Lower-loop reentry is a subtype of right atrial flutter dependent on the TA-ER isthmus, characterized by a shorter cycle length than typical atrial flutter (217 vs 272 ms, P<0.01).
Observational (n=29)
Lower-loop reentry is a distinct subtype of right atrial flutter dependent on the TA-ER isthmus, which can be effectively targeted by linear ablation.
Absolute Event Rate: 217% vs 272%
p-value: p=<0.01
BACKGROUND: The mechanisms of an atrial flutter (AFL) that is more rapid and at times more irregular than typical AFL are unknown. METHODS AND RESULTS: Twenty-nine patients with AFL were studied. Atrial electrograms were recorded from a 20-pole catheter placed against the tricuspid annulus (TA), with its distal electrodes lateral to the isthmus between the TA and the eustachian ridge (ER), and from the His bundle and coronary sinus catheters. Atrial extrastimuli were delivered in the TA-ER isthmus during typical AFL. Episodes of a right atrial flutter rhythm that was different from typical AFL were induced in 3 patients and occurred spontaneously in 3 patients. This sustained AFL, designated as lower-loop reentry (LLR), involved the lower right atrium (RA), as manifested by early breakthrough in the lower RA, wave-front collision in the high lateral RA or septum, and conduction through the TA-ER isthmus. Linear ablation resulting in bidirectional conduction block in the TA-ER isthmus terminated spontaneous LLR in 3 patients and rendered LLR noninducible in all patients. The cycle length of LLR was shorter than that of typical AFL (217+/-32 versus 272+/-40 ms, P<0. 01). Alternating LLR and typical AFL in 1 patient resulted in cycle length oscillation. CONCLUSIONS: LLR is a subtype of right atrial flutter and depends on conduction through the TA-ER isthmus.
Cheng et al. (1999) conducted an observational in Atrial flutter (n=29). Electrophysiological mapping and linear ablation vs. Typical atrial flutter was evaluated on Cycle length (p=<0.01). Lower-loop reentry is a subtype of right atrial flutter dependent on the TA-ER isthmus, characterized by a shorter cycle length than typical atrial flutter (217 vs 272 ms, P<0.01).