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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↗
PubMed1998

[Current indications for implantable automatic defibrillators].

Since the first implantation in man in 1980 implantable cardioverter defibrillator technology has greatly improved and the number of devices implanted has increased considerably in recent years. Non-thoracotomy lead systems and biphasic shocks are now the approach of choice, offering nearly a 100% success rate. This paper version reviews the current indications for the implantation of implantable cardioverter defibrillator and is an upgraded of an article previously published by the Arrhythmia's Section of the Spanish Society of Cardiology. Recommendations for qualification of centres implanting defibrillators and follow up are also addressed.

Aged↗
PubMed1998

[Patients with structural heart disease, syncope of unknown etiology and inducible ventricular arrhythmias treated with implantable defibrillators].

OBJECTIVES: This study evaluates the hypothesis that in patients with syncope of unknown origin and heart anomalies, inducible ventricular arrhythmias are specific arrhythmias and therefore should be treated as such. BACKGROUND: Although syncope is a frequent clinical entity, the evaluation and treatment of patients with syncope without a clear etiology still remains undefined. Many patients with syncope of undetermined origin undergo invasive electrophysiologic evaluation. Abnormalities of the sinus node, prolongation of conduction times or inducible arrhythmias found during these evaluations are usually assumed to be the cause of syncope, and are consequently treated. However, whether tachyarrhythmias are truly the cause of syncope, and whether treatment of these tachyarrhythmias can prevent recurrent syncope and arrhythmic death, is unknown. PATIENTS AND METHODS: An electrophysiological study was performed on 160 patients with structural heart disease and syncope of unknown origin. In 23 out of the 160 patients (16%), programmed electrical stimulation induced sustained ventricular arrhythmias. In 18 out of the 23 patients an automatic defibrillator was implanted and they form the study group. RESULTS: In these 18 patients, programmed ventricular stimulation induced sustained monomorphic ventricular tachycardia in 12, sustained polymorphic ventricular tachycardia in 2 and ventricular fibrillation in 4. During a mean follow-up of 14 months, 9 patients received 81 appropriate therapies from the device (53 because of ventricular tachycardia and 23 because of ventricular fibrillation). The probability of appropriate therapy was 100% at 1 year follow-up. There were no episodes of sudden death and 1 patient died of congestive heart failure. CONCLUSIONS: In patients with syncope of undetermined origin, heart disease and inducible ventricular tachyarrhythmias treated with a implantable cardioverter defibrillator, there is a high incidence of appropriate therapies. Our results support the practice of using implantable cardioverter defibrillators in patients with syncope of unknown origin, heart disease and inducible ventricular arrhythmias.

Adolescent↗
PubMed2002

Defibrillation.

The field of defibrillation is one of the most rapidly advancing areas in resuscitation. Defibrillation is also one of the most promising interventions for achieving improved survival from cardiac arrest. The purpose of this article is to provide an overview of the science and clinical applications of defibrillation.

Adult↗
PubMed2000

A randomized trial comparing heparin initiation 6 h or 24 h after pacemaker or defibrillator implantation.

OBJECTIVES: The purpose of this randomized study was to evaluate the prevalence of pocket hematomas in patients treated with heparin 6 h or 24 h after pacemaker or defibrillator implantation. BACKGROUND: The risks of pocket hematoma and need for evacuation after device implantation have not been defined in patients who require anticoagulation. METHODS: Forty-nine consecutive patients with an indication for anticoagulation with heparin after implantable defibrillator or pacemaker implantation were randomized to receive intravenous heparin either 6 h (n = 26) or 24 h (n = 23) postoperatively. Both groups also received warfarin on a daily basis starting the evening of surgery. Twenty-eight patients who received postoperative warfarin alone and 115 patients who did not receive anticoagulation were followed up in a study registry. RESULTS: A pocket hematoma developed in 6 of 26 patients (22%) who were treated with intravenous heparin 6 h postoperatively, as compared with 4 of 23 patients (17%) who were treated with intravenous heparin 24 h postoperatively (p = 0.7). In total, a pocket hematoma developed in 10 of 49 patients (20%) treated with heparin, 1 of 28 patients (4%) treated with warfarin alone and 2 of 115 (2%) patients who received no anticoagulation (p < 0.001). CONCLUSIONS: Intravenous heparin initiation 6 h or 24 h after pacemaker or defibrillator implantation is associated with a 20% prevalence of pocket hematoma formation. Warfarin therapy or no anticoagulation is associated with only a 2% to 4% risk of pocket hematoma formation.

