RADIOFREQUENCY CATHETER ABLATION OF ATRIAL-FLUTTER

Though not as common as atrial fibrillation, atrial flutter is frequently encountered in everyday cardiological practice. Though generally thought to be benign, it may be difficult to treat both in respect to its conversion to sinus rhythm and prevention of recurrences. It is often poorly tolerated. There are resistant, invalidating forms for which catheter ablation of the His bundle may be considered as a last resort. This is only a palliative measure even if effective from the functional point of view. A new technique for treating atrial flutter by a direct action on the atrial tissue has been recently introduced. The basis of this method is the concept of circus movement of the activation in the right atrium, the wave front circulating in an anti-clockwise direction in common atrial flutter. The postero-inferior region of the right atrium, at Koch's triangle, is the site of slow conduction and the target of choice for catheter ablation. The detection of this zone is determined by the endocavitary recording of fragmented, prolonged electrogrammes and by atrial stimulation techniques. The application of radiofrequency currents on these bases (high energy shocks are rarely used nowadays) results in interruption of atrial flutter. However, there are no data available concerning the long-term efficacy of this technique. Since 1992, our group has used an anatomical approach for catheter ablation. This aims to apply the radiofrequency current on the isthmus of atrial tissue between the orifice of the inferior vena cava and the tricuspid annulus through which the flutter wave front passes to reach the interatrial septum. The catheter ablation aims to create a line of block in this region. Twenty-two patients have been treated in this manner. The flutter was interrupted in 19 cases during the procedure and a single application of radiofrequency current was sufficient in 3 cases. The average number of applications for conversion was 32. At 13 months, flutter had occurred in only 2 of the 19 patients. Atrial fibrillation occurred in 4 subjects, 2 of whom were converted to sinus rhythm by antiarrhythmic drugs. Therefore, radiofrequency catheter ablation of atrial flutter provides encouraging results which suggests wider indications for the technique in the future.