Clinical experience with antitachycardia pacing and improved detection algorithms in a new implantable cardioverter-defibrillator.

OBJECTIVES: This study was conducted to assess the effectiveness of antitachycardia pacing modes and detection algorithms in patients with a new third-generation implantable cardioverter-defibrillator. METHODS: Twenty-three of 42 consecutive patients had coronary artery disease, 14 had dilated cardiomyopathy, 2 had prior valve replacement and 3 had arrhythmogenic right ventricular dysplasia. The mean ejection fraction was 41 +/- 14%; there were 31 men (74%) and 11 women, with a mean age of 53 years. On the basis of preoperative and postoperative electrophysiologic studies, in 28 patients antitachycardia pacing was postoperatively programmed randomly as "burst" (66%) or autodecremental "ramp" (34%) stimulation with a first coupling interval of 81% of tachycardia cycle length and up to 8 sequences with 3 to 10 stimuli. RESULTS: During a follow-up interval of 6.3 +/- 2.2 months, 15 patients were treated by antitachycardia pacing for a median of 6 (range 1 to 59) hemodynamically stable ventricular tachycardias (175 +/- 12 beats/min). In 5 patients, 22 ventricular tachycardias (9%) were not terminated by antitachycardia pacing but by cardioversion. Seven (3%) of these episodes accelerated (> 50 ms) during antitachycardia pacing. Syncope did not occur during these episodes. In seven patients initial antitachycardia pacing in cases of supraventricular tachycardias delayed charging and redetection prevented inappropriate discharges. Additional detection algorithms were programmed only after inappropriate therapy. The sudden "onset" and "sustained rate duration" criteria were programmed in three patients and the cycle length "stability" criteria in six patients, respectively. After activation of these detection algorithms only two of the seven patients had further inappropriate device discharges. CONCLUSIONS: Thus, antitachycardia pacing by this implantable cardioverter-defibrillator effectively and appropriately terminated 91% of hemodynamically stable ventricular tachycardias. Inappropriate device discharges were prevented in some patients by antitachycardia pacing and additional detection algorithms.

Do patients with an implantable defibrillator live longer?

OBJECTIVES: This study was done to provide information on the potential benefit of implantable cardioverter-defibrillator therapy regarding sudden and arrhythmia-related deaths and to examine whether such therapy improves survival. BACKGROUND: Implantation of automatic cardioverter-defibrillators is reported to abort sudden cardiac death due to malignant tachyarrhythmias. METHODS: Between 1989 and 1992, 107 patients were screened for implantation of a third-generation implantable cardioverter-defibrillator combined with endocardial leads. Mean age was 57 +/- 13 years and mean ejection fraction was 40 +/- 15%. Sudden death, total arrhythmia-related death and total cardiac death were compared with the occurrence of fast ventricular tachyarrhythmias (> 240 beats/min), assuming that most of these arrhythmias would have been fatal without treatment by the implantable cardioverter-defibrillator. RESULTS: The surgical mortality rate was 2.7% in all 107 patients and 1% in the 99 patients who qualified for endocardial leads. During a follow-up period of 12 +/- 8 months, actuarial survival rate free of events at 6 months as well as at 12 and 18 months was 100% for sudden death, 97% for total arrhythmia-related death and 95% for total cardiac death. In contrast, after 6, 12 and 18 months, the rate of survival free of fast ventricular tachycardia was only 83%, 74% and 69%, respectively, and the rate of survival free of any ventricular tachyarrhythmia was only 59%, 49% and 40%, respectively. CONCLUSIONS: The outcome of patients treated with an implantable cardioverter-defibrillator and endocardial defibrillation leads is excellent. For many patients, this treatment is probably lifesaving.

Algorithm for the prevention of ventricular tachycardia onset: the Prevent Study.

The Prevent Study is designed to investigate the effect of a rate-smoothing algorithm on the onset of ventricular tachycardia in patients with implanted cardioverter defibrillators (ICD) with dual-chamber pacing and sensing function. Included in the study are patients who require ICD therapy for recurrent ventricular tachycardia or aborted cardiac arrest. After giving informed consent to the study, the patients receive a Ventak AV ICD (CPI-Guidant, St. Paul, MN). The patients are randomized to start either with active or inactive rate-smoothing algorithm. After 3 months, all patients cross over to the opposite group. Questionnaires are used to investigate quality-of-life issues. A total of 240 patients will be enrolled in the study, with a minimum follow-up of 6 months.

