Cryoablation of the para-Hisian region

Basis: the ablation of the para-Hisian region is a challenge due to the risk of inadvertent lesion of a bundle of His. Cryoablation, due to its slower progression, allows interruption of the application in case of signs of undesired lesions and catheter adhesion during the applications, which has made cryoablation the ideal method for these patients. Objectives: to demonstrate the results of an initial series of patients referred for cryoablation of para-Hisian pathways. Patients and methods: From April 2015 to August 2017, 13 patients were referred for cryoablation due to the necessity for a para-Hisian approach detected in previous ablation procedures. Of the 13 patients, seven were submitted a radiofrequency ablation attempt (RF) and presented failure or recurrence, five performed only electrophysiological studies, and no ablation was attempted, and one was indicated primarily. The mean age was 32 ± 16 years. Eleven patients had manifest anomalous pathways (APs), one hidden and one nodal reentrant tachycardia (NRT) with a transient atrioventricular block (AB) during RF. A cycle of 4 minutes followed by one more cycle in case of a positive result. Results: Of the 13 patients, 11 had an acute success in eliminating the accessory pathway. One patient had multiple accessory pathways, one right side, and one left side. In this patient, it was possible only the ablation of the left pathway. In all others, it was observed exuberant Hisian potential at the point of application with success. The patient with NRT was ablated in the M region without intercurrences. Four applications were required on average to eliminate the accessory pathway successfully. The mean local temperature was -74 ºC. In five patients, the occurrence of third-degree right branch block (RBB) was observed. In one patient, early application of RBB was interrupted and the bonus application was not applied. This wasthe only acutely successful patient who presented clinical recurrence. Transient AB was not observed in any patient. No complications were observed. Conclusion: Cryoablation of para-Hisian pathways and NRTs in regions surrounding the His was an effective method for treatment in this population of patients refractory or refused for RF treatment. The occurrence of acute RBB does not seem to be a criterion for the interruption of applications.