Dual-loop intra-atrial reentry in humans

Background-Dual-loop atrial reentrant tachycardias have not been clinically described. Methods and Results-Five patients (3 men, 2 women; mean age, 48+/-16 years) were studied 24+/-15 years after surgical closure of an ostium secundum at rial septal defect for drug-resistant atrial tachycardia, Complete tachycar dia mapping was per formed in the right atrium with multipolar catheters an d a 3-dimensional electroanatomic mapping system (Biosense), followed by li near radiofrequency ablation of the narrowest part of each complete loop. S ix tachycardias with a typical flutter morphology, a cycle length of 262+/- 40 ms, and a superior f-wave axis (-77+/-11 degrees) were mapped, 4 with a Biosense map including 106+/-32 points. Five figure-8 tachycardias had a co unterclockwise loop around the tricuspid valve sharing a common anterior ch annel with a clockwise loop around the lateral atriotomy scar. One tachycar dia was thought to have 2 counterclockwise loops around the same obstacles. Radiofrequency delivery in the cavotricuspid isthmus in each case transfor med the tachycardia without any pause in a different morphology tachycardia with an inferior P-wave axis (50+/-42 degrees) and nearly the same cycle l ength (272+/-39 ms) but with the periatriotomy loop alone. This arrhythmia required ablation of a second isthmus: between the lower end of the atrioto my and the inferior vena cava in 4 and the superior tricuspid annulus in 1. After a follow-up of 19+/-6 months, there were no recurrences. Conclusions-Figure-8 double-loop tachycardias mimicking the ECG pattern of a common atrial flutter occur in some patients after a surgical atriotomy, Ablation of 1 loop produces a sudden transformation to a new reentrant tach ycardia formed of the remaining loop that requires ablation at a second ist hmus.