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PubMed2004

Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure.

BACKGROUND: We tested the hypothesis that prophylactic cardiac-resynchronization therapy in the form of biventricular stimulation with a pacemaker with or without a defibrillator would reduce the risk of death and hospitalization among patients with advanced chronic heart failure and intraventricular conduction delays. METHODS: A total of 1520 patients who had advanced heart failure (New York Heart Association class III or IV) due to ischemic or nonischemic cardiomyopathies and a QRS interval of at least 120 msec were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy (diuretics, angiotensin-converting-enzyme inhibitors, beta-blockers, and spironolactone) alone or in combination with cardiac-resynchronization therapy with either a pacemaker or a pacemaker-defibrillator. The primary composite end point was the time to death from or hospitalization for any cause. RESULTS: As compared with optimal pharmacologic therapy alone, cardiac-resynchronization therapy with a pacemaker decreased the risk of the primary end point (hazard ratio, 0.81; P=0.014), as did cardiac-resynchronization therapy with a pacemaker-defibrillator (hazard ratio, 0.80; P=0.01). The risk of the combined end point of death from or hospitalization for heart failure was reduced by 34 percent in the pacemaker group (P<0.002) and by 40 percent in the pacemaker-defibrillator group (P<0.001 for the comparison with the pharmacologic-therapy group). A pacemaker reduced the risk of the secondary end point of death from any cause by 24 percent (P=0.059), and a pacemaker-defibrillator reduced the risk by 36 percent (P=0.003). CONCLUSIONS: In patients with advanced heart failure and a prolonged QRS interval, cardiac-resynchronization therapy decreases the combined risk of death from any cause or first hospitalization and, when combined with an implantable defibrillator, significantly reduces mortality.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Why cardioverter-defibrillator implantation might not be the best idea for your elderly patient.

Over the last decade, implantable cardioverter-defibrillators (ICDs) have become a part of mainstream clinical practice, with improvements in survival in a broad range of patients. Given the overall limited life expectancy of elderly patients, their frequent comorbidities, and the complications associated with ICD implantation, it may not be reasonable to expect results with ICD implantation in the elderly to be comparable to that found in the clinical trials. In this paper, the authors review the available scientific literature and discuss why mainstream ICD use in the elderly may not be advisable.

Aged↗
PubMed1995

Long-term outcomes and modes of death of patients treated with nonthoracotomy implantable defibrillators.

Long-term outcomes of all patients who underwent nonthoracotomy implantable cardioverter-defibrillator (ICD) implantation at our institution from April 1991 to October 1994 were studied using the intention-to-treat analysis. Of 94 consecutive patients, 81 underwent nonthoracotomy ICD implantation and 13 underwent thoracotomy (for concomitant surgery in 11 and unavailability of nonthoracotomy leads in 2). Six of 81 patients had a high defibrillation threshold, 4 subsequently underwent thoracotomy, and 2 were treated with amiodarone. Surgical mortality was 0%. The duration of follow-up was 20 +/- 13 months, and was > 12 months in 74% of 67 living patients. Actuarial survival rates at 1 and 2 years were, respectively, 98% and 94% for sudden death and 91% and 83% for total mortality. Deaths during long-term follow-up were mostly due to nonsudden cardiac or noncardiac deaths. Two-year mortality rates were 12% and 25% in patients with ejection fraction > or = 30% and < 30%, respectively. Thus, instances of sudden death and surgical mortality are very few in patients with nonthoracotomy ICDs. Deaths during long-term follow-up are mostly due to nonsudden cardiac and noncardiac deaths. Therefore, ICD therapy may have greater impact on survival in patients with lower risks of nonsudden cardiac and cardiac death (e.g., younger patients with minimal heart disease) than in patients with severe cardiac or noncardiac disease. Prospective studies are needed to address this question.

Actuarial Analysis↗
PubMed1993

Nonthoracotomy lead system for implantable defibrillator.

