ELECTROCARDIOGRAPHIC PATTERNS AND RESULTS OF RADIOFREQUENCY CATHETER ABLATION OF CLOCKWISE TYPE-I ATRIAL-FLUTTER

Introduction: Counterclockwise right atrial propagation is usually obs erved in common atrial flutter, but little is known regarding flutter with clockwise right atrial rotation, The aim of this study is to desc ribe the ECG characteristics and results of catheter ablation of atria l flutter with clockwise right atrial rotation. Methods and Results: A mong the 38 patients with type I atrial flutter in this study populati on, right atrial impulse propagation was counterclockwise in 20 and cl ockwise in 8. In the remaining 10 patients, both clockwise and counter clockwise patterns were seen, Clinical and ECG parameters associated w ith clockwise flutter were compared to those of 28 cases of counterclo ckwise atrial flutter. Ablation was performed in 11 of 18 cases using a technique identical to that used for counterclockwise flutter. A cla ssical ''sawtooth'' pattern of the flutter wave was observed in 28 of 28 counterclockwise and 14 of 18 clockwise flutter. A shorter plateau phase, a widening of the negative component of the F wave in the infer ior leads, and a negative F wave in V-1 were the most consistent findi ngs in clockwise flutter. Coronary sinus recording always showed septa l to lateral left atrial impulse propagation. Ablation was successful in 11 of 11 cases of clockwise flutter in whom this procedure was perf ormed, with 9.5 +/- 11.6 radiofrequency pulses delivered between the t ricuspid valve and the coronary sinus ostium (n = 5) or the inferior v ena cava (n = 5), and in the proximal coronary sinus (n = 1), After a follow-up of 46.6 weeks, two recurrences of clockwise flutter were enc ountered, which were successfully treated with a second session. Concl usion: Contrary to commonly accepted concepts, clockwise rotation of a trial flutter is not an infrequent phenomenon and can mimic counterclo ckwise rotation, It can also be successfully ablated by radiofrequency pulses.