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PubMed1998

Randomized comparison of a 90 uF capacitor three-electrode defibrillation system with a 125 uF two-electrode defibrillation system.

INTRODUCTION: A variety of factors, including the number of defibrillation electrodes and shocking capacitance, may influence the defibrillation efficacy of an implantable defibrillator system. Therefore, the purpose of this study was to compare the defibrillation energy requirement using a 125 uF two-electrode defibrillation system and a 90 uF three-electrode defibrillation system. METHODS AND RESULTS: The defibrillation energy requirements measured with both systems were compared in 26 consecutive patients. The two-electrode system used a single transvenous lead with two defibrillation coils in conjunction with a biphasic waveform from a 125 uF capacitor. The three-electrode system used the same transvenous lead, utilized a pectoral implantable defibrillator generator shell as a third electrode, and delivered the identical biphasic waveform from a 90 uF capacitor. The two-electrode system was associated with a higher defibrillation energy requirement (10.8 +/- 5.5 J) than was the three-electrode system (8.9 +/- 6.7 J, p < 0.05), however, the leading edge voltage was not significantly different between systems (361 +/- 103 V vs. 397 +/- 123 V, P = 0.07). The two-electrode system also had a higher shocking resistance (49.0 +/- 9.0 ohms vs. 41.4 +/- 7.3 ohms, p < 0.001) and a lower peak current (7.7 +/- 2.6 A vs. 10.1 +/- 3.7 A, p < 0.001) than the three-electrode system. CONCLUSIONS: A three-electrode defibrillation system that utilizes a dual coil transvenous lead and a subcutaneous pectoral electrode with lower capacitance is associated with a lower defibrillation energy requirement than is a dual coil defibrillation system with higher capacitance. This finding suggests that the utilization of a pectoral generator as a defibrillation electrode in conjunction with smaller capacitors is a more effective defibrillation system and may allow for additional miniaturization of implantable defibrillators.

Aged↗
PubMed1988

Mechanism of death in patients with the automatic implantable cardioverter defibrillator.

Fifty patients underwent primary implantation of an automatic implantable cardioverter defibrillator between August 1983 and April 1988 and were entered into a long-term surveillance program. There were a total of 14 deaths (28%) in the entire group occurring at a mean of 8.7 months postimplantation. Eleven deaths were cardiac and three were noncardiac (two pneumonia, one leukemia). The group of deceased patients were similar to the survivors in all respects except for a statistically lower ejection fraction (23% vs 32%) at the time of implantation. In addition, 13/14 (93%) of the deceased patients experienced at least one appropriate AICD discharge at a mean of 4.5 months post implantation. Recorded ECGs at the time of death revealed that most of the sudden deaths were due to electromechanical dissociation and not to AICD-treatable arrhythmias. These data suggest therefore that death in AICD patients is usually cardiac, due primarily to low ejection fraction and occurs in patients who have previously received AICD discharges.

Adult↗
PubMed1999

Surgery for postinfarction ventricular tachycardia in the pre-implantable cardioverter defibrillator era: early and long term outcomes in 100 consecutive patients.

OBJECTIVE: To report outcome following surgery for postinfarction ventricular tachycardia undertaken in patients before the use of implantable defibrillators. DESIGN: A retrospective review, with uniform patient selection criteria and surgical and mapping strategy throughout. Complete follow up. Long term death notification by OPCS (Office of Population Censuses and Statistics) registration. SETTING: Tertiary referral centre for arrhythmia management. PATIENTS: 100 consecutive postinfarction patients who underwent map guided endocardial resection at this hospital in the period 1981-91 for drug refractory ventricular tachyarrhythmias. RESULTS: Emergency surgery was required for intractable arrhythmias in 28 patients, and 32 had surgery within eight weeks of infarction ("early"). Surgery comprised endocardial resections in all, aneurysmectomy in 57, cryoablations in 26, and antiarrhythmic ventriculotomies in 11. Twenty five patients died < 30 days after surgery, 21 of cardiac failure. This high mortality reflects the type of patients included in the series. Only 12 received antiarrhythmic drugs after surgery. Perioperative mortality was related to preoperative left ventricular function and the context of surgery. Mortality rates for elective surgery more than eight weeks after infarction, early surgery, emergency surgery, and early emergency surgery were 18%, 31%, 46%, and 50%, respectively. Actuarial survival rates at one, three, five, and 10 years after surgery were 66%, 62%, 57%, and 35%. CONCLUSIONS: Surgery offers arrhythmia abolition at a risk proportional to the patient's preoperative risk of death from ventricular arrhythmias. The long term follow up results suggest a continuing role for surgery in selected patients even in the era of catheter ablation and implantable defibrillators.

