%). We did not find age or sex to be independent predictors of survival. However, the risk of not returning home was higher among patients whose arrest occurred between 2301 and 0700 than among those whose arrest was between 0701 and 1500 (adjusted OR 3.2, 95% CI 1.0-10.1). Survival was significantly decreased after pulseless ventricular tachycardia or ventricular fibrillation arrest (adjusted OR 4.2, 95% CI 1.4-12.5) and even more so after pulseless electrical activity or asystole arrest (adjusted OR 21.0, 95% CI 6.2-71.7) than after respiratory arrest.</AbstractText>Overall, survival following cardiopulmonary resuscitation in hospital does not appear to have changed markedly in 40 years. The type of arrest is highly predictive of survival, whereas age and sex are not.</AbstractText> |
3,005 | Impact of community-wide police car deployment of automated external defibrillators on survival from out-of-hospital cardiac arrest. | Disappointing survival rates from out-of-hospital cardiac arrests encourage strategies for faster defibrillation, such as use of automated external defibrillators (AEDs) by nonconventional responders.</AbstractText>AEDs were provided to all Miami-Dade County, Florida, police. AED-equipped police (P-AED) and conventional emergency medical rescue (EMS) responders are simultaneously deployed to possible cardiac arrests. Times from 9-1-1 contact to the scene were compared for P-AED and concurrently deployed EMS, and both were compared with historical EMS experience. Survival with P-AED was compared with outcomes when EMS was the sole responder. Among 420 paired dispatches of P-AED and EMS, the mean+/-SD P-AED time from 9-1-1 call to arrival at the scene was 6.16+/-4.27 minutes, compared with 7.56+/-3.60 minutes for EMS (P<0.001). Police arrived first to 56% of the calls. The time to first responder arrival among P-AED and EMS was 4.88+/-2.88 minutes (P<0.001), compared with a historical response time of 7.64+/-3.66 minutes when EMS was the sole responder. A 17.2% survival rate was observed for victims with ventricular fibrillation or pulseless ventricular tachycardia (VT/VF), compared with 9.0% for standard EMS before P-AED implementation (P=0.047). However, VT/VF benefit was diluted by the observation that 61% of the initial rhythms were nonshockable, reducing the absolute survival benefit among the total study population to 1.6% (P-AED, 7.6%; EMS, 6.0%).</AbstractText>P-AED establishes a layer of responders that generate improved response times and survival from VT/VF. There was no benefit for victims with nonshockable rhythms.</AbstractText> |
3,006 | Life span of ventricular fibrillation frequencies. | The nature and organization of electrical activity during ventricular fibrillation (VF) are important and controversial subjects dominated by 2 competing theories: the wavebreak and the dominant mother rotor hypothesis. To investigate spatiotemporal characteristics of ventricular fibrillation (VF), transmembrane potentials (V(m)) were recorded from multiple sites of perfused rabbit hearts using a voltage-sensitive dye and a photodiode array or a CCD camera, and the time-frequency characteristics of V(m) were analyzed by short-time fast Fourier transform (FFT) or generalized time-frequency representation with a cone-shaped kernel. The analysis was applied to all pixels to track VF frequencies in time and space. VF consisted of blobs, which are groups of contiguous pixels with a common frequency and an ill-defined shape. At any time t, several VF frequency blobs coexisted in the field of view, and the number of coexisting blobs was on average 5.9+/-2.1 (n=8 hearts) as they appeared and disappeared discontinuously with time and were not fixed in space. The life span of frequency blobs from birth to either annihilation or breakup to another frequency had a half-life of 0.39+/-0.13 second (n=4 hearts). The Ca2+ channel blocker nifedipine increased the stability of VF frequencies and reduced the number of frequency blobs progressing to a single frequency. In conclusion, VF consists of dynamically changing frequency blobs, which have a short life span and can be modified by pharmacological interventions, suggesting that VF is maintained by dynamically changing multiple wavelets. |
3,007 | Cardiac microstructure: implications for electrical propagation and defibrillation in the heart. | Our understanding of the electrophysiological properties of the heart is incomplete. We have investigated two issues that are fundamental to advancing that understanding. First, there has been widespread debate over the mechanisms by which an externally applied shock can influence a sufficient volume of heart tissue to terminate cardiac fibrillation. Second, it has been uncertain whether cardiac tissue should be viewed as an electrically orthotropic structure, or whether its electrical properties are, in fact, isotropic in the plane orthogonal to myofiber direction. In the present study, a computer model that incorporates a detailed three-dimensional representation of cardiac muscular architecture is used to investigate these issues. We describe a bidomain model of electrical propagation solved in a discontinuous domain that accurately represents the microstructure of a transmural block of rat left ventricle. From analysis of the model results, we conclude that (1) the laminar organization of myocytes determines unique electrical properties in three microstructurally defined directions at any point in the ventricular wall of the heart, and (2) interlaminar clefts between layers of cardiomyocytes provide a substrate for bulk activation of the ventricles during defibrillation. |
3,008 | Effects of implantable cardioverter defibrillator implantation and shock application on serum endothelin-1 and big-endothelin levels. | The incidence of ventricular tachyarrhythmias in the early post-operative period following implantable cardioverter-defibrillator (ICD) implantation is relatively high compared with that in control periods. Since endothelin-1 (ET-1) has been proven to be an endogenous arrhythmogenic substance, we investigated the changes in serum ET-1 and big-ET levels in patients undergoing ICD implantation. Serum concentrations of ET-1 and big-ET were measured in 14 patients with various heart diseases before the operation, as well as 1 min and 1 h after the last shock therapy. Big-ET levels and the sum of ET-1 and big-ET levels were unchanged immediately after the operation, but had increased significantly by 1 h after implantation (before, 1.57+/-0.61 pmol/l; 1 min, 1.86+/-0.87 pmol/l; 1 h, 4.29+/-1.65 pmol/l for big-ET; before, 3.44+/-1.07 pmol/l; 1 min, 3.79+/-1.29 pmol/l; 1 h, 6.36+/-2.03 pmol/l for big-ET+ET-1). There was a significant correlation between left ventricular ejection fraction and big-ET level measured 1 h after the last shock delivery (r=-0.542, P<0.05). We conclude that the increased big-ET level observed 1 h after the last induction and shock therapy of ventricular fibrillation might have a pathophysiological role in the increased incidence of post-operative spontaneous ventricular arrhythmias. |
3,009 | Involvement of endothelin-1 in acute ischaemic arrhythmias in cats and rats. | This study aims to investigate the role of endothelin-1 (ET-1) in the genesis of acute ischaemic arrhythmias. In anaesthetized cats and rats receiving continuous monitor of electrocardiogram and arterial blood pressure, the ischaemic arrhythmias during 60-min myocardial ischaemia elicited by the occlusion of the left anterior descending coronary artery (LAD) were analysed. To prevent the putative arrhythmic effects of endogenous ET-1, ET(A) receptor antagonist BQ610 (1.5-6.0 nmol/kg) was intracoronary injected just before LAD occlusion in cats, and preproET-1 mRNA antisense oligodeoxynucleotide (AS-ODN; 30-90 nmol/kg) was intravenously injected 2 h before LAD occlusion in rats. The results showed that BQ610 dose-dependently decreased the incidences of ventricular tachycardia (VT) and ventricular fibrillation (VF), and the numbers of ventricular ectopic beats (VEBs). At the dose of 6.0 nmol/kg, the incidence of VT decreased significantly from 33.3% in normal saline (NS) control group to zero (P<0.01), and total VEBs decreased significantly from 831+/-162 to 158+/-51 (P<0.05). In rats receiving ET-1 AS-ODN, plasma ET-1 decreased significantly after 2 h, and remained stable at 30 min of LAD occlusion. However, in rats receiving the control, NS or sense ODN, plasma ET-1 remained unchanged after administration, but increased significantly during LAD occlusion. The ischaemic arrhythmias were dose-dependently suppressed in the presence of ET-1 AS-ODN. At the dose of 90 nmol/kg, the incidence of VT decreased significantly from 100% in both the control groups to 30%. The numbers of single VEBs, consecutive VEBs, VT and total VEBs were also significantly decreased, from 60+/-15 in NS group to 19+/-12, 11+/-3 to 2+/-2, 155+/-41 to 11+/-11, and 239+/-49 to 35+/-25 respectively. In the present cat and rat models of coronary artery occlusion, antagonism of either ET(A) receptors or endogenous ET-1 synthesis prevented the ischaemic arrhythmias, indicating that ET-1 is possibly an important promotive factor in the genesis of acute ischaemic arrhythmias. |
3,010 | The ET(A) receptor antagonist LU 135252 has no electrophysiological or anti-arrhythmic effects during myocardial ischaemia/reperfusion in dogs. | The anti-arrhythmic effects of ET(A) receptor antagonists during myocardial ischaemia and reperfusion remain controversial. Moreover, the electrophysiological mechanism has not yet been identified. The aim of this study was to investigate the potential anti-arrhythmic and electrophysiological effects of the ET(A) receptor antagonist LU 135252 (LU) during myocardial ischaemia and reperfusion in a canine model. A bolus of LU (1 mg/kg; n=10) or saline (control; n=10) was injected into the left anterior descending coronary artery before ligation of this vessel for 30 min, which was followed by a 90-min reperfusion period. LU bolus administration (0.5 mg/kg) was repeated every 30 min. There were no differences in mean arterial blood pressure or coronary blood flow between the two groups. The determined left ventricular ischaemic mass was 25.5+/-1.8% and 27.8+/-2.2% of the total left ventricular mass in the control and LU groups respectively. The total incidence of ventricular fibrillation during ischaemia and reperfusion was 40% in the control and 50% in the LU group (not significantly different). The incidence of non-sustained and sustained ventricular tachycardias during ischaemia, reperfusion and over the whole period (ischaemia plus reperfusion) in the control group was 50%, 50% and 70% respectively, and that in the LU group was 80%, 70% and 100% respectively (no significant differences between groups). The number of ventricular premature beats was not decreased by LU during either ischaemia or reperfusion [median (25th-75th percentile): ischaemia, 20 (13-37) and 56 (32-130) for LU and control groups respectively; reperfusion, 15 (2-21) and 39 (7-74) respectively; ischaemia+reperfusion, 16 (4-35) and 43 (10-82) respectively; no significant differences between groups]. During ischaemia, the monophasic action potential duration at 90% repolarization (MAPD(90)) decreased significantly, while during reperfusion a significant prolongation of MAPD(90) was observed in the left anterior descending region that was similar in the two groups. In conclusion, LU did not affect repolarization changes and did not have anti-arrhythmic effects during either ischaemia or reperfusion in this model. |
3,011 | Expressed monophasic action potential alternans before the onset of ventricular arrhythmias induced by intracoronary bolus administration of endothelin-1 in dogs. | We showed previously a direct arrhythmogenic effect of the intracoronary infusion of endothelin-1 (ET-1). We aimed to examine the electrophysiological effects of intracoronary bolus administration of ET-1 using monophasic action potential (MAP) recordings. Eight mongrel dogs received boli of ET-1 (1 and 2 nmol) into the left anterior descending coronary artery. These intracoronary ET-1 boli rapidly caused a marked decrease in coronary blood flow (1 nmol, 78+/-7%; 2 nmol, 89+/-7%). Ischaemic changes of MAP morphology, a decrease in upstroke velocity (baseline, 1.78+/-0.2 V/s; 1 nmol, 0.95+/-0.18 V/s; 2 nmol, 0.45+/-0.21 V/s; P<0.01) and a decrease in MAP duration at 90% repolarization (MAPD(90)) [1 nmol, from 191+/-3 to 176+/-5 ms (P<0.05); 2 nmol, from 212+/-4 to 180+/-8 ms (P<0.05)] occurred after ET-1 bolus administration. However, at 7-10 min after the 1 nmol bolus, a significant increase in MAPD(90) was observed (10 min, in the left ventricular anterior epicardial region: from 191+/-3 to 206+/-6 ms; P<0.05). The incidence of ventricular arrhythmias was as follows: after the 1 nmol ET-1 bolus: ventricular tachycardia, 3/8 animals; ventricular fibrillation, 1/8; after the 2 nmol ET-1 bolus: ventricular tachycardia, 5/7; ventricular fibrillation, 5/7. MAP alternans was present in each animal (1 nmol, 18.2+/-5.8%; 2 nmol, 10.8+/-2.5%). Thus electrophysiological and coronary blood flow changes indicate the predominance of an ischaemic arrhythmogenic effect of the bolus administration of ET-1 (shortening of action potential duration; appearance of MAP alternans), whereas the observed delayed prolongation of MAPD(90) suggests a direct arrhythmogenic effect of ET-1. The expressed MAP alternans could have a pathogenic role in the onset of ventricular arrhythmias induced by an intracoronary bolus of ET-1. |
3,012 | Electrophysiologic investigation in Brugada syndrome; yield of programmed ventricular stimulation at two ventricular sites with up to three premature beats. | Numerous reports on the inducibility of ventricular tachyarrhythmias (VT) in patients with atypical right bundle branch block and right precordial ST-elevation (Brugada syndrome) are based on multicentre studies that have used different stimulation protocols. Therefore, we prospectively investigated the inducibility of VT in these patients using a uniform protocol.</AbstractText>In 41 consecutive patients (29 males) showing a pattern of right bundle branch block and ST-elevation, programmed ventricular stimulation was performed in the right ventricular apex with up to three premature stimuli at sinus rhythm and at four different paced cycle lengths (500, 430, 370, and 330 ms) until refractoriness was reached or reproducible induction of a sustained (>30s) VT occurred. If a VT was not reproducibly inducible, the same protocol was repeated in the right ventricular outflow tract.</AbstractText>A history of life-threatening events defined as syncope (n=17) or aborted sudden cardiac death (n=13) was present in 30 patients (73%); 11 individuals were asymptomatic. Inducibility (68%) was similar between symptomatic (n=21, 70%) and asymptomatic patients (n=7, 64%). In 16 (39%) patients, VT were reproducibly inducible. If patients were only stimulated in the right ventricular apex, inducibility rate decreased to 39%. If only two premature beats at two sites were used it was as low as 32%. The mean coupling intervals of the second and third premature stimuli inducing sustained VT were short: 189+/-21 ms vs 186+/-22 ms, respectively. Forty-four percent of all patients (i.e. 64% of the inducible patients) had inducible VT only with coupling intervals shorter than 200 ms.</AbstractText>The stimulation protocol markedly influences the extent of inducibility of VT in patients with right bundle branch block and ST-segment elevation. These findings question the significance of previous multicentre studies using different stimulation protocols and should have implications for further studies.</AbstractText>Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.</CopyrightInformation> |
3,013 | [Atrial fibrillation in heart failure]. | Atrial fibrillation is a common arrhythmia in patients with congestive heart failure caused by left ventricular dysfunction and is associated with significant morbidity and possibly increased mortality rates. It occurs with increasing frequency as the severity of heart failure increases.</AbstractText>As therapeutic options, two basic strategies are available: rhythm control with or without pharmacological manipulation to increase the chance of successful cardioversion and to maintain sinus rhythm, and rate control with anticoagulation. So far, a clear benefit of one of these two strategies over the other has not been demonstrated for patients with atrial fibrillation generally, nor have there been convincing data for the subgroup of heart failure patients. Traditionally, digoxin has been used in patients with heart failure and atrial fibrillation; however, it has no proven potential to restore sinus rhythm and is slow and not very effective in rate control requiring the addition of another rate-limiting agent, preferably a beta-blocker or calcium antagonist. Amiodarone has been evaluated in numerous clinical trials in patients with heart failure and appears to be safe and effective in terms of conversion to sinus rhythm, maintenance of sinus rhythm as well as control of ventricular rate. Dofetilide may be another option in patients with atrial fibrillation and heart failure, although a direct comparison with amiodarone is lacking. The problem with all antiarrhythmic drugs specifically in patients with heart failure is their toxicity. Because of their proarrhythmic effects, Class I antiarrhythmics are contraindicated in patients with heart failure. Torsades de pointes is the most serious adverse effect of sotalol and dofetilide. Amiodaron has less proarrhythmic risk but has numerous non-cardiac toxicities that require frequent monitoring.</AbstractText>Overall, due to a low efficacy rate and high proarrhythmic risks, an ideal antiarrhythmic agent for patients with atrial fibrillation and heart failure does not exist, and drug selection should be highly individualized. In patients with chronic atrial fibrillation and heart failure, anticoagulation with warfarin for prevention of thromboembolic events is mandatory.</AbstractText> |
3,014 | [Secondary catheter ablation of atrial fibrillation]. | In patients with drug-refractory atrial fibrillation there are some non-pharmacologic therapeutic options for heart rate control or recurrence prophylaxis that do not primarily aim at the induction or maintenance of atrial fibrillation itself.</AbstractText>Using radiofrequency ablation AV nodal conduction can be completely interrupted (AV node ablation) or partly impaired (AV node modulation), which allows subsequent control of the effective ventricular rate (if necessary by pacer maker implantation). Atrial fibrillation, however, does continue undisturbed in the atria, with its associated risk of thromboembolic complications.</AbstractText>The other option of a secondary catheter ablation approach to atrial fibrillation consists of a combination of antiarrhythmic medication using Class Ic or III antiarrhythmics and its conversion of atrial fibrillation to isthmus-dependent atrial flutter, which can subsequently be treated by curative bi-directional isthmus blockade. Termination of the antiarrhythmic medication may lead to reoccurrence of atrial fibrillation.</AbstractText>The review discusses the mentioned options for secondary catheter ablation of atrial fibrillation together with possible indications, success rates and potential complications.</AbstractText> |
