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PubMed2005

Two adults requiring implantable defibrillators because of ventricular tachycardia and left ventricular dysfunction caused by presumed Kawasaki disease.

There is an adult patient population in Japan with undiagnosed coronary artery lesions caused by Kawasaki disease (KD) occurring before 1967, the time at which KD was first described. Two adult patients presented with a low left ventricular (LV) ejection fraction and ventricular tachycardia (VT) caused by presumed KD. A 43-year-old man with rapid VT had a history of an acute febrile illness with desquamation of the fingertips at the age of 10 months. Coronary angiography (CAG) showed segmental stenosis of the right coronary artery (RCA) and occlusion of the left anterior descending artery with a giant aneurysm. The other patient was a 48-year-old man with a history of ischemic cardiomyopathy diagnosed after a previous myocardial infarction when he was 32 years old. He had segmental stenosis of the RCA on CAG. Non-sustained VT with transient unconsciousness was observed during 24-h Holter electrocardiography. Rapid VT with syncope was induced in both patients in the electrophysiologic studies and an implantable defibrillator was required to prevent sudden death. Physicians must be aware that VT can occur in older patients with LV dysfunction many years after KD.

Adult↗
PubMed1997

Does reducing capacitance have potential for further miniaturisation of implantable defibrillators?

OBJECTIVE: To determine whether considerably smaller capacitors could replace 125 microF capacitors as the standard for use in implantable defibrillators. METHODS: Measured energy, impedance, voltage, and current delivered were compared at defibrillation threshold in 10 mongrel dogs for defibrillation using 75 microF and 125 microF capacitors alternated randomly. Defibrillation was attempted with biphasic shocks of comparable tilt between an endocardial lead in the right ventricular apex and a "dummy" active can of an experimental implantable device placed in the subpectoral position. RESULTS: A reduction of capacitor size of 40% was associated with an increase in voltage of 21% and in current of 22%. With a 65% tilt, no significant differences were found between the two capacitances with respect to the impedance or energy required for defibrillation. CONCLUSIONS: Multiple advances in electrode material, electrode configuration, shock morphology, and shock polarity have reduced defibrillation energy requirements. Smaller capacitors could be used in implantable cardioverter/defibrillators without a major decrease in effectiveness.

Animals↗
PubMed2001

Inappropriate arrhythmia detection in implantable defibrillator therapy due to oversensing of diaphragmatic myopotentials.

Nonadequate arrhythmia detection and delivery of electrical therapy is still a main problem in current implantable cardioverter defibrillator therapy. Besides supraventricular arrhythmias extra-cardiac biosignals also can cause inadequate shock delivery. The present study focuses on nonadequate arrhythmia detection due to oversensing of diaphragmatic myopotentials. Their clinical characteristics, incidence and management are presented. Three-hundred-eighty-four recipients of a transvenous cardioverter-defibrillator who were implanted and followed-up at our institution between October 1991 and June 1999 were enrolled. During a mean follow-up of 32+/-25 months a total number of 139 nonadequate episodes of arrhythmia detection due to oversensing of diaphragmatic myopotentials were observed in 33 patients (8.6%). In 11 patients a total of 32 high energy shock deliveries occurred. Oversensing of diaphragmatic myopotentials was primarily observed in patients implanted with defibrillator leads providing "integrated bipolar" sensing. The vast majority of nonadequate arrhythmia detection were observed during intrinsic bradycardia heart rate and/or antibradycardia pacing. Electrical lead failure was ruled out in every patient. In 90% of the patients with a cardioverter-defibrillator providing programmable maximal sensitivity (n=16), the reduction of maximum sensitivity was effective in preventing further episodes of nonadequate arrhythmia detection. In 48% of the patients with devices without programmable maximal sensitivity (n=17), surgery revision was necessary to solve the problem.

Adult↗
PubMed2001

Syncope in pharmacologically unmasked Brugada syndrome: indication for an implantable defibrillator or an unresolved dilemma?

