The automatic implantable cardioverter-defibrillator. Long-term clinical experience and outcome at a hospital without an open-heart surgery program.

From November 1982 through April 1989, 111 patients with refractory sustained ventricular tachycardia/fibrillation had the automatic cardioverter-defibrillator implanted at our institution, the first community hospital involved in implantation of such a device. We have reviewed our long-term clinical experience to assess the feasibility, learning curve, and efficacy of device implantation in a facility with cardiac electrophysiology expertise but without open-heart surgery facilities. All patients were considered inoperable or at high risk for other concomitant surgery. Eighty-six patients (77%) underwent uneventful implantation. Nine patients (8%) died prior to hospital discharge. Operative mortality declined from 10.9% to 5.4% during the first half (55 patients; November 1982 through September 1986) and second half (56 patients; October 1986 through April 1989) of the experience. Other postoperative complications occurred in 16 patients (14%), 12 of whom experienced complications during the first half of the experience. At 22 +/- 20 (mean +/- SD) months' follow-up, 78 (76%) of 102 patients discharged were alive, and 24 patients (24%) had died. Fifty patients (49%) had experienced at least one automatic cardioverter-defibrillator discharge associated with hypotensive symptoms. The actuarial incidence of sudden death at 1, 2, and 3 years was 1.2%, 5.5%, and 6.2%, respectively. We concluded that the automatic implantable cardioverter-defibrillator is an effective therapy for refractory ventricular tachycardia/fibrillation and that device implantation at community hospitals with an experienced cardiac electrophysiology team is both feasible and practical.

Ventricular pacing threshold and time to capture postdefibrillation in patients undergoing implantable cardioverter-defibrillator implantation.

To assess the effect of defibrillation and amiodarone on ventricular pacing threshold and time to capture in patients undergoing automatic implantable cardioverter-defibrillator (AICD) implantation, 28 patients were prospectively evaluated. The patients were entered into one of two protocols: Ia--epicardial ventricular pacing threshold measured at baseline (preventricular fibrillation induction) and 10 and 60 seconds postdefibrillation with 20 J, or Ib--two fibrillation-defibrillation sequences were performed 3 minutes apart and ventricular pacing thresholds were measured for each sequence at baseline and at 10 and 60 seconds postdefibrillation with 20 J. Ten patients also underwent asynchronous pacing at 1.1 times baseline threshold during ventricular fibrillation with measurement of time to capture postdefibrillation. All patients were randomly assigned to receive either amiodarone or no antiarrhythmic drug therapy. Ventricular fibrillation was induced with AC (applied for 1-2 seconds), and standard epicardial bipolar and epicardial patch electrodes of the AICD were used for pacing and defibrillation, respectively. Ventricular pacing threshold at baseline, 10 seconds, 60 seconds, and 3 minutes postdefibrillation did not differ significantly. There were no significant differences in patients with or without amiodarone therapy. Furthermore, there was no transient loss of ventricular capture postdefibrillation or significant difference in time to capture with amiodarone (less than or equal to 2 seconds). We conclude that following internal defibrillation with 20 J: (1) ventricular pacing threshold at 10 seconds, 60 seconds, and 3 minutes were not significantly different from baseline with one or two fibrillation-defibrillation sequences, (2) time to capture was short, and (3) there was no significant difference in no drug versus amiodarone. These findings have direct clinical importance in considering device therapy with both pacing and defibrillating capabilities.

Implantation of the automatic implantable cardioverter defibrillator.

Since February 1980 the automatic implantable cardioverter defibrillator has been implanted in over 1,500 patients. Sudden death rates have been reduced to 2%-4% annually. This report reviews the implantation techniques, their indications, and our clinical experience in 200 patients.

Success of chronic defibrillation and the role of antiarrhythmic drugs with the automatic implantable cardioverter/defibrillator.

Because the automatic internal cardioverter defibrillator's long-term ability to reduce arrhythmic mortality in patients with ventricular tachycardia/fibrillation is unknown, it is important to determine whether the threshold for defibrillation changes over time. Serial defibrillation thresholds were measured in 23 patients over a mean replacement time of 24.8 +/- 7.5 months. In all cases the lead system was a superior vena cava coil to a left ventricular epicardial patch. The defibrillation threshold for the entire group increased from 12.3 +/- 4.7 J to 16.9 +/- 5.9 J (p less than 0.05). Striking increases in the defibrillation threshold were seen in the subgroup of patients taking amiodarone (from 10.9 +/- 4.3 J at implantation to 20.0 +/- 4.7 J at replacement, p less than 0.05). Defibrillation threshold decreased in patients taking no antiarrhythmic drugs or taking class I agents. Thus, the increase in mean defibrillation threshold was the result of an increase in the patients taking amiodarone. These data suggest that at initial implantation lead systems associated with the lowest defibrillation threshold should be used and the defibrillation threshold should be measured at generator change to guarantee an adequate margin of safety.