Anticoagulants↗
PubMed2001

Recurrence of symptomatic ventricular arrhythmias in patients with implantable cardioverter defibrillator after the first device therapy: implications for antiarrhythmic therapy and driving restrictions. CARE Group.

OBJECTIVES: The purpose of this study was to investigate whether clinical or electrophysiologic characteristics could predict initial and subsequent implantable cardioverter defibrillator (ICD) therapy. BACKGROUND: Identification of markers to predict subsequent ICD therapy and symptoms after the first event could affect patient management. METHODS: We analyzed baseline and follow-up data on 125 ICD patients followed for 408+/-321 days. Medications and ICD programming were not changed after first ICD therapy. RESULTS: Implantable cardioverter defibrillator therapy occurred in 58 patients (46%). Clinical features were as follows: mean left ventricular ejection fraction (LVEF) 29%+/-15%; coronary artery disease 84%; presenting arrhythmia with sustained monomorphic ventricular tachycardia (SMVT) in 68%. In a multivariate analysis the relative risk for ICD therapy in patients presenting with SMVT versus cardiac arrest (CA) was 2.57 (range, 1.32 to 5.01), and for patients with LVEF < or =25%, 1.95 (1.11 to 3.45), respectively (p < 0.05). Implantable cardioverter defibrillator therapy was not predicted by any other variable. Forty-six patients had second ICD therapy. Mean time to second ICD therapy was only 66+/-93 days compared with 138+/-168 days for first ICD therapy (p < 0.05). No predictor for second ICD therapy was found. Regarding symptoms, impaired consciousness during initial ICD therapy was predicted only by SMVT cycle length <250 ms at electrophysiologic testing. In contrast, symptoms were similar between first and second ICD therapy (p = 0.0001). Of note, ventricular tachycardia cycle length preceding first and second ICD therapy was similar (r = 0.76, p = 0.001). CONCLUSIONS: First ICD therapy tends to occur in patients presenting with SMVT and LVEF < or =25%. Subsequent therapy occurs sooner and is unpredictable, suggesting that antiarrhythmic drug therapy should be considered after the first symptomatic ICD therapy. Symptoms during first ICD therapy predict subsequent symptoms, and patients presenting with SMVT and asymptomatic first ICD therapy are at very low risk for future syncopal ICD therapy.

Aged↗
PubMed1997

Conscious sedation with combined hypnotic agents for implantation of implantable cardioverter-defibrillators.

OBJECTIVES: The objective of this study was to evaluate the feasibility, safety and efficacy of placing implantable cardioverter-defibrillators (ICDs) in the electrophysiology laboratory using conscious sedation with combined hypnotic agents and deep sedation with etomidate. BACKGROUND: Implantable cardioverter-defibrillators with transvenous leads permit the use of simplified implantation techniques similar to those used for the insertion of permanent pacemakers. However, implantation of ICDs without general anesthesia has thus far gained limited acceptance. METHODS: In 162 patients, conscious sedation during ICD placement was achieved with combined intravenous midazolam, morphine and promethazine (Phenergan). Intravenous etomidate was administered to induce deep sedation for defibrillation threshold testing. First-time implantations were in the prepectoral position (n = 142), but some patients with preexisting devices received abdominal implants (n = 20). The results were compared with those of concurrent patients (n = 56) who received prepectoral implants under propofol anesthesia administered by an attending anesthesiologist. RESULTS: The anesthetic protocol was implemented without major intraoperative complications. During deep sedation with etomidate, episodes of apnea, hypoxia or arterial hypotension requiring therapeutic intervention did not occur. During a mean (+/-SD) follow-up period of 257 +/- 140 days (median 227, range 14 to 482), there were, among the 162 patients, a total of two nonsudden cardiac deaths-one 71 days and the other 157 days after the operation. There were two nonsudden deaths in the concurrent control subjects (n = 56)-one 13 days and the other 110 days after the operation. CONCLUSIONS: Implantation of ICDs under conscious sedation with combined hypnotic agents and deep sedation with etomidate is a safe and effective procedure with low perioperative morbidity and low long-term complication rates.

