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 523 records · Page 29Linked to original sources
PubMed2001

The natural history of recovery following sudden cardiac arrest and internal cardioverter-defibrillator implantation.

The purposes of this review are to 1) summarize current knowledge regarding the "natural history of recovery" (physical functioning, psychological adjustment, and neurologic impairments) following sudden cardiac arrest and internal cardioverter-defibrillator implantation over the first year; and 2) discuss the implications for the development of nursing intervention programs based on the natural history of recovery. The natural history serves as a basis for understanding the recovery experiences of sudden cardiac arrest survivors as well as determining how intervention programs might help the most.

Activities of Daily Living↗
PubMed2005

Cost-effectiveness of implanted defibrillators in young people with inherited cardiac arrhythmias.

BACKGROUND: The implanted cardioverter-defibrillator (ICD) has been shown to improve survival in adult patients with high risk acquired cardiac disease, with a cost-effectiveness ratio in the range of $30,000 to $185,000 per quality-adjusted-life-year saved. However, data on the benefit and cost-effectiveness of device therapy in high-risk patients with inherited cardiac disorders are limited. METHODS: We developed two separate computer-based analytical models to compare non-ICD with ICD therapy in patients (age range: 10-75 years) with long QT syndrome (LQTS) and hypertrophic cardiomyopathy (HCM). In each disease entity patients were stratified into low-risk (no known risk factors); high-risk (known risk factors [primary prevention]); and very high-risk (prior near-fatal events [secondary prevention]). Net costs were defined as the difference between costs resulting from treatment of the disease and savings due to gained productivity attributable to prevention of sudden cardiac death. Outcome was defined as costs per quality-adjusted life-years saved. RESULTS: In LQTS, defibrillator therapy was shown to be cost effective in high-risk male patients (incremental cost-effectiveness ratio [ICER]=$3328 per quality-adjusted-life-year saved), and cost saving in high-risk females (ICER=$7102 gained per quality-adjusted-life-year saved) and very high-risk males and females (ICER=$15,483 and 19,393 gained per quality-adjusted-life-year saved, respectively). In HCM, defibrillator therapy was cost saving in both male and female high-risk (ICER=$17,892 and $17,526 gained per quality-adjusted-life-year saved, respectively) and very high-risk (ICER $22,944 and $22,329 gained per quality-adjusted-life-year saved, respectively) patients. Defibrillator therapy was not shown to be cost effective in low-risk patients with either LQTS or HCM (ICER in the range of $400,000 to $600,000 lost per quality-adjusted-life-year saved). Sensitivity analyses were consistent with the results in each risk group. CONCLUSIONS: In appropriately selected patients with inherited cardiac disorders, early intervention with ICD therapy is cost-effective to cost saving due to added years of gained productivity when the lifespan of an individual at risk is considered.

Arrhythmias, Cardiac↗
PubMed1995

Position of epicardial patch electrodes for implantable defibrillation significantly affects shock strength requirements.

OBJECTIVE: To assess the impact of epicardial patch electrode position on internal defibrillation efficacy. METHODS: Two mesh patch electrodes (13 cm2) were positioned on the epicardium of acute, isoflurane-anesthetized pigs (n = 7, 40-47 kg). Defibrillation efficacy was determined for three different patch positions: P1 = anterior-basal right ventricle (RV) and lateral-apical left ventricle (LV); P2 = lateral RV and lateral LV; and P3 = anterior-basal septal region and posterior-apical septal region. To quantify defibrillation efficacy, single capacitor discharge, fixed-tilt (68%) biphasic waveforms were delivered to the heart 10 seconds after initiation of ventricular fibrillation. Initial shock intensities were selected using an up/down protocol. Conversion data were used to construct sigmoidal curves relating probability of defibrillation to energy delivered, peak voltage, and peak current in each animal. RESULTS: Mean peak voltage and current at 50% defibrillation probability were 40% higher for P2 than they were for either P1 or P3 (p < 0.05). Similarly, mean energy delivered was 75% higher for P2. In this pig model, position of epicardial patch electrodes affects defibrillation efficacy. CONCLUSION: Apical-to-basal shock vectors (P1 and P3) yielded significantly lower defibrillation shock strength requirements than did a lateral-wall-to-lateral-wall vector (P2), which was perpendicular to the intraventricular septum. These data may help explain the disparity in defibrillation thresholds observed in the human population of patients undergoing implantable cardioverter defibrillator testing with epicardial patch electrodes.