Aneurysm↗
PubMedDate not supplied

Resource loss predicts depression and anxiety among patients treated with an implantable cardioverter defibrillator.

OBJECTIVE: Many patients treated with an implantable cardioverter defibrillator (ICD) experience clinically significant depression and anxiety after ICD implantation. As ICD use continues to evolve, it is important to understand the correlates of depression and anxiety to identify patients at greatest risk of poor psychological functioning. Conservation of resources theory, a general theory of stress, states that people experience greater stress if they perceive that they are losing personal, social, and material resources. We hypothesized that perceptions of resource loss would be related to symptoms of depression and anxiety after controlling for other known predictors. METHODS: One hundred patients treated with an ICD completed standardized depression and anxiety questionnaires along with questionnaires assessing social support, physical functioning, and resource loss. Clinical variables for patients were obtained from prospectively obtained medical records. RESULTS: Over 20% of the sample exhibited elevated symptoms of depression and anxiety. Patients' depression levels were associated with poor social support, poor physical functioning, a history of depression, and a greater length of time since ICD implantation. Having experienced one or more clinical ICD shocks was related to depression but not anxiety. Higher levels of perceived resource loss were associated with higher levels of both depression and anxiety after controlling for all other predictors. CONCLUSIONS: Resource loss may help to determine psychological distress after ICD implantation. Understanding how resource loss contributes to depression and anxiety may help to identify patients at greatest risk of poor psychological functioning and may suggest treatment strategies.

Adult↗
PubMed1998

[Dual-chamber implantable automatic defibrillators. Experiences apropos of 16 cases].

In view of the large number of inappropriate shocks observed in patients with implanted defibrillators, improved detection of ventricular arrhythmias has become a major objective. The addition of an atrial catheter has been proposed to improve discrimination between ventricular and non-ventricular arrhythmias. Besides this function, the additional catheter could be used for DDD pacing without risk of interaction between the pacemaker and defibrillator. The authors report their initial experience in 16 patients implanted with a DDD pacemaker. The indication was resuscitated sudden death (N = 5) or ventricular tachycardia (N = 11). The choice of a DDD defibrillator was justified by a bradycardia (N = 9), haemodynamic factors (N = 4) or supraventricular tachycardia (N = 3). The devices used were the Defender 9001 (ELA Medical SA, France, N = 3), the Ventak AV 1810 and the Ventak AV II DR 1821 (Guidant/CPI, Inc. USA, N = 11 and N = 2 respectively). There were three immediate complications. After 2 to 29 months' follow-up, 5 patients had received appropriate treatment by their devices. Five patients had inappropriate shocks : one patient received a shock triggered by electrical interference, two others had no active sensing algorithme when the shocks were delivered, and the other two had an activated algorithme with 1/1 conduction of a supraventricular arrhythmia. No recurrences were recorded after reprogramming the device. DDD or VDD pacing was permanent in 9 patients and intermittent in 3 others. Seven patients had dilated cardiomyopathy and severe cardiac failure and were clinically improved by dual chamber pacing. In many patients, candidates for a defibrillator, this new generation of devices has improved specificity of arrhythmia detection and cardiac pacing without risk of interaction. The authors propose a classification of the indications for a DDD defibrillator.

Algorithms↗
PubMed1991

Renal extracorporeal shock wave lithotripsy performed in patient with implantable cardioverter defibrillator.

