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Aims Although arrhythmia surgery and radiofrequency catheter ablation to cure atrioventricular nodal reentrant tachycardia differ in technical concept, the late results of both methods, in terms of elimination of the arrhythmogenic substrate and procedure-related new and different arrhythmias, have never been compared. This constituted the purpose of this prospective follow-up study. Methods and Results Between 1988 and 1992, 26 patients were surgically treated using perinodal dissection or ‘skeletonization’, and from 1991 up to 1995, 120 patients underwent radiofrequency modification of the atrio-ventricular node for atrioventricular nodal reentrant tachycardia. The acute success rates of surgery and radiofrequency catheter ablation were 96% and 92%, respectively. Late recurrence rate in the surgical and radiofrequency catheter ablation groups was 12% and 17%, respectively. Mean follow-up was 53 months in the surgical group and 28 months in the radiofrequency catheter ablation group. The final success rate after repeat intervention was 100% in the surgical group and 98% in the radiofrequency catheter ablation group. Comparison of the initial and recent series of radiofrequency catheter ablated patients showed an increased initial success rate with fewer applications. In the radiofrequency catheter ablation group, a second- or third-degree block developed in three patients (2%), requiring permanent pacing, whereas in the surgical group no complete atrioventricular block was observed. Inappropriate sinus tachycardia needing drug treatment was observed in 13 patients (11%), mostly after fast pathway ablation, but was never observed after surgery. New and different supraventricular tachyarrhythmias arose in 27% of the patients in the surgical group and in 11% of the radiofrequency catheter ablation group, but did not clearly differ. Conclusion This one-institutional follow-up study demonstrated comparable initial and late success rates as well as incidence of new and different supraventricular arrhythmias following arrhythmia surgery and radiofrequency catheter ablation for atrioventricular nodal reentrant tachycardia. Today radiofrequency catheter ablation has replaced arrhythmia surgery for various reasons, but the late arrhythmic side-effects warrant refinement of technique.

Background It is still unknown whether a fast heart rate or an irregular ventricular response in atrial fibrillation causes tachycardiomyopathy. Reduction in the variability of RR intervals without an increase in heart rate might be an alternative treatment when antiarrhythmic drugs fail to control the irregularity accompanying atrial fibrillation. Subjects and methods Eight patients underwent temporary right ventricular pacing, using a novel rate-smoothing algorithm prior to DC cardioversion or His bundle ablation. A rate-smoothing algorithm was utilized by right ventricular apical stimulation. Spontaneous and paced RR intervals during atrial fibrillation were quantified and processed for statistical analysis. Results The rate-smoothing algorithm resulted in a substantial reduction in the variance of the RR intervals (slow mode 73·1%, fast mode 40·0%) and RR range (slow mode 49·3%, fast mode 34·3%). In contrast to previous algorithms, the mean heart rate during pacing intervention in atrial fibrillation did not change significantly to the heart rate directly preceding the pacemaker intervention (+2%). Conclusions This initial study of the novel rate-smoothing algorithm shows that pacing intervention is a relatively safe, rapid and reliable alternative therapy for controlling irregular ventricular rhythms due to atrial fibrillation. Incorporation of the algorithm in implantable pacemakers appears justified, but demands further prospective studies in patients to evaluate relief of symptoms and reduction of tachycardiomyopathy due to atrial fibrillation.

In two patients with a symptomatic posteroseptally localized accessory atrioventricular pathway, but with distinct electrocardiographic patterns, a coronary sinus diverticulum appeared to be the site of this connection. Radiofrequency catheter ablation in the diverticulum was implemented to interrupt the pathway in both cases. This study demonstrates the necessity to perform coronary sinus angiography when ablation attempts in the posteroseptal region are not immediately successful, or optimal signals are not detected.

Mechanisms of ventricular arrhythmias were assessed by the application of ECG criteria derived from experimental electrophysiology. These interval criteria describe for ideal and modulated parasystole, resettable spontaneous automaticity, early and delayed after depolarizations and reentry, how QRS complexes of ectopic ventricular origin relate to those of supraventricular origin. Ventricular arrhythmias were studied in: (a) longterm, 1-lead ECG recordings of 85 patients with uncomplicated and untreated acute myocardial infarction (AMI) (group I); (b) one-hour, 4-lead ECG recordings of 23 comparable patients with AMI (group 2), and (c) one-hour, 4-lead ECG recordings of 10 patients with chronic ventricular arrhythmias (group 3). All QRS complexes of ectopic ventricular origin having identical morphology (V type) were assumed to be the manifestation of a single site in the ventricle. The supraventricular rhythm in groups 2 and 3 was varied by programmed atrial stimulation to increase the range of intervals and patterns of the V types in the ECG. Positive evidence for a particular mechanism was obtained by applying tested criteria in 38% of 263 V types in group I (mainly reentry, but also early and delayed afterdepolarizations). In group 2, there was positive evidence in 67% of 84 V types (mainly reentry, but also early and delayed afterdepolarizations) and also in 67% of 18 V types in group 3, (mainly reentry). The application of these ECG criteria to ventricular arrhythmias identifies mechanisms in a satisfactory proportion. The yield can be increased by artificial variation of the heart rate.

Disabling monomorphic ventricular bigeminy has not been described as an indication for surgery. Three young patients with this arrhythmia sometimes deteriorating into ventricular tachyarrhythmias and in whom drug therapy failed completely were accepted for surgical ablation of the arrhythmogenic area. The earliest endocardial site of origin was located preoperatively by catheter mapping of the spontaneously occurring ventricular bigeminy in the left and right ventricles. For maximum preservation of myocardial muscle and function, the preoperative mapping and surgical procedure were performed through the aortic root; mapping by transaortic multipolar balloon was done during normothermic coronary perfusion and cryocoagulation was done during cardioplegic arrest. Cryocoagulation of the endocardial site was performed using the transaortic approach and epicardial cryocoagulation at the opposite site was done afterwards. In the two patients in whom the preoperative mapping results were consistent with those of preoperative catheter mapping, the arrhythmia could be abolished, as documented during long-term follow-up. In the only patient in whom the mapping results were not in agreement, the ventricular arrhythmia reoccurred and was the cause of death at five months after surgery. Postoperative wall-motion studies performed in the two surviving patients showed limited scars in the area of cryocoagulation and minor damage to the coronary arteries in that area. The transaortic approach can be considered as a new and important surgical option for endocardial mapping and cryocoagulation which prevents the damaging effects of a left ventriculotomy.