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Biomedical subjects

G Breithardt

Publications and source records attributed to G Breithardt.

At least 343 records · Page 19Linked to original sources
PubMed1992

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.

Adult↗
PubMed1992

Efficacy of antiarrhythmic drugs in patients with arrhythmogenic right ventricular disease. Results in patients with inducible and noninducible ventricular tachycardia.

BACKGROUND: Ventricular tachyarrhythmias are the major clinical manifestation of arrhythmogenic right ventricular disease. Although antiarrhythmic therapy has been widely advocated, there is only limited information available on the efficacy of antiarrhythmic drugs in these patients. METHODS AND RESULTS: The short- and long-term efficacies of various antiarrhythmic agents were retrospectively and prospectively analyzed in 81 patients (mean age, 39 +/- 14 years; range, 16-68 years; 61.7% males) with arrhythmogenic right ventricular disease. In 42 patients with inducible ventricular tachycardia during programmed ventricular stimulation, the following efficacy rates were obtained: class Ia and Ib drugs (n = 18), 5.6%; class Ic drugs (n = 25), 12%; beta-blockers (n = 8), 0%; sotalol (n = 38), 68.4%; amiodarone (n = 13), 15.4%; verapamil (n = 5), 0%; and drug combinations (n = 26), 15.4%. Only one of the 10 patients not responding to sotalol was treated effectively by amiodarone, whereas the remaining nine patients proved to be drug refractory toward all other drugs tested (3.8 +/- 2.3 drugs, including amiodarone in five cases) and underwent nonpharmacological therapy. During a follow-up of 34 +/- 25 months, three of the 31 patients (9.7%) discharged on pharmacological therapy had nonfatal recurrences of ventricular tachycardia after 0.5, 51, and 63 months, respectively. In 39 patients with noninducible ventricular tachycardia during programmed ventricular stimulation, the following efficacy rates were observed: class Ia and Ib drugs (n = 16), 0%; class Ic agents (n = 23), 17.4%; beta-blockers (n = 7), 28.6%; sotalol (n = 35), 82.8%; amiodarone (n = 4), 25%; verapamil (n = 24), 50%; and drug combinations (n = 11), 9.1%. During a follow-up of 14 +/- 13 months, four of 33 patients (12.1%) discharged on antiarrhythmic drugs had nonfatal relapses of their clinical ventricular arrhythmia. CONCLUSIONS: Thus, in arrhythmogenic right ventricular disease, sotalol proved to be highly effective in patients with inducible as well as noninducible ventricular tachycardia. Patients with inducible ventricular tachycardia not responding to sotalol are likely to not respond to other antiarrhythmic drugs and should be considered for nonpharmacological therapy without further drug testing. Amiodarone did not prove to be more effective than sotalol and may not be an alternative because of frequent side effects during long-term therapy, especially in young patients. Verapamil and beta-blockers were effective in a considerable number of patients with noninducible ventricular tachycardia and may be a therapeutic alternative in this subgroup. Class I agents appear to be rarely effective in the treatment of both inducible and noninducible ventricular tachycardia in arrhythmogenic right ventricular disease.

Adolescent↗
PubMed1992

How to evaluate class III antiarrhythmic drug efficacy clinically: the benefits and shortcomings of the invasive approach.

Ventricular tachycardia and ventricular fibrillation are frequent complications of organic heart disease. There is sufficient evidence that serial electrophysiologic testing is able to predict long-term efficacy of antiarrhythmic agents in patients with malignant ventricular tachyarrhythmias. This approach has not only been useful for the evaluation of class I drugs, but recent studies have shown that this invasive method may also be useful for the management of patients undergoing treatment with class III antiarrhythmic agents such as amiodarone and sotalol. The results of several studies suggest that class III agents are more effective than class I drugs in patients presenting with ventricular tachycardia or ventricular fibrillation. Proarrhythmic complications in patients treated with class III antiarrhythmic drugs are mainly characterized by torsades de pointes. Their incidence does not exceed 5%. Further studies are necessary to elucidate the mechanisms underlying this type of proarrhythmia. By the use of currently available stimulation techniques, patients who might develop torsades de pointes while on therapy with a class III agent cannot be identified.

Amiodarone↗
PubMed1992

[Ventricular cardiac arrhythmias 1992. Summary and perspectives].

The treatment of tachycardias has undergone marked changes. Doubts on the effectiveness and the benefits of antiarrhythmic drug therapy are the reason for a re-evaluation of the use of so-called class I- and class III-antiarrhythmic drugs. At the same time, there has been an increased awareness of new techniques for risk assessment; for instance, in postmyocardial infarction patients, not only the type and frequency of spontaneous arrhythmias but also other parameters like extent of left ventricular dysfunction, ventricular late potentials, inducible ventricular arrhythmias and effects of the autonomous nervous system should be considered. Serial electrophysiological testing to predict the efficacy of antiarrhythmic drug therapy has recently been challenged. Non-pharmacological approaches have been used in an increasing proportion of patients. Nevertheless, there is also an increasing interest in new antiarrhythmic drugs, especially those that prolong repolarization (class III).