Over a 2-year period, 110 patients underwent attempted implantation of an automatic cardioverter-defibrillator using the nonthoracotomy lead system. Indications included sustained monomorphic ventricular (n = 62), nonsustained with poor ventricular function (n = 7), ventricular fibrillation (n = 21), ventricular tachycardia/fibrillation (n = 18), and familial long QT syndrome (n = 2). There were 90 male and 20 female patients. Mean age was 57 +/- 15 years. Sixty percent had previous coronary bypass or valve operations, or both. Mean left ventricular ejection fraction was 30% +/- 14%, cardiac index was 2.4 +/- 0.9 L/m2, and systolic pulmonary artery pressure was 41 +/- 14 mm Hg. Under general anesthesia, the nonthoracotomy lead was introduced through the left subclavian vein. The subcutaneous patch and generator were placed posteriorly on the serratus muscle and left upper quadrant, respectively. The length of the procedure was 116 +/- 44 minutes and the mean number of defibrillation shocks for a successful implant was 8 +/- 4. Eighty-five patients (77%) had successful implantations. Failures were due to high defibrillation threshold (n = 23) and inability to place a right ventricular lead (n = 2). Predictors of failure included preoperative antiarrhythmic drugs and cardiac index of 1.8 +/- 4 L/m2 or less (p = 0.004). Three patients (2.7%) died after the operation of heart failure (n = 2) and chronic heart transplant rejection (n = 1). Complications included lead migration or dislodgment (n = 8), infection (n = 1), and hematoma (n = 3). In summary, the nonthoracotomy lead system may provide an alternative in patients undergoing cardioverter-defibrillator implantation.

Aged↗
PubMed2005

Primary prevention of sudden cardiac death: indications for cardioverter-defibrillator implantation.

Sudden cardiac death accounts for 400,000 to 450,000 deaths annually in Europe and in the United States. In patients with previous life-threatening arrhythmia, several perspective, randomized, controlled studies have demonstrated that implantable cardioverter-defibrillator (ICD) therapy is superior to the best antiarrhythmic therapy in prolonging survival. Furthermore, in a stratified-risk population with coronary artery disease, left ventricular ejection fraction < or = 35%, non-sustained ventricular arrhythmias, and inducible ventricular tachycardia, the ICD supports the class I level of recommendation by the guidelines published in 1998. The American College of Cardiology, American Heart Association, and North American Society of Pacing and Electrophysiology have updated the 1998 guidelines on the implantation of arrhythmia devices including in a class IIa level of recommendation also patients with a previous Q wave myocardial infarction and left ventricular ejection fraction < or = 30%, independently of their arrhythmic risk profile. In the recent years several randomized studies assessed the role of ICD treatment for primary prevention of sudden cardiac death and total mortality reduction in high-risk groups of patients with ischemic and non-ischemic dilated cardiomyopathy, with special reference to those with heart failure and ventricular dysfunction. This article reviews those trials that have resulted in defining indications for ICD, and that will expand its use in the future.

Cardiomyopathy, Dilated↗
PubMed1993

Heart transplantation after cardioverter-defibrillator implantation. A case control study.

A case control study was performed to determine whether previous implantable cardioverter-defibrillator (ICD) insertion adversely affects outcome after heart transplantation. Six male heart transplant recipients who had undergone ICD insertion 12 +/- 5 months before heart transplantation were compared to a cohort of six heart transplant recipients who were matched according to age, preoperative status and hemodynamics, date of transplantation, graft ischemic time, history of a previous cardiac operation, and duration of follow-up. There were no significant differences in operating room time, chest tube drainage, time to extubation, and the duration of intensive care unit or hospital stay between the two groups. Furthermore, there were no significant differences in the number of units of packed cells, fresh frozen plasma, platelets and cryoprecipitate transfused. The number of treated rejection episodes and the number of patients requiring intravenous antibiotics for infection in the first 90 days was identical between groups. It was concluded that heart transplantation after ICD implantation did not appear to carry more risk than heart transplantation after a previous cardiac operation. Our limited experience supports the potential use of the ICD in patients with life-threatening ventricular dysrhythmias who are awaiting transplantation.

Blood Loss, Surgical↗
PubMed1996

Increased Monday incidence of life-threatening ventricular arrhythmias. Experience with a third-generation implantable defibrillator.