Comparison of frequency of aggravation of ventricular tachyarrhythmias after implantation of automatic defibrillators using epicardial versus nonthoracotomy lead systems.

The time of onset of 4,471 episodes of ventricular tachycardia (VT) or fibrillation (VF) in 40 of 65 patients with an implantable cardioverter-defibrillator (ICD) with endocardial defibrillation electrodes (group 1) and in 53 of 123 with epicardial defibrillation electrodes (group 2) was analyzed to examine whether the incidence of VT/VF immediately after surgery is greater than during further follow up and whether the site of lead placement exerts an influence on the occurrence of these arrhythmias. Actuarial survival rates free of VT/VF were 77, 65, and 54% at 1, 3 and 6 months, respectively, for group 1, and 84, 66 and 52%, respectively, for group 2. The probability of VT/VF was increased only during the first week after surgery; in that week, 12.8% of all patients had VT/VF, without significant differences between groups 1 and 2. Until the end of the first month, this percentage increased to 23%, whereas only 12 to 15% of patients had VT/VF during subsequent months. In 19 patients with third-generation devices capable of terminating tachycardias by overdrive pacing, 326 of 412 VT/VF episodes occurring in the first week after surgery were terminated by antitachycardia pacing, and only 86 had to be terminated by cardioversion or defibrillation. No postoperative exacerbation of inappropriate ICD therapies was observed in any group; 2 to 5% of patients per month received ICD therapies for atrial fibrillation or sinus tachycardia. Patients who received appropriate ICD therapies in the first week after surgery were at high risk of recurrence of VT/VF.(ABSTRACT TRUNCATED AT 250 WORDS)

[Drug therapy of tachycardic atrial arrhythmias]. / Medikamentöse Therapie tachykarder Vorhofrhythmusstörungen.

There are defined indications for the acute pharmacological management of AV-nodal reentry tachycardias, AV reentry tachycardias and for the acute and chronic ventricular rate control in atrial fibrillation. Possible indications arise for the chronic pharmacologic therapy of AV reentry tachycardias, pharmacological cardioversion and prophylaxis of atrial fibrillation. In future there will be a trend towards nonpharmacological management of atrial arrhythmias.

[Structure of the Australian system of 'Diagnosis Related Groups' regarding cardiovascular diseases and corresponding cost weights in Germany]. / Ubersicht der australischen und deutschen diagnosebezogenen Fallgruppen mit deren Relativgewichten für die Kardiologie.

BACKGROUND: An adapted system of 'Diagnosis Related Groups' (DRG's) will be introduced for Germany at the beginning of 2003. This article focuses on the structure of the Australian DRG system (AR-DRG 4.1) regarding the diseases of the cardiovascular system and corresponding cost weights in Germany (G-DRG 1.0). METHODS: Cardiac diagnoses, procedures and cost weights (with a different base rate) were compared between the Australian and German DRG's. RESULTS: Categories and procedures for diagnostics and therapies are shown regarding coronary interventions, electrophysiological strategies including implantation of pacemakers and cardioverter/ defibrillators, hybrid treatment modalities, transcatheter closure of interatrial/-ventricular communications as well as interventions during intensive care treatment.

Radiofrequency catheter ablation of ventricular tachycardia following implantation of an automatic cardioverter defibrillator.