Anti-Arrhythmia Agents↗
PubMed1992

Aortic valve replacement with stentless xenografts.

Between 15th June 1991 and 15th August 1992, 40 patients underwent aortic valve replacement with the newly designed Edwards stentless aortic bioprosthesis 2500. The patients' ages ranged from 24 years to 80 years (mean 60.3 years). Preoperatively, 17 patients presented with pure aortic stenosis, three with aortic regurgitation and 20 with mixed lesion. The operations were performed with normothermic extracorporeal cardiopulmonary bypass and cold cardioplegic arrest. The implanted valves ranged in diameter from 21 mm to 27 mm. Ten patients received a subcoronary implantation, with the lower row of sutures being interrupted and the upper being continuous. The so-called miniroot technique was used in the other 30, also involving lower interrupted and running upper sutures after adaptation of the coronary ostia to the preformed openings in the graft. The aortic cross-clamp time ranged from 51 minutes to 94 minutes (mean 71 minutes). There was no operative mortality but three patients died early after the operation due to cardiac tamponade, sepsis and pneumonia. There was no late mortality or morbidity in the surviving patients up to 16 months postoperatively. Echocardiography, performed at discharge and twice a year thereafter showed no signs of significant valve incompetence in any patient, and continuous wave Doppler measurements indicated that resting pressure gradients across the aortic valve were low or absent. Our preliminary experience with the stentless aortic xenograft shows improved hemodynamic function as compared to stent mounted xenografts or mechanical prostheses. Further studies are needed, however, to establish the long-term performance of this device.

Adult↗
PubMed1992

[Initial presentation of ventricular pre-excitation after catheter ablation of concealed retrograde conducting accessory atrioventricular pathways].

Catheter ablation using radiofrequency or direct current energy was performed in 19 consecutive patients with concealed accessory pathways. Four patients developed manifest preexcitation for the first time following ablation. The concealed accessory pathways of these four patients were localized at right lateral, left posteroseptal, left posterolateral, and left lateral sites, respectively. In two patients, manifest preexcitation developed immediately after attempted ablation. In the other two patients, preexcitation occurred after 4 and 14 days. Electrophysiologic testing revealed in all four patients that the origin of manifest preexcitation corresponded to the site of the concealed pathway. Successful catheter ablation using radiofrequency current was performed in three patients. One patient preferred surgical interruption of the accessory pathway. The reason for this sudden emergence of preexcitation of these patients with only retrograde conducting pathways remains to be investigated. The anterograde conduction capacity might have been modified by damaging the site of the accessory pathway insertion.

Adult↗
PubMed1992

[Percutaneous high frequency current catheter ablation in permanent ventricular tachycardia of the "bundle-branch reentry" type after implantation of an automatic cardioverter-defibrillator].

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.

Aged↗
PubMed1992

[Ventricular late potentials--methods and clinical importance].

Ventricular late potentials are due to regionally depressed inhomogenous conduction, mainly in the border zone of a previous myocardial infarction. They can be recorded noninvasively using high-resolution signal-averaging techniques. They are almost never detectable in normals, whereas they represent a frequent finding in postmyocardial infarction patients. The presence of ventricular late potentials after previous myocardial infarction predicts the subsequent occurrence of hemodynamically severe sustained ventricular tachycardia and/or sudden cardiac death. Their predictive significance can be increased by combining signal-averaging with long-term ECG recording and estimates of left-ventricular ejection fraction. However, despite recent major improvements in identification of patients at risk, there is still a need for an effective mode of prevention of serious ventricular tachyarrhythmias after myocardial infarction.

Death, Sudden↗
PubMed1992

[High frequency current catheter coagulation using pulsed energy delivery. Results with isolated myocardial tissue].

The feasibility and efficacy of pulsed radiofrequency (RF) current delivery was assessed and compared to results obtained by continuous energy delivery. Energy was delivered to ventricular preparations of isolated porcine hearts (HAT 100, 500 kHz, Osypka, FRG). In the pulsed mode, impulse duration and pause duration were varied between 50 and 500 ms. Total duration of coagulation was 30 s in all cases. The depth of induced lesions was significantly enhanced by a short impulse- and pause duration (50-70 ms) compared to continuous RF energy delivery. At long pause durations (200-500 ms) and short impulse duration, depth and diameter of lesions significantly decreased. The incidence of sudden increases in impedance was markedly attenuated when energy was delivered discontinuously. Thus, pulsed RF energy delivery can be used to enhance the depth of RF lesions. The decreased incidence of sudden rises in impedance during pulsed energy delivery further enhances the feasibility of RF coagulation. An improvement in heat transfer to deeper tissue layers can be considered as the mechanism responsible for these effects.

Animals↗
PubMed1992

[Biophysical aspects of high frequency catheter ablation. Studies of the significance of sudden changes in impedance].

