Parahisian Atrial Tachycardia: Cryoablation from the Aortic Cusp

A 29-year-old female patient with Ebstein anomaly was referred to our division for drugresistant symptomatic wide-complex tachycardia. Her preprocedural electrocardiograms showed a sinus rhythm without delta wave and a wide-complex short RP tachycardia with a rate of 150 bpm during palpitation. During conventional electrophysiologic study earliest local activation times during the tachycardia were obtained from the right parahisian region (Figure 1). A few second of initial radiofrequency ablation attempts using standard 4-mm tip radiofrequency ablation (RFA) catheter to this region resulted in cessation of the tachycardia and reversible ventriculo-atrial block. Then applying cryothermal energy using 4-mm tip cryoablation (CA) catheter (The Freezor® Cardiac CryoAblation Catheter, Minneapolis, USA) at -30 0C, cryomapping, to the initial site resulted in cessation of the tachycardia and reversible ventriculo-atrial block. The RFA catheter was advanced to the non-coronary cusp of the aortic valve which has close proximity to parahisian region [1,2]. During application of radiofrequency energy the tachycardia stopped but significant prolongation in ventriculo-atrial conduction was detected. Lastly, cryothermal energy was applied in the non-coronary cusp. Cryomapping stopped the tachycardia without any ventriculo-atrial or atrio-ventricular block (Figure 2). Therefore, CA at -70 0C was performed with 2 freeze-thaw cycles (Figure 3a and b). No tachycardia was induced with control programmed and burst pacing maneuvers and the patient was asymptomatic at 6-month follow-up.