Aged↗
PubMed1999

Sudden death in implantable cardioverter-defibrillator recipients: clinical context, arrhythmic events and device responses.

OBJECTIVES: We sought to investigate the nature of terminal events and potential contributory clinical and nonclinical (e.g., device-related) factors associated with sudden death (SD) in recipients of an implantable cardioverter-defibrillator (ICD). BACKGROUND: The ICD is very effective in terminating ventricular tachycardia (VT) or ventricular fibrillation (VF), but protection against SD is not absolute. Little is known about the nature and potential causes of SD in patients with ICDs. METHODS: We analyzed 25 cases of out-of-hospital SD among patients enrolled in the clinical investigation of the Cadence Tiered-Therapy Defibrillator System. RESULTS: All patients (24 men and 1 woman, mean age 62+/-10 years) received epicardial lead systems. The majority (92%) had coronary artery disease and a previous myocardial infarction (MI), with a mean left ventricular ejection fraction 0.25+/-0.07. At device implantation, the mean defibrillation threshold was 13+/-5 J. Sudden death occurred 13+/-11 months later. Twenty patients (80%) had received appropriate ICD therapies before death, and 18 (72%) were receiving > or = 1 antiarrhythmic drugs at the time of death. Sudden death was tachyarrhythmia-associated in 16 patients (64%), non-tachyarrhythmia-associated in 7 (28%) and indeterminate in 2 (8%). In the 16 patients with tachyarrhythmia-associated SD, the overall first therapy success rate in tachycardia and fibrillation zones was 60% and 67%, respectively. However, despite protracted therapies (> or = 2 shocks) in 7 (66%) of 12 patients who received fibrillation therapies, the final tachyarrhythmic episode was ultimately terminated by the ICD in 15 (94%) of the 16 patients, whereas 1 patient died after multiple (initially successful) internal and external shocks for intractable VT/VF during exercise. In 10 patients (40%) one or more, primarily clinical, factors potentially contributory to SD were identified: heart failure (n=8), angina (n=2), hypokalemia (n=1), adverse antiarrhythmic drug treatment (n=1) and acute MI (n=1). An additional 10 patients (40%) had experienced an increase in frequency of ICD shocks within 3 months of SD. Appropriate battery voltages and normal circuitry function were found in all devices interrogated and analyzed after death. CONCLUSIONS: In this select group of patients receiving a third-generation ICD, SD was associated with VT or VF events in nearly two-thirds of patients, and death occurred despite ultimately successful, although often protracted, device therapies. These observations, along with evidence of recent worsening clinical status, suggest acute cardiac mechanical dysfunction as a frequent terminal factor. In recipients with ICDs, SD directly attributable to device failure seems to be rare.

Adult↗
PubMed1999

Shocks as predictors of survival in patients with implantable cardioverter-defibrillators.

OBJECTIVES: The objective of the study was to determine whether the occurrence of shocks for ventricular tachyarrhythmias during therapy with implantable cardioverter-defibrillators (ICD) is predictive of shortened survival. BACKGROUND: Ventricular tachyarrhythmias eliciting shocks are often associated with depressed ventricular function, making assessment of shocks as an independent risk factor difficult. METHODS: Consecutive patients (n = 421) with a mean follow-up of 756+/-523 days were classified into those who had received no shock (n = 262) or either one of two shock types, defined as single (n = 111) or multiple shocks (n = 48) per arrhythmia episode. Endpoints were all-cause and cardiac deaths. A survival analysis using a stepwise proportional hazards model evaluated the influence of two primary variables, shock type and left ventricular ejection fraction (LVEF <35% or >35%). Covariates analyzed were age, gender, NYHA Class, coronary artery disease, myocardial infarction, coronary revascularization, defibrillation threshold and tachyarrhythmia inducibility. RESULTS: The most complete model retained LVEF (p = 0.005) and age (p = 0.023) for the comparison of any shock versus no shock (p = 0.031). The occurrence of any versus no shock, or of multiple versus single shocks significantly decreased survival at four years, and these differences persisted after adjustment for LVEF. In the LVEF subgroups <35% and <25%, occurrence of multiple versus no shock more than doubled the risk of death. Compared with the most favorable group LVEF > or =35% and no shock, risk in the group multiple shocks and LVEF <35% was increased 16-fold. CONCLUSIONS: In defibrillator recipients, shocks act as potent predictors of survival independent of several other risk factors, particularly ejection fraction.