A 30-year-old Caucasian male was referred for evaluation of a 2-year history of recurrent post-exertion lightheadedness and near syncopal spells in the setting of a family history of unexplained sudden cardiac death. Cardiac evaluation demonstrated normal heart structure, but the 12-lead surface ECG was suggestive of but not diagnostic of Brugada syndrome. An exercise stress test reproduced the patient's usual symptoms during the recovery period, and was consistent with a typical vasovagal faint. The same symptoms were observed during a head-up tilt table test. However, given the family history and ECG, pharmacological testing with procainamide, isoprenaline and metoprolol, as well as programmed ventricular stimulation, were undertaken. Pharmacological provocation further supported a diagnosis of Brugada syndrome, whereas programmed ventricular stimulation was considered non-diagnostic regarding ventricular tachyarrhythmia susceptibility. Consequently, despite ECG and pharmacological findings suggestive of Brugada syndrome, there appeared to be sufficient evidence to believe that this patient's symptoms were the result of neurally mediated syncope and not due to ventricular tachyarrhythmias. The patient was treated with midodrine, and has remained symptom-free for 16 months. Thus, given the frequency with which vasovagal syncope occurs in young patients, its occurrence is not unexpected in individuals with concomitant diagnoses such as Brugada syndrome. In as much as current recommendations favour implantable defibrillators in symptomatic Brugada syndrome, the identification of other causes of syncope in such patients poses an uncomfortable, and currently unsettled dilemma.

Adult↗
PubMed2000

Factors affecting the frequency of subcutaneous lead usage in implantable defibrillators.

Subcutaneous leads (SQ) add complexity to the defibrillation system and the implant procedure. New low output devices might increase the requirement for SQ arrays, although this might be offset by the effects of active can and biphasic technology. This study sought to assess the impact of these technologies on SQ lead usage, and to determine if clinical variables could predict the need for an SQ lead. Patients receiving nonthoracotomy systems (n = 554) at our institution underwent step-down-to-failure DFT testing with implant criteria of a 10-J safety margin. SQ leads were used only after several endovascular configurations failed. Use of biphasic waveforms significantly lowered the frequency of use of SQ leads from 48% to 3.7% (P < 0.000001). SQ leads were required in 4.4% of patients with cold can devices and 2.6% of patients with active can devices (P = NS). There was no increase in SQ lead usage with low energy (< 30-J delivered energy) devices. Clinical variables (including EF, heart disease, arrhythmia, and prior bypass) did not predict the need for an SQ lead. The implant DFT using SQ arrays (14.5 +/- 6.5 J) was not significantly lower than that for SQ patches (16.6 + 6.0 J). We conclude that biphasic waveforms significantly reduce the need for SQ leads. Despite this reduction, 3.7% of implants still use an SQ lead to achieve adequate safety margins. The introduction of lower output devices has not increased the need for SQ leads, and when an SQ lead is required, there is not a significant difference in the implant DFT of patches versus arrays. Clinical variables cannot predict which patients require SQ leads.

Aged↗
PubMed2004

Implantation of submammary implantable cardioverter defibrillators.

Implantable cardioverter defibrillators (ICDs) are routinely placed in the left pectoral area using a transvenous approach. This approach may result in poor cosmetic outcome and cause psychological problems, especially in younger patients. To avoid this, several alternative implantation techniques have been developed. For cosmetic reasons, we used a submammary technique to implant ICDs into three young women. Apart from defibrillation threshold testing, the procedures were performed under local anesthesia. Threshold testing was done under general anesthesia. Appropriate defibrillation thresholds were obtained in all three cases, and all the patients tolerated the procedure well. There were no complications in a mean of 22 months of follow-up, and the cosmetic results were very good.

Adult↗
PubMed1998

Implantable defibrillators and/or amiodarone: alternatives or complementary therapies.

Many patients with an implanted cardioverter defibrillator (ICD) also receive antiarrhythmic drug therapy. Although an expanding number of patients are receiving ICD therapy, many will not have received previous antiarrhythmic treatment. For patients with an ICD, infrequent arrhythmias and a low probability of inappropriate device discharges, no antiarrhythmic therapy is required. However, for those patients who require an antiarrhythmic drug, amiodarone is a reasonable first choice because of safety in patients with poor LV function. It may be particularly useful for patients with high density ventricular arrhythmias. However, the interactions between ICDs and antiarrhythmic therapy requires close monitoring in order that patient benefit can be optimised, and this review focuses on those interactions.

