Vagal Reactions during Cryoballoon-Based Pulmonary Vein Isolation: A Clue for Autonomic Nervous System Modulation?

Abstract

Although paroxysmal atrial fibrillation (AF) is known to be initiated by rapid firing of pulmonary veins (PV) and non-PV triggers, the crucial role of cardiac autonomic nervous system (ANS) in the initiation and maintenance of AF has long been appreciated in both experimental and clinical studies. The cardiac intrinsic ANS is composed of ganglionated plexi (GPs), located close to the left atrium-pulmonary vein junctions and a vast network of interconnecting neurons. Ablation strategies aiming for complete PV isolation (PVI) remain the cornerstone of AF ablation procedures. However, several observational studies and few randomized studies have suggested that GP ablation, as an adjunctive strategy, might achieve better clinical outcomes in patients undergoing radiofrequency-based PVI for both paroxysmal and nonparoxysmal AF. In these patients, vagal reactions (VR) such as vagally mediated bradycardia or asystole are thought to reflect intrinsic cardiac ANS modulation and/or denervation. Vagal reactions occurring during cryoballoon- (CB-) based PVI have been previously reported; however, little is known on resulting ANS modulation and/or prevalence and significance of vagal reactions during PVI with the CB technique. We conducted a review of prevalence, putative mechanisms, and significance of VR during CB-based PVI.

Second-generation cryoballoon ablation for recurrent atrial fibrillation after an index cryoballoon procedure: a staged strategy with variable balloon size

“…Finally, with this redo approach, we aimed to achieve a more comprehensive anatomical ablation of the area where the (networks to the) GPs are located [ 19 ], with the intention to focus the ablation more towards the ostium (23 mm) or the antral area (28 mm) of the pulmonary vein. As initiation and maintenance of AF is also affected by GPs [ 20 – 24 , 28 ], this approach may provide additional benefit for AF-free survival [ 25 – 27 ]. Appreciating the abovementioned rationale and the higher force of CB-2 balloons, we adopted this systematic approach of redo procedures with a CB-2 balloon using a different balloon size as compared to the index CB procedure.…”

Spastic occlusion of coronary artery during cryoballoon pulmonary vein isolation

“…Vagal reaction, such as vagally mediated bradycardia or asystole, can occur during ablation near GP with both radiofrequency ablation and cryoenergy ablation. 7 Therefore, it is possible to speculate that the cause of coronary artery spasm was the vagally mediated effect via left superior GP by CB application. Actually, the heart rhythm during right coronary spastic occlusion showed AF bradycardia, which was suggested to be mediated with the vagal effect via left superior GP.…”

Autonomic nervous system modulation and clinical outcome after pulmonary vein isolation using the second‐generation cryoballoon

“…A 3‐minute resting 12‐lead electrocardiogram was obtained one day before (after the washout of AADs) and after the index procedure (at 1, 3, 6, and 12 months on the same condition), and the average HR was automatically calculated if sinus rhythm was maintained (Electrocardiograph ECG‐1550, Nihon Kohden, Tokyo). ANS modulation was defined as a >20% decrease in the cycle length according to the previously reported definition during the follow‐up period relative to before the procedure.…”

“…An intraprocedural vagal reaction was defined as sinus bradycardia (<40 bpm), asystole, atrioventricular (AV) block, or hypotension that occurred during the balloon inflation, manipulation, freezing, thawing, deflation, or after the deflation, according to the previously reported definition . Temporary pacing was performed when the cycle length prolonged to >2,000 milliseconds during the procedure.…”