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PubMed1998

[National Registry of Automatic Implantable Defibrillators in 1996].

The results of the Spanish Registry of Automatic Defibrillators implanted between February 1996 and January 1997 are reported. A questionnaire per patient was completed by every implanting physician, in every center. The questionnaire was designed by the Section of Electrophysiology and Arrhythmias of the Spanish Society of Cardiology. The data from 306 automatic defibrillators implanted were reported. The percentage of defibrillators per inhabitant in Spain is close to 1 per 100,000. Eighty-five percent were first implants, while a 13% were replacements. Most of the electrodes used were endocardial. Chronic ischemic heart disease was found in 54% of the patients. Forty-six percent of the patients had syncopal ventricular tachycardia, 31% ventricular fibrillation and 23% sustained monomorphic ventricular tachycardia. The generator pocket was pectoral in 87% of the patients and abdominal in 13%. The implant of the defibrillator was associated with other cardiac surgery in only 3% of the patients.

Aged↗
PubMed2001

Bidirectional defibrillation using implantable defibrillators: a prospective randomized comparison between pectoral and abdominal active generators.

The objective of this study was to compare the effects of active abdominal and pectoral generator positions on DFTs in a bidirectional tripolar ICD system. Twenty-five consecutive patients had ICD systems implanted under general anesthesia. A transvenous single lead bipolar defibrillation system and an active 57-cc test emulator in the abdominal and pectoral positions were used in the same patient. A randomized, alternating step-down protocol was used starting at 15 J with 3-J decrements until failure. The mean implantation time was 114 +/- 23 minutes, the mean arrhythmia duration was 14.5 +/- 1.5 seconds, and the mean recovery time was 5.4 +/- 1.1 minutes. The mean DFTs in the abdominal and pectoral positions were 10.9 +/- 5.1 and 9.7 +/- 5.2 J, respectively (NS), the mean intraindividual DFT difference (abdominal minus pectoral) was -0.89 +/- 4.15 J (range -9.5 to 8 J). The 95% confidence interval showed a -2.60 to +0.82 J mean difference (NS). The DFT was < 15 J in 72% and 88% of the patients and the defibrillation impedance was 41 +/- 3 and 44 +/- 3 omega, abdominal versus pectoral positions. There was no difference in DFT between active abdominal and pectoral generator bidirectional tripolar defibrillation. The pectoral position may be considered the primary option, but in cases of high DFTs the abdominal site should be considered an alternative to adding a subcutaneous patch. In some patients, the anatomy may favor an abdominal position. Possible differences in the long-term functionality on the leads are not yet well known and need to be further evaluated.

Aged↗
PubMed1993

Return to arc welding following defibrillator implantation.

A male arc welder who was fitted with an implantable defibrillator wished to return to his former employment. Device testing and ambient magnetic field measurements were performed at his place of work. During welding, artifacts were seen on the intracardiac electrogram but there was no resulting disturbance of sensing function. Measured field strengths were too low to result in device inactivation. The patient resumed his work without incident. This appears to be the first reported case of a patient with an implantable defibrillator returning to this "electrically hostile" environment following thorough screening.

Defibrillators, Implantable↗
PubMed2002

Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator: the Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial.

