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 811 records · Page 45Linked to original sources
PubMed2005

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

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

Aged↗
PubMed2006

Effect of defibrillation testing on management during implantable cardioverter-defibrillator implantation.

BACKGROUND: Verification of defibrillation efficacy by defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator implantation is the current standard. Generally, defibrillation of ventricular fibrillation at 10 J below the maximum output of a device is felt to establish an adequate safety margin. Nonetheless, DFT testing adds to cost and carries some potential for morbidity, whereas its impact on outcomes in the modern era of defibrillator technology is unclear. We aimed to determine the frequency that DFT testing resulted in a change at device implant and to identify clinical and echocardiographic predictors of the need for DFT testing. METHODS: We reviewed all implantable cardioverter-defibrillators that were implanted at the London Health Sciences Centre (Ontario, Canada) from June 1999 to August 2003 and used multivariate analysis to determine variables associated with DFT test failures and elevated DFT values. When a defibrillation failure was not observed, a lowest energy to defibrillate (LED) was recorded. RESULTS: Among 168 implants, DFT testing was successful with a minimum 10-J safety margin in 152 (90%), whereas the remaining 16 required changes at device implant. In a multivariate analysis, use of amiodarone was independently associated with DFT failure (odds ratio, 4.6; 95% confidence interval, 1.2-17.0). Significantly higher mean DFT/LED values were observed among patients on amiodarone (1.36 J; P = .0041). Those with nonischemic cardiomyopathy had a higher mean DFT/LED compared with those with ischemic cardiomyopathy (1.44 J; P = .028). CONCLUSIONS: Use of amiodarone is associated with a 4-fold increase in risk of DFT failure and subsequent need for changes at implant to achieve a safe threshold. Defibrillation threshold testing appears to be most useful for patients taking amiodarone.

Amiodarone↗
PubMed1994

Clinical experience with the implantable cardioverter defibrillator.

The implantable cardioverter defibrillator has played an increasingly greater role in the management of episodes of sudden cardiac-related death related to ventricular tachycardia or ventricular fibrillation. This study reviews the cases of 142 patients who underwent insertion of an implantable cardioverter defibrillator, 104 who received a device alone (group I) and 38 who underwent insertion of the device in combination with other cardiac surgical procedures (group II). The overall operative mortality was 3.5% and this did not differ between the two groups. The complication rate was higher for group II than for group I patients, and consisted primarily of an increased incidence of atrial arrhythmias (53% versus 13%; p < 0.001). Late complications included three device infections requiring removal of the defibrillator. The late mortality did not differ between the two groups and was primarily related to congestive heart failure. Sudden cardiac-related death was an uncommon late event, with an actuarial freedom from sudden cardiac-related death of 98%, 97%, and 87% at 1, 2, and 5 years, respectively. The morbidity and mortality rate are low in association with the insertion of an implantable cardioverter defibrillator, even when this is combined with other cardiac surgical procedures. Its insertion is also associated with a low subsequent rate of sudden cardiac-related death.

Adult↗
PubMed2006

The role of remote monitoring in the reduction of inappropriate implantable cardioverter defibrillator therapies.

Implantable cardioverter defibrillators (ICDs) with the integrated Home Monitoring feature use dedicated mobile phone and internet links to provide the physicians and technicians in the ICD clinic with the essential device- and arrhythmia-related data stored in the ICD diagnostic memory. Various counters, graphs and intracardiac electrograms are automatically transmitted via Home Monitoring each day to allow prompt, remote presentation of arrhythmias or detection of technical problems. One of the most inconvenient side-effects of the ICD therapy is inappropriate intervention of the device. Home Monitoring data can help the physician to identify and subsequently reduce the incidence of inappropriate ICD therapy.

Arrhythmias, Cardiac↗
PubMed2004

T wave oversensing in implantable cardioverter defibrillators.

The implantable cardioverter defibrillator is the treatment of choice for patients with ventricular tachycardia, especially in the setting of structural heart disease, but inappropriate therapy continues to be a problem. In this report we describe a short case series of patients who presented with T wave oversensing. We propose a classification in 2 categories, T wave oversensing occuring in the setting of persistently low R wave amplitude, and T wave oversensing occuring in the setting of transiently low R wave amplitude.

Adult↗
PubMedDate not supplied

Psychological disturbances, adjustment, and the development of phantom shocks in patients with an implantable cardioverter defibrillator.

