PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Defibrillators, Implantable”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1989

Right mini-thoracotomy: an adjunct to left subcostal automatic implantable cardioverter defibrillator implantation.

High defibrillation thresholds are encountered in some patients during implantation of the automatic implantable cardioverter defibrillator (AICD). In a consecutive series of 52 patients with AICD implants, 46 had allepicardial implants by left subcostal thoracotomy, and 8 of these patients had thresholds greater than 30 J. Placement of an apicolateral large left ventricular patch and an extrapericardial large right atrial patch electrode through a limited right thoracotomy produced substantial reduction in their thresholds. Especially in patients who have had previous intrapericardial operations, this technique provides a simple solution to the problem of high thresholds.

Electric Countershock↗
PubMed1991

Retrospective analysis of patients undergoing one- or two-stage strategies for myocardial revascularization and implantable cardioverter defibrillator implantation.

Internal defibrillation leads were placed at time of coronary revascularization in 79 patients. In 34, an implantable cardioverter defibrillator (ICD) was placed simultaneously (group I). A two-stage strategy (selective implantation of the ICD in patients with postoperative spontaneous or inducible ventricular tachycardia [VT]) was followed in 45 patients (group II). Group I patients had failed more antiarrhythmic drug trials (2.9 +/- 1.6 vs 1.5 +/- 1.6; P = 0.02), including amiodarone (62% vs 20%; P less than 0.001). There were four operative deaths in each group. Postoperatively, VT was present in 27 group II patients (60%), 25 of whom received an ICD (two refused device implantation). Patients with postoperative VT had a lower left ventricular ejection fraction than those without VT (33 +/- 9 vs 47 +/- 16; P = 0.01). Actuarial survival at 1, 2, and 3 years was 88 +/- 6, 88 +/- 7, and 88 +/- 10 in group I; and 83 +/- 6, 76 +/- 7, and 76 +/- 11 in group II (NS). No patient without an ICD (based on the postoperative electrophysiological study [EPS]) died suddenly. Five patients (6%) had ICD system infection. Sudden death was largely prevented by either strategy, but relatively high rates of operative mortality and ICD system infection were observed. Prospective studies should identify patients more likely to benefit from one or another strategy.

Aged↗
PubMed1991

Late results of the left subcostal approach for automatic implantable cardioverter defibrillator implantation.

A left subcostal surgical approach was used to implant an automatic implantable cardioverter defibrillator (AICD) in 48 patients with a history of nonfatal cardiac arrest or documented ventricular tachycardia/fibrillation. Electrophysiologic studies before surgery yielded induction of monomorphic or polymorphic ventricular tachycardia in 40 patients, whereas 8 were noninducible. Mean (+/- standard deviation) age was 58 +/- 12 years. Mean ejection fraction was 33 +/- 16%. Thirty patients (63%) had documented coronary artery disease; 14 patients (29%) had previous coronary bypass surgery. The mean intraoperative defibrillation threshold was 13.8 +/- 6.6 J. In 6 patients, an adjunctive right minithoracotomy was used to position 1 patch over the right atrium and thus optimize the defibrillation threshold. Patients with prior exposure to amiodarone and previous coronary bypass surgery had higher defibrillation thresholds at implantation. Two perioperative deaths occurred. There were no infections. Long-term follow-up yielded a 1- and 5-year survival of 0.88 and 0.58, respectively, and a freedom from sudden cardiac death of 1.0 and 0.97, respectively. The nonthoracotomy, left subcostal surgical approach is safe and effective, provides adequate defibrillation thresholds in most patients, and yields long-term survival comparable to other implantation techniques.

Cardiac Pacing, Artificial↗
PubMed1991

Implantable cardioverter defibrillator implanted by nonthoracotomy approach: initial clinical experience with the redesigned transvenous lead system.

Standard implantation procedure for the implantable cardioverter defibrillator (ICD) has traditionally required a thoracotomy approach. A newly revised nonthoracotomy defibrillator lead system that uses a single transvenous tripolar endocardial lead alone or in combination with a subcutaneous/submuscular patch lead was introduced into clinical trials in September, 1990. Fourteen patients requiring a cardioverter defibrillator for recurrent sustained ventricular tachycardia (eight patients) or aborted sudden cardiac death (six patients) were evaluated for implantation of this lead system. Primary successful lead system implantation was obtained in nine patients. The remaining five patients had unacceptably high defibrillation thresholds (DFTs) for implantation. One of the nine initially successful implants demonstrated unacceptable DFTs and cross-talk inhibition from a permanent pacemaker necessitating removal of the nonthoracotomy lead system and replacement with a conventional lead system via thoracotomy. All remaining primary implanted patients experienced successful conversion of induced ventricular fibrillation prior to hospital discharge. Continued follow-up and greater experience to confirm the durability and efficacy of the nonthoracotomy AICD lead system are needed.