Aged↗
PubMed2002

Quality of life in the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: The primary aim of this study was to compare quality-of-life outcome between patients randomized to implantable cardioverter defibrillator (ICD) therapy and patients randomized to amiodarone treatment in the Canadian Implantable Defibrillator Study (CIDS). A secondary aim was to evaluate the effects on quality-of-life outcomes of receiving shocks from the device. METHODS: Quality of life was assessed in 317 English-speaking participants by use of the Rand Corporation's 38-item Mental Health Inventory (MHI) and the Nottingham Health Profile (NHP). Assessments were done in the hospital at baseline and with mailed questionnaires after 2, 6, and 12 months of follow-up. Sixty-two percent of patients completed the follow-up assessments at 6 and 12 months. RESULTS: Repeated measures analysis of variance revealed significant time by treatment group interaction effect on total MHI and the psychological distress and psychological well-being sub-scales, and on 5 of the 7 NHP scales (energy, physical mobility, emotional reactions, sleep disturbance, and lifestyle impairment) (P <.05). Emotional and physical health scores were shown to improve significantly in the ICD group and were either unchanged (emotional health) or deteriorated (energy and physical mobility) in the amiodarone-treated group by means of post-hoc comparisons. Quality of life did not improve in the subgroup of patients in the ICD-treated group who received > or =5 shocks from their device. CONCLUSION: Quality of life is better with ICD therapy than with amiodarone therapy. The beneficial quality-of-life effects from an ICD are not evident in patients who receive numerous shocks from their device.

Aged↗
PubMed1995

[10 years of therapy with implantable defibrillators--observation in 353 patients].

Since January 1984, the cardioverter-defibrillator (ICD) has been implanted in 353 patients (pts). Epicardial ICD implantation was performed in 207 pts and 146 pts underwent non-thoracotomy ICD implant. Overall operative mortality was 3% (12/353 pts) and was significantly higher in pts with epicardial ICD implantation (11/207 pts, 5%) than in patients who received non-thoracotomy ICDs (1/146 pts, < 1%) (p < 0.05). During a mean follow-up of 25 +/- 23 months, 63 pts (19%) died: 8 pts (0.8% per year) from sudden arrhythmic death and 6 pts (0.8% per year) suddenly without an underlying arrhythmia. Cardiac death was observed in 36 pts (4% per year) and 13 pts (2% per year) died from other causes. Appropriate ICD discharges were observed in 245 pts (72%) with a mean incidence of 22 +/- 44 IC discharges per pt. In pts with third-generation ICDs, 3,542 ventricular tachyarrhythmias (VTA) were observed and terminated by primary ICD shocks in 778 VTA (22%). Antitachycardia pacing was attempted in 2,764 VTA (78%) and was successful in 2,484 VTA (90%).

Aged↗
PubMed2005

Cardioverter defibrillator implantation in an adult with isolated noncompaction of the ventricular myocardium.

Isolated noncompaction of the ventricular myocardium is an unclassified cardiomyopathy and is thought to be due to arrest of myocardial morphogenesis. Fatal ventricular arrhythmias may occur in approximately half of the patients and account for half of the death in this disorder. In this report, we describe a patient with isolated noncompaction of the ventricular myocardium in whom implantation of automatic cardioverter defibrillator was thought to be effective to prevent the risk of sudden cardiac death.

Defibrillators, Implantable↗
PubMed2001

Comparison of internal cardioverter defibrillator implantation techniques: subpectoral position.

BACKGROUND: To compare surgical techniques for subpectoral implantation of internal cardioverter defibrillator (ICD). METHODS: Sequential comparison with review of the literature. SETTING: University Hospital. PARTICIPANTS: the patients requiring ICD. INTERVENTIONS: ICD insertions and device testing. MEASUREMENTS: defibrillation and pacing thresholds, defibrillator lead impedance, operative time, and proximity of generator site to midline, clinical outcomes. RESULTS: Comparable efficacy in defibrillation, surgical time and medial placement. No wound infections, seromas or lead dislodgments. Preservation of pectoral muscle integrity. CONCLUSIONS: Lateral single incision subpectoral ICD generator placement can be applied consistently with good RESULTS.

Arrhythmias, Cardiac↗
PubMed2004

Evaluation of safety and efficacy of pacemaker and defibrillator implantation by axillary incision in pediatric patients.

