Radiofrequency Catheter Ablation of an Automatic Atrial Tachycardia in an Adult

[Long-term efficacy of radiofrequency catheter ablation in atrial tachycardia]

INTRODUCTION AND OBJECTIVES

Radiofrequency ablation has shown to be an effective treatment for supraventricular tachycardias including flutter and atrial tachycardia, however the clinical information available on atrial tachycardia is limited. The aim of this study was to evaluate the immediate and long term effectiveness of radiofrequency ablation in patients with atrial tachycardia and to establish predictors of effectiveness and arrhythmia recurrence.

METHODS

We analyzed a series of 126 procedures of atrial tachycardia ablation in 117 patients (69% women) with a mean age of 50 +/- 19 years.

RESULTS

Ninety-one percent of the foci were located in the right atrium. A mean of 6 applications were necessary to achieve an efficacy of 74% during the first procedure with a total of 80%. The only predictor of ablation success was the number of foci being smaller in multifocal compared to unifocal (p < 0.01) whereas for recurrences a less premature electrogram at the application point (p = 0.02) was predictive of ablation success. Over a follow-up of 34 +/- 19 months 7.4% of patients had recurrent atrial tachycardia. The probability of recurrence at one year calculated by the Kaplan-Meier method was 12%. Seventy-one percent of the recurrences occurred during the first 3 months after ablation.

CONCLUSIONS

Ablation is an effective, safe procedure for short and long term treatment of patients with atrial tachycardia. Effectiveness depends on the number of foci while the recurrence rate is related to the prematurity of atrial electrogram at the application point.

Predictors of successful radiofrequency catheter ablation of sinoatrial tachycardia

Predictors of successful elimination of sinoatrial tachycardia (SAT) using radiofrequency current (RFC) were investigated in this report. Within 1991-1996 fourteen patients with SAT were subjected to electrophysiological study and radiofrequency catheter ablation (RFCA). Ten patients had sinoatrial reentrant tachycardia (SART), and four patients had chronic non-paroxysmal sinoatrial tachycardia (CNPSAT). The RFC (15-30 W, duration 10-30 sec) were applied during tachycardia in case of CNPSAT, and during sinus rhythm (SR) in case of SART. In 3 patients with SART RFC were delivered during tachycardia due to failing of RFC application, delivered during SR. During successful RFC attempts were noted: 1). In case of SART-transient development (3-6 sec) of SART (if RFC was delivered during SR), and acceleration of tachycardia rate with following termination of tachycardia (if application of RFC was performed during tachycardia); 2). In case of CNPSAT-transient development (4-7 sec) of low right atrial (3 patients) or junctional (1 patient) rhythm with rapid conversion to SR. All 14 patients have been free of tachycardia and have normal sinus node function during follow-up of 8-60 months. We conclude that predictors of successful elimination of SAT are: 1). In case of SART-acceleration of tachycardia rate before termination during RFC application (delivered during tachycardia), and transient development of SART during RFC application (delivered during SR); 2). In case of CNPSAT-transient development of low right atrial or junction rhythm (during application of RFC) with rapid conversion to SR.

Critical atrial site for ablation of pacing-induced atrial fibrillation in the normal dog heart

INTRODUCTION

Radiofrequency catheter ablation (RFA) has been used recently to treat atrial fibrillation (AF). The purpose of this study was to investigate a new approach to preventing AF by RFA.

