THE ROLE OF CATHETER ABLATION IN ATRIAL TACHYCARDIA, FLUTTER, AND FIBRILLATION

The first experiences of nonpharmacological treatment of ectopic atria l tachycardia (EAT), common atrial flutter (AFl), and atrial fibrillat ion (AF) were performed by surgical techniques. Many studies reported a very high success rate on the use of catheter ablation with radiofre quency current for the treatment of supraventricular arrhythmias; and recently, various preliminary reports are dedicated to the treatment o f EAT, AFl, and AF with that source of energy. To our knowledge 108 ca ses of EAT treated by catheter ablation of the the ectopic focus are r eported 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 lea ds derived from the mapping catheter to select the target for radiofre quency applications. Two hundred and one cases of AFl tested by cathet er ablation were previously reported. The majority of them (> 80%) wer e successfully treated with radiofrequency. Some working groups perfor med the procedure as the basis of electrophysiological findings, while others preferred an anatomical approach applying radiofrequency energ y at the isthmus lying between the coronary sinus ostium and the tricu spid ring, near the vena cava orifice. On the basis of these assumptio ns, we obtained 83% of final success in 12 cases of AFl treated by rad iofrequency. Finally, we discuss the problem related to the modulation of atrioventricular (AV) nodal conduction during AF. In our laborator y, five cases with chronic AF and very fast ventricular response were treated with radiofrequency with a posterior septal approach. In all p atients, 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 applicati ons in these cases.