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PubMed1999

[Clinical experience with the implantable atrial defibrillator (atrioverter) in patients with atrial fibrillation. Metrix Investigators].

Due to the limited efficacy of drug therapy in atrial fibrillation and the high rate of recurrence, strong efforts were made to find non-pharmacological strategies. For three years now, the implantable atrial defibrillator Metrix from InControl has been available as an alternative therapy. From October 1995 to the present the atrial defibrillator was implanted in 179 patients worldwide. The sensitivity of the system and its algorithms to detect atrial fibrillation is 90%; the specificity to detect sinus rhythm is 100%. In 121 of 179 patients, 748 episodes of spontaneous atrial fibrillation were treated with 2.4 shocks per episode. No proarrhythmic event or stroke was seen. A cardioversion to sinus rhythm could be achieved in 95% of patients; the overall clinical success rate was 88%. In 7% of all patients, early recurrence of atrial fibrillation (ERAF) occurred that could not be converted into stable sinus rhythm after further cardioversions and antiarrhythmic therapy. In 4.1% there were lead-related complications, in 4 patients the device had to be explanted because of ineffective therapy, and in 3 patients the device had to be changed because of loss of telemetry or early depletion of battery. In 8 patients, postoperative complications were seen (infections, pneumothorax and thrombosis of the subclavian vein). Overall, the implantable atrial defibrillator Metrix is an effective and safe alternative in treating atrial fibrillation.

Adult↗
PubMed2005

[Automated external defibrillators: perspectives and outlook].

In Germany about 80.000 patients die of sudden cardiac death each year with enormous human, social and economic consequences. Most cases of sudden cardiac death are caused by ischemia-triggered ventricular fibrillation. A precondition for survival of the victims is an optimally and fast reacting "chain of survival". One of the central links of this chain is timely defibrillation, which is the only effective therapy for treatment of ventricular fibrillation. Automated external defibrillators proved to be a major step forward in improvement of resuscitation results. It has been convincingly demonstrated, that these devices not only are safe and efficacious in the hands of rescue personnel of different qualification degrees but also in the hands of minimally trained "first responders" and even in the hands of untrained lay people. This story of success was paralleled by the development of a new generation of biphasic defibrillators, which have a superior efficacy, are lightweight and are even cheaper than conventional devices. It must however kept in mind, that progress offered by these new opportunities will only translate in better resuscitation results, when programmes are thoroughly planned, will stay under continuous quality control with regard to performance of devices and rescuers and if new knowledge in resuscitation is adequately incorporated in action protocols.

Cardiopulmonary Resuscitation↗
PubMed2005

Anesthetic management of a patient with severe dilated cardiomyopathy and an automatic implantable cardioverter-defibrillator (AICD) during total gastrectomy.

We report a case of severe dilated cardiomyopathy with an automatic implantable cardioverter-defibrillator (ICD) undergoing total gastrectomy. During the operation, the defibrillation function of the ICD was suspended and its pacing function was used solely in VOO mode. Electrodes of an external defibrillator were attached on the chest wall, and a pulmonary arterial (PA) catheter with a ventricle pacing port was inserted into the pulmonary artery. Proper perioperative management, including measures that the patient underwent the surgery uneventfully and could attain a rapid and successful discharge from the intensive care unit.

Anesthesia, General↗
PubMed2005

Internal atrial and ventricular defibrillation during electrophysiology procedures.

Over the last twenty years internal defibrillation has evolved from an experimental technique into an important adjunctive procedure in the electrophysiology laboratory. Internal deflbrillation is used for treating persistent atrial fibrillation and refractory ventricular arrhythmias. Atrial defibrillation can be performed with several electrode configurations but generally shocks from 1 to 50 joules are delivered between electrodes placed in the coronary sinus and lateral wall of the right atrium. Ventricular defibrillation is usually performed with electrodes in the right ventricle and superior vena cava, although "unipolar" configurations with an internal ventricular electrode and a skin electrode can be used. Currently, internal deflbrillation can be required in 5-10% of cases within the electrophysiology laboratory and will become more commonly used as electrophysiologists perform more complex catheter ablation procedures.

Atrial Fibrillation↗
PubMed1994

Low-energy transvenous cardioversion defibrillation of atrial tachyarrhythmias in the canine: an assessment of electrode configurations and monophasic pulse sequencing.