3,015 | [Atrial fibrillation: stimulation and pacemaker therapy]. | Pacing therapy is well established in all cases of symptomatic bradyarrhythmic atrial fibrillation. In paroxysmal or persistent atrial fibrillation, the implanted dual chamber pacemaker device should incorporate an automatic mode switching algorithm. Mode switch in case of atrial fibrillation detection avoids pacemaker mediated rapid ventricular pacing during an atrial tachyarrhythmia and allows to perform dual chamber pacing during phases of sinus rhythm which is the preferable mode due to improved hemodynamics, rate adaptation, lower progress in atrial fibrillation burden and a lower rate of thromboembolic events as compared to ventricular pacing.</AbstractText>The possibility to prevent from atrial fibrillation recurrencies by pacing is currently under investigation. Various methodological approaches, for example multisite or alternate single site pacing, preventive pacing algorithms or hybrid- and even triple-therapy concepts are used for that purpose. Due to the theoretical point of view, that all these pacing interventions may reduce atrial fibrillation but also have the potential to act in a proarrhythmic manner, the data from adequately designed trials is of major importance: Septal pacing and preventive pacing algorithms seem to have a beneficial effect in a limited number of so far available studies.</AbstractText>In clinical practice, preventive pacing and/or placement of the atrial lead in a septal position should therefore be available in those patients with a conventional pacing indication in addition to symptomatic recurrent atrial fibrillation. Preventive pacing is so far with a significant and not-predictable amount of non-responders no "early" stage of therapy in patients with recurrent symptomatic atrial fibrillation and no additional conventional pacing indication.</AbstractText> |
3,016 | [Pharmacological therapy of atrial fibrillation and atrial flutter]. | Despite the increasing availability of nonpharmacological treatment options for atrial fibrillation, drug therapy targeted at restoration and maintenance of sinus rhythm, or aimed at symptomatic ventricular rate control remains the mainstay of therapy for the majority of patients.</AbstractText>Available data suggest that these two treatment approaches yield similar responder rates with regard to symptomatic improvement.</AbstractText>Detailed results from major prospective studies investigating the prognostic effects of different atrial fibrillation treatment modalities are expected to become available soon. At present, however, the choice of the primary treatment strategy, i.e. rate control or rhythm control, still remains upon the clinical decision and expertise of the treating physician. Cardioversion by means of external biphasic shock delivery has shown to effectively convert atrial fibrillation to sinus rhythm in more than 90% of patients. Pharmacological cardioversion, in contrast, has a far lower success rate and may be followed by severe complications mandating in-hospital administration with the majority of drug regimens. For the maintenance of sinus rhythm, the proarrhythmic side effects of Class I antiarrhythmic drugs currently limit their use to those patients without any structural heart disease. Clinical investigation of newer "pure" Class III drugs have shown to excite considerable prolongation of ventricular repolarization duration resulting in a significant risk for torsade-de-pointes tachycardia. Betablockers are beneficial in many clinical situations associated with the occurrence of atrial fibrillation, such as heart failure, arterial hypertension and coronary artery disease. These substances, however, do not seem to improve cardioversion rates and their effect in maintaining sinus rhythm is only moderate. Patients with structural heart disease in whom maintenance of sinus rhythm is strongly desired, therefore, are left to amiodarone therapy. The cardiac safety profile as well as the proven effectiveness are unsurpassed by any other available drug at present. This paper reviews major studies published during the last decade implementing recent guidelines regarding pharmacological rate control, cardioversion and maintenance of sinus rhythm and the approach towards patients suffering from paroxysmal atrial fibrillation.</AbstractText> |
3,017 | [Epidemiology of atrial fibrillation]. | FREQUENCY: Atrial fibrillation is the most frequent sustained arrhythmia, especially in the elderly. The incidence accounts for 2% past the age of 40 years, 6% over 70, an approximately 15% over 90 years old.</AbstractText>Primary cause in "idiopathic" atrial fibrillation is differentiated from secondary causes of cardiac and non-cardiac origin. Important predictive cardiovascular diseases to develop atrial fibrillation are coronary heart disease, hypertension or rheumatic heart disease. Electrophysiological mechanism behind atrial fibrillation is a reentry circuit. The clinical symptoms are influenced by the conducted ventricular heart rate and the loss of atrial contraction.</AbstractText>The need for a therapeutic approach--either for recurrence of sinus rhythm or heart rate control--is mainly determined by the quality of life. Quality of life, functional capacity and maximum oxygen consumption are improved if sinus rhythm is reestablished. Finally, mortality is double as high if atrial fibrillation is present. Whether mortality is directly influenced by atrial fibrillation or fibrillation is considered as more or less the subsequent arrhythmia for an underlying disease is still under investigation.</AbstractText> |
3,018 | [Proarrhythmic effects of propafenone in a woman with hepatopathy: is it always a simple drug in clinical practice?]. | A 65-year-old woman with a history of alcoholic liver disease and presenting with fever and vomiting was admitted to an internal medicine unit. In view of recent atrial fibrillation with inadequate heart rate control, digoxin and propafenone were included in the therapeutic regimen. After a few days sinus rhythm was restored but suddenly ventricular arrhythmias with the characteristics of a non-responsive electrical storm arose shortly following the appearance of clinical symptoms of drug intoxication. |
3,019 | Mapping and ablation of idiopathic ventricular fibrillation. | Ventricular fibrillation is the main mechanism of sudden cardiac death. The feasibility of eliminating recurrent episodes by catheter ablation has not been reported.</AbstractText>Twenty-seven patients without known heart disease (13 men, 14 women, 41+/-14 years of age) were studied after being resuscitated from recurrent (10+/-12) episodes of primary idiopathic ventricular fibrillation; 23 had received a defibrillator. The first initiating beat of ventricular fibrillation had an identical electrocardiographic morphology and coupling interval (297+/-41 ms) to preceding isolated premature beats typically noted in the aftermath of resuscitation. These triggers were localized by mapping the earliest electrical activity and ablated by local radiofrequency delivery. Outcome was assessed by Holter and defibrillator memory interrogation. Premature beats were elicited from the Purkinje conducting system in 23 patients: from the left ventricular septum in 10, from the anterior right ventricle in 9, and from both in 4. The interval from the Purkinje potential to the following myocardial activation varied from 10 to 150 ms during premature beat but was 11+/-5 ms during sinus rhythm, indicating location at peripheral Purkinje arborization. The premature beats originated from the right ventricular outflow tract muscle in 4 patients. The accuracy of mapping was confirmed by acute elimination of premature beats during local radiofrequency delivery. During a follow-up of 24+/-28 months, 24 patients (89%) had no recurrence of ventricular fibrillation without drug.</AbstractText>Primary idiopathic ventricular fibrillation is a syndrome characterized by dominant triggers from the distal Purkinje system. These sources can be eliminated by focal energy delivery.</AbstractText> |
3,020 | Sudden cardiac death: from molecular biology and cellular electrophysiology to therapy. | Sudden cardiac death (SCD) is one of the most serious problems of clinical cardiology and public health, because of its unexpected and sudden occurrence and poor response to resuscitation. Until recently, the many cases of SCD, apart from those caused by coronary heart diseases (CHD), were unexplained. Advances in methodology, especially molecular biology techniques and cellular electrophysiology, ie, patch clamp technique, revealed several mutations of sodium and potassium cardiac ion channels as a background for serious arrhythmia and consequently SCD in cases earlier determined as idiopathic ventricular fibrillation. |
3,021 | Amiodarone in the prevention and treatment of arrhythmia. | There is good evidence that amiodarone is effective against a variety of arrhythmias and that it may be superior to other drugs in some settings. Because of its proven efficacy and safety, amiodarone is currently the leading antiarrhythmic drug. The electrophysiological actions of amiodarone are complex and not completely understood. It is generally classified as a Vaughan-Williams class III agent, prolonging repolarization by inhibition of outward potassium channels. Amiodarone is particularly useful because its safety has been clearly demonstrated by a large body of evidence, including several randomized trials. Compared with many other antiarrhythmic drugs, amiodarone causes few cardiovascular adverse effects; however, its overall tolerance is limited by considerable non-cardiac toxicity. Although amiodarone will continue to give way to the implantable cardioverter defibrillator (ICD) as primary therapy for many patients presenting with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF), it is likely that the use of amiodarone in ICD patients will continue to prevent ICD discharges. Evaluation of combined use of amiodarone and ICD may provide the first opportunity to conduct a placebo-controlled trial of amiodarone efficacy against VT recurrence. Pharmacological therapy remains the major approach to management of atrial fibrillation (AF), and the use of amiodarone is likely to increase in future years. This review will analyze the evidence that amiodarone is a safe and effective antiarrhythmic drug. |
3,022 | Gerbode's defect--a rare type of ventricular septal defect. | We report on an elderly lady in the sixth decade of life with congenital Gerbode's defect who refused surgery. She has atrial fibrillation, massive cardiomegaly and repeated episodes of lower respiratory tract infection. |
3,023 | [Treatment of acoustic neuroma]. | Acoustic neuroma is the most common tumour in the cerebello-pontine angle.</AbstractText>We present the results after surgery in 99 cases, and the natural course of the disease in 82 patients followed for up to 20 years (mean 3 years).</AbstractText>During the observation period, 43% of the tumours increased in size. 36% of patients suffered increasing hearing loss. Total removal was accomplished in 92 cases. In 12 cases hearing preservation was attempted; successfully in five cases. 72 patients had normal or near normal postoperative facial nerve function, whereas 19 patients got a facial nerve paralysis. Two patients died, one because of haemorrhagic infarction and cerebellar swelling, and one because of ventricular fibrillation. Five patients had to be reoperated for CSF leakage.</AbstractText>Acoustic neuroma treatment is still a challenge. We favour a team approach to treat this condition.</AbstractText> |
3,024 | Left ventricular true aneurysm without coronary artery occlusion--a case study. | Left ventricular true aneurysm is described as distinct area of the left ventricular wall with systolic dyskinesia where typical myocardial structure is replaced with fibrous tissue. Transmural infarction following occlusion of left anterior descending coronary artery is the most common cause of formation of the left ventricular aneurysm.</AbstractText>A 51-year old white male, with the history of inferolateral wall myocardial infarction 6 years ago was admitted to the emergency department at the local hospital last year because of sudden cardiac arrest due to ventricular fibrillation in the course of inferolateral myocardial infarction. Later on the patient did not come back to work, felt very weak and had dyspnea on mild exertion. Coronary angiogram performed one year later (the patient refused coronary angiography examination at the time of myocardial infarction) showed normal coronary arteries with a recessive right coronary artery. The left coronary artery was wide with normal contrast flow. Ventriculography showed large, true dyskinetic aneurysm with mural thrombus in the apical segment of the left ventricular wall. Left ventricular ejection fraction was 30%. Patient was qualified for the aneurysmectomy. A large dyskinetic aneurysm (8 cm) of the apical and anterolateral segment of the left ventricular wall was detected intraoperatively. A fresh thrombus weighing 9 g was evacuated from the inside of the aneurysm. Stoney's aneurysmectomy was performed. Histopathology showed a typical picture of scar tissue without signs of active inflammation.</AbstractText>Normal coronary angiogram does not exclude development of large true aneurysm of left ventricular wall of typical localization for acute occlusion of left anterior descendent artery.</AbstractText> |
3,025 | [Early results of mitral valve replacement in patients 65 years and older]. | 36 patients aged 65 years or more, who underwent mitral valve replacement in the Department of Cardiac Surgery, Medical University of Łódź in 2000, were assessed. This group consisted of 22 women (61.1%) and 14 men (38.9%). The mean age of the patients was 68.5 years (+/- 2.96, age range from 65 to 76 years). The analysis of preoperative clinical state of the patients revealed prevalence of diabetes mellitus in 19 pts (52.78%), chronic bronchitis in 9 pts (25%), arterial hypertension in 14 (38.89%), pulmonary hypertension in 21 pts (58.33%), atrial fibrillation in 25 pts (69.44%), ventricular arrhythmia in 2 pts (5.56%) and cigarette smoking in 15 pts (41.67%). The mean left ventricular ejection fraction was 48.89% (+/- 9.26, from 30% to 70%). All patients were operated on cardiopulmonary by-pass and cardioprotection was obtained by the use of cold crystalloid cardioplegy solution based on St. Thomas Hospital formula. 6 patients (16.67%) underwent myocardial revascularization procedure simultaneously. In early postoperative period the following complications were observed: death--6 (16.67%), low cardiac output syndrome--5 (13.89%), need of use of intraaortic contrapulsation--2 (5.56%), need of use of inotropic agents--9 (25%), respiratory failure with the need of prolonged intubation--4 (11.11%), acute renal failure--4 (11.11%), stroke--2 (5.56%), need of temporary cardiac pacing--5 (13.89%), need of rethoracotomy--1 (2.78%). The results of mitral valve replacement procedures in patients over 65 years are less satisfactory than those of aortic valve replacement procedures in the same age group, however deaths considered patients with number of risk factors. The older age of the patients should not be treated at the moment as a contradiction to the cardiac surgery, but should be considered as a one of many risk factors. |
3,026 | [Early results of aortic valve replacement in patients 65 year and older]. | 30 patients aged 65 years or more, who underwent aortic valve replacement in the Department of Cardiac Surgery, Medical University of Łódź in 2000, were assessed. This group consisted of 19 women (63.3%) and 11 men (36.7%). The mean age of the patients was 71.83 years +/- 3.76, age range from 66 to 78 years. The analysis of preoperative clinical state of the patients revealed prevalence of diabetes mellitus in 23 pts (76.7%), chronic bronchitis in 4 pts (13.3%), arterial hypertension in 8 pts (26.7%), pulmonary hypertension in 8 pts (26.7%), atrial fibrillation in 4 pts (13.3%), ventricular arrhythmia in 13 pts (43.3%) and cigarette smoking in 8 pts (26.7%). The mean left ventricular ejection fraction was 50.8% (+/- 8.12%, from 31% to 64%). All patients before aortic valve replacement procedure underwent coronary angiography. All patients were operated on cardiopulmonary by-pass and myocardial protection was obtained by the use of cold crystalloid cardioplegy solution based on St. Thomas Hospital formula. 7 patients (23.3%) underwent myocardial revascularization procedure simultaneously. In early postoperative period the following complications were observed: death--2 (6.67%), low cardiac output syndrome--4 (13.33%), need of use of intraaortic contrapulsation--3 (10%), need of use of inotropic agents--13 (43.33%), respiratory failure with the need of prolonged intubation--8 (26.67%), acute renal failure--2 (6.67%), stroke--1 (3.33%), need of temporary cardiac pacing--4 (13.33%), need of rethoracotomy--2 (6.67%). The results of aortic valve replacement procedures in patients over 65 years age good, in spite of prevalence of number risk factors in these patients. The high rate (23.3%) of patients requiring simultaneous myocardial revascularization is remarkable. The age of a patient should not be treated as a contradiction to the cardiac surgery. |
3,027 | Sick sinus syndrome. | Sinus-node dysfunction is common in the elderly and, in most cases, does not cause any symptoms. Despite the high number of laboratory investigations, most diagnoses of sinus-node dysfunction are made by 12-lead electrocardiography, which shows severe sinus bradycardia, sinus arrest, or sinoatrial block. Continuous electrocardiographic monitoring, exercise testing, and electrophysiologic investigations (including pharmacologic interventions to cause complete autonomic blockade) are sometimes useful in detecting transient or latent sinus-node abnormalities. The term sick sinus syndrome should be reserved for patients with symptomatic sinus-node dysfunction. Sick sinus syndrome has a protean presentation with variable degrees of clinical severity. Symptoms are often intermittent, changeable, and unpredictable. Because these symptoms can be observed in several other diseases, none are specific to sick sinus syndrome. Owing to the nonspecific nature of its symptoms, sick sinus syndrome can be diagnosed only when clear electrocardiographic signs corroborate symptoms. In the absence of a demonstrable link between signs and symptoms, a diagnosis can be presumed only when signs of severe sinus dysfunction are present and when every other possible cause of symptoms has been excluded carefully. Sinus-node dysfunction frequently is associated with diseases of the autonomic nervous system, and autonomic reflexes play a major role in the genesis of syncope. Survival does not seem to be affected by sick sinus syndrome. Atrioventricular block, chronic atrial fibrillation, and systemic embolism are major pathologic conditions that affect the outcome of the syndrome. Treatment should be aimed at controlling morbidity and relieving symptoms. Cardiac pacing is the most powerful therapy; physiologic pacing (atrial or dual-chamber) has been shown definitively to be superior to ventricular pacing. |