Aged↗
PubMed1992

Time to first pulse after automatic implantable cardioverter defibrillator implantation.

Should automatic implantable cardioverter defibrillator (AICD) power sources be explanted and discontinued if they have not pulsed during the first generator life? We have followed 59 patients an average of 23 months (range, 3 days to 8.4 years) after AICD implantation. The indication for AICD implantation was based on clinical dysrhythmia, history of sudden death, and findings at electrophysiologic study. Thirty-eight of 59 patients (64%) had experienced sudden death and 52/58 (90%) were inducible at electrophysiologic study. Excluding 5 inappropriate pulsing episodes, 31 of 59 patients (53%) had 235 pulses (range, 1 to 36; median, 2 pulses). The time to first pulse after implantation ranged from 1 day to 3.5 years with a median time of 2 months. In 6 patients, the first pulsing occurred later than 1 year after AICD implantation. Fifteen generators demonstrating impending power source failure have been replaced in 11 patients. Power source depletion occurred at an average of 24.1 months (range, 8 to 40 months). In 3 patients, the first pulsing occurred after generator depletion and replacement. By univariate analysis, none of 13 variables (sex, age, cardiac disease process, functional class, previous myocardial infarction, sudden death history, ejection fraction, type of dysrhythmia, inducibility with electrophysiologic testing, number of extra stimuli required for induction, left ventricular aneurysm resection, endocardial resection, or concomitant operation) was found to be a predictor of pulsing (p greater than 0.05). We conclude that the majority of patients with pulses after AICD implantation will have them during the first 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Automatic implantable cardioverter defibrillator implantation after previous open heart surgery: subcostal incision and small left anterior thoracotomy.

In order to avoid the risk of major bleeding with redo sternotomy, an alternative surgical approach for the implantation of an automatic implantable cardioverter defibrillation (AICD) is presented. A subcostal incision in combination with a small left anterior thoracotomy was used in three patients. The procedure was easy to perform, considerably shorter than a redo sternotomy and well tolerated by the patient. We recommend this approach for AICD implantation in cases with previous heart operation.

Coronary Artery Bypass↗
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↗
PubMed1991

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.

Amiodarone↗
PubMed1991

Automatic implantable cardioverter-defibrillator implantation without thoracotomy using an endocardial and submuscular patch system.

The automatic cardioverter-defibrillator lead system is implanted by a thoracotomy procedure that may result in atelectasis, pleural effusion, cardiac tamponade and lengthy convalescence. A new defibrillator lead system that allows selection of different defibrillating current pathways is implanted without a thoracotomy. Ten patients requiring a cardioverter-defibrillator for recurrent sustained ventricular tachycardia (five patients) or aborted sudden cardiac death (five patients) were evaluated for implantation of this lead system. A lead configuration with a bidirectional defibrillating current pathway was implanted in nine patients. The defibrillation threshold with this lead configuration was 15 J in five patients, 20 J in three and 30 to 35 J in one patient. In the remaining patient the lead system had a 40 J defibrillation threshold and was not implanted. No perioperative complications occurred. Induced ventricular fibrillation was successfully terminated at the predischarge and intermediate follow-up (8 to 12 weeks) electrophysiologic studies. During the follow-up period, there were three deaths (one sudden, two due to heart failure) and two lead system failures (oversensing with inappropriate shocks in one patient and patch lead fracture in another). Implantation of the cardioverter-defibrillator lead system by a nonthoracotomy approach is feasible, has no significant perioperative complications and is well tolerated by patients. Effective defibrillation was demonstrated immediately as well as at intermediate follow-up study. The occurrence of patch lead fracture and oversensing requires improvement in the present (nonthoracotomy) lead system technology.

Cardiac Pacing, Artificial↗
PubMed1989

Nursing care for patients with implantable defibrillators.

Patients with implantable defibrillators are a new patient population that presents challenging issues and concerns. The size of this population will increase as the device's availability increases and design improvements are made that widen its applicability. These protocols have evolved during our first year with these patients and will doubtless change as we accrue experience in assisting patients to assume the role of being their own most important healthcare manager.

