Pseudo cryomapping for ablation of atrioventricular nodal reentry tachycardia: A single center North American experience

BACKGROUND: Most literature for cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) is based on −30 degree celsius cryomapping with 4 & 6 mm distal electrode catheters. The cryomapping mode is not available on the 6 mm cryocatheter in the United States. We describe a technique for ‘pseudo’ mapping at −80° using a 6 mm cryocatheter and report on short and long term outcomes. METHODS: A retrospective analysis of all index cases (n = 253) of cryoablation of AVNRT at a single North American institution during the period of 2003–2010 was performed. The majority of cases utilized a 6 mm distal electrode tip catheter. Long term follow up (2.4 ± 1.8 years) was performed via review of the medical record and by questionnaire or telephone if necessary. RESULTS: Acute ablation success was achieved in 93% of cases, with transient conduction defects noted in 39% of cases, and long term conduction defects in 1.6% of cases (4 patients with PR prolongation, 2 of which were permanent). General anesthesia, male gender and presence of structural heart disease were more common in the acute failure cohort. The recurrence rate for AVNRT was 8%. These patients tended to be younger and had more transient A-V conduction defects during the index procedure than those without a recurrence. CONCLUSIONS: In conclusion, anatomic cryoablation of AVNRT utilizing a 6 mm electrode catheter with mapping performed at −80° Celsius is a safe procedure with good long term efficacy. Transient A-V block during the index procedure increases the risk of late recurrence.