3,028 | Predictors for maintenance of sinus rhythm after cardioversion in patients with nonvalvular atrial fibrillation. | Recurrence of atrial fibrillation (AF) after cardioversion (CV) to sinus rhythm (SR) is determined by various clinical and echocardiographic parameters. Transesophageal echocardiographic (TEE) parameters have been the focus of clinicians' interests for restoring and maintaining SR. This study determined the clinical, transthoracic, and TEE parameters that predict maintenance of SR in patients with nonvalvular AF after CV. We enrolled 173 patients with nonvalvular AF in the study. TEE could not be performed in 26 patients prior to CV. Twenty-five patients had spontaneously CV prior to TEE. Six patients were excluded because of left atrial (LA) thrombus assessed by TEE. CV was unsuccessful in 6 patients. The remaining 110 consecutive patients (56 men, 54 women, mean age 69 +/- 9 years), who had been successfully cardioverted to SR, were prospectively included in the study. Fifty-seven (52%) patients were still in SR 6 months after CV. Age, gender, the configuration of the fibrillation wave on the electrocardiogram, pulmonary venous diastolic flow, and the presence of diabetes, hypertension, coronary artery disease, mitral annulus calcification, and mitral valve prolapse (MVP) did not predict recurrence. Duration of AF, presence of chronic obstructive pulmonary disease (COPD), LA diameter, left ventricular ejection fraction (EF), left atrial appendage peak flow (LAAPF), LAA ejection fraction (LAAEF), pulmonary venous systolic flow (PVSF), and the presence of LA spontaneous echo contrast (LASEC) predicted recurrence of AF 6 months after CV. In multivariate analysis, LAAEF < 30% was found to be the only independent variable (P < 0.0012) predicting recurrence at 6 months after CV in patients with nonvalvular AF. LAAEF more than 30% had a sensitivity of 75% and a specificity of 88% in predicting maintenance of SR 6 months after CV in patients with nonvalvular AF. In conclusion, TEE variables often used to determine thromboembolic risk also might be used to predict the outcome of CV. |
3,029 | The independent association of renal dysfunction and arrhythmias in critically ill patients. | The purpose of this study was to quantify the impact of baseline renal dysfunction on incidence and occurrence of cardiac arrhythmias in the coronary ICU.</AbstractText>Renal dysfunction is an established predictor of all-cause mortality in the ICU setting. We set out to evaluate the independent contributory effect of renal dysfunction to arrhythmias and mortality in this population.</AbstractText>We analyzed a prospective coronary care unit registry of 12,648 admissions by 9,557 patients over 8 years at a single, tertiary center. An admission serum creatinine level was available for 9,544 patients. Those patients not receiving long-term dialysis were classified into quartiles of corrected creatinine clearance with cutpoints of 46.2 mL/min/72 kg (group 1), 63.1 mL/min/72 kg, and 81.5 mL/min/72 kg. Dialysis patients (n = 527) were considered as a fifth comparison group (group 5).</AbstractText>Baseline characteristics including older age, African-American race, diabetes, hypertension, history of previous coronary disease, and heart failure were incrementally more common with increasing renal dysfunction strata. There were graded, independent increased risks for accelerated idioventricular rhythm (relative risk [RR], 2.43; 95% confidence interval [CI], 1.40 to 4.20; p = 0.002), sustained ventricular tachycardia (RR, 2.07; 95% CI, 1.02 to 4.22; p = 0.04), ventricular fibrillation (RR, 2.42; 95% CI, 1.13 to 5.15; p = 0.02), and complete heart block (RR, 3.64; 95% CI, 1.77 to 7.48; p = 0.0004, group 5 vs group 1).</AbstractText>We conclude that baseline renal function is a powerful, independent predictor of cardiac arrhythmias in the coronary ICU population.</AbstractText> |
3,030 | Interactions of antiarrhythmic drugs and implantable devices in controlling ventricular tachycardia and fibrillation. | Implantable cardioverter defibrillators (ICDs) have proven highly successful in the treatment of life-threatening ventricular arrhythmias. Despite the efficacy of the ICD in terminating ventricular arrhythmias, antiarrhythmic drugs remain an important adjunct to ICD therapy. The use of antiarrhythmic drug therapy in combination with the ICD is synergistic in terms of beneficial effects, but also has the potential for some adverse interactions. Knowledge and recognition of these potential interactions is important for any physician managing patients with an ICD. This review summarizes the benefits and adverse effects of ICD in combination with antiarrhythmic drug therapy, and provides guidelines to ensure safe application of this hybrid therapy. |
3,031 | Beta-adrenergic blocking drugs as antifibrillatory agents. | Beta-Adrenergic blockade is associated with a significant reduction in mortality in most patients with structural heart disease. Clinical trial data involving patients after myocardial infarction or with congestive heart failure demonstrate that a reduction in sudden death accounts for much of the observed mortality reduction. Beta-adrenergic blockade inhibits the proarrhythmic effects of both neural and humoral sympathetic stimulation and inhibits the vagal withdrawal that accompanies ischemia. Although it does not have a dramatic effect on spontaneous ectopy or inducible monomorphic ventricular tachycardia, experimental and clinical data suggest that it inhibits the development of ventricular fibrillation by several mechanisms. |
3,032 | [Ventricular fibrillation in a 27-year-old patient with heart contusion]. | Patients with a blunt chest trauma often sustain myocardial contusion. The spectrum of symptoms varies from regional myocardial dysfunction to myocardial rupture or sudden cardiac death.</AbstractText>After a kick against his chest, a 27-year-old patient was resuscitated because of ventricular fibrillation. ECG and enzymatic pattern corresponded to an acute myocardial infarction, the echocardiogram revealed an apical and anteroseptal hypokinesia. 10 days after the acute event, coronary arteriography and ventriculography did not show any abnormalities.</AbstractText>On the basis of the anamnesis, a myocardial contusion must be discussed as reason for the ventricular fibrillation and the pathologic findings in ECG and echocardiogram. This has to be considered in the therapy.</AbstractText> |
3,033 | Is beta-blockade useful in heart failure patients with atrial fibrillation? An analysis of data from two previously completed prospective trials. | Beta-adrenergic blockade is of proven value in chronic heart failure. It is uncertain, however, if beta-blockade provides a similar degree of clinical benefit for heart failure patients with atrial fibrillation (AF) as those in sinus rhythm (SR).</AbstractText>To compare the effectiveness of beta blockade in patients with heart failure and AF.</AbstractText>Patients with chronic heart failure were randomized to treatment (double blind) with metoprolol 50 mg twice daily or carvedilol 25 mg twice daily in addition to standard therapy. Response was assessed after 12 weeks by a quality of life questionnaire, New York Heart Association class, exercise capacity (6-min walk test), radionucleotide ventriculography for LVEF, 2-D echocardiography measurement of left ventricular (LV) dimensions and diastolic filling and 24-h electrocardiograph monitoring to assess heart rate changes.</AbstractText>Both beta-blockers produced significant improvements in LVEF in both the SR group: (+6+/-10% at 12-week, P<0.001) and the AF group: (+11+/-9% at 12-week, P<0.05). However, significant improvement in symptoms (P<0.001) and exercise capacity (P<0.001) were observed only in the SR group but not in the AF group despite a significant improvement in LVEF.</AbstractText>Beta-blockers were effective in improving LV ejection fraction in chronic heart failure patients in either SR or AF but had less effect on symptoms and exercise capacity in those with AF.</AbstractText> |
3,034 | Doppler-echocardiographic indices of diastolic function in heart failure admissions with preserved left ventricular systolic function. | Many patients admitted to hospital with heart failure have preserved left ventricular (LV) systolic function. The incidence of isolated diastolic dysfunction as a cause of such admission remains unclear. We aimed to examine diastolic function in unselected admissions from the community with heart failure using the European Study Group on Diastolic Heart Failure (ESGDHF) Doppler-echocardiographic indices of diastolic dysfunction. Primary heart failure was confirmed in 210 of 309 sequential admissions with suspected heart failure. Doppler echocardiography was used to assess left ventricular ejection fraction, wall thickness and parameters of diastolic function including E:A ratio, E-wave deceleration time and isovolumic relaxation time. Of 210 patients studied (118 female), ejection fraction was <45% in 111, leaving a population of 99 with preserved systolic function. We excluded those with significant valvular disease, leaving 56 patients (mean age=77 years) with an ejection fraction >45% and no other relevant abnormality. Twenty were in atrial fibrillation. E-wave deceleration time was >280 ms in 42%. E:A was reversed in 30 of 36 patients in sinus rhythm, but only seven met the ESGDHF criterion of E:A<0.5. Isovolumic relaxation time was >105 ms in 38%. Wall thickness was increased in 75% of cases. The ESGDHF Doppler-echocardiographic criteria for diastolic heart failure were fulfilled in 43%. In clinically confirmed heart failure, 27% of patients had preserved systolic function and no significant valvular disease. Only 43% of this group had confirmed diastolic heart failure by these ESGDHF criteria. The pathophysiological basis of the syndrome in the remaining 57% remains unclear. |
3,035 | Brugada syndrome: current clinical aspects and risk stratification. | Brugada syndrome is a primary electrical disease of the heart that causes sudden cardiac death or life-threatening ventricular arrhythmias, especially in younger men. Genetic analysis supports that this syndrome is a cardiac ion channel disease. A typical electrocardiographic finding consists of a right bundle branch block pattern and ST-segment elevation in the right precordial leads. The higher intercostal space V(1) to V(3) lead electrocardiogram could be helpful in detecting Brugada patients. Although two types of the ST-segment elevation are present, the coved type is more relevant to the syndrome than the saddle-back type. These patterns can be present permanently or intermittently. Recent data suggest that the Brugada-type electrocardiogram is more prevalent than the manifest Brugada syndrome. Asymptomatic individuals have a much lower incidence of future cardiac events than the symptomatic patients. Although risk stratification for the Brugada syndrome is still incomplete, the inducibility of sustained ventricular arrhythmias has been proposed as a good outcome predictor in this syndrome. In noninvasive techniques, some clinical evidence supports that late potentials detected by signal-averaged electrocardiography are a useful index for identifying patients at risk. The available data recommend prophylactic implantation of an implantable cardioverter defibrillator to prevent sudden cardiac death. This review summarizes recent information of the syndrome by reviewing most of new clinical reports and speculates on its risk stratification. |
3,036 | European clinical experience with a dual chamber single pass sensing and pacing defibrillation lead. | Dual chamber ICDs are increasingly implanted nowadays, mainly to improve discrimination between supraventricular and ventricular arrhythmias but also to maintain AV synchrony in patients with bradycardia. The aim of this study was to investigate a new single pass right ventricular defibrillation lead capable of true bipolar sensing and pacing in the right atrium and integrated bipolar sensing and pacing in the right ventricle. The performance of the lead was evaluated in 57 patients (age 61 +/- 12 years; New York Heart Association 1.9 +/- 0.6, left ventricular ejection fraction 0.38 +/- 0.15) at implant, at prehospital discharge, and during a 1-year follow-up. Sensing and pacing behavior of the lead was evaluated in six different body positions. In four patients, no stable position of the atrial electrode could intraoperatively be found. The intraoperative atrial sensing was 2.3 +/- 1.6 mV and the atrial pacing threshold 0.8 +/- 0.5 V at 0.5 ms. At follow-up, the atrial sensing ranged from 1.5 mV to 2.2 mV and the atrial pacing threshold product from 0.8 to 1.7 V/ms. In 11 patients, an intermittent atrial sensing problem and in 24 patients an atrial pacing dysfunction were observed in at least one body position. In 565 episodes, a sensitivity of 100% and a specificity of 96.5% were found for ventricular arrhythmias. In conclusion, this single pass defibrillation lead performed well as a VDD lead and for dual chamber arrhythmia discrimination. However, loss of atrial capture in 45% of patients preclude its use in patients depending on atrial pacing. |
3,037 | Matching approved "nondedicated" hardware to obtain biventricular pacing and defibrillation: feasibility and troubleshooting. | Biventricular ICDs may offer increased benefit for patients with severe congestive heart failure and ventricular arrhythmia. Currently there are no approved dedicated biventricular ICDs available. Twenty-one consecutive patients who had approved nondedicated hardware implanted for biventricular pacing and defibrillation were included in this study. All device therapies were evaluated using stored electrograms. During mean follow-up at 13 +/- 7 months, 8 (36%) patients had inappropriate shocks. Ventricular fibrillation therapy was delivered for slow ventricular tachycardia because of double counting in two patients. In one patient, AV nodal reentrant tachycardia below detection rate cut off triggered device therapy because of ventricular double counting. Sinus tachycardia or premature atrial contraction initiating AV conduction and ventricular double counting resulted in shocks in five patients. The number of shocks per patient ranged from 1 to 64. Two patients required transient disconnection of the LV lead and subsequent ICD generator replacement for premature battery depletion. Two patients required AV junction ablation and three needed slow pathway ablation. Two patients were treated by upgrading to a device that was capable of a higher atrial tracking rate. The patients with impaired AV conduction or constant ventricular pacing did not have inappropriate therapy for sinus tachycardia or supraventricular arrhythmia. Use of conventional nondedicated hardware for biventricular pacer/defibrillator is feasible but should be considered only in patients with poor AV node function or less likely to require antitachycardic therapy, to avoid ICD double counting of ventricular sensed events and consequent high incidence of inappropriate therapies. |
3,038 | Lightning and the Heart: Fractal Behavior in Cardiac Function. | Physical systems, from galactic clusters to diffusing molecules, often show fractal behavior. Likewise, living systems might often be well described by fractal algorithms. Such fractal descriptions in space and time imply that there is order in chaos, or put the other way around, chaotic dynamical systems in biology are more constrained and orderly than seen at first glance. The vascular network, the syncytium of cells, the processes of diffusion and transmembrane transport might be fractal features of the heart. These fractal features provide a basis which enables one to understand certain aspects of more global behavior such as atrial or ventricular fibrillation and perfusion heterogeneity. The heart might be regarded as a prototypical organ from these points of view. A particular example of the use of fractal geometry is in explaining myocardial flow heterogeneity via delivery of blood through an asymmetrical fractal branching network. |
3,039 | Combination drug therapy with vasopressin, adrenaline (epinephrine) and nitroglycerin improves vital organ blood flow in a porcine model of ventricular fibrillation. | There is increasing evidence that the combination of epinephrine (adrenaline) with vasopressin may be superior to either epinephrine or vasopressin alone for treatment of cardiac arrest. However, the optimal combination, and dosage of cardiovascular drugs to minimize side effects, and to improve outcome has yet to be found. We therefore evaluated whether the combination of vasopressin plus epinephrine plus nitroglycerin (EVN), would improve vital organ blood flow during cardiopulmonary resuscitation (CPR) when compared with epinephrine (EPI) alone. After 4 min of ventricular fibrillation (VF) and 4 min of standard CPR, pigs were randomized to the combination of epinephrine (45 microg/kg) plus vasopressin (0.4 U/kg) plus nitroglycerin (7.5 microg/kg; n=12), or epinephrine (40 microg/kg; n=12) alone. Cerebral and myocardial blood flow was measured with radiolabeled microspheres. Defibrillation was attempted after 19 min of VF including 15 min of CPR. Mean+/-SEM coronary perfusion pressures were significantly (P < 0.01) higher 5 min after EVN vs. EPI alone (34+/-3 vs. 24+/-3 mmHg, respectively). At the same time, mean+/-SEM left ventricular, and global cerebral blood flow was also significantly (P < 0.05) higher after EVN vs. EPI alone (0.78+/-0.11 vs. 0.48+/-0.08 ml/min/g; and 0.37+/-0.05 vs. 0.22+/-0.0 3 ml/min/g, respectively). Spontaneous circulation was restored in 11 of 12 animals in the EVN group vs. 6 of 12 swine after EPI alone (P = N.S.). In conclusion, the combination of EVN significantly improved vital organ blood flow during CPR compared with EPI alone. Addition of nitroglycerin to the combination of low dose epinephrine with vasopressin during cardiac arrest may be beneficial. |
3,040 | Transthoracic biphasic waveform defibrillation at very high and very low energies: a comparison with monophasic waveforms in an animal model of ventricular fibrillation. | The purpose of this study was to compare truncated exponential biphasic waveform versus truncated exponential monophasic waveform shocks for transthoracic defibrillation over a wide range of energies. Biphasic waveforms are more effective than monophasic shocks for defibrillation at energies of 150-200 Joules (J) but there are few data available comparing efficacy and safety of biphasic versus monophasic defibrillation at energies of <150 J or >200 J. Thirteen adult swine (weighing 18-26 kg, mean 20 kg) were deeply anesthetized and intubated. After 15 s of electrically-induced ventricular fibrillation (VF), each pig received truncated exponential monophasic shocks (10 ms) and truncated exponential biphasic shocks (5/5 ms) in random order. Energy doses ranged from 70 to 360 J. Success was defined as termination of VF at 5 s post-shock. For both biphasic and monophasic waveforms success rate rose as energy was increased. Biphasic waveform shocks (5/5 ms) were superior to 10 ms monophasic waveform shocks at the very low energy levels (at 70 J, biphasic: 80+/-9%, monophasic; 32+/-11% and at 100 J, biphasic; 96+/-3% and monophasic 39+/-11%, both P < 0.01). No significant differences in shock success were seen between biphasic and monophasic waveform shocks at 200 J or higher energy levels. Shock success of > 75% was achieved with 200 J (10 J/kg) for both waveforms. Pulseless electrical activity (PEA) or ventricular asystole occurred in 4 animals receiving monophasic shocks and 1 animal receiving biphasic shocks. Biphasic waveform shocks (5/5 ms) for transthoracic defibrillation were superior to monophasic shocks (10 ms) at low energy levels. Percent success increased with increasing energies. PEA occurred infrequently with either waveform. |