CONTEXT: Implantable cardioverter defibrillator (ICD) therapy with backup ventricular pacing increases survival in patients with life-threatening ventricular arrhythmias. Most currently implanted ICD devices provide dual-chamber pacing therapy. The most common comorbid cause for mortality in this population is congestive heart failure. OBJECTIVE: To determine the efficacy of dual-chamber pacing compared with backup ventricular pacing in patients with standard indications for ICD implantation but without indications for antibradycardia pacing. DESIGN: The Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial, a single-blind, parallel-group, randomized clinical trial. SETTING AND PARTICIPANTS: A total of 506 patients with indications for ICD therapy were enrolled between October 2000 and September 2002 at 37 US centers. All patients had a left ventricular ejection fraction (LVEF) of 40% or less, no indication for antibradycardia pacemaker therapy, and no persistent atrial arrhythmias. INTERVENTIONS: All patients had an ICD with dual-chamber, rate-responsive pacing capability implanted. Patients were randomly assigned to have the ICDs programmed to ventricular backup pacing at 40/min (VVI-40; n = 256) or dual-chamber rate-responsive pacing at 70/min (DDDR-70; n = 250). Maximal tolerated medical therapy for left ventricular dysfunction, including angiotensin-converting enzyme inhibitors and beta-blockers, was prescribed to all patients. MAIN OUTCOME MEASURE: Composite end point of time to death or first hospitalization for congestive heart failure. RESULTS: One-year survival free of the composite end point was 83.9% for patients treated with VVI-40 compared with 73.3% for patients treated with DDDR-70 (relative hazard, 1.61; 95% confidence interval [CI], 1.06-2.44). The components of the composite end point, mortality of 6.5% for VVI-40 vs 10.1% for DDDR-70 (relative hazard, 1.61; 95% CI, 0.84-3.09) and hospitalization for congestive heart failure of 13.3% for VVI-40 vs 22.6% for DDDR-70 (relative hazard, 1.54; 95% CI, 0.97-2.46), also trended in favor of VVI-40 programming. CONCLUSION: For patients with standard indications for ICD therapy, no indication for cardiac pacing, and an LVEF of 40% or less, dual-chamber pacing offers no clinical advantage over ventricular backup pacing and may be detrimental by increasing the combined end point of death or hospitalization for heart failure.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Does device-based testing save time during automatic implantable cardioverter-defibrillator implantation?

BACKGROUND: Defibrillation testing can be done either via an external cardiac defibrillator or directly via the implanted defibrillator during implantation (device-based testing). The advantage of one testing methodology over the other has not been adequately studied. METHODS AND RESULTS: Seventy-four patients (72% men) were randomized into two groups depending on the defibrillation testing methodology used--external cardiac defibrillation and device-based testing groups. R-wave, pacing threshold, pacing impedance, defibrillation threshold, defibrillation pathway impedance and total procedure time were not significantly different between the two groups. CONCLUSIONS: Device-based testing did not significantly reduce the procedure time. Lead and defibrillation parameters were similar in both the groups; lead repositioning and replacement were required in three patients in the external cardiac defibrillation group.

Aged↗
PubMed2006

The cost effectiveness of implantable cardioverter-defibrillators: results from the Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II.

OBJECTIVES: We sought to evaluate the cost implications of the implantable cardioverter-defibrillator (ICD), using utilization, cost, and survival data from the Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II. BACKGROUND: This trial showed that prophylactic implantation of a defibrillator reduces the rate of mortality in patients who experienced a previous myocardial infarction and low left ventricular ejection fraction. Given the size of the eligible population, the cost effectiveness of the ICD has substantial implications. METHODS: Our research comprises the cost-effectiveness component of the randomized controlled trial, MADIT-II, based on utilization, cost, and survival information from 1,095 U.S. patients who were assigned randomly to receive an ICD or conventional medical care. Utilization data were converted to costs using a variety of national and hospital-specific data. The incremental cost-effectiveness ratio (iCER) was calculated as the difference in discounted costs divided by the difference in discounted life expectancy within 3.5 years. Secondary analyses included projections of survival (using three alternative assumptions), corresponding cost assumptions, and the resulting cost-effectiveness ratios until 12 years after randomization. RESULTS: During the 3.5-year period of the study, the average survival gain for the defibrillator arm was 0.167 years (2 months), the additional costs were 39,200 dollars, and the iCER was 235,000 dollars per year-of-life saved. In three alternative projections to 12 years, this ratio ranged from 78,600 dollars to 114,000 dollars. CONCLUSIONS: The estimated cost per life-year saved by the ICD in the MADIT-II study is relatively high at 3.5 years but is projected to be substantially lower over the course of longer time horizons.

Cost-Benefit Analysis↗
PubMed1994

Clinical outcome of patients with malignant ventricular tachyarrhythmias and a multiprogrammable implantable cardioverter-defibrillator implanted with or without thoracotomy: an international multicenter study. PCD Investigator Group.