Animals↗
PubMedDate not supplied

Electrode system for permanent implantable defibrillators: transvenous catheter and subcutaneous plate electrodes.

The permanently implanted automatic defibrillator offers an alternative treatment for heart patients with high risk of ventricular fibrillation, who cannot be safely treated by surgery or drugs. Because of size and energy requirements, permanently implanted automatic defibrillators are not presently practical for many of these patinets, and sudden death from ventricular fibrillation remains a majof health problem. This study, which determines the optimal electrode configuration of the transvenous catheter when used in conjunction with a subcutaneous plate or disk electrode for transvenous ventricular defibrillation, attempts one of many changes needed to improve the defibrillator's efficiency so that it will be a viable alternative treatment for delicate heart patients.

Animals↗
PubMed1999

Implantable defibrillators and antiarrhythmic drugs in patients at risk for lethal arrhythmias.

The high mortality rate and frequency of ventricular arrhythmias in patients with congestive heart failure has prompted numerous clinical trials aimed at reducing mortality by addressing arrhythmic death. Recently completed trials have suggested that for patients who have survived cardiac arrest, the preferred treatment may be an implantable cardioverter defibrillator (ICD). From the standpoint of primary prevention, implantable defibrillators and amiodarone have received the most attention. It remains unclear, however, to which patients these studies apply, and if and how the results might be generalized. No available studies confirm an additional benefit of pharmacologic or device-based antiarrhythmic therapy beyond that offered by optimal treatment with beta blockers, angiotensin-converting enzyme inhibitors, and lipid-lowering drugs in the majority of patients with cardiomyopathy. Clinical trials are ongoing to address these issues.

Amiodarone↗
PubMed1997

[The absence of interference between GSM mobile telephones and implantable defibrillators: an in-vivo study. Groupe Systèmes Mobiles].

INTRODUCTION AND OBJECTIVES: The electromagnetic field created by mobile telephones can cause pacemaker dysfunction. Although implantable cardioverter defibrillators are also susceptible to electromagnetic interference, few studies have addressed this issue and compatibility with the GSM mode has not been tested. This study was developed to detect possible "in vivo" interference between GSM mobile telephones and implantable cardioverter defibrillators. MATERIAL AND METHODS: The study group is composed of 30 patients with 8 different models of defibrillators. Twenty six had endocardial leads and 4 epicardial. Three GSM mobile phones were used: Siemens S3 COM and Motorola 6200 in all cases and Ericsson GA 318 in one. The tests were performed under continuous electrocardiographic monitoring. All therapies were deactivated and sensitivities were set to maximal parameters. The telephones were positioned in close contact to the defibrillator can and precordium, in two different angles. Three situations were evaluated: calling, established contact for 15 seconds and ringing. The protocol was repeated during pacing to assess the possibility of pacemaker mode inhibition. RESULTS: No cases of electromagnetic interference were observed. One patient presented non-sustained ventricular tachycardia episodes during the tests that were detected by the defibrillator. CONCLUSIONS: These results suggest that electromagnetic interference by GSM mobile phones are not a probable cause of implantable defibrillators dysfunction.

Defibrillators, Implantable↗
PubMed2003

Atrial pacing therapies for prevention of atrial fibrillation in patients with implantable defibrillators.

Atrial fibrillation (AF), atrial flutter and atrial tachycardia (AT) occur frequently in patients following implantation of an implantable cardioverter defibrillator (ICD) for the treatment of ventricular tachyarrhythmias. Some new generation ICDs have incorporated atrial antitachycardia pacing therapy (ATP) and atrial pacing algorithms designed specifically for the prevention of AF. In the GEM III AT clinical evaluation, atrial ATP efficacy for termination of AF and AT was assessed. Overall ATP efficacy for AF/AT, based on device classification, was 40% when adjusted using the Generalized Estimating Equations to account for correlated data that arises from utilizing multiple episodes in some patients. However, many episodes of AF/AT were noted to terminate within 10 minutes of onset. Applying a more conservative definition of efficacy, termination within 20 sec of delivery of the last atrial ATP, efficacy for termination of AF/AT was 26%. 50 Hz burst pacing was shown to have minimal efficacy for termination of AF and modest incremental benefit following ramp or burst pacing therapies for AT. These observations provide a more realistic expectation of the value of atrial ATP in the ICD population with AF. Atrial ATP terminates some episodes of AT but previously reported efficacy rates of 40-50% are exaggerated and in part reflect spontaneous terminations of some AF/AT episodes.