3,041 | Does veno-arterial bypass without an artificial lung improve the outcome in dogs undergoing cardiac arrest? | We hypothesized that maintaining circulation and blood pressure by veno-arterial bypass (V-A bypass) without oxygenation would improve cardiopulmonary resuscitation (CPR) and survival rates. A total of 32 dogs, divided into four groups, were subjected to normothermic ventricular fibrillation (VF) for 15 min. The method of CPR was the same in the four groups, except for the method and timing of V-A bypass. We attempted to resuscitate the dogs without V-A bypass (control), with V-A bypass not including an artificial lung during VF, with V-A bypass not including an artificial lung during CPR, and with V-A bypass including an artificial lung during CPR. CPR was continued until restoration of spontaneous circulation (ROSC) or for 30 min. Although blood pressure was well maintained, severe hypoxemia was observed during V-A bypass without an artificial lung. The resultant hypoxemia was very detrimental. ROSC was achieved more easily in all dogs in the bypass group with an artificial lung. No significant difference in survival rates was demonstrated among the four groups (P = 0.11). We concluded that V-A bypass without oxygenation does not improve the chances for CPR and outcome after cardiac arrest in dogs. Our results suggest that oxygenation is indispensable in CPR. |
3,042 | Coronary revascularization: a procedure in transition from on-pump to off-pump? The role of glucose-insulin-potassium revisited in a randomized, placebo-controlled study. | To investigate an optimized glucose-insulin-potassium (GIK) solution regimen as an alternate myocardial protective strategy in off-pump coronary artery bypass graft (OP-CAB) surgery and as a supplement to conventional coronary artery bypass graft (CABG) surgery using cardiopulmonary bypass (CPB).</AbstractText>Prospective, randomized, placebo-controlled.</AbstractText>Single institution, cardiothoracic specialty hospital.</AbstractText>Forty-four patients scheduled for elective multivessel coronary artery surgery using either conventional CPB (n = 22) or OP-CAB techniques (n = 22).</AbstractText>Preischemic, ischemic, and postischemic administration of GIK solution was carried out, optimally dosed to ensure nonesterified fatty acid (NEFA) suppression, and supplemented with magnesium, a glycolytic enzymatic cofactor.</AbstractText>GIK solution therapy reduced plasma NEFA levels (p < 0.001) in OP-CAB surgery and CPB groups but failed to affect the incidence of non-Q wave perioperative myocardial infarction, incidence of postoperative atrial fibrillation, incidence of postoperative infection, reduction in creatinine clearance, or duration of postoperative intensive care unit or hospital length of stay. After adjusting for GIK solution therapy, OP-CAB surgery resulted in significantly less ischemic injury (troponin I >15 microg/L, 19.0% v 91.3%; p = 0.0001) and reduced postoperative infections (14.3% v 43.5%; p = 0.049).</AbstractText>GIK solution therapy achieved NEFA suppression and an insignificant trend toward reduced biochemical parameters of ischemic injury in OP-CAB surgery and CPB groups, but no major clinical benefit (perioperative myocardial infarction, intensive care unit length of stay, or hospital length of stay) was shown after elective CABG surgery in low-risk patients. Compared with CPB, OP-CAB surgery significantly reduced ischemic injury and postoperative infections.</AbstractText>Copyright 2002, Elsevier Science (USA). All rights reserved.</CopyrightInformation> |
3,043 | Implantable cardioverter defibrillator therapy for life-threatening arrhythmias in young patients. | This study examined the indications, efficacy and outcomes of implantable cardioverter defibrillator (ICD) use in the pediatric population.</AbstractText>ICDs are first-line therapy for adults resuscitated from sudden cardiac death (SCD) or at high risk for life-threatening ventricular arrhythmias. Use of ICDs in children and young adults is infrequent and there are few data regarding this group.</AbstractText>We abstracted and analyzed data for all patients in whom ICDs were implanted.</AbstractText>A total of 38 devices were implanted in 27 patients. Age ranged from 6 to 26 years (mean, 14) and weight ranged from 16 to 124 kg (mean, 47). Diagnoses included long QT syndrome (9), hypertrophic cardiomyopathy [6], repaired congenital heart disease [5];, and idiopathic ventricular tachycardia/fibrillation [4]. Indications comprised resuscitated SCD [15], syncope [9], and life-threatening ventricular arrhythmia [3]. Initial device placement was infraclavicular in 13, abdominal in 13 and intrathoracic in 1. Epicardial leads were used with 5 systems. A single coil lead was used in 17. Seven patients, all previously resuscitated from SCD, experienced 88 appropriate successful discharges. There were 6 inappropriate discharges in 3 patients. Mean time to device replacement was 3.1 years (n = 11). Complications included 2 infected systems, 2 lead dislodgments, 2 lead fractures, 1 post-pericardiotomy syndrome, 1 adverse event with defibrillation threshold (DFT); testing, and 1 patient with psychiatric sequelae. No deaths occurred with implanted ICDs.</AbstractText>These data demonstrate that ICDs provide safe and effective therapy in young patients. The indications for ICDs as primary preventive therapy remain uncertain.</AbstractText> |
3,044 | Cardiac remodeling and atrial fibrillation in transgenic mice overexpressing junctin. | Junctin is a 26-kDa integral membrane protein, colocalized with the ryanodine receptor (RyR) and calsequestrin at the junctional sarcoplasmic reticulum (SR) membrane in cardiac and skeletal muscles. To elucidate the functional role of junctin in heart, transgenic (TG) mice overexpressing canine junctin (24-29 folds) under the control of mouse a-myosin heavy chain promoter were generated. Overexpression of the junctin in mouse heart was associated with heart enlargements, bradycardia, atrial fibrillation, and increased fibrosis. Many ultrastructural alterations were observed in TG atria. The junctional SR cisternae facing transverse-tubules contained a dense matrix of calsequestrin in TG heart. According to echocardiography, TG mice showed enlarged left ventricles, dilated right atriums, and ventricles with paradoxical septal motion and impaired left ventricular systolic function. Overexpression of junctin led to down-regulation of triadin and RyR but to up-regulation of dihydropyridine receptor. The L-type Ca2+ current density and action potential durations increased, which could be the cause for the bradycardia in TG heart. This study provides an important example of pathogenesis leading to substantial cardiac remodeling and atrial fibrillation, which was caused by overexpression of junctin in heart. |
3,045 | Protective effects of melatonin on myocardial ischemia/reperfusion injury in vivo. | The production of oxygen free radicals has been strongly implicated as an important pathophysiological mechanism mediating myocardial ischemia/reperfusion (I/R) injury. Various antioxidants have cardioprotective effects. Melatonin, an indoleamine synthesized by the pineal gland, is a potent antioxidant and a direct free radical scavenger. This is the first in vivo study to evaluate the effect of melatonin (0.5, 1.0, and 5.0 mg/kg, i.v. bolus) on myocardial I/R injury in anesthetized Sprague-Dawley rats. Results demonstrate that pretreatment with intermediate or high doses of melatonin (1.0 and 5.0 mg/kg) at 10 min before left coronary artery occlusion markedly suppressed ventricular tachycardia (VT) and ventricular fibrillation (VF), while reducing the total number of premature ventricular contractions and total duration of VT and VF that occurred during the 45-min ischemic period. Pretreatment with melatonin dramatically improved survival rate of rats when compared with the I/R-only group. After 1-hr reperfusion, melatonin caused a significant reduction in infarct size when compared with I/R-only group. Meanwhile, pretreatment with melatonin (1.0 mg/kg) significantly reduced superoxide anion production and myeloperoxidase activity; the latter is an index of neutrophil infiltration in the ischemic myocardium. Additionally, pretreatment with melatonin (1.0 and 5.0 mg/kg) significantly attenuated ventricular arrhythmias and mortality elicited by reperfusion following 5-min ischemia. In conclusion, melatonin suppresses ischemia- and reperfusion-induced ventricular arrhythmias and reduces infarct size resulting from I/R injury. The pronounced cardioprotective activity of melatonin may be mediated by its antioxidant activity and by its capacity for neutrophil inhibition in myocardial I/R. |
3,046 | Acute management of atrial fibrillation: Part I. Rate and rhythm control. | Atrial fibrillation is the arrhythmia most commonly encountered in family practice. Serious complications can include congestive heart failure, myocardial infarction, and thromboembolism. Initial treatment is directed at controlling the ventricular rate, most often with a calcium channel blocker, a beta blocker, or digoxin. Medical or electrical cardioversion to restore sinus rhythm is the next step in patients who remain in atrial fibrillation. Heparin should be administered to hospitalized patients undergoing medical or electrical cardioversion. Anticoagulation with warfarin should be used for three weeks before elective cardioversion and continued for four weeks after cardioversion. The recommendations provided in this two-part article are consistent with guidelines published by the American Heart Association and the Agency for Healthcare Research and Quality. |
3,047 | [Transient atrial fibrillation induced by adenosine in a patient with atrial tachycardia]. | The administration of adenosine during atrial tachycardia usually terminates the arrhythmia or induces AV block and makes the diagnosis clear. We present a patient with atrial tachycardia in which the administration of adenosine induced a transient atrial fibrillation (AF). A continuous transition between both arrhythmias was observed and the original tachycardia persisted after the termination of the AF. This proarrhythmic effect may be due to the adenosine-mediated shortening of the atrial refractory periods, which produces a decreased wavelength of the reentry circuits and the potential coexistence of several wave-fronts in the atria, favoring the development of AF. The recognition of this uncommon effect is important, since the repeated administration of increasing doses of adenosine may induce sustained AF. |
3,048 | B-type natriuretic peptide in the diagnosis of cardiac disease in elderly day hospital patients. | heart failure is primarily a disease of elderly people. Current guidelines suggest all patients with suspected heart failure should undergo objective assessment, usually by echocardiography. In the UK resources are limited and not all patients have access to echocardiography. The electrocardiogram is widely used as a pre-screening investigation. Recently the natriuretic peptides have been shown to correlate well with left ventricular function, and evidence is accumulating which suggests that B-type natriuretic peptide may have a role in detecting cardiovascular disease. Elderly patients attending day hospital often have non-specific cardiovascular symptoms. B-type natriuretic peptide measurement in parallel with conventional electrocardiogram, may offer a novel method of identifying those with significant cardiac disease, which may warrant treatment. This study assessed the role of B-type natriuretic peptide and electrocardiogram in the detection of cardiac disease in patients attending Day Hospital.</AbstractText>prospective cohort study of patients referred to Day Hospital with suspected cardiovascular disease.</AbstractText>this study prospectively evaluated 299 consecutive patients attending day hospital over a period of 13 months. Patients underwent clinical assessment, electrocardiography, echocardiography and natriuretic peptide measurement. Objective evidence of cardiac disease was based on electrocardiogram and echocardiographic findings.</AbstractText>Medicine for the Elderly Day Hospital, Royal Victoria Hospital, Dundee.</AbstractText>sensitivity, specificity, positive and negative predictive values of screening tests for left ventricular systolic dysfunction. Receiver-Operating-Characteristic curves for ability of B-type natriuretic peptide to detect cardiac disease (including left ventricular systolic dysfunction, valvular disease, atrial fibrillation and left ventricular hypertrophy). Mean B-type natriuretic peptide levels with 'incremental' levels of cardiovascular disease.</AbstractText>299 patients (mean age 79; 65% female) completed the assessment. Ten percent of patients had left ventricular systolic dysfunction but 50% had objective evidence of cardiac disease. B-type natriuretic peptide was significantly elevated in patients with left ventricular systolic dysfunction, atrial fibrillation, left ventricular hypertrophy and valvular disease. Both B-type natriuretic peptide and the electrocardiogram were sensitive in detecting left ventricular systolic dysfunction but lacked specificity. Combining B-type natriuretic peptide with the electrocardiogram improved detection of left ventricular systolic dysfunction. B-type natriuretic peptide levels increased progressively as the number of different cardiac abnormalities increased.</AbstractText>B-type natriuretic peptide may be a useful marker for cardiac disease in patients attending Day Hospital. Half of the patients assessed had cardiac disease detected. Both the electrocardiogram and B-type natriuretic peptide were sensitive in the detection of left ventricular systolic dysfunction but lacked specificity. B-type natriuretic peptide was superior to the electrocardiogram in the detection of valvular disease. If used to pre-screen cardiovascular disease in Day Hospital patients, B-type natriuretic peptide and the electrocardiogram could reduce the need for echocardiography in some patients before implementing evidence-based treatments. B-type natriuretic peptide increases progressively as the number of different cardiac abnormalities increases and this may explain why B-type natriuretic peptide is of such prognostic value in older patients.</AbstractText> |
3,049 | Prolonged sustained ventricular fibrillation without loss of consciousness in patients supported by a left ventricular assist device. | Patients with cardiomyopathy of either ischemic or nonischemic origin are at increased risk for malignant ventricular arrhythmias. Normally sustained ventricular fibrillation (VF) leads to death very rapidly. We report two patients who remained in sustained VF, supported by a left ventricular assist device, for a prolonged period of time. Perfusion pressure through the device was sufficient to allow the patients to remain awake and responsive for several hours while in VF. The cases represent two of the longest reported episodes of sustained VF recorded in awake patients implanted with such devices. |
3,050 | Assessment of the left atrial appendage mechanical function by three-dimensional echocardiography. | We evaluated the feasibility of three-dimensional echocardiography, in the assessment of left atrial appendage (LAA) function.</AbstractText>Forty-five patients underwent multiplane transoesophageal echocardiography. In addition to Doppler and two-dimensional echocardiography, data for three-dimensional echocardiography reconstruction were obtained during transoesophageal echocardiography. Left atrial appendage ejection fraction based on three-dimensional echocardiography volume measurements (EFv) and two-dimensional echocardiography area measurements (EFa), coupled with other echocardiographic data, were related to left atrial appendage late peak emptying velocity, a frequently used indicator of left atrial appendage function. Multiple regression analysis has revealed a significant association of peak emptying velocity with EFv (P<0.0001), spontaneous echocardiographic contrast (P=0.001), tricuspid regurgitation (P=0.03) and left ventricular hypertrophy (P=0.05). No significant relation was observed between peak emptying velocity and EFa, presence or absence of atrial fibrillation, left ventricular dysfunction, mitral stenosis and insufficiency, left atrial dilatation, pulmonary venous peak systolic, diastolic and peak reverse flow velocity at atrial contraction as well as left atrial appendage volumes derived from two-dimensional echocardiography and three-dimensional echocardiography. In a simple linear correlation, the degree of association between peak emptying velocity and EFv was higher as between peak emptying velocity and EFa (r=0.7 vs 0.4, both P<0.001). Observer variabilities for calculating EFv were considerably lower than for two-dimensional echocardiography derived EFa. Ejection fractions determined by two-dimensional echocardiography area measurements at 45 degrees, 90 degrees and 135 degrees cutplane angulations were related to EFv only at 135 degrees.</AbstractText>Left atrial appendage ejection fraction calculation by three-dimensional echocardiography is feasible, more accurate than by two-dimensional echocardiography and has lower observer variability. Furthermore, an optimal cutplane angulation of the left atrial appendage view at 135 degrees has been demonstrated.</AbstractText>Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.</CopyrightInformation> |
3,051 | [Focal atrial fibrillation. Clinical characteristic and results of radiofrequency ablation]. | Atrial fibrillation can originate in arrhythmogenic foci coming from the pulmonary veins. Patients with atrial fibrillation, initiated from triggering foci, can be treated with radiofrequency ablation.</AbstractText>To report the results of radiofrequency ablation in patients with focal atrial fibrillation.</AbstractText>Thirteen patients with focal atrial fibrillation (8 male, aged 19 to 60 years old) are reported. Twelve had frequent crises refractory to antiarrhythmic drugs. Two had also flutter and tachycardia. One had a permanent atrial fibrillation lasting five years. Two had ventricular dysfunction and left atrial dilatation. The triggering focus was identified during the electrophysiological study, by the precocity of the potential that initiated the atrial fibrillation.</AbstractText>All patients had early atrial extrasystolic beats, isolated or repetitives, that preceded atrial fibrillation. During the electrophysiological study, 18 foci (3 in the right and 15 in the left atrium all in pulmonary veins) were identified. Radiofrequency ablation had immediate success in 11 patients. In 5, a flutter was also ablated. One patient had a sinus dysfunction after the procedure and atrial fibrillation was not eliminated. In this and other patient in whom the procedure failed, a pacemaker was implanted and the atrioventricular node was blocked. In a follow up, ranging from 4 to 31 months, eight patients are asymptomatic and 3 recidivated. No complications have been detected.</AbstractText>Patients with focal atrial fibrillation have common clinical and electrocardiographic features. Radiofrequency ablation of the triggering focus is possible and effective in most cases.</AbstractText> |