Aged↗
PubMed1999

Beta-blocker use and survival in patients with ventricular fibrillation or symptomatic ventricular tachycardia: the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial.

OBJECTIVES: To evaluate whether use of beta-adrenergic blocking agents, alone or in combination with specific antiarrhythmic therapy, is associated with improved survival in persons with ventricular fibrillation (VF) or symptomatic ventricular tachycardia (VT). BACKGROUND: The ability of beta-blockers to alter the mortality of patients with VF or VT receiving contemporary medical management is not well defined. METHODS: Survival of 1,016 randomized and 2,101 eligible, nonrandomized patients with VF or symptomatic VT followed in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial through December 31, 1996 was assessed using Cox proportional hazards analysis. RESULTS: The 817 (28%) patients discharged from hospital receiving beta-blockers had less ventricular dysfunction, fewer symptoms of heart failure and a different pattern of medication use compared with patients not receiving beta-blockers. Before adjustment for important prognostic variables, beta-blockade was not significantly associated with survival in randomized or in eligible, nonrandomized patients treated with specific antiarrhythmic therapy. After adjustment, beta-blockade remained unrelated to survival in randomized or in eligible, nonrandomized patients treated with amiodarone alone (n = 1142; adjusted relative risk [RR] = 0.96; 95% confidence interval [CI] 0.64-1.45; p = 0.85) or a defibrillator alone (n = 1347; adjusted RR = 0.88; 95% CI 0.55 to 1.40; p = 0.58). In contrast, beta-blockade was independently associated with improved survival in eligible, nonrandomized patients who were not treated with specific antiarrhythmic therapy (n = 412; adjusted RR = 0.47; 95% CI 0.25 to 0.88; p = 0.018). CONCLUSIONS: Beta-blocker use was independently associated with improved survival in patients with VF or symptomatic VT who were not treated with specific antiarrhythmic therapy, but a protective effect was not prominent in patients already receiving amiodarone or a defibrillator.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Current concepts in electrical defibrillation.

The electrical defibrillator has been proven to be a life-saving device in the treatment of cardiac arrest due to ventricular tachycardia or ventricular fibrillation. An understanding of the physiology and technology behind this device is useful for providers of emergency care. In this article, we review the current concepts in electrical defibrillation and briefly discuss the developmental history. The physiology and the technical considerations will make up the bulk of the discussion. The latest developments in electrical defibrillation also will be reviewed.

Defibrillators, Implantable↗
PubMed1996

[Anesthesia and implantable automatic defibrillator].

Since the introduction of first generation automatic implantable cardioverter defibrillators (AICD) in 1980, an increasing number of such devices have been inserted in patients at high risk for sudden death by ventricular tachycardia or fibrillation (VT/VF). With the improvement of technology and implanting techniques, devices may be inserted at present subcutaneously into the abdominal or the thoracic wall, rather than by thoracotomy. The anaesthesist is involved in the primary implantation of the AICD and the secondary testing of efficiency. Implantation generally requires general anaesthesia and the extension of monitoring is guided by the patient's underlying disease(s). The efficiency of the implanted system is tested one to two months later in inducing VT/VF under general anaesthesia and in determining the defibrillation threshold. The anaesthetist may also have to take care of patients with a AICD. For such cases the following recommendations can be made: a) gloves should be worn by doctors and nurses coming into contact with these patients, in order to limit the risk of electrification; b) a ring magnet must be available to inactivate the unit; c) in case of external defibrillation, the external paddles should be oriented perpendicularly to the line joining the two implanted electrodes; d) AICD should be disabled during electrocautery and prior to electroconvulsive therapy; e) the assistance of a electrophysiologist may be helpful for the management of these patients.

Anesthesia↗
PubMed1994

The implantable cardioverter defibrillator: the end of the thoracotomy approach.