Prevention of recurrent atrial fibrillation and flutter remains a difficult clinical problem. Consequently, development of an easily implantable automatic atrial cardioverter defibrillator is appealing. In this context we have examined the feasibility of intracavitary low-energy shocks delivered via transvenously positioned electrodes for termination of induced atrial tachyarrhythmias in canine models. This study extends these observations with use of single-pathway (5 msec pulse duration) and dual-pathway sequential (5/5 msec, 0.2 msec separation) shocks of varying leading edge voltages (100 to 400 V) in a closed-chest canine talc-pericarditis model. Bipolar 9.5 French electrode catheters (electrode surface areas, 0.62 cm2) were positioned at the superior vena cava-right atrium (SVC-RA) junction (labeled SVC) and right ventricular (RV) apex, with a subcutaneous plate over the chest wall. For single-pathway shocks, overall treatment effectiveness was comparable among the three vectors tested (RV apex to SVC, 35%; RV apex to subcutaneous plate, 17%; and SVC to subcutaneous plate, 35%). Furthermore, there was no evident relationship between leading edge voltage and shock effectiveness. In contrast, although each of the dual-pathway shock vector combinations tested also showed similar overall effectiveness, there was an apparent dose-response effect as leading edge voltage increased. The SVC (common) to RV apex (pulse 1) and subcutaneous plate (pulse 2) achieved 60% effectiveness at 400 V (approximately 4 joules). Thus this study provides additional evidence favoring feasibility of low-energy transvenous atrial cardioversion defibrillation. However, further refinement of energy delivery is essential for the implantable automatic atrial cardioverter defibrillator concept to become clinically accepted.

Animals↗
PubMed1994

Complications of pacemaker-defibrillator devices: diagnosis and management.

Treatment of resuscitated patients with implantable cardioverter defibrillators has become increasingly more common as a method for the prevention of sudden cardiac death. Major complications such as perioperative death (incidence 2% to 8%), infection (2% to 11%); and lead-related problems (3% to 27%) have been described in previous trials. In our experience with 140 patients, problems were related to leads (n = 11), the device (n = 2), pacing (n = 1), sensing (n = 13), and defibrillation function (n = 5). Additional problems that occurred during the perioperative period included infection (n = 11), hematoma, and seroma (n = 2). Thrombus formation along endocardial leads was observed in 13 of 62 (21%) patients. Different arrhythmias (n = 10), such as sinus tachycardia, atrial fibrillation, and nonsustained, slow or incessant ventricular tachycardia with shock delivery, were also detected. Surgical management (predominantly for the major problems) was used in 31 (48%) patients, drug treatment in 25 (39%), and reprogramming of the device in 24 (38%) patients. All of these problems can result in an increase in mortality rates. This article provides an overview of the complications of cardioverter defibrillator treatment and is based on both published data and our series.

Arrhythmias, Cardiac↗
PubMed1993

Surgical experience with defibrillator implantation using nonthoracotomy leads.

Between October 10, 1989, and June 17, 1991, 109 patients with life-threatening ventricular arrhythmias received an implantable cardioverter-defibrillator at our institution. In 50 patients, nonthoracotomy lead systems consisting of a subcutaneous chest wall patch electrode near the cardiac apex and one (Cardiac Pacemakers, Inc: Endotak C) or two (Medtronic: Transvene) transvenous electrodes were tested. The mean ejection fraction was 0.44 +/- 0.15 with a range from 0.19 to 0.81. Twenty-four patients had a history of open heart operation. In 43 patients the nonthoracotomy lead system was implanted, whereas in 7 patients epicardial patch lead systems were required due to elevated defibrillation thresholds during nonthoracotomy lead testing. There was one perioperative death unrelated to the operative procedure (hydrocephalus internus). Hemorrhage from the subcutaneous patch pocket or the device pocket that required reintervention occurred in 4 patients. During a mean follow-up of 13 +/- 5 months (range, 4 to 26 months) no dislocation of an endocardial lead, insulation defect, or lead fracture has been observed. In 1 patient, the lead system had to be removed due to infection of the subcutaneous patch pocket. The cardiovascular survival rate was 98% at 12 and 18 months, and freedom from sudden cardiac death was 100% at 6 and 12 months. In conclusion, defibrillator implantation using nonthoracotomy lead systems is feasible with a success rate of 86%, and during short-term follow-up no problems related to the lead system such as dislocation, fracture, or insulation defect have occurred.