OBJECTIVES: The present study reports on the complementary role of two nonpharmacological options of antiarrhythmic therapy. BACKGROUND: Catheter ablation, antitachycardia surgery, and the implantable cardioverter defibrillator (ICD) have become important tools in the management of ventricular tachyarrhythmias. However, the emergence of ventricular tachyarrhythmias after implantation of an ICD is possible because the arrhythmogenic substrate is not affected. PATIENTS AND METHODS: Six of 180 patients developed frequent episodes of monomorphic ventricular tachycardia (n = 2) or incessant ventricular tachycardia (n = 4) following implantation of an ICD and underwent radiofrequency (RF) catheter ablation. Catheter ablation was performed using a RF generator HAT 200. Energy was delivered between a 4-mm tip electrode of the ablation catheter and a patch electrode. RESULTS: Catheter ablation was done 6.8 +/- 5 months following ICD implantation; 6 +/- 2.2 RF impulses were delivered at the site of origin of ventricular tachycardia characterized by early endocardial activation during ventricular tachycardia, identical pace mapping and long latency between stimulus, and QRS-complex in five patients. New bundle branch reentry was the underlying mechanism of ventricular tachycardia in one patient. RF catheter ablation resulted in termination of incessant ventricular tachycardia. Immediately postablation, the documented ventricular tachycardia was rendered noninducible in all patients. No ICD malfunctions have been observed. One patient died due to heart failure 24 hours after successful ablation of the incessant ventricular tachycardia. During a follow-up of 5-19 months, episodes of ventricular tachycardia recurred in four patients. All episodes could be controlled by the ICD without frequent cardioversions. CONCLUSION: RF catheter ablation is a complementary therapeutic option in case of frequent or incessant ventricular tachycardia after ICD implantation.

[Therapy of ventricular tachyarrhythmia with implantable cardioverters/defibrillators--mortality and complications using epicardial electrodes]. / Therapie ventrikulärer Tachyarrhythmien mit implantierbaren Kardioverter/Defibrillatoren--Sterblichkeit und Komplikationen bei der Verwendung epikardialer Elektroden.

Technical improvements of third generation implantable cardioverter defibrillators (ICD) like antitachycardia pacing modalities lead to an extended use of ICDs, not only in patients with aborted sudden cardiac death, but also in patients with hemodynamically tolerable ventricular tachycardia. In addition, anticipated results of current prospective studies might indicate the prophylactic use of ICDs in patients with high risk for sudden cardiac death, but without documented ventricular tachyarrhythmias. This report reviews mortality and complications associated with the ICDs with epicardial defibrillation leads. Mortality is separated in cardiac death, sudden cardiac, arrhythmogenic "not so sudden" cardiac death, and overall mortality. Pulmonary complications and infections are related to the underlying disease and the surgical procedure. Device- and lead-related complications, high defibrillation thresholds, pacemaker interactions, inappropriate shocks, arrhythmic effects, syncope, and psychosocial problems are reported, respectively.

Role of ventricular tachycardia surgery and catheter ablation as complements or alternatives to the implantable cardioverter defibrillator in the 1990s.

Although the implantable cardioverter defibrillator is used increasingly, other nonpharmacological approaches have their indications and merits. Furthermore, as the natural history of ventricular tachyarrhythmias or their underlying structural cardiac abnormality, i.e., coronary artery disease, dilated cardiomyopathy, arrhythmogenic right ventricular disease, etc. change, the mode of therapy may be modified accordingly. Because of the disappointing results of the CAST study in previously asymptomatic patients after myocardial infarction and the evidence that failure of one or two antiarrhythmic drugs tested by programmed ventricular stimulation in patients with documented sustained ventricular tachycardia or fibrillation predicts further drug failure, there will be a significant increase in the use of implantable cardioverters defibrillators in the 1990s. However, care should be taken to avoid inappropriate use of these devices.

Nd:YAG laser-photocoagulation: acute electrophysiological, hemodynamic, and morphological effects in large irradiated areas.

