Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Defibrillators, Implantable”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,315 records · Page 73Linked to original sources
PubMed2004

[The implantable automatic defibrillator].

Technical advances in the design of implantable automatic defibrillators have been constant since the introduction of these devices in the mid 80s. The most obvious advance is the miniaturisation of the devices from which all components have benefited. The capacity of the batteries has improved inversely proportionally to their size, even if the longevity has not always lived up to expectations. The volumic energy of the condensers has improved and their technology also, and their size has decreased. Condensers are still usually made by the electrolytic/aluminium method but tantalum technology is bound to become more generalised because it presents so many advantages. Above all, the circuitry has benefited from the progress of micro-electronics, associating miniaturisation with an increase in more and more complex functions...but requiring more electrical current. Of these functions, algorithms to detect arrhythmias has reduced the number of inappropriate shocks but do not yet have excellent specificity either in single or in dual chamber sensing. Defibrillators incorporating a multisite anti-bradycardiac function are more and more popular because of the close relationship between cardiac failure and sudden death.

Algorithms↗
PubMed1992

Failure of defibrillator paddle as mimic for subcutaneous patch lead during nonthoracotomy implantable cardioverter defibrillator lead configuration assessment.

It is a common, although virtually unsubstantiated, practice to assess the efficacy of nonthoracotomy lead systems for implantable cardioverter defibrillators using a defibrillator paddle as mimic for the subcutaneous patch lead. We report a case in which an adequate defibrillation threshold was documented with the nonthoracotomy lead system using a defibrillator paddle but not following implantation of the true subcutaneous patch lead. This case suggests that the substitution of a defibrillator paddle for the subcutaneous patch lead during nonthoracotomy lead system evaluation may have significant limitations in assessing lead configuration efficacy.

Adult↗
PubMed1999

Technologic advances in implantable cardioverter defibrillators.

Multiple technologic advances in the implantable cardioverter defibrillator (ICD) have resulted in smaller size, easier implantation, and improved detection, therapy, and stored diagnostic information. Advanced dual-chamber ICDs are currently available that allow dual-chamber rate-responsive pacing with mode switching, enhanced detection algorithms, antitachycardia pacing, low-energy cardioversion, high-energy shocks, and extensive diagnostics. Based on improvements in lead systems and improved energy waveforms, almost all devices are being implanted with nonthoracotomy leads in the pectoralis area. The results of recent clinical trials have expanded indications for the ICD for primary and secondary prevention of sudden cardiac death. With advances in capacitor and battery technology coupled with improved lead systems and waveform resulting in lower defibrillation thresholds, it is likely that lower-output, smaller devices will be developed. In the future, ICDs may have expanded indications and may incorporate physiologic sensors to access hemodynamic significance of arrhythmias and algorithms for prediction and prevention of cardiac arrhythmias.

Defibrillators, Implantable↗
PubMed1990

A practical approach to teaching the automatic implantable cardioverter-defibrillator patient.

An implantable defibrillator is a surgically implanted device capable of continuously monitoring the patient's heart rhythm and automatically delivering a cardioverting or defibrillating shock to the heart. This article describes one approach to teaching the implanted defibrillator patient. Preoperative, postoperative, and discharge teaching goals and content are discussed. A case study illustrates the need for contact with the emergency medical system.

Arrhythmias, Cardiac↗
PubMed1991

Long-term community hospital experience with the internal defibrillator.

Seventy-seven patients with drug refractory ventricular tachycardia (57) and ventricular fibrillation (20) received the implantable defibrillator. There were 55 men and 22 women with a mean age of 63 +/- 10 years. The anatomical diagnoses were coronary artery disease in 61 patients, cardiomyopathy in 15 patients, and aortic stenosis in one patient. The mean ejection fraction was 32 +/- 12%. Concurrent surgery at defibrillator implantation was coronary bypass in eight patients and aortic valve replacement in one patient. There were no intraoperative mortalities. The mean ventricular fibrillation termination threshold was 13 +/- 6 joules. During a follow-up period of 16 +/- 10 months (range 2-40 months) four patients died: electrical mechanical dissociation (two patients), respiratory failure, and sepsis. Thirty-eight patients (51%) continued receiving antiarrhythmic drug therapy, with quinidine sulfate and procainamide being the most frequently utilized agents. Fifty-four patients (72%) have received a mean of 9 +/- 10 shocks (range 1-44). Implantable defibrillators are often needed in patients seen in large community hospitals. This technology can be administered successfully in this setting with complications and results comparable to those reported from university hospitals. Implantable defibrillators are effective in preventing arrhythmic death and can be used with low risk to the patients.

Anti-Arrhythmia Agents↗
PubMed1993

Implantable cardioverter defibrillator: the role of thoracoscopy.