BACKGROUND: Examination of the timing of cardiac events provides important pathophysiological information. Previous studies have shown that the onset of acute myocardial infarction occurs most frequently on Monday. The septadian (day of the week) pattern of occurrence of sudden cardiac death and lethal ventricular arrhythmias has not been examined previously. METHODS AND RESULTS: We examined the septadian distribution of life-threatening (cycle length < 280 ms) ventricular arrhythmias in 683 consecutive patients receiving a Ventak PRx, a third-generation implantable defibrillator with an event recorder. There was a prominent Monday peak, with a midweek decline and a secondary peak later in the week. A marked trough is apparent on both weekend days. The observed pattern was independent of age, sex, ejection fraction, NYHA functional class, type of heart disease, and the use of antiarrhythmic drugs but was not observed in patients receiving beta-blockers. CONCLUSIONS: Potentially lethal arrhythmias are not random events but occur in a daily pattern suggesting a relationship to the beginning and end of the work week. The absence of a Monday peak in patients receiving beta-blockers suggests that the pattern may be influenced by beta-blockers. This information may be useful in devising strategies to prevent sudden cardiac death.

Aged↗
PubMed1982

The automatic implantable defibrillator. New Modality for treatment of life-threatening ventricular arrhythmias.

The automatic implantable defibrillator continuously monitors cardiac rhythm, identifies ventricular fibrillation and then delivers corrective defibrillatory discharges when indicated; it weighs 250 grams and has a volume of 145 cc. When a suitable arrhythmia is detected, a 25 Joule pulse is delivered through a superior vena cava catheter electrode and another electrode placed over the cardiac apex. As of March 1981, sixteen survivors of multiple cardiac arrests refractory to antiarrhythmic therapy had undergone implantation of the automatic defibrillator. There was no operative mortality and the morbidity was minimal. Electrophysiologic studies were performed before and after surgery to confirm failure of drug therapy and to ensure the device's ability to terminate malignant arrhythmias. Eight spontaneous and fourteen of the seventeen induced malignant arrhythmias were properly recognized and corrected by the device. The discharges were well tolerated by awake patients. A number of problems including recycling delays and spurious discharges have been identified and corrected. There were three late deaths with pulmonary edema noted in two patients, and asystole in one. The autopsies revealed no myocardial damage attributable to the automatic defibrillator. Although the ultimate role of this approach to prevention of sudden arrhythmic death has yet to be determined, the results obtained to date are encouraging and indicate that a useful modality for treating malignant ventricular arrhythmias has been added to our armamentarium.

Adolescent↗
PubMed1999

Beta-blocker use and survival in patients with ventricular fibrillation or symptomatic ventricular tachycardia: the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial.

OBJECTIVES: To evaluate whether use of beta-adrenergic blocking agents, alone or in combination with specific antiarrhythmic therapy, is associated with improved survival in persons with ventricular fibrillation (VF) or symptomatic ventricular tachycardia (VT). BACKGROUND: The ability of beta-blockers to alter the mortality of patients with VF or VT receiving contemporary medical management is not well defined. METHODS: Survival of 1,016 randomized and 2,101 eligible, nonrandomized patients with VF or symptomatic VT followed in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial through December 31, 1996 was assessed using Cox proportional hazards analysis. RESULTS: The 817 (28%) patients discharged from hospital receiving beta-blockers had less ventricular dysfunction, fewer symptoms of heart failure and a different pattern of medication use compared with patients not receiving beta-blockers. Before adjustment for important prognostic variables, beta-blockade was not significantly associated with survival in randomized or in eligible, nonrandomized patients treated with specific antiarrhythmic therapy. After adjustment, beta-blockade remained unrelated to survival in randomized or in eligible, nonrandomized patients treated with amiodarone alone (n = 1142; adjusted relative risk [RR] = 0.96; 95% confidence interval [CI] 0.64-1.45; p = 0.85) or a defibrillator alone (n = 1347; adjusted RR = 0.88; 95% CI 0.55 to 1.40; p = 0.58). In contrast, beta-blockade was independently associated with improved survival in eligible, nonrandomized patients who were not treated with specific antiarrhythmic therapy (n = 412; adjusted RR = 0.47; 95% CI 0.25 to 0.88; p = 0.018). CONCLUSIONS: Beta-blocker use was independently associated with improved survival in patients with VF or symptomatic VT who were not treated with specific antiarrhythmic therapy, but a protective effect was not prominent in patients already receiving amiodarone or a defibrillator.

Adrenergic beta-Antagonists↗
PubMed1993

Determinants of successful nonthoracotomy cardioverter-defibrillator implantation: experience in 101 patients using two different lead systems.