3,052 | Posterior pericardiotomy reduces the incidence of supra-ventricular arrhythmias and pericardial effusion after coronary artery bypass grafting. | The aim of this prospective study was to demonstrate the effectiveness of posterior pericardiotomy in reducing the incidence pericardial effusions and consequently reducing the related supraventricular tachyarrhythmias and development of delayed posterior cardiac effusions.</AbstractText>This prospective randomized study was carried out in 150 patients undergoing coronary artery bypass grafting in Bayindir Hospital Department of Cardiovascular Surgery between April 2000 and October 2001. One hundred and fifty patients were divided into two groups; each group included 75 patients. A 4-cm longitudinal incision was made parallel and posterior to the left phrenic nerve, extending from the left inferior pulmonary vein to the diaphragm in posterior pericardiotomy group (group I). Posterior pericardiotomy was not performed in conventional treatment group (group II).</AbstractText>Atrial fibrillation was developed in seven patients (9.3%) in group I and in 24 patients (32%) in group II (P<0.001). Atrial flutter and other supraventricular tachyarrhythmia (SVT) prevalence was not statistically significant. Early pericardial effusion was developed 42.6% (32/75) and 10.6% (8/75), respectively, in group II and group I (P<0.0001), but no late pericardial effusion developed in group I despite seven (9.3%) late pericardial effusions developing in group II (P<0.013).</AbstractText>Posterior pericardiotomy is a simple, safe and effective technique for reducing not only the prevalence of early pericardial effusion and related atrial fibrillation but also delayed posterior pericardial effusion and tamponade.</AbstractText> |
3,053 | Prevention of ventricular fibrillation by cilostazol, an oral phosphodiesterase inhibitor, in a patient with Brugada syndrome. | We report the case of 67-year-old man with Brugada syndrome, in whom daily episodes of ventricular fibrillation (VF) occurred every early morning for 4 days. The episodes of VF were completely prevented by an oral administration of cilostazol, a phosphodiesterase inhibitor. This effect was confirmed by the on-and-off challenge test, in which discontinuation of the drug resulted in recurrence of VF and resumption of the drug again prevented VF. This effect may be related to the suppression of I(to) secondary to the increase in heart rate and/or to an increase in Ca2+ current (I(Ca)) due to an elevation of intracellular cyclic AMP concentration via inhibition of phosphodiesterase activity. This drug might have an anti-VF potential in patients with Brugada syndrome. |
3,054 | Successful defibrillation of a dental patient in cardiac arrest. | Cardiac arrest is a very rare event in a dental patient. However, practitioners have a duty of care to their patients if ever such an event occurs. The cardiac arrest discussed in this case report occurred in an elderly person with an implanted pacemaker whilst undergoing restorative dental treatment. Cardiac arrest was diagnosed and cardiopulmonary resuscitation instituted immediately, followed within three minutes by successful defibrillation using the School's semi-automatic defibrillator. |
3,055 | Implantable defibrillator use for de novo ventricular tachyarrhythmias encountered after cardiac surgery. | De novo postoperative life-threatening ventricular arrhythmias are poorly understood. Long-term benefits of, and need for, treatment is uncertain. To assess the therapeutic advantage of ICD to manage new-onset, life-threatening ventricular tachyarrhythmias after cardiac surgery. Patients included were those with an ICD implanted for de novo life-threatening ventricular tachyarrhythmias encountered 48 hours or more after cardiac surgery. Primary endpoints were total survival, time to first ICD therapy, and appropriateness of ICD therapy. Mean projected survival and projected time to first ICD therapy were calculated by the Kaplan-Meier method. Twenty-seven postoperative patients (left ventricular ejection fraction 0.22 +/- 0.07) were followed for 26 +/- 17.6 months. The index arrhythmia was sustained monomorphic ventricular tachycardia in 17 (63%) and ventricular fibrillation in 10 (37%). Electrophysiological study was positive in 22 (81%) of 27. Total survival and mean projected survival after ICD implant were 22 (81%) of 27 and 25.6 months, respectively, to end of follow-up. The majority received ICD therapy (21/27 [78%]), 20 (74%) of 27 receiving appropriate therapy. The mean time to first ICD therapy and mean projected time to first ICD therapy was 5.6 +/- 7.8 months and 10.5 months, respectively. De novo postoperative ventricular arrhythmias are associated with a high probability of late recurrence. The ICD is useful for these patients. |
3,056 | [Management of lethal ventricular arrhythmias after cardiac surgery]. | Arrhythmias are commonly occur after cardiac surgery. Recurrent sustained ventricular tachycardia and ventricular fibrillation in the acute phase after cardiac surgery is the most lethal arrhythmia and may warrant acute intervention and aggressive treatment. Although class I agents are usually ineffective and exacerbate the heart failure in cases with a low ejection fraction, nifekalant(a newer class III agent) and amiodarone can be effective. Hemodynamically tolerable sustained monomorphic ventricular tachycardia can be successfully terminated with ramp or burst pacing via an epicardial ventricular pacing lead. Initiation of intra-aortic balloon pumping and emergency percutaneous cardiopulmonary bypass and emergency catheter ablation can be considered for those patients not responding to the conventional resuscitative measures. |
3,057 | [Review of arrythmias related to acute myocardial infarction and its treatment]. | Because reperfusion therapy for AMI has been widely performed, complicated fatal ventricular arrythmias related to AMI has been dramatically decreased. However, there still remain the incidence of fetal arrhythmias such as ventricular fibrillation(VF), ventricular tachycardia(VT) at the early phase in occurrence of AMI. Besides spreading bolus intravenous administration of mutant-tPA, Bystander CPR, Public access defibrillation (PAD), and setting of automated external defibrillators(AED) in the public facilities are actually required to reduce the mortality of AMI. In this article, we reviewed that arrhythmias associated with AMI and strategy for treatments of complicated arrhythmias in the clinical settings. |
3,058 | [Heart failure]. | Survival of patients with heart failure has improved over the past decade due to advances in medical therapy. However, sudden cardiac death continues to cause 35 to 65% of death. Ventricular arrhythmias are important causes of sudden cardiac death in patients with heart failure. The risks of antiarrhythmic drugs are increased in patients with heart failure. Therefore, in the absence of a clear indication, antiarrhythmic drug therapy should be avoided. A number of recent randomized trials have provided evidence that beta-adrenergic blockers, angiotensin-converting enzyme(ACE) inhibitors and angiotensin II receptor blockers(ARB) significantly reduces the risk of sudden death in patients with chronic congestive heart failure. For patients who have a history of sustained ventricular tachycardia(VT) or ventricular fibrillation(VF) amiodarone or an implantable cardioverter defibrillator(ICD) should be considered, and these therapy may benefit some high risk patients who have nonsustained VT. |
3,059 | [Preexcitation syndrome]. | Atrial fibrillation occurring in patients with Wolff-Parkinson-White(WPW) syndrome is a potentially life threatening arrhythmia because it lead to ventricular fibrillation which may be caused by a rapid ventricular response because of one or multiple accessory pathways with a very short anterograde refractory period. The incidence of sudden cardiac death by ventricular fibrillation in the WPW syndrome ranged from 0 to 0.6%. To avoid the sudden cardiac death, atrial fibrillation in the WPW syndrome should be terminated immediately by direct current cardioversion or intravenous administration of antiarrhythmic drug, especially sodium channel blocker. Radiofrequency catheter ablation on the accessory pathways is a first line treatment to prevent ventricular fibrillation. |
3,060 | [Ventricular fibrillation/tachycardia]. | Ventricular fibrillation and rapid ventricular tachycardia called as pulseless tachycardia are both fetal and need immediate therapy to respore sinus rhythm. Sustained monomorphic ventricular tachycardia is also known to have a poor prognosis. Diagnosis of these arrhythmias should be followed by electrophysiologic study for risk stratification. The efficacy of the antiarrhythmic drug therapy is known to be limited. Catheter ablation can cure the arrhythmia but the success rate is limited: 50-70% in selected patients. Though symptomatic, ICD is the most reliable therapy so far. Antiarrhythmic drugs or catheter ablation should be tried as adjunctive therapy in fatal ventricular arrhythmias. |
3,061 | [Current status of surgery for the treatment of arrhythmia]. | The success of the radiofrequency catheter ablation procedure for most types of supraventricular and ventricular tachycardia largely eliminated the role of surgical therapy of arrhythmias. However, there remains a subset of arrhythmia patients in whom the catheter approach has not been successful and types of arrhythmias with high recurrence rates following initially successful catheter ablation procedures where surgery can provide more definitive therapy. On the other hand, collaborations therapy with surgery and catheter procedure has become more important. For example, some of the new treatment strategies are based on the replacement of the surgical incisions of the Maze procedure using intraoperative radiofrequency coagulation thereby preventing functional determined reentrant circuits. It can be expected that intraoperative ablation for arrhythmia will become an important curative treatment strategy. |
3,062 | [Recent advances in radiofrequency catheter ablation]. | Radiofrequency catheter ablation has been established as a first-line treatment of various paroxysmal tachycardias, and its developments are still ongoing. As recent advances of radiofrequency catheter ablation, we can point out the following issues: 1) transaortic approach for idiopathic ventricular tachycardia(VT) of LBBB-form with inferior axis, 2) new approach guided by mid-diastolic potential for verapamil-sensitive VT, 3) pulmonary vein(PV) isolation technique guided by PV ostial circular electrogram mapping for paroxysmal atrial fibrillation, 4) new ablation strategies for macro-reentry tachycardia such as incisional atrial tachycardia and VT post old myocardial infarction guided by electro-anatomical mapping, and 5) cooled-tip ablation technique for atrial flutter and VT resistant to conventional system. |
3,063 | [Implantable cardioverter-defibrillator(ICD)]. | Implantable Cardioverter-defibrillator(ICD) has been accepted as an effective therapy for the patients with life-threatening ventricular tachyarrhythmias in our country. Especially, down sizing and further development(e.g. atrial sensing/pacing) of ICD generator allows us to consider the indication of the device in the majority of VT/VF patients. Furthermore, not only secondary prevention trials but also primary prevention trials, comparing ICD with the antiarrhythmic agents(mainly amiodarone), demonstrate a superior efficacy of ICD to improve the patients mortality. Under these circumstances, we have to recognize the strong current toward the ICD at the present time. However, an essential problem of ICD therapy, not to prevent VT/VF recurrence, remains to be resolved. |
3,064 | [The trend of anti-arrhythmic drug development]. | New anti-arrhythmic drugs have been developed by the progress of molecular-biological and physiological research on an ion channel and the elucidation of pharmacological effects of traditional anti-arrhythmic drugs. After CAST study, K+ channel blockers instead of Na+ channel blockers were developed and used in anti-arrhythmic treatment. In Sicilian Gambit, it was advocated that the anti-arrhythmic drug selection was based on both pharmacological action of drugs and mechanism of arrhythmias, including electrical remodeling which was mainly studied on atrial fibrillation and structural remodeling such as myocardial fibrosis. Furthermore, the target of anti-arrhythmic treatment will be not only the arrhythmic control with drugs but changing many factors related to the arrhythmic substrates, modulators and triggers of arrhythmias. |
3,065 | [Microvolt T wave alternans as a predictor for sudden cardiac death]. | The microvolt T wave alternans(MTWA) is a new promising method for identifying patients with lethal ventricular tachyarrhythmias. MTWA is dependent on heart rate, so that MTWA can be measured during exercise, pharmacological stress, or cardiac pacing to increase heart rate. For predicting sudden cardiac death after myocardial infarction, sensitivity of MTWA by exercise was 92%, specificity 61%, positive predictive value 7%, negative predictive value 99%. High sensitivity and negative predictive value are suggested that MTWA could be a screening test for sudden cardiac death after myocardial infarction. In addition, it is reported that MTWA is useful for predicting sudden cardiac death in patients with DCM or impaired cardiac function. Although the development of ICD has provided the effectiveness of prevention of sudden cardiac death, it is difficult to identify the patients with malignant ventricular tachyarrhythmias for primary prevention. MTWA can increase referrals of appropriate patients for further electrophysiologic evaluation and therapy. |
3,066 | [Autonomic nervous system examinations]. | Autonomic nervous system plays a critical role in the regulation of cardiovascular system. We reviewed the autonomic nervous system examinations. Time and frequency domain analyses in heart rate variability is obtained from short- and long-term ECG and have predictive values of prognosis in various conditions of heart disease. Baroreflex testing evaluates autonomic modulation of arterial pressure. Baroreflex sensitivity is expressed by the(arterial blood pressure)/(RR interval in ECG) slope in response to infusion of nitroglycerine or phenylephrine. Decrease in baroreflex sensitivity is superior to heart rate variability in identifying patients with poor prognosis in post myocardial infarction. 123I-metaiodobenzylguanidine (MIBG) is an analogue of norepinephrine and hence cardiac 123I-MIBG imaging can visualize cardiac sympathetic nervous system. Defect area in the early phase(15 to 30 min after injection) indicates localization of ventricular denervation. MIBG uptake, measured as a heart to mediastinum activity ratio, had a high predictive vale for survival. Altered MIBG uptake may also play a significant role in the assessment of arrhythmogenic potential in patients with idiopathic ventricular fibrillation or congenital long QT syndrome. |
3,067 | Hypertension and arrhythmia: blood pressure control and beyond. | Arrhythmias are common problems in hypertensive patients. The presence and complexity of both supraventricular and ventricular arrhythmias may influence morbidity, mortality, as well as the quality of life of patients. Diastolic dysfunction of the left ventricle, left atrial size and function, and left ventricular hypertrophy have been suggested as the underlying risk factors for supraventricular and ventricular arrhythmias in hypertensives. Recently, several non-invasive electrocardiographic parameters have been defined and widely investigated to identify the hypertensive patient at risk for the development of arrhythmias. These parameters include signal averaged analysis of P wave, QT interval dispersion, heart rate variability, ventricular late potentials and T wave morphology analysis. The aim of this review was to evaluate the relationships between high blood pressure, ventricular and supraventricular arrhythmias, relevant non-invasive cardiac parameters for risk assessment in hypertensive patients and the effects of blood pressure control. |
3,068 | Evolution of ventricular function during permanent pacing from either right ventricular apex or outflow tract following AV-junctional ablation for atrial fibrillation. | To compare acute and chronic ventricular function between patients, without cardiac failure, paced at either right ventricular apex or outflow tract.</AbstractText>Twenty patients. 10 paced apically and 10 in the outflow tract, underwent two radionuclide ventriculograms. Eight parameters of systolic or diastolic function were compared at each assessment, as were changes within each group over time.</AbstractText>No differences were identified in systolic function between pacing sites 6 weeks after pacing or 23 weeks later. Peak filling rate was lower (P=0.04) at the second assessment with outflow tract pacing. No other diastolic differences were identified. Between assessments, time to peak filling rate prolonged (P=0.04) with apical pacing, while left ventricular area reduced (P=0.04) and peak filling rate decreased (P=0.04) with outflow tract pacing. Septal motion was better preserved with outflow tract pacing. No other parameter changed over time. ECG measures were similar at 14.7 months.</AbstractText>No major differences were identified in systolic function between pacing sites. Some systolic parameters were better preserved with outflow tract pacing and diastolic function deteriorated subtly over time in both groups. Right ventricular pacing adversely affects left ventricular function.</AbstractText> |