The implantable cardioverter defibrillator (ICD), approved for use in 1985, is used to treat potentially lethal ventricular arrhythmias by delivering an electrical impulse to the heart to convert the rhythm back to normal. Since that time, newer studies, such as MADIT II and SCD-HeFT, demonstrated the expanding utility of the ICD, which increases the likelihood of every clinician encountering a patient with an ICD. Patients with an ICD face psychological, physical, and social adjustments. Patients with an ICD, in general, have been shown to have high levels of anxiety, depression, and a sense of helplessness. A subset experiences a phenomenon of phantom shock, which may represent a manifestation of anxiety, depression, or other emotional disturbance. It is important to be aware of this phenomenon, as a phantom shock may either represent or contribute to the patient's maladjustment to the ICD. In lieu of specific screening and treatment options for phantom shock at present, we must use a general approach for recognizing patients experiencing this phenomenon.

Adjustment Disorders↗
PubMed1999

A fuzzy logic-controlled classifier for use in implantable cardioverter defibrillators.

PURPOSE: Implantable cardioverters defibrillators (ICDs) are increasingly used in the management of life-threatening arrhythmias. Correct recognition of a treatable arrhythmia is crucial to this application. However, the computational power of microprocessors currently used in ICDs limits the range of traditional algorithms available for this application. METHODS: Classification based on fuzzy inference systems (FIS) were trained to recognize different cardiac rhythms (AF, VF, SVT, VT) from the Ann Arbor Electrogram Library. The FIS used were designed using adaptive-network-based fuzzy inference methods to optimize the classification procedure. Only computational techniques suitable for ICD design were used. RESULTS: After pretraining with the ANFIS correct rhythm classification was observed for the rhythms studied. CONCLUSION: In this preliminary study, successful rhythm classification was demonstrated using fuzzy logic techniques. In view of the computational efficiency this may have application in ICD design.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Right atrial perforation secondary to implantable cardioverter defibrillator insertion.

Implantable cardioverter defibrillator (ICD) placements can be associated with serious complications. This paper reports a patient in whom percutaneous placement of an ICD resulted in a hemopneumothorax. This was due to an active fixation lead that perforated the right atrial wall and injured the adjacent lung parenchyma. The hemothorax was drained thoracoscopically, and the atrial injury was covered with fibrin glue.

Adult↗
PubMedDate not supplied

Evidence-based medicine and policy: the case of the implantable cardioverter defibrillator.

The implantable cardioverter defibrillator (ICD) is a costly new treatment for patients at high risk of sudden cardiac death. Randomized trials of the ICD showed it to be effective in some groups of patients but not in others. While new trials testing the ICD were ongoing to clarify the evidence, policymakers faced immediate decisions about providing insurance coverage for the device. The high cost of ICDs, the large population of patients potentially eligible to receive them, the potential to reduce preventable deaths, and the unsettled state of the medical evidence provided a challenge to evidence-based medicine and to policymakers.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed2003

[Psychiatric complication of an implanted automatic defibrillator].

The implantable automatic defibrillator has completely changed the prognosis of potentially fatal ventricular arrhythmias by the delivery of an electric shock in the event of ventricular tachycardia or fibrillation. This vital device is sometimes poorly accepted from the psychological point of view by patients having been traumatised by experiences of sudden death from which they have been rescuscitated. Anxiety and depression are common and they have an important effect on the quality of life. The unpredictable occurrence of painful, multiple and uncontrollable electrical shocks may induce a state of acute stress with stunning, the resemblance of which to the model of learned helplessness described experimentally in the animal by Seligman, is discussed. The authors report the case of a 20 year old man whose automatic defibrillator was activated twenty times in one night. His state of stress and impotence was such that he lay prostate in his bed. Suicide seemed to be the only possible way of escaping from the electrical shocks of the device which was perceived as being dangerous. The management of this condition is not standardised but it requires the collaboration of the cardiac rhythmological and psychiatric teams. Medication with antidepressant drugs alone is not sufficient. The regulation of the sensitivity of the defibrillator gives the patient a feeling of mastering the situation: submission is not total! Research along this line should improve the patients' acceptation of the device and their quality of life.

Adolescent↗
PubMed1997

[The current status of implantable automatic defibrillators].

