RADIOFREQUENCY CATHETER ABLATION FOR THE TREATMENT OF COMMON ATRIAL-FLUTTER IN HUMANS

Endocardial catheter ablation has been recently been proposed for the treatment of arrhythmias originating in the right atrium. In this study, we used this technique in 5 patients with paroxysmal common atrial flutter and 3 patients with paroxysmal uncommon atrial nutter. Various antiarrhythmic agents had failed to prevent the recurrence of these episodes. In each procedure, we used a large-tip 7 F quadripolar catheter electrode that was introduced via the femoral vein into the lower part of the right atrium. The two distal electrodes were used to record double-spike potentials or fragmented electrograms. A unipolar electrogram recording from a distal electrode of the same catheter was also used to identify local activation. The targets for ablation were sites which showed double-spike potential and fragmented electrogram 40-60 msec earlier than the onset of the F wave. Application of radiofrequency (RF) energy (25-40 watts) (3-17 applications) terminated atrial nutter and prevented reinduction of atrial flutter in the 5 patients with common atrial nutter. However, atrial nutter could not be terminated with the application of RF energy in the 3 patients with uncommon atrial flutter. The sites at which ablation was successful were located inferior or posterior to the coronary sinus ostium between the inferior vena cava and the tricuspid valve annulus, and were characterized by double-spike potentials and fragmented electrograms with activation times greater than or equal to 40 msec before the onset of the F wave. This area may represent the exit site from the area of slow conduction, since pacing from this site showed concealed entrainment of the F wave, and a local electrogram to the onset of the F wave coincided with the pacing spike to the onset of the F wave. Follow-up of these 5 patients (19.4+/-10.4 weeks) revealed recurrence of the original atrial nutter in 1 patient and a new type of atrial nutter in 1 patient. The other 3 patients have been episode-free, although an antiarrythmic agent was given for the treatment of paroxysmal atrial fibrillation in 2 patients. We conclude that the application of RF energy to the presumed critical area in the atrial nutter reentrant circuit seems to be effective in terminating and preventing common atrial nutter. Long-term follow-up is required for the recurrence of atrial flutter.