The effect of extracorporeal shock wave lithotripsy on the automatic implantable cardioverter defibrillator is unknown. To evaluate what effect might occur, a non-implanted automatic implantable cardioverter defibrillator was subjected to a full course of extracorporeal shock wave lithotripsy while inactive. Bench testing by the manufacturer after lithotripsy demonstrated normal function of the device. A patient with an automatic implanted cardioverter defibrillator who required contralateral extracorporeal shock wave lithotripsy then underwent this procedure. The right renal calculus was destroyed successfully with no apparent damage to the automatic implantable cardioverter defibrillator. A test of the automatic implantable cardioverter defibrillator after lithotripsy demonstrated normal sensing and conversion of induced ventricular tachycardia.

Aged↗
PubMed2005

Implantable cardioverter defibrillator storm: nursing care issues for patients and families.

Implantable cardioverter defibrillators (ICDs) are being used for primary and secondary prevention of life-threatening cardiac arrhythmias, and evidence suggests that increased use is likely in the future. ICD storm, the delivery of two or more shocks within 24 hours, occurs in 10% to 20% of patients who have ICDs and can have long-lasting psychological and physical consequences. An understanding of the factors associated with ICD storm, relevant assessment, and patient and family teaching and counseling can help clinicians to better meet the needs of patients who have experienced ICD storm.

Adaptation, Psychological↗
PubMed2003

[Impact of primary angioplasty on the indication for implantable cardiac defibrillator in patients with myocardial infarction].

INTRODUCTION AND OBJECTIVES: Implantable cardiac defibrillators (ICD) have been shown to improve survival in patients with myocardial infarctionand LVEF < 0.30 or LVEF < 0.40 + nonsustained ventricular tachycardia + inducible sustained arrhythmias. However, these risk stratification criteria have not been evaluated in patients who are candidates for primary percutaneous transluminal coronary angioplasty (PTCA). The objective of this study was to assess the impact of both strategies on the indication for ICD in a consecutive series of post-infarction patients treated with primary PTCA. PATIENTS AND METHOD: One hundred and two consecutive patients with myocardial infarction (80 men, mean age 63.6 11.5 years) included in a single-center-based regional program of primary PTCA were included in the study. A 24-h continuous ECG recording was obtained 2 to 6 weeks after the acute event, and LVEF was determined by 2D-echocardiography one month after the infarct. Patients with nonsustained ventricular tachycardia and LVEF < 0.40 underwent programmed ventricular stimulation using a standard protocol. RESULTS: Twenty-two patients (21.6%; 95% CI, 13.6-29.6) showed at least one episode of nonsustained ventricular tachycardia in the 24 h recording. Six of them had LVEF < or = 0.40, and sustained ventricular arrhythmia was induced in 2 out of 5. LVEF < or = 0.30 was found in 3 patients, none of whom had nonsustained ventricular tachycardia. Thus, 5 patients had an indication for ICD according to either of the two risk stratification criteria. CONCLUSIONS: The prevalence of nonsustained ventricular tachycardia in post-infarction patients treated with primary PTCA is high. However, because most of them have preserved ventricular function, primary prevention with an ICD is indicated in approximately 5% of the population.

Angioplasty, Balloon, Coronary↗
PubMed2002

Inappropriate implantable cardioverter defibrillator discharge from sensing of external alternating current leak.

Implantable cardioverter defibrillators (ICDs) are now an accepted and effective therapy for treatment of survivors of sudden cardiac death (SCD) and prevention of SCD in high-risk patients. Normal ICD function and delivery of therapy depends on appropriate sensing and detection of myocardial electrical potentials. Electromagnetic interference resulting in ICD malfunction is a well-documented phenomenon, however, there are less well-known external sources of interference, which may cause life threatening ICD malfunction. We report a unique case of repeated inappropriate ICD shocks in a ten-year old boy caused by the ICD sensing alternating current from an unexpected external source.

Child↗
PubMed2005

Automatic impedance monitoring and patient alert feature in implantable cardioverter defibrillators: being alert for the unexpected!

