Cryoablation for atrioventricular nodal reentry tachycardia: Role of “mapping” and “pseudo-mapping”

The goal of catheter ablation is to create lesions that would cause local tissue destruction and thus eliminate or modify arrhythmia substrate. This is commonly accomplished by changing cellular temperature at two extremes by either heating or cooling with radiofrequency (RF) and cryothermal energy respectively. Both RF and cryoablation technologies are widely available. It is because of the “curative” outcome that catheter ablation therapy approach has become preferred, standard and guidelines recommended treatmentmodality for almost all types of supraventricular tachycardias (SVTs) including atrioventricular nodal reentry tachycardia (AVNRT) [1,2]. Both RF and cryoablation have significant differences in their biophysical mechanisms, efficacy and safety profile. Usage of RF and cryo ablation among electrophysiologists also differ significantly. The majority of pediatric electrophysiologists prefer cryoablation over RF for ablation of SVT, particularly AVNRT, in children. On the other hand, most adult electrophysiologists use cryoablation as an alternative to RF ablation, a practice which is even considered to be in accordancewith the current practice guidelines [3]. Success and failure of ablation of any arrhythmia depends largely on detailed, meticulous, accurate and precise mapping based on the electrophysiological properties and characteristics of all components responsible for the genesis and perpetuation of arrhythmia. Furthermore, the role of mapping techniques to identify optimal location for application of curative ablation lesions in case of ablation of AVNRT in all age groups cannot be overemphasized given the potential risk of permanent and irreversible atrioventricular (AV) conduction block needing a lifelong pacemaker. In this regard, since cryoablation has an ability to demonstrate the functionality of prospective ablation sites without inducing permanent injury it has distinct advantage over RF ablation [4]. Conventionally, one could perform “ice mapping” or “cryomapping”, at temperature around 30 Celsius (C) before proceeding to “cryoablation” by application of cryothermal energy to cool down temperature around 80 C to create an effective tissue lesion. In many countries, available technology allows cryomapping part of the procedure with 4 mm and 6 mm tip