Internal cardioverter defibrillator (ICD) implantation has become a standard therapy for life-threatening arrhythmias. A simple and safe surgical implantation technique is therefore mandatory in this high risk population. In a 30-month period 86 patients received 87 ICD devices. An endocavitary lead system was used as first choice in 62 patients and defibrillation thresholds (DFT) of 25 joules (J) or less were obtained in 57 patients. A thoracotomy approach was avoided using a biphasic shock wave form in 17 patients and the addition of a subcutaneous (sc) patch in 11 patients or wire array lead in 9 patients. There was one early non-technique related death (1.7%) after the transvenous approach. Reoperation was necessary in three patients with lead complications and in two patients for local device problems (one migration, one infection). With the recent progress in ICD technology, a thoracotomy approach could be avoided for the last 52 patients. For comfort and cosmetic reasons left subcostal insertion of the device has been successfully used in the last 50 patients. We conclude that the nonthoracotomy approach can now be offered to all patients in need for an ICD as a consequence of the technological progress made in the field of electric treatment of malignant ventricular arrhythmias. A stepwise approach with a minimum of implanted hardware and the use of biphasic shock systems now offers a simple and efficient treatment alternative with very low perioperative risk. Internal cardioverter defibrillator implantation in combination with open heart procedures can easily be avoided.

Adolescent↗
PubMed1997

Neuromonitoring in defibrillation threshold testing. A comparison between EEG, near-infrared spectroscopy and jugular bulb oximetry.

OBJECTIVES: The aim was to study the physiological effects of induced ventricular fibrillation and subsequent circulatory arrest for defibrillation threshold testing on the brain using the EEG, jugular bulb oxymetry and near-infrared spectroscopy. METHODS: Thirteen patients undergoing surgery for implantable cardioverter-defibrillator implantation or replacement under general anesthesia were included. We continuously monitored the jugular bulb oxygen saturation (SjO2), regional oxygen saturation (rSO2) and the EEG. RESULTS: 59 episodes of circulatory arrest were studied. In all cases the rSO2 fell instantly while the EEG changed within 12 +/- 4 seconds after induction. The EEG indicated ischemic changes, ranging from occurrence of rhythmic delta activity to cessation of all electrical activity. On successful defibrillation the rSO2 increased to values in excess of pre-arrest levels and restored towards baseline; the SjO2 initially fell followed by a similar overshoot. Recovery times increased in proportion to arrest duration. CONCLUSION: Short lasting episodes of circulatory arrest have serious, but transient effects on brain function. The rSO2 is an effective non-invasive tool for monitoring cerebral oxygenation during DFT-testing.

Adolescent↗
PubMed1997

Implantable cardioverter-defibrillator therapy: influence of left ventricular function on long-term results.

The degree of left ventricular impairment in an acknowledged important prognostic marker of long-term outcome for patients being evaluated for implantation of cardioverter-defibrillators. Just how left ventricular function impacts freedom from all-cause mortality, as well as from sudden death and cardiac death, is a subject of current major debate, and is analyzed hereunder from a large, recent multicenter ICD patient cohort. The multicenter database consists of data from 361 patients receiving implantable cardioverter-defibrillators for standard indications, that is, documented episodes of ventricular fibrillation or sustained ventricular tachycardias with poor hemodynamic toleration. Data were collected from 1988 to 1995 at three centers in Germany. Two-hundred and three patients (56%) had a left ventricular ejection fraction (LVEF) > 0.30 (group I), and 158 patients (44%) had a LVEF < or = 0.30 respectively (group II). The mean follow-up was 23.9 months (range 3-98 months). Overall survival at 5 years for group II patients was lower, as expected, at 74.1% versus 94.2%, respectively (P < 0.0001). Mortality was higher for each different cause of death in group II patients than in Group I: sudden arrhythmic deaths, 5 versus 1 (P < 0.048); nonsudden cardiac deaths, 16 versus 5 (P < 0.002); noncardiac deaths, 7 versus 2 (P < 0.03). Group II patients received a higher rate of at least one presumably appropriate shock at 86 (54.4%) versus 89 (43.8%) in group I (P < 0.05). However (and somewhat surprisingly), neither the time from ICD implantation to death, comparing only the patients who died, nor the event-free probability of appropriate shocks due to very rapid, sustained ventricular arrhythmias (> 230 beats/min), including a presumed risk of sudden arrhythmogenic death, differed between groups I and II. Sudden cardiac death was only marginally affected by LVEF (group I, 1.5% actuarial, 5-year survival 99.5%; group II, 3.1% and 95.8%, respectively). Therefore, the lower overall survival in ICD patients with LVEF < or = 0.30 resulted mainly from causes of death that cannot be directly influenced by cardioverter-defibrillator therapy. However, because group II patients had a far higher incidence of at least one ventricular tachyarrhythmia terminated by ICD shocks than group I patients, they also probably derived benefit from ICD therapy.