We successfully implanted 11 pacemakers, 6 defibrillators, and 1 biventricular pacemaker in 18 pediatric patients (15 female; 4 to 15 years, average age: 9) using the retropectoral transvenous approach with a hidden axillary incision. The average follow-up period was 24 months (range 49 months). Eight patients had congenital structural heart conditions (d-transposition of great arteries S/P Mustard operation, d-transposition of great arteries S/P arterial switch operation, truncus arteriosus, right ventricular diverticula, ventricular septal defect, hypertrophic cardiomyopathy). Four patients had acquired heart conditions (dilated cardiomyopathy, myocarditis). Excellent sensing and pacing thresholds were achieved in all attempted implantations. There was no pneumothorax. There was one lead dislodgement. One lead fracture distant from the subclavian vein occurred 4 months after implantation. Implantation of pacemakers and defibrillators via axillary incisions can be safe and effective in pediatric patients. This approach avoids skin erosion when implanting large devices such as defibrillators or biventricular devices in small patients with limited muscle mass while achieving superior aesthetic results. The axillary or extrathoracic venous entry site avoids subclavian crush syndrome.

Adolescent↗
PubMed2004

Seasonal variation of mortality in the Antiarrhythmics Versus Implantable Defibrillators (AVID) study registry.

OBJECTIVES: We postulated that the pattern of death would be nonrandom with respect to temporal variables. BACKGROUND: Previous studies have demonstrated increased sudden death is associated with periods of relative stress, and overall mortality is associated with temporal variables. METHODS: In the Antiarrhythmics Versus Implantable Defibrillators (AVID) registry, vital status was obtained for 4,450 patients (who had a recent episode of sustained ventricular arrhythmias or unexplained syncope and inducible ventricular tachycardia) through the National Death Index Service as of December 31, 1997 (follow-up 25.5 +/- 13.7 months). RESULTS: Mortality was not associated with the day of the week or with holidays but was associated with season (P = .033). Seasonal variation was present both in northern and southern sites. Mortality was higher during the winter months compared to the remaining months (111.2% in winter vs 96.5% in other months, P = .036). In addition, increased mortality was associated with a high-risk season variable defined (prior to evaluation of treatment arm associations) as spring in the north and winter in the south (P < .001). The hazard ratio for death associated with this "high-risk season" measured 1.25 (P = .001) compared to the other seasons in each region. A test of interaction between "high-risk" season and implantable cardioverter-defibrillator (ICD) status suggested that the group with ICDs experienced reduced mortality during the "high-risk season" compared to the group without ICDs (P = .047). CONCLUSIONS: Mortality was higher in the winter months and in the respective regional "high-risk" seasons. Furthermore, seasonal variation in mortality may have been due to variation in sudden arrhythmic death, and associated increases in mortality were reduced by ICD therapy.

Anti-Arrhythmia Agents↗
PubMedDate not supplied

Domains of nursing intervention after sudden cardiac arrest and automatic internal cardioverter defibrillator implantation.

PURPOSE: The purpose of the study was to explore individual and family experiences after sudden cardiac arrest and automatic internal cardioverter defibrillator implantation during the first year of recovery. This report specifically addresses the domains of concern expressed and helpful strategies used by participants that are relevant to the development of future intervention programs. DESIGN: A grounded theory approach was used to gain an understanding of areas of concern of sudden cardiac arrest survivors and families that could be used when designing future nursing interventions. Semistructured interviews were conducted with both sudden cardiac arrest survivors and 1 family member each at 5 points during the first year of recovery (hospitalization; 1, 3, 6, and 12 months after hospitalization). Participants were asked to identify those specific areas that most concerned them and that they would like assistance with during the first year. A total of 150 interviews were conducted with 176 hours of data generated. SETTING: The study focused on 10 northwest urban community medical centers and participants' homes within a 50-mile driving distance from the medical centers. SAMPLE: The sample included 15 first-time sudden cardiac arrest survivors (13 men and 2 women) and 1 family member each between the ages of 31 and 72 years. RESULTS: Domains of concern identified by participants that can be used to design future nursing intervention programs included preventive care, dealing with automatic internal cardioverter defibrillator shocks, emotional challenges, physical changes, activities of daily living, partner relationships, and dealing with health care providers. Suggestions of helpful strategies used by participants during the first year are outlined. IMPLICATIONS: Domains of concern and helpful strategies identified by participants provide a framework for the development and testing of nursing intervention programs to enhance recovery following sudden cardiac arrest for survivors and their families.