Video techniques have been used in many centers to assist with pericardial patch placement for implantable defibrillators. Although there are some specific instances where this technique would be helpful, the success of the transvenous systems will limit the application of this approach.

Defibrillators, Implantable↗
PubMed1996

Problems in managing patients with long QT syndrome and implantable cardioverter defibrillators: a report of two cases.

Implantable cardioverter-defibrillators (ICDs) have been a successful adjunct to the management of arrhythmias in patients with Long QT syndrome (LQTS). In two patients, interactions between LQTS and the ICD were diagnosed and corrected. Oversensing of T waves was confirmed in the first, while in the second, the arrhythmia disappeared when T wave abnormalities improved after cessation of H2 blocker therapy. In patients with LQTS and an ICD, T wave oversensing should be considered. Interventions that may have an adverse effect on repolarization should be avoided.

Adrenergic beta-Antagonists↗
PubMed1988

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.

Arrhythmias, Cardiac↗
PubMed2002

A 12-month quality of life assessment of cardiac arrest survivors treated with or without an implantable cardioverter defibrillator.

BACKGROUND: Previous studies indicate that the implantable cardioverter defibrillator (ICD) has a large impact on the quality of life of patients. The effects of having an ICD over longer periods of times has been less studied. OBJECTIVE: To assess the quality of life and well-being of cardiac arrest survivors who have received an implantable cardioverter defibrillator (ICD) or other treatment. METHODS: 168 patients were monitored for 1 year and completed four questionnaires. RESULTS: No differences were found between the two treatments regarding quality of life (except for pain, ICD patients perceived less pain) and well-being. A significant improvement in physical and social function, and in mental health was found in the first 6 months. Older patients (60 years or older) perceived less improvement in their health than younger patients. Women reported having poorer social function. The prevalence of anxiety and probable depression was high irrespective of the treatment received: anxiety and depressive symptoms did not change significantly between 1 and 12 months after discharge. Patients with higher anxiety scores experienced less improvement in health and patients with more depressive symptoms experienced poorer social function. CONCLUSIONS: The prevalence of anxiety and probable depression was high in cardiac arrest survivors. Probable depression affected social function. Those patients who felt anxious experienced less health improvement. Quality of life and well-being were not affected by the type of treatment. We conclude that surviving an out-of-hospital cardiac arrest has a greater impact on patients than the treatment received.

Adult↗
PubMed1996

Impact of implant techniques on complications with current implantable cardioverter-defibrillator systems.

Implantable cardioverter-defibrillator (ICD) treatment has been in use since 1980 to prevent sudden cardiac death. The high efficacy of the original epicardial systems to terminate tachyarrhythmias was impaired by a substantial perioperative mortality and morbidity. The more "modern" transvenous ICD systems have shown a similar high efficacy in terminating ventricular tachyarrhythmias, but with a lower mortality and morbidity. As a background for discussing the impact on complications with present transvenous implantation techniques, the literature was reviewed. A large pacemaker series was used for comparison. Lead complications clearly related to design, material, or manufacture were not reviewed. The present review, covering 107 references over 40 years, gives support for the notion that in transvenously implanted ICD patients the incidence of acute and late complications related to implantation technique is now acceptable. The rate of hematomas, symptomatic thromboembolic complications, perforations, and to a certain degree infections could be improved, however. The major risk factors for implantation-related complications are discussed, and suggestions for future improvement are given.

Defibrillators, Implantable↗
PubMedDate not supplied

I-123 MIBG imaging and heart rate variability analysis to predict the need for an implantable cardioverter defibrillator.

BACKGROUND: Iodine 123 metaiodobenzylguanidine (MIBG) imaging and heart rate variability (HRV) analysis were compared in patients with an implantable cardioverter defibrillator (ICD) who did and did not receive defibrillator discharges. Although the ICD has been shown to abort potentially fatal ventricular arrhythmias, identification of patients who most benefit from this device remains difficult. As the autonomic nervous system has been implicated in the genesis of these arrhythmias, we undertook a pilot study to evaluate local myocardial sympathetic innervation with the use of I-123 MIBG myocardial imaging, as well as central autonomic tone with the use of HRV, in patients with implantable defibrillators. Test results were correlated with the occurrence of ICD discharges. METHODS AND RESULTS: Seventeen patients with previously implanted defibrillators were studied. Of these, 10 had at least 1 appropriate device discharge for ventricular tachyarrhythmias, whereas 7 had no discharge. Patients with a discharge had a significantly lower I-123 MIBG heart-mediastinal tracer uptake ratio, higher I-123 MIBG defect scores, more extensive sympathetic denervation, and significantly reduced values for several HRV parameters, particularly those in the frequency domain. When combined, the I-123 MIBG heart-mediastinal ratio and HRV 5-minute low-frequency variables were highly predictive of defibrillator discharges. All patients with a heart-mediastinal ratio lower than 1.54 and 5-minute low frequency lower than 443 ms(2) had an ICD discharge (4/4), whereas no patient with an uptake ratio greater than 1.54 and 5-minute low frequency greater than 443 ms(2) did (0/3, P =.03). CONCLUSIONS: Cardiac autonomic assessment using a combination of myocardial scintigraphic and neurophysiologic techniques may help select patients who would most benefit from an implantable defibrillator by identifying those at increased risk for potentially fatal arrhythmias.