Adolescent↗
PubMed1994

Simplified subxiphoid placement of implantable cardioverter defibrillators using a posterior rectus pocket.

A simplified subxiphoid procedure using a single longitudinal epigastric incision and posterior rectus pocket for implantable cardioverter defibrillators was used in 100 patients. Through a single incision, ventricular patches are placed via a transverse pericardiotomy, and a pouch is created behind the rectus abdominis muscle in the left upper quadrant for placement of the implantable cardioverter defibrillator. Patients have minimal discomfort soon after operation, and the implantable cardioverter defibrillator generator is imperceptible to most.

Defibrillators, Implantable↗
PubMed1994

Options in managing the patient with high defibrillation thresholds.

The desired defibrillation threshold (DFT) obtained during intraoperative testing of an implantable cardioverter defibrillator (ICD) should be 10 J lower than the maximal energy delivered by the ICD generator. Of the 206 patients undergoing ICD implantation since December 1986, 8 (3.9%) have had initial DFTs with less than the 10-J safety margin using the standard large patch-large patch configuration. Patches were implanted by left thoracotomy in 6 and sternotomy in 1, and 1 had implantation of a transvenous defibrillation lead and subcutaneous patch. Of note, 6 (75%) of the 8 patients with high DFTs had prior open heart operations, half were on a regimen of long-term amiodarone therapy, and the mean left ventricular mass index was quite large but not significantly greater than that of patients with low DFTs. Multiple techniques was tried to improve the DFTs in this group. Satisfactory DFTs were eventually obtained in 7 (88%); the threshold was lowered from a mean of 41.4 +/- 3.8 J to 26.9 +/- 8.8 J (p = 0.002). The most effective techniques were addition of a superior vena cava lead attached by a Y connector to one of the large patch leads in some patients and conversion to a biphasic-waveform generator in 2 others. Adding a third epicardial lead did not lower the DFTs. There were no major postoperative complications or deaths attributable to these supplemental procedures. Using these techniques, satisfactory DFTs were obtained in almost all patients with an ICD.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

One-incision approach for insertion of implantable cardioverter defibrillators.

The placement of a transvenous implantable cardioverter defibrillator (ICD) system through a single infraclavicular skin incision has been a surgical goal for years. The development of a new investigational model of ICD with substantially reduced dimensions (volume, 83 cm3; mass, 132 g) has made the one-incision approach a clinical reality. Between March and September 1993, 4 female and 19 male patients (mean age, 60 +/- 9.6 years; range, 46 to 73 years) underwent implantation of this device for the treatment of ventricular fibrillation (n = 14) or ventricular tachycardia (n = 9). One transvenous lead was placed in the right ventricular apex and another in the left subclavian vein. A subpectoral pocket was formed in the infraclavicular area from the same incision to house the ICD generator and, if necessary, the subcutaneous patch. The mean operation time (81.5 +/- 32.7 minutes; range, 54 to 195 minutes) was significantly shorter than that noted for a previous series made up of patients undergoing traditional transvenous ICD implantations. In 20 patients (87%), endovenous defibrillation without a subcutaneous patch successfully caused externally induced ventricular fibrillation to revert with a mean minimum energy output of 21.9 +/- 3.5 J (range, 12 to 24 J). Endovenous defibrillation was more successful when biphasic (n = 16/17 [94%]) shocks rather than monophasic shocks (n = 4/6 [67%]) were used. No mortality, morbidity, or surgical complications were observed. These results indicate that the one-incision approach and the small size of the ICD generator can substantially facilitate ICD implantation and result in a reduction in the surgical trauma, the operation time, and the amount of material implanted.

Aged↗
PubMed1995

Defibrillator patch electrode constriction: an underrecognized entity.

Pericardial constriction associated with the placement of intrapericardial defibrillator patches is a rare occurrence that is reported only one tenth as often in defibrillator patients as in patients undergoing other types of cardiac operations. Although this discrepancy may be attributable to a lower incidence of constriction with the defibrillator patch electrode procedure, it may also indicate a failure to recognize that progressive right heart failure and signs of low cardiac output that could be due to pericardial constriction and not progressive systolic dysfunction. Because surgical removal of the patches and decortication of the epicardial surface is the only effective therapy, it is important to recognize this uncommon, but profoundly debilitating entity.

Adult↗
PubMed1992

Ventricular fibrillation detection using the evoked electrogram from the braided endocardial defibrillation lead.

