Cryoballoon ablation of atypical mitral isthmus-dependent left atrial flutter

Excerpt

An 87-year-old woman underwent pulmonary vein isolation (PVI) with concomitant posterior wall isolation (PWI) within the region of the pulmonary venous component (PVc), using a 28-mm cryoballoon (Arctic Front Advance; Medtronic, Minneapolis, MN), for the treatment of symptomatic persistent atrial fibrillation (a). Subsequently, the rhythm spontaneously converted into a clockwise mitral isthmus-dependent left atrial flutter (cycle length: 240 ms), with the earliest activation noted on the distal coronary sinus (CS 1,2). It was decided to ablate the tachycardia using the available cryoballoon. A single 3-min cryoapplication delivered to the superior aspect of the anterior mitral isthmus (b, c), guided by intracardiac echocardiography (CARTOSound; Biosense Webtster, Irvine, CA), resulted in cycle length wobble. The cycle length eventually stretched to 360 ms, prior to termination during a second 3-min cryoapplication delivered to the inferior aspect of the isthmus (d). An additional 4 cryoballoon applications were delivered along the lateral/inferolateral aspects of the mitral isthmus to achieve conduction block (e), as demonstrated by a proximal to distal activation in the coronary sinus atrial electrograms when pacing (asterisk) from within the left atrial appendage (f). During cryoapplications, the circular mapping catheter (Achieve; Medtronic) was placed across the mitral valve, unanchored. Care was taken not to occlude the valvular orifice. Stability during applications was maintained through cryo-adhesion. …