3-Iodobenzylguanidine↗
PubMed1998

Physiologic cardiac pacing in patients with contemporary implantable cardioverter-defibrillators.

Contemporary implantable cardioverter-defibrillators (ICD) incorporate single-chamber ventricular pacing capability. However, because poor ventricular function and/or congestive heart failure is common in the ICD population, the provision of more "physiologic" pacing modes has been receiving increased attention. To evaluate the potential impact of ICDs with physiologic pacing features, we assessed the frequency with which atrial-based pacing modes with or without rate responsiveness are currently used in ICD recipients. Further, we characterized those clinical variables at initial ICD implant that tended to be associated with subsequent need for physiologic pacing. Clinical findings were reviewed in 250 consecutive patients who received ICDs with VVI pacing capability at the University of Minnesota Cardiac Arrhythmia Center between January 1991 and February 1997. Adjunctive physiologic pacing was undertaken in 35 patients (14%): 13 before or at the same time as their ICD, and 22 within a mean of 2.5 years after initial ICD surgery. A history of atrial tachyarrhythmia before ICD implantation (p <0.0001) and treatment with antiarrhythmic drugs at the time of ICD surgery (p <0.05) were predictors of subsequent need for physiologic pacing. The type of presenting ventricular tachyarrhythmia and electrophysiologic parameters (such as the HV interval and the shortest atrial pacing cycle length associated with 1:1 anterograde atrioventricular conduction) were not associated with a subsequent decision to implant a physiologic pacing system. Thus, we conclude that despite the need to implant a second device, physiologic pacing is currently used in an important subset of ICD recipients. Further, certain clinical features at time of ICD implant appear to characterize these patients and may prove helpful in patient selection for the next generation "dual-chamber" ICD.

Adolescent↗
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↗
PubMed2002

Advanced rhythm discrimination for implantable cardioverter defibrillators using electrogram vector timing and correlation.

INTRODUCTION: Discrimination of ventricular and supraventricular arrhythmias remains one of the major challenges for appropriate implantable defibrillator (ICD) therapy delivery. The electrogram vector timing and correlation (VTC) algorithm was developed for such rhythm discrimination. The VTC algorithm differentiates normally conducted supraventricular beats from abnormally conducted ventricular beats by comparing the timing and correlation of rate and shock channel electrograms. METHODS AND RESULTS: Rate and shock channel electrograms of sinus rhythm and induced arrhythmias were collected from 93 patients during ICD placement. The algorithm was developed using data from 50 patients and prospectively tested in a software model with the remaining 43 patients. A sinus rhythm reference was formed by averaging complexes of the shock channel signal aligned by the peak amplitude of the rate channel. Eight features measuring the amplitude and timing of shock channel signal characteristics were extracted from the reference for comparison. When a high-rate rhythm was detected, the VTC algorithm computed the correlation of the arrhythmia complex features with the reference. Rhythms with a sufficient number of uncorrelated beats were classified as ventricular tachycardia (VT). In a dual-chamber implementation, the VTC algorithm is integrated with ventricular and atrial rate comparison (V>A) and stability above an atrial fibrillation rate threshold. The test set consisted of 117 arrhythmias. Dual-chamber sensitivity was 100% (81/81 VT) and specificity was 97% (35/36 supraventricular tachycardia). Single-chamber analysis demonstrated 99% sensitivity and 97% specificity. CONCLUSION: The VTC algorithm demonstrated high sensitivity and specificity in discriminating between ventricular and supraventricular arrhythmias.

Aged↗
PubMed1990

Revised implantation procedure for programmable automatic implantable cardioverter defibrillator: don't discard the magnet.

The newest implantable defibrillator (Ventak 1550 AICD) introduces radiofrequency telemetric communication that obviates the need for activation and deactivation of the device by a magnet during implantation. We present three of our first ten cases of implantation in which difficulties in intraoperative sensing would have been undetected without use of the magnet for audible evaluation of sensing. Based on this experience, we recommend a revised implantation protocol in which audible confirmation of sensing for 30 to 60 seconds by means of a sterile magnet is performed twice (with a pacemaker, if present in DOO or VOO mode): at the time of system test before induction of arrhythmia with testing cables connected to permit recording of rate, morphology, and ECG interpretation channel signals; and after final connection of the leads to the AICD. This simple additional maneuver is a powerful troubleshooting tool during implantation that permits prompt identification of sensing problems.