Pathologic findings related to the lead system and repeated defibrillations in patients with the automatic implantable cardioverter-defibrillator.

The purpose of the present study was to examine at autopsy the effect of multiple defibrillations on the myocardium and the pathologic consequences of short- and long-term placement of the intravascular and interpericardial leads of the automatic implantable cardioverter-defibrillator. Twenty-five patients were examined at autopsy; 8 of them underwent lead implantation only and 17 received both leads and the automatic implantable cardioverter-defibrillator. Twelve patients (48%) died of ventricular tachycardia or ventricular fibrillation; seven (28%) died of other causes. Acute pericarditis occurred in all patients, resulting in a localized, progressive fibrosis around the apical patch lead without giving rise to pericardial restriction. Thrombus formation was associated with the superior vena cava spring electrode in four patients (17%) and the right ventricular rate-sensing electrode in one patient (4%). Asymptomatic pulmonary emboli occurred in two patients (8%). In one patient who underwent defibrillation 59 times, superior vena cava changes consisted of vein wall destruction, fibrosis and thrombus formation. Pathologic changes under the apical patch related to defibrillation were observed in seven patients; two of these had fewer than 5 defibrillations, one had 8 defibrillations and four had 21 to 74 defibrillations. These changes consisted of contraction band necrosis in four patients, vacuolar cytoplasmic clearing and loss of myocytes confined to the myocardium under the patch electrode in five patients who had multiple defibrillations. The observed pathologic changes were estimated to affect less than 2% of the total myocardial mass. Thus, the automatic implantable cardioverter-defibrillator lead system and multiple defibrillations result in localized myocardial injury confined to the tissue under the patch electrode.(ABSTRACT TRUNCATED AT 250 WORDS)

[Implantable defibrillators. Clinical experience]. / Les défibrillateurs implantables. Expérience clinique.

The clinical experience with the Automatic Implantable Cardioverter-Defibrillator (AICD) now extends to over 800 patients suffering from malignant ventricular arrhythmias, most of them survivors of sudden cardiac death. This device monitors cardiac rhythm for long periods of time, identifies ventricular fibrillation and life-threatening ventricular tachycardias, and then restores normal heart action with effective electrical discharges. The AICD practically eliminates the need for trained personnel and the time constraints associated with conventional out-of-hospital resuscitation, significantly decreasing the arrhythmic and total mortality rates of the implantees. Through August, 1985, 130 consecutive patients underwent implantation of the AICD at The Johns Hopkins Hospital in Baltimore; the one-year mortality due to arrhythmias was 1.7%. These results are similar to those reported by other centers. Thus, the growing clinical experience with the automatic implantable cardioverter-defibrillator has demonstrated a marked reduction of the mortality rate of the implantees.

Recent clinical experience with the automatic implantable cardioverter-defibrillator.

The automatic implantable cardioverter-defibrillator is an electronic device designed to monitor the heart continuously, identify ventricular tachycardias and ventricular fibrillation, and terminate the life-threatening arrhythmias with an internal countershock. This device has been proved to be safe and effective, and its use has led to a significant decrease of arrhythmic mortality in the implantees.

Clinical experience with the automatic implantable defibrillator.

Since February 1980, worldwide, over 400 survivors of sudden arrhythmic death have been treated with the automatic implantable defibrillator. Recently, the device has been further improved; it is now a cardioverter-defibrillator (AICD), able to treat ventricular tachycardias as well as ventricular fibrillation. There are two defibrillating electrodes which are used also for waveform analysis; one is located in the superior vena cava, the other is placed over the cardia apex. A third bipolar right ventricular electrode serves for rate counting and R-wave synchronization. When ventricular fibrillation occurs, a 25-joule pulse is delivered; when ventricular tachycardia faster than a preset rate is detected, the discharge is R-wave synchronized. Special batteries can deliver over 100 shocks or provide a three-year monitoring life. Implantation of the device can be achieved through a thoracotomy or by a subxiphoid or a subcostal approach. Thus far, the longest follow-up period has been 58 months. Actuarial analysis shows the one-year mortality attributed to arrhythmias reduced to less than 2%. Thus, the automatic cardioverter-defibrillator can reliably identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in survival in properly selected high-risk patients.

Transhiatal (blunt) esophagectomy for malignant and benign esophageal disease: clinical experience and technique.

"Blunt" transhiatal esophagectomy was performed in 23 selected patients. Nineteen had squamous carcinoma of the esophagus (upper third, 1; middle third, 12; distal third, 6), and 2 had adenocarcinoma of the distal esophagus. The other 2 patients had severe lye strictures. Resection with reconstruction was performed in one stage. Esophagogastric continuity was restored using the stomach in the posterior mediastinal position in 20 patients and in the substernal position in 2. The colon in the posterior mediastinal position was used in 1 patient with a lye stricture. Transmural tumor extension or cervical or celiac nodal metastases or both were present in 18 of 21 patients with carcinoma. There was 1 hospital death due to pericardial tamponade. Morbidity included a transient cervical anastomotic leak in 3 patients, one temporary and three permanent unilateral recurrent laryngeal nerve palsies, one intraoperative splenic injury, and severe hemorrhage requiring sternotomy for control in 1 patient. Pulmonary complications occurred in 4 patients: aspiration pneumonia (1) and moderate atelectasis (3). Three patients have died (11, 12, and 17 months postoperatively) in the group with cancer, with follow-up time of 3 to 30 months (mean, 15 months). Transhiatal blunt esophagectomy is a safe and effective procedure in many patients with either esophageal cancer or extensive, benign esophageal strictures.

