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Aims: Ablation of the atrial isthmus between the tricuspid annulus and the inferior vena cava changes P-wave morphology during low lateral right atrial pacing. For better understanding of the mechanism of this alteration, the sequence of activation of the inter-atrial septum and the left atrium were compared before and after ablation of the isthmus between the inferior vena cava and the tricuspid annulus., Methods and Results: In 13 patients, left atrial mapping was performed using a duodecapolar electrode catheter advanced to the far distal coronary sinus. The inter-atrial septum was mapped using a right atrial duodecapolar electrode catheter. Conduction times were measured during low lateral right atrial pacing from the pacing artefact and during sinus rhythm from the earliest right atrial electrogram to every intra-cardiac electrogram before and after the ablation. During low lateral right atrial pacing, isthmus ablation resulted in a significant delay in every left atrial lead. Changes were maximal at the posterior aspect of the left atrium and minimal at its anterior aspect. No significant change was discernible on the inter-atrial septum. During sinus rhythm, atrial activations remained unchanged., Conclusion: Electrocardiographic changes of P-wave morphology result from alteration in the sequence of left atrial activation rather than that of the inter-atrial septum.

The first radical approach to the treatment of atrioventricular nodal reentrant tachycardia was surgical dissection of the perinodal region. This technique has been replaced by the delivery of radiofrequency energy by an ablation catheter to the region of the atrioventricular node. The aim of this report is to describe the authors' experience of atrioventricular nodal application of radiofrequency current. The study comprised 53 cases (32 women and 21 men, mean age 46 +/- 17 years) with frequent attacks of reciprocating tachycardia. Endocavitary electrophysiological investigation confirmed the intranodal reentrant mechanism. The region of application of the radiofrequency current was located radiologically and then the precise site determined by the recording of nodal electrical activity. The appearance of junctional rhythm during the procedure was also used as a means of identification of the zone of ablation. Dual conduction persisted after ablation in 35 patients. However, no episode of tachycardia could be induced after the procedure. The AH interval increased during application of radiofrequency current in 3 cases but this abnormality regressed in the 2 months following the procedure. Recurrences of nodal reentrant tachycardia were observed in 14 cases (26%), 24 hours to 2 months after ablation. The rate of recurrence was significantly higher in patients who did not have a junctional rhythm during application of the radiofrequency current (62% vs 4%, p < 0.05). The number of recurrences was also greater in the group of patients with persistence of slow intranodal conduction after the radiofrequency ablation (p < 0.04). A second session of radiofrequency ablation was undertaken in 14 patients and a third session was required for 2 of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Background: Previous reports have shown that radiofrequency ablation can terminate atrial flutter and prevent recurrences. However, different methods have been used, and the current experience remains limited. The objective of the present study was to determine the efficacy of radiofrequency ablation of atrial tissue in patients with atrial flutter using an anatomically guided approach., Methods and Results: We treated 22 patients aged 30 to 73 years. Atrial flutter was recurrent for a mean of 5 years despite the administration of multiple antiarrhythmic drugs. Radiofrequency current was directed to the atrial isthmus between the inferior vena cava and the tricuspid ring, regardless of the morphology of local electrograms. Radiofrequency energy was applied during typical atrial flutter in 12 patients, atypical atrial flutter in 2 patients, and successively both forms in 8 patients. In 19 patients, atrial flutter abruptly terminated. In 3 patients, atrial flutter persisted despite 37, 48, and 25 applications, respectively. Atrial recordings demonstrated that atrial flutter termination occurred as a consequence of conduction block at the site of radiofrequency energy application, regardless of the type of atrial flutter. The number of applications before termination ranged from 1 to 82 (mean, 32). Atrial flutter could no longer be induced in every case. There were no complications. During a 13-month mean follow-up, atrial flutter recurred in only 2 of the 19 patients who had a successful ablation. Four patients experienced chronic atrial fibrillation, and 2 of them returned to sinus rhythm with antiarrhythmic therapy., Conclusions: Radiofrequency ablation of atrial flutter using anatomic guidance is feasible and effective. Further experience is needed to delineate its role as an alternative approach to the management of refractory atrial flutter.

The authors report the long term results of His bundle ablation for supraventricular tachycardia in a series of 49 patients. This retrospective study was based on a patient population of 27 men and 22 women with an average age of 59 at the time of ablation, between 1984 and 1993. The indication for His bundle ablation was invalidating supraventricular tachycardia resistant to antiarrhythmic therapy in all cases. One group of patients (Group I, n = 31 patients) underwent high energy electrical shock and the second group (Group II, n = 18 patients) recruited after 1991, underwent radiofrequency catheter ablation. Complete atrioventricular block was obtained in the first group in 1 to 4 sessions whereas 17 patients of Group II were treated in a single session. During a follow-up period of an average of 40 months, 2 patients were lost to follow-up and 6 died, 3 of cardiac failure, 1 of a cerebrovascular accident, 1 of pulmonary carcinoma and 1 of unknown cause. In Group I, atrioventricular conduction persisted in 1 patient (primary failure) and reappeared in one other patient, but, in Group II, complete atrioventricular block persisted even in the patient in whom the interruption was not obtained with a single session of radiofrequency ablation. The patients were generally physically improved and satisfied not to have any palpitations. A decrease in exercise capacity estimated by the NYHA classification was observed in 38% of patients without apparent cardiac disease who developed dyspnea. On the other hand, 43% of patients with cardiac disease and in NYHA class > or = 2 were improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Aims Ablation of the atrial isthmus between the tricuspid annulus and the inferior vena cava changes P-wave morphology during low lateral right atrial pacing. For better understanding of the mechanism of this alteration, the sequence of activation of the inter-atrial septum and the left atrium were compared before and after ablation of the isthmus between the inferior vena cava and the tricuspid annulus. Methods and Results In 13 patients, left atrial mapping was performed using a duodecapolar electrode catheter advanced to the far distal coronary sinus. The inter-atrial septum was mapped using a right atrial duodecapolar electrode catheter. Conduction times were measured during low lateral right atrial pacing from the pacing artefact and during sinus rhythm from the earliest right atrial electrogram to every intra-cardiac electrogram before and after the ablation. During low lateral right atrial pacing, isthmus ablation resulted in a significant delay in every left atrial lead. Changes were maximal at the posterior aspect of the left atrium and minimal at its anterior aspect. No significant change was discernible on the inter-atrial septum. During sinus rhythm, atrial activations remained unchanged. Conclusion Electrocardiographic changes of P-wave morphology result from alteration in the sequence of left atrial activation rather than that of the inter-atrial septum. [ABSTRACT FROM PUBLISHER]