Algorithms↗
PubMed1992

Radiofrequency catheter ablation of the AV node to improve the function of an antitachycardia implantable defibrillator.

A case of coexisting atrial fibrillation and ventricular tachycardia in a patient with an implantable cardioverter defibrillator is described. Despite careful reprogramming, the device was not always able to distinguish between the two arrhythmias and continued to deliver inappropriate antitachycardia therapy including DC shocks. Attempts to pharmacologically control the atrial fibrillation were unsuccessful so radiofrequency ablation of the atrioventricular node was performed. Following successful ablation, there have been no further false detections no episodes of further ventricular tachycardia.

Aged↗
PubMed2006

Incidence and causes of inappropriate detection and therapy by implantable defibrillators of cardioversion in patients with ventricular tachyarrhythmia.

BACKGROUND: Implantable cardioverter defibrillator (ICD) is the only effective therapy in patients with life threatening ventricular arrhythmias. Inappropriate detection and therapy by ICDs are the most common causes of side effects that affect the quality of life in ICD recipients. This study evaluated the incidence and causes of inappropriate detection and therapy by ICDs in patients in our hospital. METHODS: From January 2000 to December 2005, fifty patients who received ICD implantation for ventricular arrhythmias for prevention of sudden cardiac death were evaluated in this study. Each ICD was programmed using clinical arrhythmic and cardiac data of the patient before discharge. Patients were followed up by standard schedule after implantation and all data retrieved from each device were collected and saved for further analysis. RESULTS: No arrhythmic event was detected in 12/50 (24%) patients during the period of follow-up. Among the remaining patients, 11 (22%) experienced inappropriate detections and therapies during follow-up in this study. ICD detected 383 ventricular tachyarrhythmia (VT) and 108 ventricular fibrillation (VF) episodes and delivered 678 therapies. In VT group, ICD delivered 413 antitachycardiac pacings (ATPs) and 118 shocks, among which 78 ATPs and 9 shocks were initiated by 55/383 (14.3%) inappropriate detections. In VF group ICD delivered 147 shocks, among which 56 shocks were initiated by 28/108 (26.9%) inappropriate detections. Overall, more than 50% of these episodes were caused by atrial fibrillation (AF) with rapid ventricular response, followed by electromagnetic or myopotential interference. In addition, most inappropriate therapies occurred within one year after ICD implantation. CONCLUSIONS: About one fifth of patients experienced ICD inappropriate detection and therapy after implantation. The main cause was AF with rapid ventricular response, followed by electromagnetic or myopotential interference.

Adult↗
PubMed2006

Is implantable defibrillator indicated in all patients on cardiac resynchronization therapy?

Implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) have been introduced during the recent years to improve survival, decrease hospital readmissions and mortality, and to improve functional status and quality of life for patients with heart failure and left ventricular systolic dysfunction (LVSD). Studies which evaluated the use of CRT or ICD alone or compared CRT with CRT-ICD in patients with heart failure and LVSD are listed in this article. The results obtained are already influencing clinical practice in the US, where it has been estimated that 90% of patients receiving a CRT device now are being implanted with an ICD component. However, it is still today debated whether patients with LVSD and heart failure should be routinely offered a CRT-ICD. In fact, there are some issues that still should be solved before to establish indication for CRT-D in all heart failure patients with an indication for CRT: 1) a non complete agreement among the different societies which wrote recommendations for guidelines (a comparative table is reported); 2) a better identification of implantable patients and an amelioration of utilized devices; 3) economic and ethical ramifications of this therapy. Anyway still now the crucial question is: ''Can resynchronization be done in isolation or must be accompanied by an ICD device?''. To answer to this question we can only express which is, in our opinion, the actual position of many physicians who work in the field of pacing and electrophysiology: ''The lesson to be learned is that we still can not predict surely which patient will die of sudden death. Until a method of identifying the high risk patients can be developed, the safest strategy should be to advise a combined ICD-CRT device for patients with indication for CRT''.

Cardiac Pacing, Artificial↗
PubMed2003

Are lipid-lowering drugs also antiarrhythmic drugs? An analysis of the Antiarrhythmics versus Implantable Defibrillators (AVID) trial.