Recent advances in implantable cardioverter defibrillator (ICD) technology have enabled implementation of an automatic monitoring feature in ICDs that provides daily measurements of several technical parameters such as battery status, pacing, and high-voltage impedance. The system alerts the patient with an audible alarm to contact the physician in case the measured parameters are not within normal limits. Early detection of intermittent and potentially serious complications justifies routine use of this feature. This report describes a patient with an ICD who died suddenly due to ventricular fibrillation, which was not appropriately treated by the device. The cause of device malfunction was most likely an intermittent lead fracture that was not detected by the automatic impedance monitoring and alert feature of this device. Based on these data, potential benefits and theoretical pitfalls of automatic impedance monitoring and alert features are discussed.

Adult↗
PubMed1993

A follow-up study of patients with implantable cardioverter defibrillators.

This study involves 381 patients who received an implantable cardioverter defibrillator (ICD) for management of serious ventricular dysrhythmias and were followed for up to 9 years. The device was effective in preventing sudden cardiac death (SCD), with survival rates of 97% at 3 years and 94% at 5 years. Complication rates were low. Two hundred and twenty-five patients received at least one shock; 2.3 shocks per patient year were received. Shocks were categorized as appropriate, indeterminate, or inappropriate. Definitions of these categories and their occurrence are discussed and the characteristics and experiences of these patients are described.

Death, Sudden, Cardiac↗
PubMed2006

The impact of gender on survival amongst patients with implantable cardioverter defibrillators for primary prevention against sudden cardiac death.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) are a life-saving therapy for many patients with cardiovascular disease at increased risk of fatal dysrhythmias. As men comprise the majority of the study population (67-92%) in clinical trials, the benefit to women is unknown. We performed a meta-analysis of primary prevention trials to evaluate the impact of ICDs in men and women on death from any cause. METHODS: Included trials met the following criteria: (i) randomized controlled trials versus standard of care, (ii) ICD used as primary prevention in a well-described protocol and (iii) data provided on risk of death from any cause for both male and female patients. RESULTS: Five clinical trials were included in this meta-analysis. The risk of death from any cause was significantly reduced by 26% in male patients who received ICD therapy compared to control, hazard ratio (HR) 0.74 (95% CI 0.60-0.91) but not amongst female patients, HR 0.81 (95% CI 0.60-1.09). As the COMPANION trial evaluated the combination of biventricular pacemaker with ICD therapy we conducted a separate analysis without the inclusion of this study. Male patients receiving ICD therapy demonstrated a similar 24% reduction in risk of death from any cause, HR 0.76 (95% CI 0.58-0.99) whilst female patients demonstrated a reduction of only 12%, HR 0.88 (95% CI 0.63-1.22). CONCLUSIONS: Unlike their male counterparts, females did not significantly benefit from ICD therapy and without concurrent biventricular pacing, appear only to achieve a nonsignificant 12% reduction in risk of death.

Aged↗
PubMed1995

Holter functions of the implantable cardioverter defibrillator: what is still missing?

The technology of the implantable cardioverter defibrillator (ICD) offers the opportunity to overcome the present limits of the invasive and noninvasive approaches of clinical electrophysiology. The invasive approach enables us to reproduce severe arrhythmias if they are inducible, but does not give information concerning the way they spontaneously arise. The noninvasive approach (Holter) gives this information, but it usually concerns only trivial arrhythmias with different therapeutic targets. One hopes in the future, by means of an important extension to ICD technology, which is not technically possible for the time being, to have access to pertinent information and to a better understanding of the circumstances leading to severe spontaneous arrhythmias, potentially lethal. For the moment, we only have the diagnostic certainty leading to the therapeutic intervention. It is based on an ECG and on the sequence of cardiac cycles preceding the rhythmic controlled accident. These data allow verification of but not explanation of the events. To have a chance to be understood and explained, these "events" must be replaced in the context of the "nonevents." Ideally, one should have all the gross information concerning the last 24 hours and subsequently analyze them. It is already a big step, thanks to the defibrillators the right to therapeutic error has been gained, a unique and fatal accident has been transformed into a repeatable event, and therefore, access is gained to the evolution of the responsible disease.

