Atypical atrial flutter originating in the right atrial free wall

Background-Data from experimental models of atrial nutter indicate that mac ro-reentrant circuits may be confined by anatomic and functional barriers r emote from the tricuspid annulus-eustachian ridge atrial isthmus. Data char acterizing the various forms of atypical atrial nutter in humans are limite d. Methods and Results-In 6 of 160 consecutive patients referred for ablation of counterclockwise and/or clockwise typical atrial nutter, an additional a typical atrial nutter was mapped to the right atrial free wall. Five patien ts had no prior cardiac surgery. Incisional atrial tachycardia was excluded in the: remaining patient, High-density electroanatomic maps of the reentr ant circuit were obtained in 3 patients. Radiofrequency energy application from a discrete midlateral right atrial central line of conduction block to the inferior vena cava terminated and prevented the reinduction of atypica l atrial nutter in each patient. Atrial nutter has not recurred in My patie nt (follow-up, 18+/-17 months; range, 3 to 40 months). Conclusions-Atrial nutter can arise in the right atrial free wall. This for m of atypical atrial flutter could account for spontaneous or inducible atr ial flutter observed in patients referred for ablation and is eliminated wi th linear ablation directed at the inferolateral right atrium.