OBJECTIVES: This study sought to evaluate the antiarrhythmic effects of lipid-lowering drug therapy as assessed by ventricular tachyarrhythmia (ventricular tachycardia [VT]/ventricular fibrillation [VF]) recurrences recorded by an implantable cardioverter defibrillator (ICD) in patients with atherosclerotic heart disease (ASHD). BACKGROUND: Randomized trials of lipid-lowering drugs suggest reduction of sudden death (SD) in patients with ASHD. Because SD is usually secondary to VT/VF, this observation suggests that lipid-lowering therapy has antiarrhythmic effects. METHODS: The probability of VT/VF recurrence in patients with ASHD treated with an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial who did not receive lipid-lowering drug therapy (n = 279) was compared with that in patients who received early and consistent lipid-lowering therapy (n = 83). In addition, all-cause mortality and cardiac mortality of all patients in the AVID trial with ASHD who did not receive lipid-lowering therapy (n = 564) were compared with that of those who received early and consistent lipid-lowering therapy (n = 149). RESULTS: Using multivariate analyses, lipid-lowering therapy was associated with a reduction in the relative hazard for VT/VF recurrence of 0.40 (95% confidence interval [CI] 0.15 to 0.58) (adjusted p = 0.003) in the ICD subgroup. Lipid-lowering therapy was also associated with a reduction in the relative hazard for all-cause mortality of 0.36 (95% CI 0.15 to 0.68) (adjusted p = 0.03) and a reduction in the relative hazard for cardiac mortality of 0.39 (95% CI 0.16 to 0.78) (adjusted p = 0.04) in the larger study population. CONCLUSIONS: In patients with ASHD who have received an ICD, lipid-lowering therapy is associated with reduction in the probability of VT/VF recurrence, suggesting that part of the benefit of lipid-lowering therapy may be due to an antiarrhythmic effect.

Aged↗
PubMed1985

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.

Death, Sudden↗
PubMed2001

[Ventricular arrhythmias induced by appropriate antibradycardia pacing in patients with implantable defibrillators].

INTRODUCTION AND OBJECTIVES: The induction of ventricular arrhythmias by appropriate antibradycardia ventricular pacing in patients with implantable cardioverter defibrillators has been reported in only a few cases. The aim of this study was to assess the incidence, characteristics and management of these episodes. METHODS: The follow-up records of 180 patients with implantable cardioverter defibrillators with intracardiac electrogram storage were reviewed. Pacing induced episodes were defined as those occurring immediately after an appropriate paced stimulus in a patient with sporadic paced beats. We assessed the number and type of episodes, mode of onset, therapy administered and the efficacy of different prevention measures. RESULTS: Pacing induced episodes were found in 9 patients (5%). Seven received device administered therapy which was effective in all cases. One to 95 episodes were observed per patient, of which 138 were monomorphic ventricular tachycardias and 20 polymorphic ventricular tachycardia/ventricular fibrillation episodes. All were induced by a paced ventricular beat after a post-extrasystolic pause or after long RR intervals during atrial fibrillation. Pacing induced arrhythmias were prevented by changing the pacing rate or hysteresis in 3 out of 6 patients and by decreasing the stimulus energy in 3 out of 3. Antibradycardia pacing function was disabled in 4 patients. CONCLUSIONS: Ventricular arrhythmias induced by appropriate antibradycardia ventricular pacing are relatively common in patients with implantable cardioverter defibrillators. Effective prevention can be achieved in most cases by changing the pacing rate or the pacing stimulus energy, however in selected cases the antibradycardia function may be disabled.

Aged↗
PubMed1995

A new transvenous internal cardioverter-defibrillator: implantation technique, complications, and short-term follow-up.

Twenty-four patients with ventricular fibrillation or sustained ventricular tachycardia underwent implantation of a new transvenous defibrillator. All patients had a device implanted without thoracotomy. High placement of a shock lead in the anonymous vein and inversion of the shock-wave polarity allowed avoidance of placement of subcutaneous patches. Implantation time decreased from 138 minutes for the first 12 patients to 82 minutes for the last 12 patients, with 4 and 11 subpectoral pockets, respectively. Three patients required a minor reintervention. No bleeding or infection occurred. One episode of pulmonary edema and one pulmonary embolism were seen in the postoperative course. No postoperative deaths were observed. During a mean follow-up period of 4.12 months, 58% of the 24 patients had symptomatic arrhythmic episodes, with shocks in 50% of the 24. Inappropriate shocks were delivered in three cases (atrial fibrillation and T-wave sensing). One episode was not terminated even with four internal shocks. One patient had ventricular fibrillation because of a sensing problem. By reprogramming of sensitivity, back-up pacing, and adjustment of drug therapy these arrhythmic complications could be prevented. Pectoral implantation of a cardioverter-defibrillator is easy and can be performed by cardiologists experienced in pacemaker implantation. Careful postoperative observation, reprogramming after the first spontaneous event, and prehospital discharge induction of ventricular fibrillation will prevent arrhythmic complications.