3,069 | Age-related determinants of outcome after acute myocardial infarction: a dobutamine-atropine stress echocardiographic study. | To investigate the cause of worse survival in older patients after myocardial infarction (MI).</AbstractText>Prospective 18-month and longer follow-up study of a cohort of 167 patients (mean age +/- standard deviation 58 +/- 12, including 71 aged >or=65) with acute MI for cardiac events, defined as cardiac death, recurrent MI, or resuscitated ventricular tachycardia or fibrillation (VT/VF).</AbstractText>Milwaukee County Medical Complex and the Zablocki Veterans Affairs Medical Center, Milwaukee, WI.</AbstractText>One hundred sixty-seven patients who underwent dobutamine-atropine stress echocardiography (DASE) in the first week (2-7 days) after acute MI and were medically managed.</AbstractText>Comparison of event rates in older (>or=65 years) and younger (<65 years) patients and of clinical, resting echocardiographic, DASE, and angiographic findings in patients with and without events. Coronary angiography was performed in 141.</AbstractText>Older and younger patients tolerated DASE well. During follow-up, there were 29 cardiac events (cardiac death in 17, nonfatal MI in 10, and VT/VF in 2). Events were more common in older patients (26% vs 12%, P <.05), especially death (19% vs 5%, P <.05). Scar size in the infarct zone by DASE was larger (4.0 +/- 2.8 vs 3.0 +/- 2.7 segments, P <.05) and remote wall motion abnormalities more common (47 vs 29%, P <.05) in older patients. Univariate determinants of outcome (P <.05) in older patients were diabetes mellitus; remote wall motion abnormalities; angiographic multivessel disease; scar size; ejection fraction; and resting, low-, and peak-dose wall motion score. Univariate determinants in younger patients were similar, but diabetes mellitus was not. Multivariate analysis revealed that remote wall motion abnormalities and scar size by DASE were independently predictive of outcome in older and younger patients and diabetes mellitus only in older patients. Low- and peak-dose DASE data enhanced (P <.01) the prediction of outcome in all patients with acute MI relative to clinical data and resting echocardiography.</AbstractText>DASE was more predictive of outcome than clinical data and resting echocardiography in both age groups. Scar size and remote wall motion abnormalities were the primary determinants of outcome irrespective of age. The worse prognosis of older patients correlated with diabetes mellitus, greater scar size, and higher incidence of remote inducible ischemia.</AbstractText> |
3,070 | [Use of implantable cardioverter defibrillators in the secondary prevention of malignant ventricular arrhythmias: lessons from large studies]. | The efficacy of implantable cardioverter defibrillator (ICD) therapy and medical therapy in the treatment of patients with ventricular fibrillation and sustained ventricular tachycardia had been compared in large randomized studies. In this section, we aimed to summarize what we have learned from large studies on the effects of amiodarone and ICD therapy in prevention of cardiac arrest in patients with malignant ventricular arrhythmias. The analyzed studies are; The multicenter unsustained Tachycardia Trial (MUSTT), Antiarrhythmics vs. implantable defibrillator (AVID), Cardiac Arrest Study Hamburg (CASH) and the Canadian Implantable Defibrillator Study (CIDS). |
3,071 | [Brugada syndrome or ARVD (arrhythmogenic right ventricular dysplasia) or both? Significance and value of right precordial ECG changes]. | We report about a 20-year old patient suffering cardiopulmonary resuscitation due to ventricular fibrillation. We diagnosed Brugada syndrome after exclusion structural heart disease and a positive Ajmalin test and implanted an ICD. In that there is a 20-30% familiar disposition, it was necessary that all family members undergo a cardiac examination. It was found that one brother and one sister presented the beginning of a right ventricular dilatation and a fibrolipomatous area in the anterior wall segment of the right ventricle. This result is compatible with a "concealed" arrhythmogenic right ventricular dysplasia (ARVD). As a prognostic indication we decided to implant an ICD prophylactically. The case report demonstrates the value of familiar examination of patients with an unclear ventricular arrhythmogenic event. |
3,072 | Relationship between clinical and echocardiography-derived parameters and atrial activation as measured by the P-wave signal-averaged electrocardiogram. | P-wave signal averaging is used in an attempt to detect patients at risk of atrial arrhythmias, particularly atrial fibrillation. Although many studies utilized this method, data on the relationship between clinical and echocardiographic variables and signal averaged P-wave parameters are sparse. Thus, we performed a prospective study to evaluate the influence of important clinical and echocardiographic variables on P-wave parameters. The study included 100 probands without demonstrable cardiac disease. P-wave signal averaging was performed after echocardiographic examination in all subjects. Overall P-wave duration averaged 122 +/- 16 ms and correlated significantly with age, left atrial and left ventricular end-diastolic diameter on univariate analysis (r = 0.287, 0.393 and 0.375; p = 0.004, < 0.0001 and < 0.0001, respectively). On multivariate analysis, however, age was the only independent factor affecting signal averaged P-wave duration (p = 0.02). There were statistically significant differences in left atrial size and P-wave duration if probands were grouped according to their age.</AbstractText>There is a significant relationship between signal averaged P-wave duration and age. This may be due to increased atrial fibrosis in elderly subjects. These data should be considered when signal-averaged P wave duration is used as a risk stratifier in patients prone to atrial fibrillation.</AbstractText> |
3,073 | Efficacy of antitachycardia pacing confirmed by stored electrograms. A retrospective analysis of 613 stored electrograms in implantable defibrillators. | The implantable defibrillator (ICD) is an established therapy in the prevention of sudden cardiac death by defibrillation of ventricular fibrillation. Another specific feature of the ICDs is antitachycardia pacing (ATP) of ventricular tachycardia. Several studies report success rates of ATP in 83 to 98% of cases. In clinical practice the success of terminating ventricular tachycardia is estimated only by automatic device analysis. Therefore the objective of this study was to confirm the efficacy of ATP based on the evaluation of stored electrograms. From the German Ventritex MD-register stored electrograms of 613 monomorphic ventricular tachycardias in 44 patients were analyzed retrospectively. The cycle length of the ventricular tachycardias was between 265 and 560 ms. The success rate of ATP-induced termination of the episodes reached 89.3%; another 2.3% of the ventricular tachycardias were accelerated by antitachycardia pacing into ventricular fibrillation. Left ventricular function did not influence the success rate, but the success rate was lower for fast ventricular tachycardias > 200/min (63.9%). For ventricular tachycardias < 150 bpm there was no restriction of ATP effectiveness. Of the episodes 72.9% were terminated by the first ATP burst. In these cases the duration of tachycardia was very short (11.9 +/- 2.8 s). Fifty-eight ventricular tachycardias (9.5%) had to be terminated by means of a shock, and only one case required 2 shocks. In patients with more than 10 episodes an individual therapy success > 90% was recorded for 80% of them. The very high success rate of the first ATP attempt in ICD therapy can be achieved with uniform programming, and is confirmed for ventricular tachycardias analyzed on the basis of stored electrograms. |
3,074 | Safety and feasibility of dobutamine and dipyridamole stress echocardiography in hypertensive patients. | To establish whether safety and feasibility of dobutamine and dipyridamole stress echocardiography are affected by history of hypertension.</AbstractText>Data on 2200 consecutive pharmacologic stress echocardiography (959 dobutamine and 1241 dipyridamole) performed between October 1990 and February 2001 at a single cardiology centre, were analysed.</AbstractText>There were two complications (1/480 tests) during dobutamine (one sustained ventricular tachycardia and one severe asthmatic attack following antidote administration) and two (1/620 tests) during dipyridamole (one non-Q wave myocardial infarction and one sustained ventricular tachycardia) stress. Complications or limiting side effects were observed in 83/959 patients (48/430 hypertensives and 35/529 normotensives) with dobutamine and in 34/1241 patients (17/571 hypertensives and 17/670 normotensives) with dipyridamole stress. Therefore, the overall feasibility was 88.8% in hypertensives and 93.4% in normotensives (P = 0.013) for dobutamine, and 97% in hypertensives and 97.5% in normotensives (P = 0.64) for dipyridamole. Dipyridamole was significantly more feasible than dobutamine in both hypertensive (P < 0.0001) and normotensive (P = 0.0006) subjects. Logistic regression analysis failed to identify clinical or echocardiographic predictors of adverse reactions with dipyridamole, while history of hypertension [odds ratio (OR) = 1.8, 95% confidence interval (CI) 1.1-2.8, P = 0.0138] was the only independent predictor of cumulative adverse reactions with dobutamine stress. In addition, history of hypertension (OR = 3.2, 95% CI, 1.2-8.5, P = 0.0166), resting wall motion abnormalities (OR = 1.8, 95% CI, 1.1-3.1, P = 0.0282), and age over 70 years (OR = 4.8, 95% CI, 1.5-15.3, P = 0.0087) predicted hypertensive response, ventricular tachycardia, and atrial fibrillation, respectively. No covariate was associated with hypotensive response during dobutamine test.</AbstractText>Dipyridamole has a slightly better safety profile and significantly higher feasibility than dobutamine stress both in hypertensives and in normotensives. In addition, the history of systemic hypertension is an independent predictor of cumulative adverse effects during dobutamine but not during dipyridamole stress.</AbstractText> |
3,075 | Impact of age and sex on plasma natriuretic peptide levels in healthy adults. | Assays for natriuretic peptides have received considerable attention as potential screening tests for congestive heart failure and left ventricular dysfunction. However, information regarding the impact of age, sex, and other physiologic characteristics on natriuretic peptide levels is limited. We examined a healthy reference sample of 911 subjects (mean age 55 years, 62% women) from the Framingham Heart Study who were free of hypertension, valvular disease, diabetes, atrial fibrillation, obesity, coronary heart disease, congestive heart failure, and renal failure, and who had normal left ventricular systolic function. Plasma brain natriuretic peptide and N-terminal atrial natriuretic peptide levels were measured, and multivariable regression used to assess correlates of natriuretic peptide levels. The strongest predictors of higher natriuretic peptide levels were older age and female sex. Other multivariable predictors included lower diastolic blood pressure (higher pulse pressure), lower body mass index, and higher left atrial size. Reference limits were then formulated based on the empirical distribution of natriuretic peptide levels by gender both across all ages and partitioned by age. Age-pooled reference limits compared with age-specific limits classified a higher proportion of healthy elderly subjects (17% vs 2.5%), but a lower proportion of healthy young subjects (1% vs 2.5%) as "abnormal." We conclude that interpretation of natriuretic peptide levels should take into consideration gender and possibly age. The reference limits derived from this large, healthy community-based sample will aid in the identification of elevated natriuretic peptide levels in clinical practice. |
3,076 | A case of impairment of mitochondrial fatty acid beta-oxidation. | We describe a patient with impairment of mitochondrial fatty acid P-oxidation. A Japanese baby boy was delivered in the 38th week of gestation by emergency cesarean section due to fetal asphyxia. His birth weight was 1,985 g (<10th percentile), length 44.8 cm (<10th percentile), and head circumference 31.0 cm (10th percentile). His Apgar scores were 3 and 5 at 1 min and 5 min, respectively. Blood glucose was 12 mg/dl at 1 hour after birth, requiring glucose administration. On day 1 his serum CK was 20,780 IU/l, which was thought to be due to asphyxia. His serum CK levels gradually began to decrease. At 3 months of age, he sucked poorly, had poor body weight gain, and muscle hypotonia was observed. On day 117 his general condition was impaired, and marked hepatomegaly was observed. The blood glucose level was 43 mg/dl. The patient's urine was negative for ketone bodies. His serum triglyceride level was 3,670 mg/dl. Abdominal CT scan revealed a fatty liver. Serum levels of acyl carnitine from very-long chain fatty acid increased. On day 118 he died due to ventricular fibrillation. On necropsy, massive lipid deposition was observed in the liver, cardiac muscle, kidney, skeletal muscle, and intestinal mucosa. The ratio of very-long chain acyl-CoA dehydrogenase (VLCAD) activity for C16/C8 fatty acid was 0.50 (normal control 1.29), suggesting abnormal VLCAD. He was diagnosed as having impairment of mitochondrial fatty acid beta-oxidation, presumably due to the VLCAD deficiency. |
3,077 | Aortic and mitral valve surgery on the beating heart is lowering cardiopulmonary bypass and aortic cross clamp time. | The concept of cardiac surgery on the beating heart is acceptable rationale for the cardiac surgery in the next millenium. Beating heart (off-pump) coronary artery bypass grafting (CABG) techniques have led us to consider the possibility for performing the aortic and mitral valve surgery (mitral valve repairs and replacements - with or without CABG) on the beating heart with the technique of retrograde oxygenated coronary sinus perfusion.</AbstractText>We used the technique of retrograde oxygenated blood coronary sinus perfusion in 78 patients (Group All) - (36 patients were with extremely low ejection fraction (Group X) - 62% of whom were in New York Heart Association (NYHA) class 4 and 34% of whom were in NYHA class 3). The procedures for the patients were: aortic, mitral and tricuspid valve surgery, in combination with CABG in ischemic patients. CABG was done in all the cases off-pump. In addition, we performed a case match study for 37 patients with good ejection fraction (51.65 +/- 11.88) (Beating Heart Group) operated on the beating heart with most appropriate group of patients (No. 37) operated in our institutions on arrested heart (ejection fraction 51.07 +/- 12.93) (Arrested Heart Group). The case match selection criteria were: gender, left ventricular ejection fraction, atrial fibrillation, hypertension, pulmonary hypertension, and diabetes. The selected beating heart group and selected arrested heart groups were without statistically significant differences for the mentioned criteria.</AbstractText>There were statistically significant differences between Beating Heart Group and Arrested Heart Group in the duration of Cardiopulmonary Bypass Time (69.35 +/- 13.52 min. versus 93.59 +/- 28.54 min.), p<0.001, and statistically significant differences in Aortic Cross Clamp Time (46.5 +/- 8.95 min. versus 61.5 +/- 18.34 min.), p<0.001. The values for Creatinin Kinase (CK) and LDH were not statistically different, however the absolute values for Beating Heart Group were lower. There was no statistical difference in complication rate for both the groups for: sternal infection, bleeding, death, atrial fibrillation, AV block and neurological complications. The total early mortality for all the patients was 5.1% (4 out of 78) - for the group X 8.3 % (3 of 36 patients). Two were in-hospital deaths. One patient with triple-vessel disease and acute mitral insufficiency on intra aortic balloon pump (IABP) had been operated on 6 days after acute myocardial infarction (AMI). The cause of the death was systemic meticillin resistant staphylococus aureus (MRSA) infection - (eight days prior to our operation, arthrodesis of the talocrural joint was performed by an orthopedic surgeon). The other death was a female patient who was operated on after previous multiple cerebrovascular infarctions (CVI) (cause of the death was CVI). In addition, one patient died one month after the operation because of prosthetic valve endocarditis (PVE) on aortic and mitral valves (silver-coated silzone aortic and mitral valves were implanted because of chronic latent asymptomatic tibial osteitis). None of these deaths were cardiac related.</AbstractText>We conclude that beating heart valve surgery (any combination) with or without CABG significantly lower the cardiopulmonary bypass and aortic cross clamp time. In addition, the advantages of beating-heart surgery are 1) the perfused myocardial muscle, 2) the heart is not doing any work, 3) no reperfusion injury, 4) the possibility for ablation of atrial fibrillation on the beating heart, and 5) testing of the mitral valve repair is done in real physiologic conditions in the state of left ventricle beating tonus. The procedure could be the procedure of choice for the valve operation or combined operations (valve operation and CABG) in high-risk patients with low ejection fractions. There is no doubt that at present day in cardiac surgery exist at least two major factors for mortality and morbidity after cardiac surgery, which are operation - related, namely cardiopulmonary bypass time and its duration and aortic cross clamp time (ischemic time of myocardium). In the last few years a number of different techniques emerged in the field of cardiac surgery, which were directed toward better results in the selected high risk patients or to minimize the deleterious effects of cardiopulmonary bypass (CPB) on the overall postoperative performance [Calafiore 1996, Tasdemir 1998]. Due to the fact, that the cardiac muscle should be protected at most during the cardiac arrest, retrograde blood cardioplegia was successfully introduced [Buckberg 1990], and more - the warm cardioplegia is being used recently [Kawasuji 1997]. The natural status of the human heart is the beating status, so it is reasonable to try to perform the operations on the beating heart. This has been done recently with the MID - CAB and OP - CAB (off-pump CABG) operations [Tasdemir 1998]. The retrograde warm blood cardioplegia has therefore led us to the premise, that with retrograde oxygenated blood perfusion it would be possible to achieve the operations on the beating heart even in the open heart surgery, such as aortic and/or mitral valve surgery. All will agree that the most damaging effect of the cardioplegia is the reperfusion injury [Allen 1997], and it is obvious that with the technique of retrograde continuous oxygenated blood perfusion this effect will be canceled. In this article, we would like to show the how-to technique for the operations on the beating heart in the case of operations on the aortic valve replacement (AVR) with mitral valve repair (MVR) or replacement MVR and with/without concomitant coronary artery bypass (CABG) surgery. The tricuspid valve repair (PTV) is normally done on the beating heart and there it is realized what problems or technical difficulties may arise during procedures on the mitral valve: the walls of the ventricles are not flattened and the exposure of the mitral valve is challenging task. Furthermore, the free walls of the ventricles with interventricular septum are in the state of the tonus, so every force applied to better expose the aortic or mitral valve is not acceptable</AbstractText> |