Adult↗
PubMed2006

Recent primary prevention implantable cardioverter defibrillator trials.

PURPOSE OF THE REVIEW: The aim of this article is to summarize the most relevant findings of recently published trials on prophylactic implantable cardioverter defibrillator therapy. RECENT FINDINGS: A number of important randomized clinical trials on the efficacy of prophylactic implantable cardioverter defibrillator therapy in patients deemed to be at high risk for ventricular tachyarrhythmias have recently reported their results. Patients with chronic ischemic cardiomyopathy, a long history of heart failure, and an ejection fraction of 0.30 or below benefit from preventive device therapy and are thus candidates for prophylactic defibrillator implantation. For this purpose, a single chamber device appears to be appropriate since there have been no prospective studies showing convincing clinical benefit by adding an atrial lead. Prophylactic implantable cardioverter defibrillator therapy should not be used in patients with recent myocardial infarction. There is convincing evidence from one trial that benefit from the defibrillator in coronary patients accrue after a considerable time has elapsed from the most recent infarct, presumably at least 6 months or perhaps longer. Finally, in patients with chronic dilated non-ischemic cardiomyopathy and a left ventricular ejection fraction of 0.35 or below, there is also benefit from prophylactic implantable cardioverter defibrillator therapy. SUMMARY: Taken together, these trials allow an evidence-based approach to primary prevention of sudden cardiac death in patients with both ischemic and non-ischemic cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed2003

Implantable cardioverter defibrillator events in patients with asymptomatic nonsustained ventricular tachycardia: is device implantation justified?

Primary prevention trials have demonstrated that patients with coronary disease, reduced left ventricular function, and nonsustained ventricular tachycardia (NSVT) have improved survival with implantable cardioverter defibrillator (ICD) therapy, presumably secondary to effective termination of life-threatening arrhythmias. However, stored intracardiac electrograms were not always available and specific arrhythmias leading to ICD therapy were not always known. We examined the occurrence of ICD events in 51 consecutive patients who match the described patient profile to determine the frequency of appropriate and inappropriate ICD therapy. ICD detections were noted in 18 (35%) patients during a median follow-up period of 13.1 months. Appropriate therapy for sustained ventricular tachycardia (VT)/ventricular fibrillation (VF) occurred in 11 (22%) patients, with appropriate shocks in 8 (16%) patients and appropriate antitachycardia pacing (ATP) in 4 (8%) patients. The time to first appropriate therapy occurred at a mean of 17 +/- 12 months (median 18 months, range 3-36 months). Inappropriate therapy occurred in 5 (10%) patients with inappropriate shocks in 4 patients and inappropriate ATP in 2 patients. Inappropriate therapy was delivered for supraventricular arrhythmias (SVAs) in 4 patients and for T wave oversensing in 1 patient. The reason for shock therapy was unknown in 1 patient (2%) due to ICD malfunction. The mean arrhythmia rate leading to appropriate therapy for VT/VF was 232 +/- 72 beats/min (range 181-400 beats/min), and the mean rate leading to inappropriate therapy for SVT was 168 +/- 10 beats/min (range 160-180 beats/min). Patients with coronary disease and asymptomatic NSVT commonly receive appropriate defibrillator therapy. These results support the need for ICD implantation for primary prevention, with attention to careful programming of the detection rate to prevent inappropriate therapy.

Aged↗
PubMed1992

Tachycardia sensing failure of an implantable cardioverter defibrillator in a patient with hypertrophic cardiomyopathy.

A 17-year-old white male was found to have nonobstructive hypertrophic cardiomyopathy after suffering three severe syncopal episodes. He experienced an episode of sustained polymorphic ventricular tachycardia during exercise tolerance testing that required cardioversion. Electrophysiological studies were able to reproduce sustained polymorphic ventricular tachycardia that was unresponsive to standard pharmacotherapy. An automatic implantable defibrillator was placed. However, during implantation with the rate sensing electrodes on the left ventricle, it was found that the extremely polymorphic nature of the tachycardia caused such rapid fluctuations in the sensed R wave signal that the device could not properly detect the tachycardia. This was felt to be due to the automatic gain control circuit of the Ventak 1550. The problem was solved by moving the rate sensing electrodes to the lateral right ventricle. This case suggests that the unique arrhythmic substrate of hypertrophic cardiomyopathy may present sensing difficulties during automatic implantable defibrillator insertion.

Adolescent↗