Adult↗
PubMed1993

Interference from a hand held radiofrequency remote control causing discharge of an implantable defibrillator.

A 46-year-old man with a history of sustained monomorphic ventricular tachycardia underwent an implantation of a third generation multiprogrammable implantable cardioverter defibrillator. One year post implant, while manipulating a remote control to a radiofrequency modulated toy car, the patient experienced a defibrillator discharge not preceded by an arrhythmia prodrome. Subsequent interrogation of the defibrillator revealed that a 34-joule shock had been delivered and had been preceded by RR intervals ranging from 141-406 msec, consistent with sensing lead noise. The remote control utilizes a 12-volt battery and has a carrier frequency of 75.95 MHz and a modulating frequency of 50 Hz. Evaluation of the remote control and defibrillator interaction revealed that the remote control was able to trigger tachyarrhythmia sensing and reproduce the clinical episode. Interference was present only when the remote control was within 8 cm of the pulse generator and at specific angles relative to the device and only when the antenna length was > 45 cm. Interference was eliminated when a ground wire was attached to the antenna and when an aluminium shield was placed between the pulse generator and the remote control. This case report suggests that patients with third generation multiprogrammable defibrillators should be cautioned against close contact with potential sources of electromagnetic interference, such as remote control units.

Artifacts↗
PubMed2005

[Is an electrophysiological study always necessary before defibrillator implantation?].

An electrophysiological study (EPS) and a programmed ventricular stimulation (PVS) are strongly recommended and clearly indicated before the implantation of a cardioverter defibrillator (ICD), if patients present with a cardiac arrest and no structural heart disease or a hypertrophic cardiomyopathy. In these patients the prevalence of a curable cause of the cardiac arrest, such as accessory pathways or an idiopathic ventricular tachycardia (VT), is high and the ICD implantation may be avoided. The same is true for patients who present with a cardiac arrest and a short PQ interval or a delta wave. If patients present with wide-complex tachycardias and the diagnosis of VT is unclear, an EPS and PVS are also clearly indicated. If patients have syncope or nonsustained VTs and a structural heart disease, PVS may be used for risk stratification. However, EPS and PVS may be of little use in patients with a structural heart disease and an impaired left ventricular function after a survived cardiac arrest or an unstable VT, which makes them candidates for ICD implantation anyway.

Death, Sudden, Cardiac↗
PubMed2005

Electrical storm is an independent predictor of adverse long-term outcome in the era of implantable defibrillator therapy.

AIMS: Electrical storm (ES) is a life-threatening arrhythmia complication affecting patients treated with an implantable cardioverter defibrillator (ICD). Despite its increasing importance, existing data on prognosis and management of ICD patients affected by ES are limited and conflicting. METHODS: We prospectively studied 169 consecutive patients receiving an ICD. Thirty-two patients presented with at least one episode of ES during the period of observation (33+/-26 months). ES patients were older (64+/-9 vs. 59+/-13 years, P=0.013) with more advanced congestive heart failure (CHF) but a similar incidence of an underlying organic heart disease. RESULTS: Long-term total and cardiac mortality were both increased among ES patients. Seventeen of the 32 ES patients died as opposed to 19 of the 137 ICD patients without ES (53 vs. 14%, P<0.001). In multivariate Cox regression analysis adjusted for the main confounders, history of ES was significantly and independently associated with total and cardiac mortality (risk ratio (RR)=2.13, P=0.031 and RR=2.59, P=0.019, respectively). CONCLUSION: ES is a relatively frequent complication affecting ICD patients treated for secondary prevention of sudden cardiac death (SCD). Although the acute management of this serious arrhythmia complication is usually successful, occurrence of ES is a strong independent predictor of poor outcome in ICD patients.

Aged↗