UNLABELLED: To determine the effects and the underlying mechanisms of sudden rise of impedance during radiofrequency (RF) catheter ablation, 60 RF applications were delivered to isolated preparations of ventricular myocardium at three different power levels (mean: 3.7, 11.3, 19.3 watts). Pulse duration was 30 s, current voltage and catheter tip temperature were continuously monitored. Impedance rise occurred during 34 of 60 applications; the incidence of impedance rise increased at higher power levels. Impedance rise was significantly more often observed when the preparations were superfused with heparinized blood compared to saline solution (p less than 0.05). Catheter-tip temperature during radiofrequency application without impedance rise was significantly lower compared to applications with impedance rise (mean = 108 degrees C vs. 121 degrees C, p less than 0.01). The increase of catheter-tip temperature and maximal-tip temperature following impedance rise was significantly higher in blood when compared to saline solution (mean = +48 degrees C vs. +13 degrees C (p less than 0.001), Tmax: 121 degrees C vs. 245 degrees C). Following impedance rise, insulation defects of the electrode catheter and vaporized crater formation of the myocardium was often observed. CONCLUSIONS: During radiofrequency catheter ablation impedance rise occurs following overheating of the catheter electrode (greater than 110 degrees C). After impedance rise, catheter-tip temperature markedly increases. Insulation defects of the catheter and vaporized craters in the myocardium frequently occur after impedance rise. The results have important implications for the clinical use of RF-currents for catheter ablation; energy application should be immediately stopped after the occurrence of impedance rise.

Animals↗
PubMed1992

[Catheter ablation of ventricular tachycardia].

Catheter ablation of ventricular tachycardias was performed in a total of 80 patients whose tachycardias were considered as drug refractory and who were not considered to be candidates for antitachycardic surgery or implantation of an automatic cardioverter defibrillator. After careful endocardial catheter mapping including pacing interventions, either direct-current (DC) (n = 61) or radiofrequency current (RF) (n = 13) or both (n = 6) were applied of the "site of origin" of ventricular tachycardia or the "zone of slow conduction". 42 of 51 patients with coronary heart disease were discharged; ventricular tachycardia recurred in 8 cases, and 2 patients died suddenly. In the remaining 32 patients, there were no recurrences of ventricular tachycardia during a mean follow-up period of 12 month. Three patients died perioperatively. In 21 of 29 patients without coronary artery disease, no recurrences of ventricular tachycardia were observed (mean duration of follow-up 17 months) whereas 8 cases had a recurrence of ventricular tachycardia.

Cardiac Catheterization↗
PubMed1992

Catheter ablation of ventricular tachycardia using radiofrequency current.

Catheter ablation techniques have evolved as an alternative to map-guided surgery and proven effective in a variety of supraventricular tachyarrhythmias. Direct current catheter ablation has been shown to be effective in about 50 to 70% of cases. Approximately, 60% of patients with structural heart disease and monomorphic ventricular tachycardia were successfully treated using direct current ablation techniques. This overall success rate and possible risks associated with the use of direct current have stimulated the search for other energy sources appropriate for catheter ablation. Presently, only a few preliminary reports on the clinical efficacy of radiofrequency energy for the treatment of ventricular tachyarrhythmias in man exist. 23 patients with identifiable heart disease at a mean age of 52 +/- 17 years underwent radiofrequency catheter ablation. 16 patients had coronary artery disease, one patient dilative cardiomyopathy and six patients had arrhythmogenic right ventricular disease. All patients presented with chronic current sustained ventricular tachycardia. After detailed endocardial catheter mapping radiofrequency energy was applied at the site of earliest ventricular activation during ventricular tachycardia which could be entrained during fixed rate ventricular pacing at the site of origin of ventricular tachycardia. At all ablation sites a long latency between the stimulus and QRS complex was noted. Of 23 patients 18 were treated with radiofrequency alone whereas in five patients a second ablation procedure using direct current was performed. Following the ablation procedures, 14 patients (61%) remained free of ventricular tachycardia. One patient died due to congestive heart failure 21 months following ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1991

Effects of enflurane on inducibility of ventricular tachycardia.

The effects of enflurane on cardiac electrophysiologic parameters and on inducibility of ventricular tachycardia (VT) by programmed stimulation were studied in 12 patients (11 men, 1 woman, mean age +/- standard deviation 55 +/- 8 years) with drug refractory sustained monomorphic VT who underwent transcatheter ablation with high-energy direct-current shocks. One catheter ablation procedure was performed in 10 patients, whereas 2 ablation sessions were necessary in 2 patients. Programmed ventricular stimulation was performed on 2 separate days (mean interval 19). There were 2 baseline studies, 1 several days before ("baseline study I") and the second at the beginning of the ablation procedure ("baseline study II") while the patient was awake and nonsedated. The third programmed stimulation study was done 15 to 30 minutes after administration of anesthesia with enflurane, oxygen and nitrous oxide ("enflurane study"). Rate of sinus rhythm, QRS duration, PQ interval and ventricular effective refractory period were unaltered, whereas QTc interval increased significantly after initiation of anesthesia. Before and after induction of general anesthesia, clinical VT was inducible in all patients. However, in 1 patient, induction of VT was only possible by pacing in the left ventricle after enflurane administration. Based on these data, it is concluded that general anesthesia with enflurane, oxygen and nitrous oxide has no marked influence on inducibility of clinical VTs. Therefore, this type of anesthesia may be useful for nonpharmacologic, ablative procedures requiring general anesthesia.

Aged↗