Defibrillators, Implantable↗
PubMed1998

An overview of the fifth-generation implantable cardioverter defibrillator.

It has been established that treatment with an implantable cardioverter is effective for life-threatening arrhythmia including ventricular tachycardia (VT) and ventricular fibrillation (VF). Although most third and fourth-generation implantable cardioverter defibrillator (ICD) models are effective for the treatment of VT and VF, they often misinterpret supraventricular tachycardia (SVT), and the incidence of inappropriate therapy delivered is as high as 20 to 40%. To solve this clinical problem, the dual-chamber ICD was developed. According to the current reports on a study of the main fifth-generation ICD models that have been clinically used, 86 to 100% sensitivity regarding discrimination was obtained. In addition, the sensitivity for delivering appropriate therapy for VT was 97 to 100%. Since the indications for ICD therapy are being expanded, additional improvement of the device and adequate patient selection are recommended.

Algorithms↗
PubMed2001

New-generation lithotripters for treatment of patients with implantable cardioverter defibrillator: experimental approach and review of literature.

PURPOSE: The influence of shockwaves applied during extracorporeal shockwave lithotripsy on the function of implantable cardioverter defibrillators was evaluated. Mechanical influences as well as proper electrical function were tested in an experimental approach. MATERIALS AND METHODS: Two implantable defibrillators (Ventak Mini 1743 and AVII 1821) were exposed to the shockwaves of a new-generation lithotripter. Each of the antidysrhythmic devices was tested at several distances from and within the focus of the lithotripter. All studies were performed with maximum energy and the number of shockwaves used for stone treatment. The devices were connected to an ECG simulator, and continuous recording of a surface ECG, a shock ECG, and marker channel was performed. RESULTS: No macroscopic and microscopic mechanical damage was observed. The detection function of the implantable defibrillators was not altered by any electromagnetic artifacts even when brought into the focus of the shockwaves. All induced ventricular dysrhythmias were terminated properly regarding artifact sensing. However, after defibrillation, the pacing function of the Ventak Mini cardioverter defibrillator, which was programmed into the demand mode, failed. In this case, there was no post-shock pacing in the period of post-defibrillation asystole. The failure was caused by artifact oversensing. CONCLUSION: In patients with implanted cardiac devices undergoing treatment with a new-generation lithotripter, deactivation of the defibrillator is not mandatory. For safety reasons, continuous ECG recording is recommended. To avoid pacing failure by artifact oversensing, the shockwaves should be applied in a R-wave synchronous mode.

Artifacts↗
PubMed2002

Geographic differences in implantable cardioverter defibrillator usage.

Despite the demonstrated efficacy of implantable cardioverter defibrillators (ICDs) in reducing sudden and total mortality in selected patients, their implantation rates vary greatly among countries. In the United States, the implantation rate is 185 implants per million inhabitants compared with only 31 implants per million in western Europe. The differences in ICD use may be explained by the following factors: manner in which sudden cardiac death is perceived by politicians and physicians (sudden cardiac death is perceived as a "nice way of dying"); differences in indications; physicians' information; prevalence of coronary artery disease; sudden cardiac death survival rates; perceived reliability of alternative treatment (namely, antiarrhythmics including amiodarone); economic backgrounds; and health care politics. Furthermore, the cost of this treatment strategy must be considered. This issue has been raised because generalization of ICD use in patients matching clinical characteristics of patients enrolled in the primary prevention trials may represent a significant economic burden to be added to the already overloaded health care system. This low acceptance may not be entirely related to budget constraint but also to the perceived efficacy of ICDs by physicians and health authorities.

Cost-Benefit Analysis↗
PubMed2000

[Percutaneous implantation under local anesthesia of an implantable automatic defibrillator: report of the first Tunisian case].

We report the case of a 58 years old male affected by a severe relapsing ventricular tachycardia despite a well administered anti arrhythmic therapy. Etiology is an arrhythmogene right ventricular dysplasia. Considering the severity of this arrhythmia we proceed to percutaneous implantation of an automatically implantable defibrillator under local anesthesia. Evolution was favorable with a follow-up of 3 months.

Anesthesia, Local↗