Life-threatening consequences can be the result of inappropriate classification of ventricular fibrillation for patients with implantable cardioverter defibrillators. The objective of this study was to determine if analysis of the asynchronously paced evoked electrogram using the braided endocardial defibrillation lead could improve the detection of ventricular fibrillation. The depolarization portion of the evoked electrogram was integrated to obtain the paced depolarization integral. The results demonstrated that the mean of the paced depolarization integral, its SD, and the mean +/- SD were significantly different between sinus rhythm and ventricular fibrillation (p < 0.005, p < 0.05, p < 0.01, respectively). These results suggest that the paced depolarization integral obtained with the braided endocardial defibrillation lead could improve the specificity and sensitivity of ventricular fibrillation detection.

Animals↗
PubMed2004

Long-term care of the patient with the atrial defibrillator.

With an aging population, atrial fibrillation is becoming an increasingly common cause of hospital admission. Patients with recurrent, symptomatic persistent atrial fibrillation often require repeated admissions to the hospital for cardioversion. The development of the atrial defibrillator has empowered such patients to take charge of their condition and perform cardioversion on themselves at home. This liberates them from the worry of hospitalization and can increase patient confidence. The implantation of an atrial defibrillator, however, has some disadvantages, and long-term use of the device exposes patients to some of the psychological adaptations that occur in recipients of implantable devices. This article discusses in depth the patient selection process, the implantation procedure, the use of the atrial defibrillator, and problems that can arise during long-term follow-up.

Anti-Arrhythmia Agents↗
PubMed2004

Upper limit of vulnerability determination during implantable cardioverter-defibrillator placement to minimize ventricular fibrillation inductions.

The defibrillation threshold (DFT) and upper limit of vulnerability (ULV) were determined using step-down protocols in 50 patients who underwent implantable cardioverter-defibrillator placement or testing. The sensitivity and specificity of each ULV energy level was assessed for detecting an increased DFT, correlation of the DFT and ULV, and optimal shock timing for ULV determination. A ULV <10 or 11 J (failure to induce ventricular fibrillation with 10- to 11-J shocks) was 100% predictive of an acceptable DFT and may be sufficient to exclude unacceptable DFTs in 60% of implantable cardioverter-defibrillator recipients. All 4 shocks used to scan the peak of the T wave during ULV testing were necessary for accurate ULV determination.

Aged↗
PubMed2005

A comparison of the AVID and DAVID trials of implantable defibrillators.

We compared 2 studies of implantable cardiac defibrillators (ICDs) to determine the effects of device mode on outcomes. The Antiarrhythmics Versus Implantable Defibrillators (AVID) trial (1993 to 1997) demonstrated improved survival with the ICD compared with antiarrhythmic drug therapy. The Dual-chamber And VVI Implantable Defibrillator (DAVID) trial (2000 to 2002) showed that VVI pacing at 40 beats/min in patients with ICDs reduced the combined end point of death and hospitalization for congestive heart failure compared with DDDR pacing at 70 beats/min. Patients in the AVID trial (631 of 1,016) and the DAVID trial (221 of 506) meeting common inclusion and all exclusion criteria were studied. The major end points were the time to death, and the composite end point of time to death or hospitalization for congestive heart failure. Patients in the AVID and DAVID trials were similar, but more AVID patients had coronary artery disease (p = 0.04), history of myocardial infarction (p = 0.005), and previous ventricular arrhythmias (p = 0.03). DAVID patients underwent more previous revascularization procedures (coronary artery bypass surgery, p = 0.03; percutaneous coronary intervention, p = 0.001), and were more often taking beta-blocking drugs at hospital discharge (p <0.001). The backup VVI ICD groups in both studies had similar outcomes (p = 0.4), even when corrected for the previous demographic differences. The time-to- composite end point was similar in AVID patients treated with antiarrhythmic drugs and DAVID patients treated with DDDR ICDs (p = 0.6). Despite improved pharmacologic therapy and revascularization, outcomes have not improved with backup VVI pacing ICDs. If DDDR ICDs had been used in the AVID trial, benefit from ICDs for patients with serious ventricular arrhythmias could have been missed.

Adrenergic beta-Antagonists↗
PubMed2005

Implantable cardioverter-defibrillator efficacy in patients with heart failure and left ventricular dysfunction (from the MADIT II population).

