Cryoballoon ablation for atrial fibrillation: Effects on neuromodulation

Abstract

Pulmonary vein isolation (PVI) represents the mainstay of atrial fibrillation (AF) ablation, and PVI with cryoballoon catheter (CB) ablation (CB-A) has proven to be as effective and safe as radiofrequency ablation (RF-A). Although AF is initiated by triggers arising from the pulmonary veins (PV) and non-PV foci, the intrinsic cardiac nervous system (ICNS) plays a significant role in the induction and maintenance of AF. The ICNS is an epicardial neural system composed of ganglionated plexi (GPs) and a complex network of interconnecting neurons. In the left atrium, the major GPs are located in proximity to the PV-left atrial junction. Vagal reactions have been described as markers of autonomic modulation during PVI with both RF-A and CB-A. The occurrence of neuromodulation during PVI with CB-A may be explained by both the anatomical relationship between the GPs and the PVs and the characteristics of the CB. Due to the CB/PV size mismatch, the CB creates a wide ablation area that extends from the PV ostium toward the antrum, possibly including the GPs. Although targeted GPs ablation, as a supplemental strategy to PVI, has been associated with a better AF outcome in patients undergoing RF-A, the additional clinical benefit of neuromodulation during PVI with CB-A remains a matter of debate. In this review, we provide an overview of the anatomy of the ICNS, the relationship between the ICNS and AF pathophysiology, and the current evidence on the clinical relevance of neuromodulation during PVI with CB-A.

Keywords: atrial fibrillation; autonomic denervation; cardiac autonomic nervous system; cryoballoon ablation; ganglionated plexi; neuromodulation.

Figure 1

Anatomical localization of the major left atrial ganglionated plexi. Posterior view of the left and right atria displaying the presumed location of the major atrial ganglionated plexi (GPs) and the ligament of Marshall (LOM). The SLGP is located on the roof of the left atrium (LA), near the LSPV-LA junction; the ILGP is situated at the inferior aspect of the posterior wall of the LA; the ARGP is located anterior to the RSPV; the IRGP is situated at the inferior aspect of the LA. The ILGP and the IRGP are normally located 1–3 cm below the lower edge of the inferior pulmonary veins. SLGP, superior left GP; ILGP, inferior left GP; ARGP, anterior right GP; IRGP, inferior right GP; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; CS, coronary sinus; SVC, superior vena cava; IVC, inferior vena cava.

Figure 2

Extracardiac vagal stimulation during cryoballoon ablation. (A) Anteroposterior fluoroscopic view of a quadripolar catheter advanced through the right jugular vein to the jugular foramen for vagal stimulation. (B) Example of cryoballoon ablation of the right superior pulmonary vein (anteroposterior fluoroscopic view). (C) Extracardiac vagal stimulation before PVI showing a marked vagal response (asystole of around 14 s) followed by atrial fibrillation induction. (D) Extracardiac vagal stimulation at the end of cryoballoon ablation showing the absence of a vagal response (RR interval changes from 834 to 868 ms).