METHODS AND RESULTS

In open chest, anesthetized dogs, AF (lasting > 30 sec) was induced after burst stimulation, and electrophysiologic parameters were recorded before and after RFA. In group 1 (9 dogs) we performed selective and combined slow and fast pathway RFA, whereas in group 2 (11 dogs) RFA was applied as a linear lesion at the mid-atrial septum between the inferior vena cava and the fossa ovalis. After ablation, the Wenckebach cycle length was significantly prolonged only in group 1 (194 +/- 23 vs 282 +/- 35 msec, P = 0.002), whereas the interval between the stimulus (S) artifact applied at the high right atrium to the His bundle (H) (SH interval) prolonged to the same extent in both groups (162 +/- 14 vs 146 +/- 45 msec, P = NS); group 1 due to an A-H prolongation whereas in group 2 it was due to an intra-atrial conduction delay. In group 1 AF still remained inducible, although with a longer mean R-R interval (215 +/- 16 vs 433 +/- 88 msec, P < 0.05). No instance of complete AV block developed. In group 2, sustained AF was noninducible in 10 dogs and its duration was markedly shorter in the remaining one (8 sec). Gross anatomy and histology did not reveal any damage inside of Koch's triangle, and particularly to the compact AV node.

CONCLUSION

These findings suggest that RFA at the mid-atrial septum prevents AF in the normal dog heart. This approach might also be successful in those clinical settings in which the atrial septum plays a critical role in the maintenance of sustained AF.

Radiofrequency catheter ablation of left atrial tachycardia originating within the pulmonary vein in a patient with dextrocardia

A case is presented of a 38-year-old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero-lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, transesophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between the left atrium and the pulmonary veins.

The role of catheter ablation in atrial tachycardia, flutter, and fibrillation

The first experiences of nonpharmacological treatment of ectopic atrial tachycardia (EAT), common atrial flutter (AFl), and atrial fibrillation (AF) were performed by surgical techniques. Many studies reported a very high success rate on the use of catheter ablation with radiofrequency current for the treatment of supraventricular arrhythmias; and recently, various preliminary reports are dedicated to the treatment of EAT, AFl, and AF with that source of energy. To our knowledge 108 cases of EAT treated by catheter ablation of the ectopic focus are reported in the literature with a success rate superior to 90%. On the basis of our personal experience regarding 11 cases (4 of right atrium EAT and 7 of left) we discuss here the essential role of unipolar leads derived from the mapping catheter to select the target for radiofrequency applications. Two hundred and one cases of AFl tested by catheter ablation were previously reported. The majority of them (> 80%) were successfully treated with radiofrequency. Some working groups performed the procedure as the basis of electrophysiological findings, while others preferred an anatomical approach applying radiofrequency energy at the isthmus lying between the coronary sinus ostium and the tricuspid ring, near the vena cava orifice. On the basis of these assumptions, we obtained 83% of final success in 12 cases of AFl treated by radiofrequency. Finally, we discuss the problem related to the modulation of atrioventricular (AV) nodal conduction during AF. In our laboratory, five cases with chronic AF and very fast ventricular response were treated with radiofrequency with a posterior septal approach. In all patients, we obtained very encouraging results with a constant decrease of ventricular rate (from 137 +/- 33 to 69 +/- 14 beats per minute). All cases treated by modulation of AV nodal conduction demonstrated an appropriate chronotropic response to the variations of the functional state that persists during the follow-up. More experience with longer follow-up and accurate pre- and postprocedure evaluations are needed to finalize the most appropriate technique of radiofrequency applications in these cases.

Transcatheter ablation of incessant ectopic left atrial tachycardia using radiofrequency current

Catheter ablation of ectopic atrial tachycardia has been previously reported in a small number of patients in whom the ectopic focus was predominantly located in the right atrium. We report on a 51-year-old patient with atrial automatic tachycardia originating in the left atrium, in whom successful radiofrequency catheter ablation was performed via a transseptal puncture. The patient had suffered incessant atrial tachycardia for several years, refractory to antiarrhythmic drug treatment and DC-cardioversion. Radiofrequency ablation terminated left ectopic atrial tachycardia and, therefore, should have been attempted before resorting to open heart surgical ablation.

Catheter ablation of sinoatrial node reentrant tachycardia

OBJECTIVES

This study evaluates 1) the safety and efficacy of catheter delivery of radiofrequency current to eliminate sustained sinoatrial node reentrant tachycardia; 2) the incidence of sinoatrial node reentrant tachycardia in the current group of patients undergoing electrophysiologic study for paroxysmal supraventricular tachycardia; and 3) the association of sinoatrial node reentrant tachycardia with other tachyarrhythmias.