The implantable cardioverter defibrillator has become an important therapy for patients with sustained or life threatening ventricular arrhythmias. Although the concept for the implantable cardioverter defibrillator originated in the late 1960s, the first device was implanted in humans in 1980. Since then, the technology has improved rapidly the design, function and reliability of the devices have been greatly modified. There are currently five companies dealing with defibrillators in Spain incorporating multiple options in defibrillation, pacing and sensing capabilities. New devices with atrioventricular pacing and atrial defibrillation possibilities will soon become available. The purpose of this article is to review the principal functions of implantable cardioverter defibrillators currently available.

Arrhythmias, Cardiac↗
PubMed2002

The implantable cardioverter defibrillator.

The implantable cardioverter defibrillator is the optimal treatment for both primary and secondary prevention in patients with previous aborted sudden death and with life-threatening cardiac arrhythmias. This article will review the indications and the evidence supporting implantable cardioverter defibrillator use.

Arrhythmias, Cardiac↗
PubMed2002

Upgrade of permanent pacemakers and single chamber implantable cardioverter defibrillators to pectoral dual chamber implantable cardioverter defibrillators: indications, surgical approach, and long-term clinical results.

The aim of this study was to describe the indications for upgrade of pacemakers (PMs) or single chamber (VVIR) ICDs to dual chamber (DDDR) ICDs, surgical approach, hardware hybridization, and clinical outcome. Patients with preexisting PMs or VVIR ICDs may develop indications for ICD therapy or dual chamber pacing, respectively, that can be served by DDDR ICDs that incorporate preexisting transvenous leads. Fifty-seven patients underwent upgrade from PMs (29/57) or VVIR ICDs (28/57) to pectoral DDDR ICDs. Preexisting transvenous atrial and/or ventricular leads suitable for continued use were incorporated into new DDDR ICDs in 88.5% and 100% of PM and VVIR ICD upgrades, respectively. Acceptable DFTs were achieved in 56 (98.2%) of 57 patients. Appropriate VT/VF therapies were registered among 33.3% of patients during follow-up. No shocks due to lead noise were observed in any patient with hybridized transvenous leads. Atrial far-field R wave (FFRW) oversensing occurred in 24% of DDDR ICD systems incorporating a preexisting atrial lead. FFRW was overcome by programming reduced atrial sensitivity without interfering with the normal ICD system performance in all instances. Upgrade of PMs and VVIR ICDs to pectoral DDDR ICDs is safe and technically feasible in most patients. Preexisting transvenous leads can be successfully incorporated into new DDDR ICDs, simplifying the surgical procedure, minimizing transvenous hardware, and eliminating the possibility of hazardous pacemaker-ICD interactions.

Aged↗
PubMed2001

Cost-effectiveness of the implantable cardioverter-defibrillator: results from the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: In the Canadian Implantable Defibrillator Study (CIDS), we assessed the cost-effectiveness of the implantable cardioverter-defibrillator (ICD) in reducing the risk of death in survivors of previous ventricular tachycardia (VT) or fibrillation (VF). METHODS AND RESULTS: Healthcare resource use was collected prospectively on the first 430 patients enrolled in CIDS (n=212 ICD, n=218 amiodarone). Mean cost per patient, adjusted for censoring, was computed for each group based on initial therapy assignment. Incremental cost-effectiveness of ICD therapy was computed as the ratio of the difference in cost (ICD minus amiodarone) to the difference in life expectancy (both discounted at 3% per year). All costs are in 1999 Canadian dollars (C$1 approximately US$0.65). Over 6.3 years, mean cost per patient in the ICD group was C$87 715 versus C$38 600 in the amiodarone group (difference C$49 115; 95% CI C$25 502 to C$69 508). Life expectancy for the ICD group was 4.58 years versus 4.35 years for amiodarone (difference 0.23, 95% CI -0.09 to 0.55), for incremental cost-effectiveness of ICD therapy of C$213 543 per life-year gained. ICD benefit was greater in patients with low left ventricular ejection fraction (<35%), and cost-effectiveness in this group was more attractive (C$108 484). Alternative extrapolations of survival benefit and costs to 12 years indicated cost-effectiveness in the range of C$100 000 to C$150 000 per life-year gained. CONCLUSIONS: At C$213 543, the value for the money offered by ICD therapy is not attractive by currently accepted standards. Further research is warranted to identify the indications and patient subgroups for whom ICDs are a cost-effective use of resources.