The Multicenter Automatic Defibrillator Implantation Trial II demonstrated a significant 31% reduction in the risk of mortality in postinfarction patients with low ejection fraction (EF < or =30%). Recently, results from the Sudden Death in Heart Failure Trial indicated that a subgroup of patients with New York Heart Association (NYHA) class III heart failure had less benefit from an implantable cardioverter-defibrillator (ICD) than patients with less advanced heart failure. This study evaluates the association between NYHA class, EF, and blood urea nitrogen (BUN) levels as measures of heart failure and left ventricular dysfunction, and ICD benefit in reducing mortality as well as the association of these parameters with ICD therapy for ventricular tachyarrhythmias. NYHA class I was identified in 442 patients (36%), class II in 425 (35%), and class III in 350 patients (29%). EF < or =20% was present in 472 patients (38%), EF of 21% to 25% in 359 patients (29%), and EF of 26% to 30% in 401 patients (33%). BUN < or =25 mg/dl was present in 850 patients (70%) and >25 mg/dl in 368 patients (30%). Patients with higher NYHA class and BUN had higher mortality (34%) and a higher risk of arrhythmic events (33% to 35%) than patients in lower functional groups (16% to 20%). EF did not differentiate the risk. There was no evidence for significant interactions between mortality, ICD therapy, and tested parameters. In conclusion, patients with more advanced heart failure have a higher risk of mortality and arrhythmic events than patients with less severe disease. However, there is no significant difference in the benefit from ICD therapy among the above subgroups of patients in the Multicenter Automatic Defibrillator Implantation Trial.

Aged↗
PubMed2004

The implantable cardioverter defibrillator: technology, indications, and impact on cardiovascular survival.

Since the introduction of the implantable cardioverter defibrillator (ICD) for the management of patients with high risk of arrhythmic SCD, there has been increasing use of this device. Its basic promise to effectively terminate ventricular tachycardia (VT)-ventricular fibrillation (VF) has been repeatedly met. In several randomized trials, the ICD has been shown to be superior to conventional anti-arrhythmic therapy, both in patients with documented VT-VF (secondary prevention) and those with high risk such as left ventricular ejection fraction and no prior sustained VT-VF (primary prevention). In both groups, the ICD showed overall and cardiac mortality reduction. The device now can more accurately detect VT-VF and differentiate these from other arrhythmias through a series of algorithms and direct-chamber sensing. Therapy options include painless antitachycardia pacing, low-energy cardioversion, and high-energy defibrillation. The technique implant is now simple as a pacemaker with one lead attached to an active (hot) can functioning as the other electrode. Among other improvements is its weight, volume, multiprogrammability, and storage of information,dual-chamber pacing and sensing, dual-chamber defibrillation, and addition of biventricular pacing for cardiac synchronization. It is anticipated that further improvement in ICD technology will take place and the list of indications will grow.

Algorithms↗
PubMed2006

Clinical course and long-term follow-up of patients receiving implantable cardioverter-defibrillators.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are increasingly used for primary and secondary prevention of sudden cardiac death. Defibrillators were introduced into clinical practice in 1980. Since that time, factors affecting long-term survival and the natural history of defibrillator patients have not been described. OBJECTIVES: The purpose of this study was to identify clinical predictors of long-term survival in patients receiving ICDs. METHODS: The prognostic value of several clinical variables on the likelihood of survival or appropriate ICD therapy in 1,382 consecutive patients receiving ICDs from 1980 to 2003 were evaluated. Data were collected at the time of device implantation, and follow-up was completed through March 2005. RESULTS: In 70 +/- 51 months of follow-up (range 0-282 months), 792 patients died and 421 patients received appropriate ICD therapy at least once. Age, left ventricular ejection fraction, New York Heart Association (NYHA) functional class, Charlson comorbidity index, and antiarrhythmic drug use correlated with mortality. beta-Blocker and angiotensin-converting enzyme inhibitor use was associated with improved survival. Only NYHA functional class correlated with ICD therapy. Patients free of shocks for the first 5 years after ICD implantation had continued risk of arrhythmia recurrence. CONCLUSION: The heart failure characteristics of patients predicted ICD shock probability and survival better than the arrhythmia characteristics or the underlying heart disease. Antiarrhythmic drug use was associated with increased mortality. Beta-blocker and angiotensin-converting enzyme inhibitor use was associated with improved survival. A measurable arrhythmic risk even after prolonged shock-free intervals indicates the need for continued ICD therapy in all patients with appropriate ICD indications.

Adolescent↗