Automatic implantable cardioverter-defibrillator structural characteristics.

There are a number of equipment options and surgical techniques available for automatic implantable cardioverter-defibrillator implantation. The system can be successfully used even in problem cases where restrictions may be imposed because of physical build or the presence of other implanted devices. The sensing requirements and energy output of the units can be tailored to the exact needs of the particular patient. Battery life and device function are easily monitored periodically following implantation, making possible elective replacement of the pulse generator when the batteries become depleted.

Implantable cardioverter-defibrillator: patient selection and implantation protocol.

The experience obtained from the clinical trials with the automatic implantable cardioverter-defibrillator have reemphasized the need for a detailed pathophysiologic evaluation of the patient preoperatively. This evaluation requires careful documentation of the probable cause of the ventricular tachyarrhythmia and evaluation of other surgical needs of the patient, as well as consideration of the interactive effects of pacemakers and concurrent pharmacologic therapy postoperatively.

Clinical performance of the implantable cardioverter-defibrillator.

The automatic implantable cardioverter-defibrillator has been implanted in 276 patients with ventricular tachyarrhythmias refractory to therapy with a follow-up period up to 50 months (average 9.75 months). The functional performance of the device has so far been most encouraging. The risks and complications associated with its use are acceptable and quite similar to those observed in patients with implanted pacemakers. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation is dealt with successfully through recycling. Actuarial analysis indicates that the device has a significant impact on the survival rate of the implantees, reducing the one-year mortality rate attributed to arrhythmias to only 2%.

The automatic implantable cardioverter-defibrillator.

The automatic implantable cardioverter-defibrillator is an electronic device designed to monitor the heart continuously, to identify malignant ventricular tachyarrhythmias, and then to deliver effective countershock to restore normal rhythm. There are two defibrillating electrodes which are also used for waveform analysis; one is located in the superior vena cava, the other is placed over the cardiac apex. A third bipolar right ventricular electrode serves for rate counting and R-wave synchronization. When ventricular fibrillation occurs, a 25 joule pulse is delivered; when ventricular tachycardia faster than a preset rate is detected, the discharge is R-wave synchronized. The device can recycle three times if required. Special batteries can deliver over 100 shocks or provide a 3-year monitoring life. Implantation of the device is made either through a thoracotomy or by a subxiphoid approach. Thus far, the device has been implanted in 160 patients with a follow-up of 42 months. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation occurred only rarely and is dealt with most successfully through recycling. Actuarial analysis of the initial 52 patients has indicated 22.9% one-year total mortality, a 52% decrease from the 48% mortality that would be expected in the same group of patients without the device; the mortality attributed to arrhythmias was only 8.5%. In conclusion, the automatic cardioverter-defibrillator can reliably identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in survival in properly selected high-risk patients.

Use of the automatic implantable cardioverter-defibrillator in the treatment of malignant ventricular tachyarrhythmias.

Since February, 1980 nearly 200 automatic cardioverter - defibrillators have been implanted in patients with malignant ventricular arrhythmias. The currently-employed device weighs 298 grams and occupies a volume of 162 cm3. There are two defibrillation electrodes which also serve as sensors: one, an intravascular catheter placed in the superior vena cava at the level of the right atrium; the other, a flexible rectangular patch placed extrapericardially over the apex of the heart. Additionally, there is a bipolar right ventricular electrode for rate counting and R-wave synchronization which will eventually be used for pacing as well. The unit is powered by lithium batteries with a projected monitoring life of three years, or the capability of discharging approximately 100 times. The arrhythmia detector activates the cardioverter -defibrillator about 15 to 20 seconds after diagnosing a "treatable" arrhythmia, identified on the basis of a striking absence of isoelectric potential segments characteristic of ventricular fibrillation and many ventricular tachycardias. The diagnosis also requires fulfillment of individually-programmed heart rate criteria. If the initial discharge of 25 joules is ineffective, the device will recycle as many as three times with a final pulse of up to 42 joules. Of the twelve nonsurvivors among the initial 52 implantees who underwent implantation through September, 1982, only four deaths were unwitnessed and considered to be sudden and arrhythmic; the other eight deaths were due to heart failure or unrelated causes. Thus, from a predicted mortality of 48% in the same group of patients if the automatic defibrillator had not been implanted, the "sudden death" mortality was reduced to 8.5%.