Premium
Histopathology of Cryoballoon Ablation‐Induced Phrenic Nerve Injury
Author(s) -
ANDRADE JASON G.,
DUBUC MARC,
FERREIRA JOSE,
GUERRA PETER G.,
LANDRY EVELYN,
COULOMBE NICOLAS,
RIVARD LENA,
MACLE LAURENT,
THIBAULT BERNARD,
TALAJIC MARIO,
ROY DENIS,
KHAIRY PAUL
Publication year - 2014
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/jce.12296
Subject(s) - medicine , phrenic nerve , diaphragmatic breathing , anesthesia , surgery , pathology , respiratory system , alternative medicine
Cryoballoon‐Induced Phrenic Nerve Injury Introduction Hemi‐diaphragmatic paralysis is the most common complication associated with cryoballoon ablation for atrial fibrillation, yet the histopathology of phrenic nerve injury has not been well described. Methods and Results A preclinical randomized study was conducted to characterize the histopathology of phrenic nerve injury induced by cryoballoon ablation and assess the potential for electromyographic (EMG) monitoring to limit phrenic nerve damage. Thirty‐two dogs underwent cryoballoon ablation of the right superior pulmonary vein with the objective of inducing phrenic nerve injury. Animals were randomized 1:1 to standard monitoring (i.e., interruption of ablation upon reduction in diaphragmatic motion) versus EMG guidance (i.e., cessation of ablation upon a 30% reduction in the diaphragmatic compound motor action potential [CMAP] amplitude). The acute procedural endpoint was achieved in all dogs. Phrenic nerve injury was characterized by Wallerian degeneration, with subperineural injury to large myelinated axons and evidence of axonal regeneration. The degree of phrenic nerve injury paralleled the reduction in CMAP amplitude (P = 0.007). Animals randomized to EMG guidance had a lower incidence of acute hemi‐diaphragmatic paralysis (50% vs 100%; P = 0.001), persistent paralysis at 30 days (21% vs 75%; multivariate odds ratio 0.12, 95% confidence interval [0.02, 0.69], P = 0.017), and a lesser severity of histologic injury (P = 0.001). Mature pulmonary vein ablation lesion characteristics, including circumferentiality and transmurality, were similar in both groups. Conclusion Phrenic nerve injury induced by cryoballoon ablation is axonal in nature and characterized by Wallerian degeneration, with potential for recovery. An EMG‐guided approach is superior to standard monitoring in limiting phrenic nerve damage.