Laser-photocoagulation (LPC) of arrhythmogenic myocardium has been reported to successfully ablate ventricular tachycardia. The purpose of this study was to investigate the acute hemodynamic and electrophysiological effect of continuous laser energy (Nd:YAG, 1060 nm) applied via a 0.4-mm quartz fiberoptic on the epicardial surface of the heart in nine dogs. A total of 51 +/- 2.3 pulses was delivered in each animal to induce homogeneous tissue necrosis. Applied energy was 12.3 +/- 2.7 J/mm2, irradiated surface measured 12.6 +/- 3.0 cm2, lesion depth was 6.3 +/- 1.2 mm (range: 5.0-8.1 mm), lesion volume was 8.1 +/- 2.8 cm3 (6.8% of left ventricular [LV] mass). After LPC, epicardial stimulation threshold significantly rose from 1.0 +/- 0.3 to 10.2 +/- 4.9 mA in the border zone to nontreated tissue and from 0.9 +/- 0.4 to 32 +/- 15.7 mA in the center of the lesions. Loss of epicardial activation in the irradiated areas could be demonstrated by epicardial mapping. Ventricular extrasystoles during LPC were seen in all dogs, ventricular tachycardia in seven, and ventricular fibrillation in two dogs. After LPC, cardiac output and LV dP/dtmax significantly decreased by 14.2% and 11.2%. LPC induced predictable homogeneous tissue edema, eosinophilic staining, contraction band necrosis, and sharp demarcated hemorrhagic border zones with a sharp electrical border zone to nontreated tissue and loss of epicardial activation. During LPC, various arrhythmogenic effects could be observed. However, no persistent arrhythmic activity developed after LPC. The results confirm the feasibility of epicardial LPC of the myocardium. Although not rested in this study, LPC of arrhythmogenic tissue may also be feasible as a treatment modality of ventricular tachycardia.

[Percutaneous high frequency current catheter ablation in permanent ventricular tachycardia of the "bundle-branch reentry" type after implantation of an automatic cardioverter-defibrillator]. / Perkutane Hochfrequenzstrom-Katheterablation bei permanenter ventrikulärer Tachykardie vom "bundle branch reentry"-Typ nach Implantation eines automatischen Kardioverter-Defibrillators.

A 65-year-old female patient with a history of recurrent sustained ventricular tachycardia presented with an incessant ventricular tachycardia (cycle length 360-400 ms) following implantation of a cardioverter-defibrillator (ICD). The tachycardia could not be terminated by antiarrhythmic drug treatment, antitachycardia pacing or internal defibrillation via the ICD. An invasive electrophysiologic study revealed that the mechanism of this newly occurring tachycardia was bundle branch reentry. The patient underwent emergency catheter ablation using radiofrequency (RF) current. Endocardial mapping of the right bundle branch and of the distal His bundle was performed and a bundle branch reentry tachycardia was diagnosed. After delivery of the fifth RF-impulse, the tachycardia terminated and complete AV block was induced. No malfunction of the ICD was observed following RF-ablation. The patient was hemodynamically stable with a junctional escape rhythm and antibradycardia pacing back-up of the ICD (VVI-mode). This case report demonstrates the feasibility of RF catheter ablation in the treatment of incessant bundle branch reentry tachycardia as a complementary option after implantation of an ICD.

A prospective randomized cross-over comparison of mono- and biphasic defibrillation using nonthoracotomy lead configurations in humans.

INTRODUCTION: For current implantable defibrillators, the nonthoracotomy approach to implantation fails in a substantial number of patients. In a prospective randomized cross-over study the defibrillation efficacy of a standard monophasic and a new biphasic waveform was compared for different lead configurations. METHODS AND RESULTS: Intraoperatively, in 79 patients receiving nonthoracotomy defibrillation leads, the defibrillation threshold was determined in the initial lead configuration for the mono- and biphasic waveform. In each patient, both waveforms were used alternately with declining energies (20, 15, 10, 5 J) until failure of defibrillation occurred. Three different initial lead configurations were tested in different, consecutive, nonrandomized patients using a bipolar endocardial defibrillation lead alone (A; n = 36) or in combination with a subcutaneous defibrillation patch (B; n = 24) or array (C; n = 19) lead. The lowest successful defibrillation energy with the biphasic waveform was less than, equal to, or higher than with the monophasic waveform in 64%, 28%, and 8% of patients, respectively, and on average significantly lower with the biphasic waveform for all three lead configurations (A: 11.3 +/- 4.4 J vs 14.5 +/- 4.5 J; B: 9.7 +/- 4.7 J vs 15.1 +/- 4.5 J; C: 7.9 +/- 4.5 J vs 12.4 +/- 4.9 J). Defibrillation efficacy at 20 J was significantly improved by the biphasic waveform (91% vs 76%). CONCLUSION: In combination with nonthoracotomy defibrillation leads, the biphasic waveform of a new implantable cardioverter defibrillator showed superior defibrillation efficacy in comparison to the standard monophasic waveform. Defibrillation thresholds were improved for lead systems with and without a subcutaneous patch or array lead.