3,078 | A novel SCN5A arrhythmia mutation, M1766L, with expression defect rescued by mexiletine. | Mutations in the cardiac sodium channel gene, SCN5A, cause congenital long QT syndrome (LQT3), Brugada syndrome, idiopathic ventricular fibrillation, and conduction disease by distinct cellular and clinical electrophysiological phenotypes.</AbstractText>Postmortem molecular analysis of SCN5A was conducted on an infant who presented shortly after birth with self-terminating torsades de pointes. The infant was treated with lidocaine, propranolol, and mexiletine and was stable for 16 months manifesting only a prolonged QT interval. The infant collapsed suddenly following presumed viral gastroenteritis, was found in 2:1 AV block, and was subsequently declared brain dead. Genomic DNA was subjected to SCN5A mutational analyses and DNA sequencing revealing a novel, spontaneous germline missense mutation, M1766L. The M1766L mutation was engineered into the hH1a clone by site-directed mutagenesis, transfected into embryonic kidney cells (HEK-293), and studied by voltage clamp.</AbstractText>The M1766L mutation caused a significant decrease in the sodium channel expression. Co-expression with beta1 subunit, incubation at low temperature, and most effectively incubation with mexiletine partially 'rescued' the defective expression. In addition to this pronounced loss of function, M1766L also showed a 10-fold increase in the persistent late sodium current.</AbstractText>These findings suggest that M1766L-SCN5A channel dysfunction may contribute to the basis of lethal arrhythmias, displays an overlapping electrophysiological phenotype, and represents the first sodium channelopathy rescued by drug.</AbstractText> |
3,079 | Myocardial repolarization and drugs. Impossibility to predict the dominance of anti-arrhythmic over pro-arrhythmic effects of drugs due to differential and ventricular electrical remodeling. | It is known that application of anti-arrhythmic drugs for the acute treatment of arrhythmias can not only result in successful termination or prevention, but also can lead to unwanted pro-arrhythmic effects. On the basis of two arrhythmias, atrial fibrillation and Torsade de Pointes arrhythmias, we will highlight the relevance of differential atrial and ventricular electrical remodeling to explain the delicate and dynamic balance between anti-arrhythmic efficacy and pro-arrhythmogenic consequences of class III anti-arrhythmic drugs. |
3,080 | Cardiac arrhythmias in cardiothoracic surgery. | Most patients with cardiopulmonary disease are predisposed to develop perioperative arrhythmias with the individual patient risk depending upon the type of operative procedure performed, the risk profile of the patient, and the complexity of the post-operative course. There are several management options that may tend to prevent perioperative arrhythmias that should be considered in certain patient subsets. Most important of these is the use of beta-blocker therapy before and after operation in patients with coronary risks factors undergoing non-cardiac thoracic procedures and in patients having coronary artery bypass grafting. The common supraventricular arrhythmias including atrial fibrillation and flutter, multifocal atrial tachycardia, and paroxysmal supraventricular tachycardia must be properly diagnosed and treated appropriately. Placement of atrial pacing wires for use after open cardiac surgery is of great value both for diagnosis, and in some cases, for treatment of arrhythmias. Fortunately, serious life threatening ventricular arrhythmias occurs less commonly but the clinician must recognize and correct important predisposing factors and know how to treat these when they occur. A specific protocol for arrhythmia management that sets guidelines for drug choice and therapies for each of the common arrhythmias is useful for clinicians and adds predictability to patient care. |
3,081 | Apex-to-base dispersion of refractoriness underlies the proarrhythmic effect of hypokalaemia/hypomagnesaemia in the rabbit heart. | Apex-to-base differences in the density of potassium currents have been recently described in isolated rabbit myocytes. The significance of those findings for arrhythmogenesis in the whole heart is not known. We aimed to examine electrophysiological effects of hypokalaemia/hypomagnesaemia in isolated working rabbit hearts. Monophasic action potential duration (MAPD(90)), effective refractory period (ERP) and conduction delay were measured at 3 left ventricular sites (basal epicardium, apical epicardium, apical endocardium) in control (K(+) = 4mmol/L, Mg(2+) = 1mmol/L) and hypokalaemia/hypomagnesaemia (K(+) = 2mmol/L, Mg(2+) = 0.5mmol/L) groups. It was found that hypokalaemia/hypomagnesaemia shortened ERP in the apical epicardial region (by 22 +/- 6ms), without any significant effect in the basal area. Consequently, hypokalaemia/hypomagnesaemia increased transepicardial dispersion of refractoriness (from 10 +/- 3 to 25 +/- 7ms, P <.05) and increased inducibility of ventricular fibrillation (from 10% to 100%, P <.05). Similar effects were seen in hearts with left ventricular hypertrophy secondary to perinephritis-induced hypertension. These results suggest that hypokalaemia/hypomagnesaemia is pro-arrhythmic in normal or hypertrophied hearts due to an increase in apex-to-base dispersion of refractoriness. |
3,082 | Optimization of transthoracic ventricular defibrillation-biphasic and triphasic shocks, waveform rounding, and synchronized shock delivery. | The aim of this study is to optimize the truncated exponential waveform for transthoracic ventricular defibrillation. Discharge of a capacitor gives a fast-rising waveform with a spike; rounding of the waveform slows the rate of rise and removes the spike. Defibrillation thresholds for electrically induced VF were determined for rounded and conventional biphasic and triphasic waveforms (apex-anterior paddles; 130 microF capacitor; 3-10 ms phase duration), and for the Lown waveform in 29 anesthetized pigs. Rounding of the leading edge of the biphasic waveform reduced the threshold voltage and current for defibrillation at 3 + 3 ms and 6 + 6 ms phase duration, relative to the conventional unrounded biphasic or the Lown waveforms. The threshold delivered energy was lower for rounded truncated exponential biphasic shocks at 3 + 3 ms (55.3 +/- 2.5 J) than at 6 + 6 ms (67.6 +/- 2.9 J; reduction 15.9 +/- 3.8%; P <.001; n = 29) phase duration. Triphasic shocks (total duration 6-12 ms) showed no advantages over biphasic shocks in this model. The rounded waveform (6 + 6 ms phase duration) had a reduced delivered energy at threshold (9%) with transthoracic shock delivery synchronized to peak (71.1 +/- 4.2 J) or trough (71.5 +/- 4.9 J) of the high amplitude body surface electrocardiogram signal in ventricular fibrillation, compared with unsynchronized shocks (78.7 +/- 4.7 J; P <.05). In this study a biphasic, rounded waveform of total duration 6 or 12 ms, was optimal for the correction of electrically-induced ventricular fibrillation. Synchronization to the peak or trough of the high amplitude electrocardiogram signal gave a further reduction in the energy to defibrillate. |
3,083 | QRS aberration during atrial fibrillation at rest and during exercise. Effect of a selective potassium channel blocking agent. | This study assesses the occurrence of and identifies clinical characteristics associated with the development of aberrant conduction during infusion of the I(kr)-blocker almokalant. Class III drugs may induce aberrant conduction by prolongation of cardiac repolarization, especially during atrial fibrillation (AF). Ninety-two patients with AF received a 6-hour almokalant infusion, aiming at conversion to sinus rhythm (SR). Fiftyfive of the patients received an identical infusion during SR. During almokalant infusion, the number of patients with intermittent QRS aberration during AF increased, from 21% to 80% at rest, and was further increased to 89% during exercise, with predominantly left, and sequential bilateral, bundle branch aberrancy. Patients with aberrant conduction showed signs of more advanced myocardial disease. Predictors of the development of QRS aberration were female gender, arrhythmia duration, and decreased left ventricular ejection fraction, while use of calcium antagonists decreased the probability. No patient showed aberration during regular SR. Twenty-one patients experienced aberrantly conducted supraventricular premature beats. In conclusion, aberrant conduction is common during infusion of the I(kr)-blocker almokalant during AF, and seems to be more frequent in females and in patients with more advanced myocardial disease. |
3,084 | Conversion of recent-onset atrial fibrillation or flutter with ibutilide after amiodarone has failed. | To evaluate whether ibutilide can convert atrial fibrillation or flutter in patients in whom amiodarone has failed.</AbstractText>Clinical study in a university hospital intensive care unit (ICU).</AbstractText>Twenty-six patients were studied, in whom atrial fibrillation or flutter persisted for a maximum of 6 h at maximum. Patients were monitored continuously during the arrhythmia. Medical conversion was necessary due to symptomatic or hemodynamic causes.</AbstractText>All patients initially received amiodarone (150 mg i.v.) and after 2 h of persistent arrhythmia ibutilide (1 mg or, without success and body weight > 70 kg, 2 mg i.v.). Before the administration of ibutilide 1 g magnesium was administered, and high normal levels of potassium serum levels were achieved (4.5-5.0 mmol/l). RESULTS. After amiodarone atrial flutter persisted in 73% and atrial fibrillation in 27% of patients. After ibutilide the QT interval was prolonged from 327 +/- 61 to 387 +/- 62 ms. The QTc interval increased from 456 +/-32 to 461 +/- 66 ms. Conversion to normal sinus rhythm was achieved in 22 of 27 of cases. Nonsustained torsade de pointes tachycardia was seen in three patients (11%). No patient showed sustained ventricular tachycardia. Patients with proarrhythmic effects were characterized by a decreased left ventricular function.</AbstractText>In ICU patients ibutilide led to conversion to sinus rhythm in 81.5% of patients in whom amiodarone was unsuccessful. Nonsustained tachycardias were seen in 11%; sustained ventricular tachycardia was not seen. Ibutilide seems to be well suitable for conversion of recent onset atrial fibrillation or flutter and had no severe side effects in this study population.</AbstractText> |
3,085 | MC(3) receptors are involved in the protective effect of melanocortins in myocardial ischemia/reperfusion-induced arrhythmias. | Myocardial ischemia/reperfusion induces ventricular tachycardia (VT), ventricular fibrillation (VF) and a high degree of lethality. Since ACTH-(1-24) (adrenocorticotropin) protects against such injuries in rats, we investigated which melanocortin MC receptor is involved. Ischemia was produced in anesthetized rats by ligature of the left anterior descending coronary artery (5 min), and reperfusion-induced VT, VF, lethality and time-course of arterial blood pressure within the 5 min following reperfusion were evaluated. I.v. administration of the selective MC(3) receptor agonist gamma(1)-melanocyte-stimulating hormone (gamma(1)-MSH), as well as of an equimolar dose (162 nmol/kg) of both the non-selective agonist ACTH-(1-24) and alpha-MSH, significantly prevented VT and VF, and increased survival. Coronary reperfusion was followed by an abrupt and massive fall in mean arterial pressure and pulse pressure, in saline-treated rats. Treatment either with ACTH-(1-24) or gamma(1)-MSH completely prevented such fall. The protective effect of ACTH-(1-24) against the occurrence of VT, VF and lethality was neither affected by adrenalectomy, nor by i.v. pretreatment with the selective MC(4) receptor antagonist HS014 and the MC(4)-MC(5) antagonist HS059. On the other hand, the MC(3)-MC(4) receptor antagonist SHU 9119 prevented such protective effect. Moreover, the selective MC(1) receptor agonist MS05 (162 nmol/kg i.v.) failed to reduce the incidence of arrhythmias and lethality. These data demonstrate that MC(3) receptors mediate the protective effect of melanocortins in myocardial ischemia/reperfusion-induced arrhythmias, in rats. |
3,086 | Lower serum digoxin concentrations in heart failure and reassessment of laboratory report forms. | Serum digoxin concentrations (SDC) have been used clinically since the early 1970s. Whereas the therapeutic range for SDC is frequently cited as either 0.8 to 2.0 ng/mL or 0.5 to 2.0 ng/mL, studies over the past decade suggest an upper limit of 1.0 ng/mL for treating heart failure. The same upper limit for SDC is suggested for patients with heart failure and atrial fibrillation with rapid ventricular response. Reducing the upper limit of the therapeutic range to 1.0 ng/mL on computerized and paper laboratory report forms may guide clinicians to avoid unnecessarily high SDC, thus minimizing risk of digoxin toxicity without sacrificing therapeutic benefit for heart failure. |
3,087 | Decompression-triggered positive-pressure ventilation during cardiopulmonary resuscitation improves pulmonary gas exchange and oxygen uptake. | Intermittent positive-pressure ventilation (IPPV) is the "gold standard" of ventilation during cardiopulmonary resuscitation (CPR), but continuous positive airway pressure (CPAP) is increasingly discussed as an alternative. This study investigated hemodynamics and pulmonary gas exchange applying CPAP enhanced with pressure support ventilation (CPAP(PSV)) during CPR.</AbstractText>Twenty-four pigs were subjected to ventricular fibrillation and CPR with CPAP(PSV), CPAP, or IPPV. Measurements were taken before (hemodynamics, blood gases, inert gas measurements) and 10 (hemodynamics, blood gases) and 20 (hemodynamics, blood gases, inert gas measurements) minutes after induction of ventricular fibrillation. Although no significant intergroup differences in hemodynamics were found, arterial partial pressure of oxygen (PaO(2)) was significantly higher during CPAP(PSV) compared with CPAP or IPPV (98+/-10, 61+/-27, and 71+/-30 mm Hg, respectively, P<0.05). CPAP(PSV) resulted in an alveolar-arterial partial pressure of oxygen difference of 56+/-17 mm Hg, whereas during CPAP, 83+/-21 mm Hg was detected, and during IPPV, 98+/-29 mm Hg was detected (P<0.05). Pulmonary blood flow to lung units with a normal VA/Q ratio in percent of cardiac output was 76+/-17% during CPAP(PSV), 61+/-21% during CPAP (P<0.01), and 54+/-13% during IPPV (P<0.01). Oxygen uptake (VO(2)) was significantly higher during CPAP(PSV) than with the other ventilation modes (P<0.05) and comparable to the baseline value in intragroup comparison. Return of spontaneous circulation was recorded in 8 of 8 animals in the CPAP(PSV) group, in 6 of 8 in the CPAP group, and in 3 of 8 in the IPPV group.</AbstractText>CPAP(PSV) provides a straightforward and effective alternative to IPPV or CPAP during CPR that provides significantly higher PaO(2) and VO(2).</AbstractText> |
3,088 | Adverse outcomes of interrupted precordial compression during automated defibrillation. | Current versions of automated external defibrillators (AEDs) require frequent stopping of chest compression for rhythm analyses and capacity charging. The present study was undertaken to evaluate the effects of these interruptions during the operation of AEDs.</AbstractText>Ventricular fibrillation was electrically induced in 20 male domestic swine weighing between 37.5 and 43 kg that were untreated for 7 minutes before CPR was started. Defibrillation was attempted with up to 3 sequential 150-J biphasic shocks, but each was preceded by 3-, 10-, 15-, or 20-second interruptions of chest compression. The interruptions corresponded to those that were mandated by commercially marketed AEDs for rhythm analyses and capacitor charge. The sequence of up to 3 electrical shocks and delays were repeated at 1-minute intervals until the animals were successfully resuscitated or for a total of 15 minutes. Spontaneous circulation was restored in each of 5 animals in which precordial compression was delayed for 3 seconds before the delivery of the first and subsequent shocks but in none of the animals in which the delay was >15 seconds before the delivery of the first and subsequent shocks. Longer intervals of CPR interventions were required, and there was correspondingly greater failure of resuscitation in close relationship to increasing delays. The durations of interruptions were inversely related to the durations of subthreshold levels of coronary perfusion pressure. Postresuscitation arterial pressure and left ventricular ejection fraction were more severely impaired with increasing delays.</AbstractText>Interruptions of precordial compression for rhythm analyses that exceed 15 seconds before each shock compromise the outcome of CPR and increase the severity of postresuscitation myocardial dysfunction.</AbstractText> |
3,089 | Sustained ventricular arrhythmias among patients with acute coronary syndromes with no ST-segment elevation: incidence, predictors, and outcomes. | The prognosis of ventricular arrhythmias among patients with non-ST-elevation acute coronary syndromes is unknown. We studied the incidence, predictors, and outcomes of sustained ventricular arrhythmias in 4 large randomized trials of such patients.</AbstractText>We pooled the datasets of the Global Use of Streptokinase and tPA for Occluded Arteries (GUSTO)-IIb, Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT), Platelet IIb/IIIa Antagonism for the Reduction of Acute Coronary Syndrome Events in a Global Organization Network (PARAGON)-A, and PARAGON-B trials (n=26 416). We identified independent predictors of ventricular fibrillation (VF) and ventricular tachycardia (VT) and compared the 30-day and 6-month mortality rates of patients who did (n=552) and did not (n=25 864) develop these arrhythmias during the index hospitalization. Independent predictors of in-hospital VF included prior hypertension, chronic obstructive pulmonary disease, prior myocardial infarction, and ST-segment changes at presentation. Except for hypertension, these variables also independently predicted in-hospital VT. In Cox proportional-hazards modeling, in-hospital VF and VT were independently associated with 30-day mortality (hazard ratio [HR], 23.2 [95% CI, 18.1 to 29.8] for VF and HR, 7.6 [95% CI, 5.5 to 10.4] for VT) and 6-month mortality (HR, 14.8 [95% CI, 12.1 to 18.3] for VF and HR, 5.0 [95% CI, 3.8 to 6.5] for VT). These differences remained significant after excluding patients with heart failure or cardiogenic shock and those who died <24 hours after enrollment.</AbstractText>Despite the use of effective therapies for non-ST-elevation acute coronary syndromes, ventricular arrhythmias in this setting are associated with increased 30-day and 6-month mortality. More effective therapies are needed to improve the survival of patients with these arrhythmias.</AbstractText> |