Activities of Daily Living↗
PubMed1995

Optimal electrode configuration for pectoral transvenous implantable defibrillator without an active can.

A new 83 cm3 implantable cardioverter-defibrillator (ICD) designed for pectoral implantation has been implanted most frequently using right ventricular and superior vena cava (RV-->SVC) electrodes; a patch electrode (RV-->patch + SVC) has been added when necessary to decrease the defibrillation threshold (DFT). The goal of this prospective study was to compare biphasic waveform DFTs for 3 electrode configurations: RV-->patch, RV-->SVC, and RV-->patch + SVC in 25 consecutive patients. The patch was positioned in a left retro-pectoral pocket, and the SVC electrode was positioned with the tip at the junction of the SVC and innominate vein. In the first 15 patients, all 3 electrode configurations were tested in random order; in the last 10 patients, only the RV-->patch and RV-->patch + SVC configurations were tested. In the first 15 patients, the stored-energy DFT for the RV-->SVC configuration (15.2 +/- 7.7 J) was higher (p < 0.001) than the DFT for the RV-->patch configuration (11.3 +/- 6.2 J) and the RV-->patch + SVC configuration (10.0 +/- 5.8 J). For all 25 patients, the DFT was lower for the RV-->patch + SVC configuration (9.7 +/- 5.1 J) than for the RV-->patch configuration (12.4 +/- 6.6 J, p = 0.005). The pathway resistance was highest for the RV-->patch configuration (72 +/- 9 omega), lower for the RV-->SVC configuration (63 +/- 6 omega, p < 0.01), and lowest for the RV-->patch + SVC configuration (46 +/- 3 omega, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMedDate not supplied

Psychological therapies for recipients of implantable cardioverter defibrillators.

Implantable Cardioverter Defibrillators (ICDs) are an increasingly common therapy for the treatment of ventricular arrhythmias. Whereas most ICD recipients adjust well to living with the implant, a substantial minority suffer anxiety, depression, and anger that appears to be related to the ICD. A large number of studies have reported on the incidence of psychopathology and common psychosocial problems among patients with ICDs, however very few psychological interventions with this cohort have been reported. In an extensive literature search we identified only a handful of studies that described outcomes of psychological interventions, and most of these were in pilot form. Only one randomized controlled study with a homogenous sample of ICD patients has been reported to date. Given the unique situation of patients with ICDs and the particular vulnerability of those who experience frequent shocks, the evaluation of interventions that may improve psychological adjustment within this group would appear a worthwhile endeavor.

Arrhythmias, Cardiac↗
PubMed2000

Detection of ventricular fibrillation in implantable defibrillators with automatic gain control amplifiers: effects of programming sensitivity.

AIMS: In newer implantable cardioverter-defibrillators with automatic gain control amplifiers the maximum possible sensitivity is programmed with the aim of securing optimal detection of ventricular fibrillation. This study was designed to prove that a reduction in maximum sensitivity is safe with respect to appropriate sensing of ventricular fibrillation, while avoiding sensing of extracardiac signals. METHODS AND RESULTS: Forty-two consecutive patients, undergoing defibrillator implantation/replacement with programmable maximum auto-gain sensing sensitivity (Ventak Mini III, Ventak AV , Guidant, St. Paul, MN, U.S.A.), were prospectively investigated. Thirty-four patients were implanted with a dual-coil lead system, providing integrated bipolar sensing (Endotak, Guidant, St. Paul, MN, U.S.A.), eight patients received a single-coil lead system with true bipolar sensing (Sprint, Medtronic, Minneapolis, MN, U.S.A.). During device implantation and pre-discharge testing, arrhythmia detection times of induced ventricular fibrillation were compared at programmed maximum (0.18 mV) and minimum (0.43 mV) sensitivity in a randomized manner. Seventy-six induced episodes of ventricular fibrillation were analysed. The mean arrhythmia detection times did not differ between the programmed sensing levels (maximum sensitivity: 1612 +/- 307 ms, vs minimal sensitivity: 1,602 +/- 330 ms; P = ns). The results were not affected by the type of implanted lead system (integrated bipolar versus true bipolar sensing). CONCLUSION: In the implantable defibrillator devices, reduction in maximum sensitivity did not impair the detection of induced episodes of ventricular fibrillation.

Amplifiers, Electronic↗