Cost-Benefit Analysis↗
PubMed2002

Effect of risk stratification on cost-effectiveness of the implantable cardioverter defibrillator.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) effectively prevent sudden cardiac death, but selection of appropriate patients for implantation is complex. We evaluated whether risk stratification based on risk of sudden cardiac death alone was sufficient to predict the effectiveness and cost-effectiveness of the ICD. METHODS: We developed a Markov model to evaluate the cost-effectiveness of ICD implantation compared with empiric amiodarone treatment. The model incorporated mortality rates from sudden and nonsudden cardiac death, noncardiac death and costs for each treatment strategy. We based our model inputs on data from randomized clinical trials, registries, and meta-analyses. We assumed that the ICD reduced total mortality rates by 25%, relative to use of amiodarone. RESULTS: The relationship between cost-effectiveness of the ICD and the total annual cardiac mortality rate is U-shaped; cost-effectiveness becomes unfavorable at both low and high total cardiac mortality rates. If the annual total cardiac mortality rate is 12%, the cost-effectiveness of the ICD varies from $36,000 per quality-adjusted life-year (QALY) gained when the ratio of sudden cardiac death to nonsudden cardiac death is 4 to $116,000 per QALY gained when the ratio is 0.25. CONCLUSIONS: The cost-effectiveness of ICD use relative to amiodarone depends on total cardiac mortality rates as well as the ratio of sudden to nonsudden cardiac death. Studies of candidate diagnostic tests for risk stratification should distinguish patients who die suddenly from those who die nonsuddenly, not just patients who die suddenly from those who live.

Amiodarone↗
PubMed2005

Cerebral oxygenation during defibrillator threshold testing of implantable cardioverter defibrillators.

BACKGROUND: The induction of ventricular fibrillation (VF) during defibrillator threshold testing of implantable cardioverter defibrillators (ICD) provokes global cerebral hypoperfusion and impaired oxygen delivery. Limited data are available on the neurophysiological effects of defibrillator threshold testing. Near infrared spectroscopy (NIRS) can noninvasively measure changes in specific chromophores, which reflect cerebral oxygenation at the intravascular and mitochondrial levels. We performed a prospective trial using NIRS to analyze cerebral cortical oxygenation during defibrillator threshold testing. METHODS: Eleven patients (men = 9; age = 64 +/- 11 years: LVEF = 44 +/- 11%) underwent subpectoral ICD implantation and defibrillator threshold testing under general anesthesia. A NIRO 300 spectrometer was used to measure the absolute changes in the concentrations of oxyhemoglobin, de-oxyhemoglobin, and cytochrome c oxidase copper moiety during each procedure. The mean arterial blood pressure was monitored simultaneously. RESULTS: The mean number of defibrillator threshold tests was two (range 2-6). Twenty-six episodes of VF (duration 13.1 +/- 9.7 seconds; cycle length 230.2 +/- 20.8 ms) and two episodes of VT (duration 15 +/- 2.8 seconds; cycle length 320 +/- 11.3 ms) were induced. Each episode of VF and VT resulted in a decrease in the mean arterial blood pressure to 23.9 +/- 7.5 mmHg (p < or = 0.05) and oxyhemoglobin (-4.2 +/- 1.7 micromol/L; p < or = 0.05) and an increase in de-oxyhemoglobin (2.7 +/- 1.4 micromol/L). There was no change in the cytochrome c oxidase copper moiety redox status (0.09 +/- 0. 30 micromol/L). CONCLUSION: Our results suggest that impaired oxygen delivery during induced VF and VT does not affect oxygen availability at the cellular intra-mitochondrial level.

Brain↗
PubMed1994

[Indications for implantable automatic defibrillators].

The automatic implantable defibrillator is an effective therapeutic tool for palliative treatment of severe ventricular arrhythmias. There is a significant reduction in sudden death in implanted patients. However, reliable data on the long term global mortality is not yet available. The indications are difficult to define apart from special cases. A large number of factors has to be taken into consideration: the clinical presentation of the arrhythmia, and the different medical and non-medical therapeutic options. At present, it is not possible to arrive at a consensus on the indications of automatic implantable defibrillators. Therefore, it is illusory to construct decisional algorithms. The authors suggest therapeutic orientations rather than strict clinical indications, based on recommendations published by the working groups on cardiac arrhythmias and pacing of the European Society of Cardiology and on their own personal experience.

Death, Sudden, Cardiac↗