3,090 | Preload-adjusted maximal power: a novel index of left ventricular contractility in atrial fibrillation. | Left ventricular contractility in atrial fibrillation is known to change in a beat to beat fashion, but there is no gold standard for contractility indices in atrial fibrillation, especially those measured non-invasively.</AbstractText>To determine whether the non-invasive index of contractility "preload-adjusted PWR(max)" (maximal ventricular power divided by the square of end diastolic volume) can accurately measure left ventricular contractility in a beat to beat fashion in atrial fibrillation.</AbstractText>Atrial fibrillation was induced experimentally using 60 Hz stimulation of the atrium and maintained in 12 sheep; four received diltiazem, four digoxin, and four no drugs (control). Aortic flow, left ventricular volume, and left ventricular pressure were monitored simultaneously. Preload-adjusted PWR(max), the slope of the end systolic pressure-volume relation (E(max)), and the maximum rate of change of left ventricular pressure (dP/dt(max)) were calculated in a beat to beat fashion.</AbstractText>Preload-adjusted PWR(max) correlated linearly with load independent E(max) (p < 0.0001) and curvilinearly with load dependent dP/dt(max) (p < 0.0001), which suggested the load independence of preload-adjusted PWR(max). After five minutes of diltiazem administration, preload-adjusted PWR(max), dP/dt(max), and E(max) fell significantly (p < 0.0001) to 62%, 64%, and 61% of baseline, respectively. Changes were not significant after five minutes of digoxin (103%, 98%, and 102%) or in controls (97%, 96%, and 95%).</AbstractText>Preload-adjusted PWR(max) correlates linearly with E(max) and is a useful measure of contractility even in atrial fibrillation. Non-invasive application of this method, in combination with echocardiography and tonometry, may yield important information for optimising the treatment of patients with atrial fibrillation.</AbstractText> |
3,091 | Echocardiographic findings of patients with retinal ischemia or embolism. | A potential source of emboli is not detected in more than 50% of patients with retinal arterial occlusive events. Echocardiographic studies are not always included in the diagnostic workup of these patients. The authors studied the diagnostic yield of transthoracic (TTE) and/or transesophageal (TEE) echocardiography in identifying potential sources of emboli in patients with retinal ischemia or embolism.</AbstractText>In a prospective study, 73 consecutive patients with clinically diagnosed retinal ischemia or embolism received a standardized diagnostic workup including retinal photography, echocardiography, and imaging studies of the internal carotid arteries. TTE was performed in 83.6% of patients, TEE was performed in 5.5% of patients, and both TTE and TEE were performed in 11.0% of patients. Ophthalmological diagnoses consisted of amaurosis fugax (n = 28), asymptomatic cholesterol embolism to the retina (n = 34), and branch or central retinal artery occlusion (n = 11).</AbstractText>Echocardiography identified a potential cardiac or proximal aortic source for embolism in 16 of 73 (21.9%) patients, including 8 who also had either atrial fibrillation or internal carotid artery stenosis of more than 50% on the side of interest. Thus, 8 of 73 (11.0%) patients had lesions detected only by echocardiography. The most commonly identified lesions were proximal aortic plaque of more than 4 mm thickness (n = 7, 9.6%) and left ventricular ejection fraction of less than 30% (n = 6, 8.2%). TEE was particularly helpful in identifying prominent aortic plaques.</AbstractText>Echocardiography frequently identifies lesions of the heart or aortic arch that can act as potential sources for retinal ischemia or embolism. Further studies are needed to evaluate the prognostic and therapeutic relevance of these findings.</AbstractText> |
3,092 | Optimizing ambulatory ECG monitoring of T-wave alternans for arrhythmia risk assessment. | Considerable scientific data support the potential value of T-wave alternans (TWA) as an index of vulnerability to ventricular fibrillation. This chapter summarizes our state of knowledge regarding the use of routine ambulatory ECGs to evaluate TWA and discusses recent methodologic approaches designed to optimize AECG-based TWA analysis for arrhythmia risk stratification. Newer methods, including the nonspectral technique of Modified Moving Average analysis, appear promising in detecting TWA during the changing conditions associated with daily activities. The Modified Moving Average approach does not require specialized electrodes and is not encumbered by the need to achieve target heart rates, as is the case for conventional spectral-based methods. Guidelines are provided for evaluating latent cardiac electrical instability using AECG-based TWA testing. These recent developments make possible the TWA analysis of ambulatory ECGs not only in prospective trials but also in vast stores of archival data. |
3,093 | Clinical value of T-wave alternans assessment. | Microvolt-level T-wave alternans (TWA) is a new arrhythmia risk marker to assess subtle changes in repolarization that has been introduced for arrhythmia risk stratification. Recent experimental studies have demonstrated that it reflects a heartrate dependent increased spatial dispersion of repolarization associated with unidirectional conduction block, and reentry that may result in the occurrence of ventricular fibrillation. Clinical studies have convincingly demonstrated that TWA is closely related to arrhythmia induction in the electrophysiology (EP) laboratory as well as to the occurrence of spontaneous ventricular tachyarrhythmias in patients undergoing EP study. Subsequent studies showed that TWA-assessed noninvasively-is predictive of future arrhythmic events in patients with implanted ICDs as well as for ventricular tachyarrhythmias in patients with congestive heart failure without a prior history of arrhythmias. There is still controversy, however, about the predictive value of TWA in patients following acute myocardial infarction (MI). Several studies which differ in patient selection, pharmacologic treatment of the patients, and endpoint definitions, have reported conflicting results. Therefore, studies with a large number of unselected patients after acute MI on optimal treatment according to contemporary therapeutic guidelines as well as of patients with reduced left ventricular ejection fraction following MI are needed to define its role with regard to identifying patients who may benefit from primary preventive ICD therapy. Future research should also focus on evaluation of alternative methods to increase heart rate (i.e., pharmacological stimulation) in an attempt to reduce the proportion of incomplete tests in patients with insufficient increase in heart rate during exercise testing. |
3,094 | Remodeling of cardiac repolarization: mechanisms and implications of memory. | Memory is a well established property of biological organisms, allowing them to adapt to their environment and respond to novel stimuli. Sensitization occurs in response to a noxious stimulus, and increases the behavioral response to subsequent stimuli. In contrast, habituation occurs in response to an innocuous stimulus, and decreases the behavioral response to subsequent stimuli. Therefore, the response of an organism to a stimulus does not simply depend on the stimulus, but also on previous stimuli that the organism has received. Similarly, the response of the heart to a stimulus does not simply depend on the stimulus, but also on previous patterns of depolarization and repolarization, due to electrical remodeling. Electrical remodeling, the persistent change in electrophysiological properties of myocardium in response to a change in rate or activation sequence, has been well described in atria. It can be induced by rapid pacing or atrial fibrillation (AF), and results in shortened atrial refractory period and increased susceptibility to atrial arrhythmias. These changes have been associated with alterations of potassium and calcium currents. However, the fundamental mechanisms responsible for triggering changes in channel expression in response to alterations in rate and activation sequence in AF are poorly understood. Even less is known about electrical remodeling in ventricle. Rapid ventricular pacing or an alteration of ventricular activation sequence produces persistent changes in heterogeneity of repolarization and, in contrast to atria, a prolongation of action potential duration. Ventricular electrical remodeling is responsible for "T-wave memory," which is observed commonly in patients after periods of altered activation sequence (e.g., chronic pacing). These changes have been associated with alterations of potassium currents, specifically I(to), implying that electrical remodeling is heterogeneously expressed in the different cell types across the transmural wall. Finally, remodeling of gap junctions may also play a prominent role in action potential changes during remodeling. The signal transduction pathways through which a change in rate or activation sequence triggers changes in the expression of ionic currents are being actively investigated. |
3,095 | Electrocardiogram of the failing heart. | In the failing heart general specific (e.g., Q-waves after acute myocardial infarction, persistent ST-elevations in post-myocardial infarction left ventricular aneurysm) and unspecific ECG changes (e.g., left bundle branch block, right bundle branch block, ST-T-alterations due to digitalis glycosides or antiarrhythmic drugs) may be seen in the conventional 12-lead ECG. In addition, atrial and ventricular tachy-arrhythmias may be detected and quantified by 24-hour-Holter ECG recordings, that may be relevant for a worse prognosis of patients with congestive heart failure. Heart rate variability as the most relevant derived ECG parameter of sympathetic tone fluctuations may be of important prognostic significance in congestive heart failure patients. An abnormal signal averaged P-wave duration may predict the incidence of atrial fibrillation, as may apply to QRS-prolongation and/or ventricular late potentials in the signal averaged ECG for the incidence of serious life-threatening ventricular tachy-arrhythmias or death from pump failure. Last but not least, cardiac repolarization abnormalities may be detected by QT dispersion-, QT-/QTc-fluctuation- or T-wave alternans studies, but the true prognostic significance of these parameters for predicting sudden cardiac death or death from pump failure in patients with congestive heart failure remains unclear. |
3,096 | [Hospitalized congestive heart failure patients with preserved versus abnormal left ventricular systolic function]. | To compare the clinical characteristics of hospitalized patients with congestive heart failure and left ventricular dysfunction versus normal systolic function.</AbstractText>Clinical records of all admissions with a heart failure diagnostic code over a one-year period were reviewed retrospectively. Of 1,953 admissions, 595 were excluded because they did not fulfill diagnostic criteria.</AbstractText>A total of 1,069 patients had 1,358 admissions with confirmed heart failure (1.27 admissions/patient). Of them, 706 patients (66%) had an echocardiographic study and 381 (54%) had ventricular dysfunction. Ventricular dysfunction was associated with previous myocardial infarction (OR = 5.8), left bundle-branch block (OR = 5.0), male sex (OR = 2.0), and smoking (OR = 1.8). Meanwhile, a negative association existed with age (OR = 0.97), previous valve surgery (OR = 0.46) and atrial fibrillation (OR = 0.49). Patients with ventricular dysfunction had more hospitalizations in the cardiology department and received more vasodilators, aspirin, and nitrates on discharge. The prescription of angiotensin converting enzyme inhibitors prescription to patients with ventricular dysfunction increased with the severity of ventricular dysfunction and was more frequent in patients admitted to the cardiology department. Systolic dysfunction increased hospital mortality (OR = 2.9).</AbstractText>Patients admitted with heart failure and systolic dysfunction had a different clinical profile than patients with a normal ejection fraction. Seven clinical variables predicted the presence of systolic dysfunction. Patients with ventricular dysfunction had more hospital mortality and were prescribed vasodilators, aspirin, and nitrates more often on discharge.</AbstractText> |
3,097 | Results of the Jostent coronary stent graft implantation in various clinical settings: procedural and follow-up results. | The Jostent coronary stent graft (CSG) is composed of a PTFE layer sandwiched between two stainless steel stents, initially introduced for the treatment of coronary perforations and aneurysms with excellent results. By providing a mechanical barrier, this stent design also may be beneficial in the treatment of complex ulcerated lesions and in-stent restenosis by preventing debris protrusion and neointimal proliferation through the stent struts. To evaluate the safety and efficacy of this stent graft, we implanted 78 CSGs in 70 patients for a broad range of indications, including coronary perforations, aneurysms, degenerated saphenous vein grafts, complex lesions, and in-stent restenosis. The primary angiographic success rate (95.9%) was high, and using intravascular ultrasound (IVUS) guidance during stent implantation and high inflation pressures (19.3 +/- 3.2 atm), stent expansion with optimal symmetry was achieved in 94.7%. One limitation of the Jostent CSG was the side-branch occlusion rate (18.6%) and the resulting non-Q-wave infarction rate in seven cases (mean CK elevation, 238 U/l), acute Q-wave MI in two cases, and transient ventricular fibrillation in one patient after occlusion of the proximal RCA side branch without further complications. Subacute stent thrombosis occurred in four cases (5.7%) 7 to 70 days after stent implantation, despite using combined antiplatelet therapy with aspirin (ASA), ticlopidine, and/or clopidogrel for 30 days. Angiographic follow-up was available in 56 patients (80.0%) after a mean of 159 +/- 49 days, and follow-up IVUS was available in 38 cases. The overall restenosis rate (> 50% diameter stenosis) was 31.6% manifest primarily as edge restenosis (29.8% stent edge vs. 8.8% stent center; P < 0.001). IVUS examinations showed a minimal late lumen loss of 0.4 +/- 2.2 mm(2) within the center of the stent graft vs. 3.2 +/- 2.3 mm(2) at the stent edges (P < 0.001). The restenosis rate in the prespecified subgroups was 33.3% for saphenous vein grafts (2/6 lesions), 30.0% in complex lesions (6/20 lesions), and 38.5% (10/26 lesions) for the treatment of in-stent restenosis. Implantation of the Jostent CSG is feasible and safe, even in complex lesion subsets, and is associated with high primary success rates provided major side branches are avoided. The use of this stent may require an extended time course of antiplatelet therapy. Frequent focal stent edge renarrowing influences the overall restenosis rate. However, in treatment of complex in-stent restenosis and vein graft lesions, stent grafts may offer benefit over conventional therapies. Covered stents such as the JoMed coronary stent graft may become essential for bailout treatment of coronary perforations. |
3,098 | Antipsychotic-related QTc prolongation, torsade de pointes and sudden death. | Sudden unexpected deaths have been reported with antipsychotic use since the early 1960s. In some cases the antipsychotic may be unrelated to death, but in others it appears to be a causal factor. Antipsychotics can cause sudden death by several mechanisms, but particular interest has centred on torsade de pointes (TdP), a polymorphic ventricular arrhythmia that can progress to ventricular fibrillation and sudden death. The QTc interval is a heart rate-corrected value that represents the time between the onset of electrical depolarisation of the ventricles and the end of repolarisation. Prolongation of the QTc interval is a surrogate marker for the ability of a drug to cause TdP. In individual patients an absolute QTc interval of >500 msec or an increase of 60 msec from baseline is regarded as indicating an increased risk of TdP. However, TdP can occur with lower QTc values or changes. Concern about a relationship between QTc prolongation, TdP and sudden death applies to a wide range of drugs and has led to the withdrawal or restricted labelling of several. Among antipsychotics available in the UK, sertindole was voluntarily suspended, droperidol was withdrawn, and restricted labelling introduced for thioridazine and pimozide. The degree of QTc prolongation is dose dependent and varies between antipsychotics reflecting their different capacity to block cardiac ion channels. Significant prolongation is not a class effect. Among currently available agents, thioridazine and ziprasidone are associated with the greatest QTc prolongation. Virtually all drugs known to cause TdP block the rapidly activating component of the delayed rectifier potassium current (I(kr)). Arrhythmias are more likely to occur if drug-induced QTc prolongation coexists with other risk factors, such as individual susceptibility, presence of congenital long QT syndromes, heart failure, bradycardia, electrolyte imbalance, overdose of a QTc prolonging drug, female sex, restraint, old age, hepatic or renal impairment, and slow metaboliser status. Pharmacodynamic and pharmacokinetic interactions can also increase the risk of arrhythmias. Further research is needed to quantify the risk of sudden death with antipsychotics. The risk should be viewed in the context of the overall risks and benefits of antipsychotic treatment. It seems prudent, where possible, to select antipsychotics that are not associated with marked QTc prolongation. If use of a QTc-prolonging drug is warranted, then measures to reduce the risk should be adopted. |
3,099 | Amiodarone and rural emergency medical services cardiac arrest patients: a cost analysis. | Recent American Heart Association guidelines suggest amiodarone as an antiarrhythmic in refractory ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT). The authors sought to assess the impact of amiodarone use on outcomes and cost associated with this practice in a rural emergency medical services (EMS) state.</AbstractText>Statewide EMS records were reviewed for the calendar year 1999. Data reviewed included prehospital diagnosis, medications given by prehospital providers to patients with cardiac arrest, and procedures performed, including cardiopulmonary resuscitation (CPR) and defibrillation. Cost-benefit analysis assumed the cost of amiodarone treatment to be $137.65 per patient encounter. Absolute risk reduction (ARR) and number needed to treat (NNT) analysis utilized resuscitation rates published in the ARREST and ALIVE trials.</AbstractText>During the study period, EMS providers diagnosed 2,189 patients as having cardiac arrest. Five hundred thirty-five (24.4%) cardiac arrest patients were defibrillated. One hundred sixty patients (7.3%), including 15 who did not receive defibrillation, were given lidocaine during resuscitation efforts. The annual cost increase from current practice for a statewide amiodarone VF/VT protocol was $21,822.40 (10,572.87%). The initial cost to stock EMS vehicles for this protocol would be $50,115.52. The cost-benefit analysis yielded a potential for one additional patient survival to hospital discharge in Maine per 3.125 years of system-wide practice at a cost of $68,840.00.</AbstractText>Based on current data, instituting amiodarone treatment for refractory VF and pulseless VT in a rural EMS setting requires the investment of substantial resources, relative to current treatment strategies, for any potential survival benefit.</AbstractText> |
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