OBJECTIVES: The long-term efficacy and safety of a third-generation implantable cardioverter-defibrillator implanted with thoracotomy and nonthoracotomy lead systems was evaluated in a multicenter international study. BACKGROUND: The clinical impact of transvenous leads for nonthoracotomy implantation and pacing for bradyarrhythmias and tachyarrhythmias in implantable cardioverter-defibrillator systems is not well defined. METHODS: The safety of the implantation procedure and clinical outcome of 1,221 patients with symptomatic and life-threatening ventricular tachyarrhythmias who underwent implantation of a third-generation cardioverter-defibrillator using either a thoracotomy approach with epicardial leads (616 patients) or a nonthoracotomy approach with endocardial leads (605 patients) in a nonrandomized manner was analyzed. The implantable cardioverter-defibrillator system permitted pacing, cardioversion, defibrillation, arrhythmia event memory and noninvasive tachycardia induction. RESULTS: Successful implantation of an endocardial lead system was achieved in 605 (88.2%) of 686 patients and an epicardial system in 614 (99.7%) of 616 (p < 0.05). Perioperative 30-day mortality rate was 0.8% (1.8% including crossovers) in endocardial implant recipients compared with 4.2% (p < 0.001) in epicardial implant recipients (3.6% without crossovers, p < 0.05, respectively). Implantation mortality risk was significantly lower for nonthoracotomy systems irrespective of left ventricular ejection fraction or New York Heart Association functional class. Pacing therapies prevented need for cardioversion or defibrillation shocks in 89% of all ventricular tachycardia episodes and were comparably effective for both lead systems. Total survival rate at 2 years was significantly higher in endocardial (87.6%) than epicardial (81.9%) lead recipients (p < 0.001). Elimination of perioperative mortality from the analysis demonstrated comparable survival in both groups (p > 0.2). CONCLUSIONS: Third-generation cardioverter-defibrillators with monophasic waveforms can be successfully implanted with epicardial (99.7%) and endocardial (88.2%) lead systems. We conclude that endocardial leads should be the implant technique of first choice. Improved patient management and tolerance for device therapy is achieved with the addition of antitachycardia pacemaker capability in these systems.

Defibrillators, Implantable↗
PubMed1997

Favorable results of implantable cardioverter-defibrillator implantation in patients older than 70 years.

BACKGROUND: The clinical results of implantable cardioverter-defibrillator (ICD) implantation in the elderly have received limited documentation. As the longevity of the U.S. population has increased, so has the need for ICD implantation in the elderly. We evaluated the efficacy and outcome of ICD implantation in elderly patients (>70 years) compared with younger patients. METHODS: The case records of all consecutive patients who underwent ICD implantation at our institution between 1986 and 1994 were reviewed. Of a total of 238 patients, 78 patients were 70 years of age or older and 160 patients were younger than 70 years of age. RESULTS: The mean age of the younger group was 58 years and that of the elderly group was 74 years. There were no statistical differences in the presence of coronary artery disease, left ventricular systolic function, the inducibility of arrhythmias, or the history of sudden cardiac death. The hospital morbidity rate was similar in both groups (6.9% in the younger group and 7.7% in the elderly group; p = not significant). The operative mortality rate was 1.9% for the younger group and 1.3% for the elderly group (p = not significant). At a mean follow-up of 33 +/- 26 months, Kaplan-Meier survival curves demonstrated similar survival rates, with 93%, 82%, and 65% of the patients alive at 1, 3, and 6 years, respectively. CONCLUSIONS: Implantable cardioverter-defibrillator implantation was equally effective in the treatment of patients older than 70 years as in younger patients. No differences in theoretic survival or morbidity were observed.

Age Factors↗
PubMed2001

Antiarrhythmic drug use in the implantable defibrillator arm of the Antiarrhythmics Versus Implantable Defibrillators (AVID) Study.

BACKGROUND: Previous retrospective or observational series suggest that many patients with an implantable cardioverter-defibrillator (ICD) will be treated with antiarrhythmic drugs (AADs) to modify the frequency or manifestation of recurrent ventricular arrhythmias. The relative clinical benefit, however, is uncertain, and deleterious interactions can occur. The objective of this clinical investigation was to study the need for, and effects of, concomitant AAD use with the ICD in a prospectively defined cohort. METHODS: All patients randomly assigned to the ICD arm of the Antiarrhythmics Versus Implantable Defibrillators (AVID) study were followed for the addition of class I or III AADs ("crossover") after hospital discharge. Addition of AADs was strictly regulated by AVID protocol. The timing and reasons for crossover and the effects on ventricular arrhythmia recurrence were analyzed. Patients were excluded if they required AADs before hospital discharge after index arrhythmias or if they had no ventricular arrhythmia before initiation of AADs. RESULTS: After a median follow-up of 135 days, 81 (18%) of the 461 eligible patients required AADs and formed the crossover group. The primary reason for crossover was frequent ICD shocks in 64% of patients. The most common AAD selected was amiodarone (in 42%). Independent predictors of crossover were lower ejection fraction, absence of ventricular fibrillation, or presence of nonsyncopal ventricular tachycardia at presentation, prior unexplained syncope, female sex, and history of cigarette smoking. Before AAD use, the 1-year arrhythmia event rate was 90%; after AAD, the event rate was only 64% (P =.0001). The time to first event was extended from 3.9 +/- 0.7 months to 11.2 +/- 1.8 months. There were 1.4 +/- 3.7 fewer ICD therapy events (P =.005) after crossover, predominantly accounted for by reduction in shocks rather than antitachycardia pacing therapies. CONCLUSIONS: The majority of patients who receive ICDs for sustained ventricular tachycardia or ventricular fibrillation can be treated without AADs. Most commonly, AADs are added to combat frequent ICD shocks, which are successfully reduced by AAD therapy.