Cohort Studies↗
PubMed1998

A comparison of pectoral and abdominal transvenous defibrillator implantation: analysis of costs and outcomes.

Traditionally cardioverter-defibrillator implantation was performed by surgeons under general anesthesia. However, with advances in lead and pulse generator technology, the surgical implantation technique has been simplified and routine pectoral pulse generator placement without general anesthesia is now possible. To assess the economic benefit of pectoral implantation, we analyzed 43 consecutive initial transvenous defibrillator implantations. The patients were grouped according to whether the implant was abdominal by a surgeon in the operating room (n = 23) or pectoral by an electrophysiologist in a laboratory (n = 20). The duration of hospitalization was significantly longer in the operating room than in the laboratory group (8.1 +/- 3.4 vs 5.8 +/- 2.4 days, p = 0.01), which was due primarily to the postoperative stay which averaged 1.9 days longer. Total costs were $40,274 +/- 6,861 for the operating room cohort and $32,546 +/- 3,634 for the lab group (p < 0.001). This reduction was due to a 32% lowering of professional costs and an 18% lowering of facility costs. We conclude that pectoral defibrillator implantation is cost effective and results in significant reductions of hospital stay.

Abdominal Muscles↗
PubMed1999

A systematic evaluation of conventional and novel transvenous pathways for defibrillation.

INTRODUCTION: Conventional implantable cardioverter defibrillators employ endocardial (shock) electrodes with a lead located in the right ventricular apex (RV) and a "hot-can" electrode located subcutaneously in the left pectoral region. In the event of a high defibrillation threshold (DFT) a third electrode is frequently employed in the superior vena cava (SVC). We report the comparison of conventional and novel locations of additional electrodes with the RV/Can configuration, in a porcine model. METHOD: In 12 anesthetized pigs (30-45 kg), endocardial defibrillation electrodes were randomized to the following locations: RV/Can, RV/Can + SVC, RV/Can + main pulmonary artery (MPA) and RV/Can + left pulmonary artery wedge position (PAW), RV/Can + high inferior vena cava (HIVC), RV/Can + Low inferior vena cava (LIVC). Ventricular fibrillation (VF) was induced using 60 Hz alternating current. After 10 seconds VF a rectangular biphasic shock was delivered by the ARD9000 (Angeion Corp). The DFT was determined for each configuration using a modified four-reversal binary search. All configurations were compared using a repeated measures analysis of variance (ANOVA) statistical test and the five 3-electrode configurations were compared to the RV/Can position using a Dunnett test. RESULTS: Mean DFTs: RV = 21.5 +/- 4.8 J, SVC = 16.8 +/- 4.7 J (p < 0.05 vs. RV), HIVC = 21.1 +/- 4.7 J (p <. 0.05), LIVC = 19.1 +/- 5.7 J (p <. 0.05 vs. RV), MPA = 16.0 +/- 5.8 J (p < 0.01), PAW = 17.5 +/- 4.6 J (p < 0.05 vs. RV). CONCLUSIONS: Relative to the RV/can configuration the addition of a third electrode in the PA, PAW or SVC significantly reduces the DFT in the pig. The addition of an electrode to the IVC did not significantly reduce the DFT in our model.

Animals↗
PubMed1999

Percutaneous extraction of transvenous defibrillator leads using the VascoExtor pacing lead removal system.

In the implantable cardioverter defibrillator era the necessity for lead removal is not negligible. A specially designed extraction lead system for percutaneous removal of such leads is lacking, in contrast to the existing pacing lead extraction systems. We report the successful percutaneous extraction of four implantable cardioverter defibrillator leads in three patients because of lead malfunction using a novel pacemaker lead extraction system, the VascoExtor (VascoMed) system. Three leads were successfully removed in two patients using traction with special locking stylets from the superior approach. One lead was removed using the system's additional extraction tools through the femoral approach. There were no complications. This preliminary experience shows that the VascoExtor (VascoMed) pacemaker lead extraction system can also be used in implantable cardioverter defibrillator lead extraction safely and effectively. In addition to the locking stylets, adjunct percutaneous extraction tools may be needed in some cases.

Cardiovascular Surgical Procedures↗