BACKGROUND

Sustained sinoatrial node reentrant tachycardia is an uncommon cause of paroxysmal supraventricular tachycardia that is reported to occur infrequently in conjunction with other arrhythmias. Although pharmacologic and surgical therapies are available, there is limited information with regard to catheter ablation of sinoatrial node reentrant tachycardia.

METHODS

Ten patients with sustained sinoatrial node reentrant tachycardia underwent electrophysiologic study and radiofrequency current ablation. Patients were followed up for 9.2 +/- 6.0 months.

RESULTS

Of 343 consecutive patients referred for electrophysiologic evaluation of paroxysmal supraventricular tachycardia, 11 (3.2%) were found to have inducible sustained sinoatrial node reentrant tachycardia. Nine of the 11 patients had other associated arrhythmias, including atrioventricular (AV) node reentrant tachycardia (6 patients), AV reciprocating tachycardia (2 patients), ectopic atrial tachycardia (2 patients) and bundle branch reentrant tachycardia (1 patient). In 10 patients, direct ablation of sinoatrial node reentrant tachycardia was attempted and was successful in all (confidence interval for failure 0-0.26). Sinoatrial node reentrant tachycardia was eliminated with a median of four radiofrequency current applications (range 1 to 10) at 20 to 30 W. Successful ablation site characteristics during sinoatrial node reentrant tachycardia included 1) atrial activation > or = 35 ms (mean 44 +/- 8 ms) before the onset of the surface P wave, 2) atrial activation > or = 20 ms (mean 28 +/- 6 ms) before the onset of high right atrial activation, and 3) significantly prolonged and fractionated electrograms (mean duration 87 +/- 21 ms). No complications were encountered, and there have been no recurrences of sinoatrial node reentrant tachycardia.

CONCLUSIONS

Sinoatrial node reentrant tachycardia may be effectively and safely treated with radiofrequency current ablation at the site of earliest atrial activation.

Radiofrequency ablation therapy in three patients with paroxysmal atrial tachycardia

Radiofrequency ablation therapy was performed in three patients with paroxysmal atrial tachycardia. There were two females and one male, aged 80, 63, and 75 years, respectively. All three patients had induction of sustained atrial tachycardia. The tachycardia could be terminated by overdrive atrial pacing or atrial premature stimulation; it could also be terminated by intravenous bolus of adenosine triphosphate. In all three patients, there was no fragmented atrial electrograms recorded within the right atrium, and there was no ventriculo-atrial conduction during ventricular pacing. The earliest atrial activation during tachycardia in these three patients was registered, respectively, at a site slightly posterior and inferior to the His-bundle recording site, at the anterior-superior border of Koch's triangle slightly posterior to the His-bundle recording site, and at the mid-lateral aspect of the right atrium over the crista terminalis at the junction of right atrial appendage and sinus venarum. Radiofrequency current was delivered to the site of the earliest atrial activation during tachycardia through a 4-mm tip electrode catheter. It resulted in termination of tachycardia and ablation of the tachycardia focus. Follow-up observation over a period of 16, 15, and 4 months, respectively, in these three patients showed no recurrence of tachycardia. A repeat electrophysiological study was performed 52 and 63 days after ablation in two patients and revealed no induction of atrial tachycardia.

Radiofrequency catheter ablation of an intraatrial reentrant tachycardia: evidence of an area of slow conduction

Radiofrequency catheter ablation for intraatrial reentrant tachycardia has not been previously reported. This article describes a patient with a demonstrable area of slowed conduction in the lateral right atrium that responded to radiofrequency catheter ablation in the area of the fractionated electrogram with elimination of the tachycardia. This patient also had the common form of atrioventricular nodal reentrant tachycardia, which was also successfully ablated.