Aged↗
PubMed1994

Effect of capacitor size and pathway resistance on defibrillation threshold for implantable defibrillators.

BACKGROUND: The time constant of truncated exponential pulses used with implantable defibrillators is determined by the output capacitor size and defibrillation pathway resistance. The optimal capacitor size is unknown. METHODS AND RESULTS: This study compared defibrillation threshold (DFT) for standard 120-microF capacitors (DFT120) and smaller 60-microF capacitors (DFT60) at implantation of cardioverter-defibrillators in 67 patients using epicardial electrodes (15 patients) or one of four transvenous electrode configurations (52 patients). Paired comparisons of DFT60 and DFT120 were made for 44 defibrillation pathways using monophasic pulses and for 53 pathways using biphasic pulses. Truncated exponential pulses with 65% tilt were used. Pooled data from all electrode configurations showed a significant inverse correlation between pathway resistance and the ratio of stored energy DFT60 to DFT120 (monophasic pulses: r = .75, P = .0001; biphasic pulses: r = .68, P = .0001). Data from all electrode configurations formed a continuum with 120-microF capacitors superior for low-resistance pathways and 60-microF capacitors superior for high-resistance pathways. For pathways with resistance < or = 40 omega, the modest advantage of 120-microF capacitors applied primarily to pathways with low DFTs: 8.2 +/- 6.1 versus 9.6 +/- 5.4 J (P = .001) for monophasic pulses and 4.1 +/- 2.8 versus 5.1 +/- 3.1 J (P < .02) for biphasic pulses. The greater advantage of 60-microF capacitors for pathways with resistance > or = 61 omega applied to pathways with higher DFTs: 12.4 +/- 4.3 versus 23.1 +/- 6.4 J (P = .0001) for monophasic pulses and 8.5 +/- 4.9 versus 12.5 +/- 6.4 J (P = .0001) for biphasic pulses. For pathways using monophasic 120-microF pulses versus 95% for 60-microF pulses. Similarly, the DFT was < or = 10 J for 48% of pathways using biphasic 120-microF capacitors versus 83% for 60-microF pulses. CONCLUSIONS: In comparison with conventional 120-microF capacitors, 60-microF capacitors had clinically insignificant higher DFTs for low-resistance pathways and clinically important lower DFTs for high-resistance pathways. Optimal capacitance is inversely related to pathway resistance for clinical defibrillation pathways and waveforms.

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PubMed2001

Patients at lower risk of arrhythmia recurrence: a subgroup in whom implantable defibrillators may not offer benefit. Antiarrhythmics Versus Implantable Defibrillator (AVID) Trial Investigators.

