Cryoablation of Septal Accessory Pathways: Learning While Freezing

Septal accessory pathways provide the invasive electrophysiologist with serious challenges, particularly in the case of para-Hisian or mid-septal insertion sites. Although radiofrequency energy has demonstrated efficacy in the elimination of accessory AV pathway conduction, it has also been associated with a non-trivial risk of heart block at septal and para-Hisian sites. Because of these concerns, many EP labs, including our own, have concluded that cryoablation is the preferred modality for the mapping and elimination of septal accessory pathways. The advantages of cryoablation in this setting are well reported, and include the potential for reversing an induced AV block, the adherence of the catheter tip to the endocardium with freezing, and more discrete and controllable lesion formation. The following two cases (concealed paraHisian pathway and mid-septal WPW) illustrate techniques and observations from our laboratory that may be useful to others gaining experience with cryoablation.