Arrhythmias, Cardiac↗
PubMed1990

An analysis of the cost effectiveness of the implantable defibrillator.

The automatic implantable defibrillator has been shown to decrease the mortality of patients who have survived cardiac arrest due to ventricular tachycardia or fibrillation and are at high risk for recurrence. We performed a cost-effectiveness analysis of this seemingly expensive new technology with data obtained from the 1984 Medicare data base, the medical literature, Medicare carriers, individual pharmacies and hospitals, and expert opinion. Analyzing combinations of principal and secondary discharge diagnoses across 18 diagnosis-related groups, we estimated the cost of hospitalization for a comparison group of patients. Hospitalization costs for the defibrillator group were obtained from reported empirical data. Rehospitalization rates and other health-care use estimates were solicited from an expert panel of physicians, and mortality rates for both groups were obtained from the literature. Using a decision-analytic model, we estimated that the net cost effectiveness of the defibrillator, when used in the high-risk patient, is approximately $17,100 per life-year saved, with sensitivity analyses suggesting that the true value lies between $15,000 and $25,000. This estimate is well within the range that is currently accepted by the US medical care system for other life-saving interventions. We also estimated the cost effectiveness of the defibrillator in a 1991 scenario to be $7,400 per life-year saved, when the device would have greater longevity, would be programmable, and would not require a thoracotomy. Sensitivity analyses suggest that the true value lies between a value that is cost saving (less expensive than pharmacologic therapy) and $19,600 per life-year saved.

Arrhythmias, Cardiac↗
PubMed1992

Use of event markers during exercise testing to optimize morphology criterion programming of implantable defibrillator.

The present generation implantable defibrillator introduced on-line event markers that can be used to evaluate tachycardia detection in the electrophysiological testing mode. These markers were used to assess the appropriateness of programming the morphology criterion for detection of ventricular tachycardia. Twenty-one consecutive patients (19 men, 2 women) performed 29 bicycle exercise tests with real-time recording of the electrocardiogram and the event markers on a multichannel recorder. Mean ejection fraction was 29% (range 15%-69%). Seven patients were taking antiarrhythmic agents. Twelve patients satisfied the morphology criterion at rest (n = 1) or during exercise (group I), and nine patients did not (group II). One patient was excluded from analysis because of continuous ventricular pacing. Mean peak heart rate was 130 beats/min in group I and 125 beats/min in group II. No statistical differences existed between the groups in relation to cycle length of ventricular tachycardia and mode of induction of arrhythmia, QRS duration on the electrocardiogram, during native rhythm, amplitude and duration of defibrillation patch R wave, calculated duty cycle at peak heart rate, and number of discharges of the automatic implantable cardioverter defibrillator at 2 to 14 months of follow-up time. It is concluded that clinical, electrocardiographic, and implantation data are unreliable in predicting satisfaction of the morphology criterion during high heart rates in native rhythm. Formal exercise testing in the electrophysiological mode enables a rational decision to be made about the appropriateness of the use of probability density function in each patient.

Algorithms↗
PubMed1992

Influence of left ventricular function on outcome of patients treated with implantable defibrillators.

BACKGROUND: The outcomes of patients treated with implantable defibrillators were compared between patients with left ventricular ejection fraction greater than or equal to 30% and less than 30%. METHODS AND RESULTS: Of 68 consecutive patients treated with implantable defibrillators, 40 patients (group 1) had left ventricular ejection fraction greater than or equal to 30%, and 28 patients (group 2) had left ventricular ejection fraction less than 30%. Sudden death, surgical mortality, nonsudden arrhythmia-related death (death within 24 hours after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillator), total arrhythmia-related death (including sudden death, surgical death, and nonsudden arrhythmia-related death), and total cardiac death were compared between the two groups. Surgical mortality was 4.4% (0% in group 1, 11% in group 2). During the follow-up of 31 +/- 27 months, actuarial survival rates free of events were 97%, 97%, and 97% in group 1 and 96%, 91%, and 82% in group 2 at 12, 24, and 36 months, respectively, for sudden death (p = NS); 97%, 97%, and 97% in group 1 and 85%, 81%, and 72% in group 2 at 12, 24, and 36 months, respectively, for sudden death and surgical mortality (p less than 0.05); 97%, 97%, and 97% in group 1 and 82%, 78%, and 70% in group 2 at 12, 24, and 36 months, respectively, for total arrhythmia-related death (p less than 0.05); and 95%, 95%, and 95% in group 1 and 82%, 69%, and 57% in group 2 at 12, 24, and 36 months, respectively, for total cardiac death (p less than 0.05). Four (57%) of seven nonsudden cardiac deaths during the initial 36-month follow-up period were causally related to arrhythmia (three surgical deaths and one arrhythmia-related nonsudden death). CONCLUSIONS: The outcome of patients treated with implantable defibrillators is strongly influenced by the degree of left ventricular dysfunction. In group 1 patients, surgical mortality, sudden death, and total cardiac death are rare. In group 2, sudden death rate may not be markedly different from that of group 1 patients. However, the risk of therapy (surgical mortality) is high. Many nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or nonsudden arrhythmia-related death). Therefore, the survival rate free of total arrhythmia-related death is significantly lower in group 2 (70% versus 97% in group 1 at 3 years). Further studies are needed to determine the roles of defibrillator therapy and other therapies in various clinical settings.

