Quick, safe, and effective maneuver to prevent phrenic nerve injury during cryoballoon ablation of atrial fibrillation

Abstract

Purpose: Phrenic nerve (PN) injury is a typical complication of cryoballoon ablation (CBA) of pulmonary veins. The PN function is monitored by palpating the abdomen during PN pacing, and freezing is prematurely terminated when a reduction in the diaphragm movement is recognized. This study aimed to investigate the efficacy and safety of a “pull-back” maneuver to prevent PN injury. Methods: A total of 284 patients were included, and the PN function was monitored by recording the diaphragmatic compound motor action potentials (CMAP) during the cryoballoon applications for pulmonary vein (PV) isolation. When the CMAP amplitude was reduced by more than 30% compared to the control, the “pull-back” maneuver (PBM) was undertaken to prevent PN injury. Results: The average CMAP amplitude significantly decreased from 0.81 ± 0.04 to 0.31 ± 0.21 (p < 0.01) mV during the cryoballoon applications of PVs in 92 PVs. The PBM was employed in all cases, and the average CMAP amplitude recovered to 0.87 ± 0.31 mV (p < 0.01) in 79 out of 92 PVs (85.9%), accomplishing the CBA. Cryofreezing had to be prematurely terminated due to failure of the PBM in 13 out of 92 cases (14.1%). Conclusions: The PBM was an effective maneuver to prevent PN injury by creating a distance between the PN and location of the cryoballoon. No adverse events were provoked by this procedure.