OBJECTIVES: This study was conducted to identify the determinants of successful nonthoracotomy cardioverter-defibrillator implantation. BACKGROUND: Until recently, either median sternotomy or thoracotomy was necessary to implant the electrodes used for internal cardioverter-defibrillator systems. A number of manufacturers have developed nonthoracotomy lead systems comprising two transvenous coil electrodes and a subcutaneous patch electrode. At present, the factors associated with the success or failure of a nonthoracotomy approach are unknown. METHODS: A total of 101 consecutive patients requiring a cardioverter-defibrillator underwent an initial nonthoracotomy approach. Factors associated with successful nonthoracotomy implantation were prospectively determined. RESULTS: A nonthoracotomy system was implanted in 72 (71%) of 101 patients. Twenty-nine patients (29%) required thoracotomy. Univariate predictors of successful nonthoracotomy implantation included smaller cardiac size (p < 0.0001), smaller cardiothoracic ratio (p < 0.0002), QRS duration < 120 ms (p = 0.003), female gender (p = 0.006), ventricular fibrillation as the presenting arrhythmia (p = 0.03) and smaller echocardiographic left ventricular size (p = 0.04). Multivariate predictors included smaller cardiac size (p < 0.002) and female gender (p < 0.007). Total actuarial survival over a mean (+/- SD) follow-up interval of 12 +/- 7 months was 91 +/- 0.03% and was not different in the thoracotomy and nonthoracotomy groups. CONCLUSIONS: A nonthoracotomy cardioverter-defibrillator system can be implanted in a majority of patients. Smaller cardiac size and female gender are associated with a high probability of successful implantation.

Actuarial Analysis↗
PubMed1989

The implantable defibrillator and the emergency physician.

The automatic implantable cardioverter defibrillator (AICD) is a proven therapy for preventing the potentially lethal consequences of recurrent ventricular arrhythmias. Given the ever-increasing number of patients who have these devices, it can be anticipated that an increasing number of these patients will likely present to emergency departments with problems associated with this therapy. We review normal automatic implantable cardioverter defibrillator function and focus on the evaluation and treatment of problems that may bring a patient to the ED. Included are interaction with the device by magnets, assessment of the propriety of shocks received by the patient, and what to do when patients state they have received a shock from the device. An algorithmic approach is presented to facilitate management of these patients.

Electric Countershock↗
PubMed2003

Amiodarone versus Implantable Defibrillator (AMIOVIRT): background, rationale, design, methods, results and implications.

Non ischemic dilated cardiomyopathy (NIDCM) is a substrate for sudden cardiac death. Treatment with amiodarone may have a positive or neutral survival benefit. The role of ICD therapy in the primary prevention of sudden cardiac death in asymptomatic NIDCM patients is not clear. The purpose of the Amiodarone versus Implantable Defibrillator (AMIOVIRT) study was to compare total mortality, arrhythmia-free survival, quality of life and costs of therapy in patients with NIDCM, asymptomatic non-sustained ventricular tachycardia (NSVT) and left ventricular ejection fraction <or=0.35 who were randomized to therapy with amiodarone (52 patients) or an ICD (51 patients). At the first scheduled interim analysis, the previously determined stopping rule for futility was reached and the study was stopped. There was no statistically significant difference in the 1- and 3-year survival rates in the patients who received amiodarone compared with those who received an ICD (90% and 87% for amiodarone group versus 96% and 88% for ICD group; p = 0.8). There was a trend towards improved arrhythmia-free survival rates (p = 0.1), and cost of medical care (8,879 dollars vs. 22,039 dollars, p = 0.1) in the patients who were treated with amiodarone as compared to the patients who were treated with an ICD. At one year, the quality of life measures were not significantly different (p = 0.1).

Amiodarone↗
PubMed1983

Trials of the automatic implantable defibrillator in man. A three-year program report.