Actuarial Analysis↗
PubMed1988

Transvenous and subcutaneous electrode system for an implantable defibrillator, improved on large pigs.

The currently required surgical procedure for implantable defibrillator implantation is a limiting factor and several groups are therefore investigating transvenous approaches. Our electrode system consists of a nondistal right ventricular catheter electrode and two or three subcutaneously (SC) placed electrodes. An optimal location for these SC electrodes is important to obtain the lowest possible defibrillation threshold (DFT) by allowing a more homogeneous current distribution within the thorax. An empirical approach consists of placing randomly the SC electrodes to find out the lowest possible DFT. A mathematical approach is to calculate the SC electrode locations for an optimal electric field distribution by using magnetic resonance images of thorax cross-sections and a specially designed computer program. Our recent experimental results are based on a series of 15 pigs weighing between 60 and 102 Kg. DFT ranged between 10 and 26 joules. We conclude that an electrode system with a right ventricular electrode and two or three subcutaneous electrodes can be optimized to reach a DFT for pigs with human-near body weights which is compatible with the energy capabilities of our implantable device.

Animals↗
PubMed1991

Lateral thoracotomy for the automatic implantable defibrillator.

In 51 patients who required automatic implantable cardioverter defibrillator implantation without additional cardiac procedures, the lead system was implanted using a lateral thoracotomy approach, with complete muscle sparing in the last 24 patients. Exposure was excellent and allowed repositioning of leads for optimal defibrillation thresholds in 18 patients. Five of 19 patients who had previously undergone intrapericardial procedures required intrapericardial dissection for lead placement to provide satisfactory defibrillation thresholds. There were no intraoperative deaths or infarctions. The 30-day mortality rate of 3.9% was comparable with those in other series, and the use of muscle-sparing techniques and supplemental epidural anesthesia prevented pulmonary complications or the need for prolonged ventilatory support. We favor a muscle-sparing lateral thoracotomy incision for automatic implantable cardioverter defibrillator insertion, particularly in patients with a history of previous intrapericardial procedures.

Adult↗
PubMed1991

Differences in the pathological changes in dogs' hearts after defibrillation with extrapericardial paddles and implanted defibrillator electrodes.

A comparison was made between the pathological changes in the myocardium of eight dogs, each receiving about 90 joules of energy in a series of defibrillation discharges, delivered either between paddles placed against the pericardium (3 dogs) or between implanted Telectronics 040-105 defibrillation patch electrodes (5 dogs). The changes in the myocardium were most pronounced where the paddles had been applied to the pericardium. There was transmural damage beneath the left and right paddle positions and in the surrounding tissues. Extensive subepicardial and subendocardial myocyte damage was obvious histologically in the right ventricle of one of the patch dogs and in all of the paddle dogs. The percentage of damaged myocardial mass, both right ventricular and total involvement, was higher in the three paddle dogs compared with the five patch dogs. There was septal damage in the heart of one paddle dog. Necrosis of the right ventricular wall was observed in three of the patch dogs and in all the three paddle dogs. Scattered necrotic myocytes and some patches of mild necrosis up to 1-mm deep were observed in the left ventricle of the patch dogs (severity score 1-3). The necrosis was more extensive in the paddle dogs, ranging from mild necrosis less than 1-mm deep to marked necrosis incorporating half-to-whole ventricular wall thickness (severity score 3-5).

Animals↗