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
Electrophysiology Service, Montreal Heart Institute, Université de Montréal, Montreal, Canada.
J Cardiovasc Electrophysiol. 2014 Feb;25(2):187-94. doi: 10.1111/jce.12296. Epub 2013 Oct 11.
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.
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.
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.
半膈肌麻痹是冷冻球囊消融治疗心房颤动最常见的并发症，然而膈神经损伤的组织病理学尚未得到充分描述。
进行了一项临床前随机研究，以明确冷冻球囊消融所致膈神经损伤的组织病理学特征，并评估肌电图（EMG）监测限制膈神经损伤的可能性。32只犬接受了右上肺静脉冷冻球囊消融，目的是诱发膈神经损伤。动物按1:1随机分为标准监测组（即膈肌运动减弱时中断消融）和EMG引导组（即膈肌复合运动动作电位[CMAP]幅度降低30%时停止消融）。所有犬均达到急性手术终点。膈神经损伤的特征为沃勒变性，伴有大的有髓轴突的神经束膜下损伤及轴突再生迹象。膈神经损伤程度与CMAP幅度降低程度平行（P = 0.007）。随机分配至EMG引导组的动物急性半膈肌麻痹发生率较低（50%对100%；P = 0.001），30天时持续性麻痹发生率较低（21%对75%；多变量优势比0.12，95%置信区间[0.02, 0.69]，P = 0.017），组织学损伤严重程度较轻（P = 0.001）。两组成熟肺静脉消融灶特征，包括圆周度和透壁性，相似。
冷冻球囊消融所致膈神经损伤本质上是轴索性的，特征为沃勒变性，有恢复潜力。EMG引导方法在限制膈神经损伤方面优于标准监测。