Since February, 1980, 65 survivors of multiple arrhythmic cardiac arrests unresponsive to therapy were referred for implantation of the automatic defibrillator. In 37 patients (Group I), automatic defibrillator implantation alone was performed by subxiphoid insertion (20 patients) or thoracotomy (17 patients). In another 28 patients (Group II), implantation was combined with definitive cardiac procedures--coronary artery bypass grafting in seven patients, bypass grafting and mitral valve replacement in four patients, and left ventricular aneurysmectomy with endocardial resection in 17 patients. There were no surgical deaths in Group I; four operative deaths occurred in Group II. The longest follow-up has been 34 months, average 15.6 months. Following hospital discharge, 44 episodes of automatic out-of-hospital resuscitation were observed in 11 Group I patients. Similarly, four resuscitations were observed in two Group II patients. Hypothetical survival curves based on the assumption that these out-of-hospital resuscitations were lifesaving indicated expected 1 year survivals rates of 45% in Group I and 85% in Group II. Excluding the perioperative deaths that were unrelated to the defibrillator, the actual 1 year survival rates observed were 75% and 95% in Groups I and II, respectively. Although definitive operation markedly reduced the number of out-of-hospital arrhythmic episodes, the automatic defibrillator appears to increase survival both when implanted alone and when used in combination with cardiac procedures.

Adolescent↗
PubMed1993

Beep detection technique for immediate documentation of R wave sensing by an implanted defibrillator.

A technique is described for follow-up clinic evaluation and documentation of R wave detection by an implanted defibrillator that emits audible tones upon magnet application whenever an R wave or other signal is sensed. A circuit comprising an electret microphone, an instrumentation amplifier, a high-pass filter, and an envelope detector is used to generate a signal that may be plotted together with a surface-lead electrocardiogram on a two-channel strip-chart recorder. The resulting plot documents the sensing function of the implanted device and serves as an indication of optimal magnet position. Alternatively, the beep detector output could be used to trigger the inscription of fiduciary markers on a single-channel strip-chart recorder equipped with an auxiliary input for this purpose.

Defibrillators, Implantable↗
PubMed2006

Syncope, other risk factors, and the implantable defibrillator for sudden death prevention in hypertrophic cardiomyopathy.

Sudden cardiac death is the most devastating complication of hypertrophic cardiomyopathy. Since HCM may present at young age, and since the risk period for sudden arrhythmic death may be long, decision-making in HCM patients may be difficult, and have lifelong implications. Community based studies show a sudden death mortality of approximately 1%/year. Certain patients can be identified by their clinical characteristics, and through testing, to have higher annual risk, as high as 4-5%/year. Risk factors sudden cardiac death include: family history of HCM and sudden death, recurrent syncope, ventricular tachycardia, as detected by Holter monitoring or exercise testing, subnormal (<20 mmHg) increase in systolic blood pressure on maximal exercise testing and lastly marked (especially >30 mm) left ventricular hypertrophy. The implantable defibrillator has been shown to avert sudden death in selected HCM patients deemed to be at high risk.

Cardiomyopathy, Hypertrophic↗
PubMed1998

Implantable cardioverter defibrillators.

Implantable cardioverter defibrillators have proven to be an effective therapy for life-threatening ventricular arrhythmias. Given the ever-increasing number of patients who have these devices, increasing numbers of patients are likely to present to emergency departments with defibrillator-related problems. This article discusses normal device function, indications for implantation, and technique of implantation. It also focuses on the evaluation and management of patients with these devices presenting to the emergency department.

Arrhythmias, Cardiac↗
PubMed2004

Recent advances in pacemaker and implantable defibrillator therapy for young patients.

PURPOSE OF REVIEW: This review is intended to highlight major clinical advances over the past year related to (1). biventricular pacing as a treatment for dilated myopathy, (2). growing clinical experience with implantable cardioverter defibrillators in pediatrics, (3). technical advances in standard antibradycardia pacing, and (4). an appraisal of the newly updated ACC/AHA/NASPE guidelines for device implant in children and adolescents. RECENT FINDINGS: Complex rhythm devices are being used more frequently in children. Biventricular pacing to improve ventricular contractility is a rapidly evolving technology that has now been applied to children and young adults with intraventricular conduction delay, such as bundle branch block after cardiac surgery. Implantable defibrillators are also being used for an expanding list of conditions, although lead dysfunction is seen as a fairly common complication in active young patients. Guidelines for device implantation have been developed, but the weight of evidence remains somewhat limited by the paucity of pediatric data in this field. SUMMARY: Thanks to refinements in lead design and generator technology, coupled with rapidly expanding clinical indications, pacemakers and implantable defibrillators have become increasingly important components of cardiac therapy for young patients. Expanded multicenter clinical studies will be needed to develop more objective guidelines for use of this advanced technology.

Adolescent↗