LAUSR

re-entry mechanisms around mitral and tricuspid annuli are frequent causes of left and right atrial flutter (AFt) respectively in patients with ipsilateral atrial pathology. However, clinical and electrophysiological characteristics of other types of atrial re-entries that could involve both AV annuli are less known. characterize biannular atrial flutters. 4 patients with AFt were submitted for ablation (aged 30, 31, 58 and 61 yo; 2 females). All had a cardiac congenital disease with a prior surgical procedure: 3 atrial septal defects (ASD) with surgical repair and 1 with transposition of the great arteries (TGA) with Senning repair. The AFt had a cycle length (CL) of 290, 315, 330 y 340 ms respectively and 1:1 AV conduction in 3 of them. For the electrophysiological study, a multipolar catheter (20 or 24 poles) was placed in the right atrium (RA) in every patient, showing counterclockwise and clockwise activation in 1 and 3 patients, respectively. Coronary sinus (CS) activation was proximal to distal in one patient and distal to proximal in the other 2. No CS activation could be obtained in the patient with Senning repair. each AFt was mapped by entrainment from different sites of the RA, showing post-pacing intervals (PPI) similar to the CL of the AFt around the tricuspid annulus in all of them and also from proximal and distal CS in the 3 patients with ASD. Access to the native left atrium (LA) was achieved in the patient with Senning repair, showing PPIs around the mitral annulus that were similar to the LC of the tachycardia. In 2 patients the attempt to get to the LA through the interatrial septum (IAS) could not be achieved and was unattempted in the other one. Recordings and PPIs of the LA roof were obtained from the right branch of the pulmonary artery in 2 patients. Counterclockwise AFt and clockwise AFt by single biannular perimitrotricuspid rotation in 1 and 3 patients respectively. The AFt was ended and no reinduction was possible after radiofrequency application that achieved cavotricuspid isthmus block in all of the patients. reentry around both AV annuli is possible as a single loop, counterclockwise or clockwise, of simultaneous rotation as a clinical mechanism of Aft. This type of AFt seems to be associated to absence or severe damage in the IAS.