OBJECTIVES: The goal of this study was to identify subgroups of arrhythmia patients who do not benefit from use of the implantable cardiac defibrillator (ICD). BACKGROUND: Treatment of serious ventricular arrhythmias has evolved toward more common use of the ICD. Since estimates of the cost per year of life saved by ICD therapy vary from $25,000 to perhaps $125,000, it is important to identify patient subgroups that do not benefit from the ICD. METHODS: Data for 491 ICD patients enrolled in the Antiarrhythmics Versus Implantable Defibrillators Study were used to create a hazards model relating baseline factors to time to first recurrent arrhythmia. The model was used to predict the hazard for recurrent arrhythmia among all trial patients. A priori cut points provided lower and higher recurrent arrhythmia risk strata. For each stratum the incremental years of life due to ICD versus antiarrhythmic drug therapy were calculated. RESULTS: Factors that predicted recurrent arrhythmia were: ventricular tachycardia as the index arrhythmia, history of cerebrovascular disease, lower left ventricular ejection fraction, a history of any tachyarrhythmia before the index event and the absence of revascularization after the index event. Survival times (over a follow-up of three years) were identical in each arm of the lowest risk sextile (survival advantage 0.03 +/- 0.12 [se] years), while the survival advantage for patients above the first sextile was 0.27 +/- 0.07 (se) years (two-sided p = 0.05). CONCLUSIONS: Patients presenting with an isolated episode of ventricular fibrillation in the absence of cerebrovascular disease or history of prior arrhythmia who have undergone revascularization or who have moderately preserved left ventricular function (left ventricular ejection fraction > 0.27) are not likely to benefit from ICD therapy compared with amiodarone therapy.

Aged↗
PubMed1994

[Complications in transvenous and transvenous-subcutaneous implantable defibrillator systems].

Due to technical improvement using the transvenous-subcutaneous approach for lead fixation for cardioverter-defibrillator implantation, the incidence of device implantation has extended enormously. While a significant lower perioperative mortality in transvenously implanted systems compared to epicardially fixed implantable cardioverter-defibrillator (ICD) has been proven, perioperative as well as complications during follow-up are not analyzed systematically. In 59 patients, in whom transvenous-subcutaneous ICDs had been implanted, 3 patients showed bleeding complications in the subcutaneous patch area, 1 patient showed a bleeding in the device pocket, and in 1 patient a seroma in the subcutaneous patch region was observed necessitating surgical revisions. During follow-up of 10 +/- 7 months, lead dislocations were observed in 6 patients, in another 6 patients patch crinkling was observed. There was 1 patient with a lead fracture as well as 1 patient with a bleeding in the subcutaneous patch region. Despite the high efficacy of this therapy used in patients with life-threatening ventricular arrhythmias, these potential complications have to be considered.

Adult↗
PubMed1998

Measurement of the upper limit of vulnerability during defibrillator implantation can substitute defibrillation threshold measurement.

We investigated whether defibrillation thresholds (DFTs) could be measured more safely during defibrillator implantation by measuring the upper limit of vulnerability (ULV) without using any special equipment. Nonthoracotomy ICD implantation with endocardial leads was performed in 13 patients, and through the use of the ICD function itself, ULV and DFT were measured using the delayed four-episode up-down algorithm. Myocardial injures caused by high-energy current were assessed by electrocardiograms and serial CPK-MB. ULV was confirmed in all cases, and it strongly correlated with DFT. The average ULV was 5.9 +/- 3.3 J, while the average DFT was 7.9 +/- 4.3 J (r = 0.89, p < 0.0001, DFT = 1.20+1.14x ULV). The average ULV was thus significantly lower (p < 0.01). Although six patients were on amiodarone therapy, the strong correlation between ULV and DFT was also maintained (r = 0.97), p < 0.01) in these patients. In all cases, the CPK-MB failed to increase, and no myocardial injuries were detectable on electrocardiograms. We confirmed that ULV could be easily and safety measured during ICD implantation, and that ULV could be used instead of DFT.

Adult↗
PubMed2003

[The impact of the Multicenter Automatic Defibrillator Implantation Trial II in a university hospital--do all patients with myocardial infarction and reduced left ventricular function need an implantable cardioverter-defibrillator?].

BACKGROUND AND OBJECTIVES: Patients with coronary artery disease (CAD) and severely compromised left ventricular ejection fraction are at high risk to die from sudden cardiac death. The Multicenter Automatic Defibrillator implantation Trial II (MADIT II) shows a significant benefit of a cardioverter-defibrillator (ICD) therapy compared to standard treatment alone in this selected group of patients. The objective of the present study was to investigate the number of patients who will fulfil the MADIT II criteria and are candidates for prophylactic ICD implantation. METHODS AND MATERIAL: From January to December 2001 a total of 2653 patients underwent coronary angiography at our institution due to angina pectoris, positive exercise stress testing, pathological SPECT myocardial perfusion images, suspected dilated cardiomyopathy or ventricular arrhythmias. According to the MADIT II inclusion criteria patients with significant coronary artery disease (diameter stenosis > 50%), ejection fraction < 0.31% and previous myocardial infarction were included. Exclusion criteria were acute coronary syndromes, patients with ventricular tachyarrhythmias or an existing indication for ICD therapy, and patients with coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty within the past or following three months. RESULTS: Out of 2653 patients 185 (7%) had an ejection fraction less than 0.31, 149 (5.6%) showed significant coronary artery stenosis and 70 (2.6%) patients fulfilled the MADIT II criteria. The mean age of these patients was 68 +/- 9 years, the left ventricular ejection fraction 24 +/- 6. In 37 patients an ICD system was implanted according to the existing guidelines. 70 patients met the MADIT II inclusion criteria, resulting in an increase of 189% of ICD implantations per year. CONCLUSION: 2.6% out of 2653 patients who were referred to coronary angiography fulfilled the criteria of MADIT II. The expanding indication for ICD therapy will result in an annual increase of 70 (189%) prophylactic ICD implantations in our study population.

Aged↗
PubMed1995

Radiological appearances of implantable defibrillator systems.

Implantable defibrillator systems have been used in over 20,000 patients worldwide. Such systems use a variety of different electrodes and the identification of these and the recognition of associated problems with them presents a challenge to the radiologist. The appearance of currently available implantable defibrillation systems and the use of radiological examination in patient follow-up and system troubleshooting is discussed based on our experience with a large population of patients receiving these devices. Radiological examination is excellent for demonstrating displacement of distortion of defibrillation electrodes, but in our experience is ineffective for the identification of lead conductor fractures.

Defibrillators, Implantable↗
PubMed2004

Arrhythmia risk stratification with regard to prophylactic implantable defibrillator therapy in patients with dilated cardiomyopathy. Results of MACAS, DEFINITE, and SCD-HeFT.

To date, generally accepted indications for prophylactic defibrillator implantation in patients with dilated cardiomyopathy do not exist. Recently, the Marburg Cardiomyopathy Study (MACAS) revealed left ventricular ejection fraction to be the only significant arrhythmia risk predictor in a relatively large patient population with dilated cardiomyopathy. Meanwhile, the preliminary results of two prospective randomized trials evaluating prophylactic defibrillator therapy in dilated cardiomyopathy have been reported. The Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation study (DEFINITE) randomized 458 patients with a history of symptomatic heart failure, a left ventricular ejection fraction < or = 35% and arrhythmias on Holter to an ICD versus no ICD. As a result, ICD therapy was associated with a significant reduction of arrhythmic deaths, which failed to result in a significant decrease in total mortality due to an insufficient number of patients in DEFINITE. The Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) was a three-arm study comparing placebo to amiodarone to prophylactic ICD therapy in a total of 2,521 patients with ischemic cardiomyopathy (51%) or nonischemic dilated cardiomyopathy (49%). All patients in SCD-HeFT had a left ventricular ejection fraction inverted exclamation mark U 35% despite optimized medical heart failure therapy. SCD-HeFT showed a significant reduction of total mortality in the ICD group, whereas amiodarone did not improve survival.

Arrhythmias, Cardiac↗
PubMed1992

[Implantable defibrillators].

Automatic implantable defibrillator therapy has changed the approach to life-threatening ventricular tachycardia completely and essentially improved survival after aborted sudden cardiac death. Since the first implantation of a defibrillator in 1980, 20,000 patients have received such a device. Nonetheless, in Germany still too many patients die of sudden cardiac death because defibrillator therapy fails to be known enough and keeps not being made use of (no more than 1,000 implants to date). In this group of patients characterized by poor ventricular function, antiarrhythmic drug therapy proved to be unreliable or even dangerous in many cases, while electrophysiologically-guided surgical interventions use to be impossible. The introduction of the implantable defibrillator enabled the incidence of sudden cardiac death to be reduced to about 2% during the first year after implant, and to 5% in the third year, respectively. In most centers with more extensive experience in defibrillator implantations, operative mortality is about 2-3%. Long-term results with defibrillator patients are controlled by the course of the underlying disease, which is coronary artery disease with large scars due to infarction in some 75% of cases. In a large group of about 10,000 patients, total mortality has been calculated to be 15% after three years. Defibrillator systems of the latest generation offer multiple programmability of tachycardia identification parameters and permit differentiated modification of therapeutic intervention. Defibrillator therapy has now been improved essentially by the introduction of endocardial lead systems and, in addition, by the defibrillator being combined with an antitachycardia pacing system.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