Long-Term Effects of Atrial Ganglionated Plexi Ablation on Function and Structure of Sinoatrial and Atrioventricular Node in Canine.

Abstract

Long-term effects of ganglionated plexi (GP) ablation on sinoatrial node (SAN) and atrioventricular node (AVN) remain unclear. This study is to investigate the long-term effects of ablation of cardiac anterior right GP (ARGP) and inferior right GP (IRGP) on function and structure of SAN and AVN in canine. Thirty-two dogs were randomly divided into an operated group (n = 24) and sham-operated group (n = 8). ARGP and IRGP were ablated in operated group which was randomly divided into three subgroups according to the period ofevaluationafter operation (1 month, 6 months, 12 months). The functional and histological characteristics of SAN and AVN, as well as the expression of connexin (Cx) 43 and Cx 45 in SAN and AVN, were evaluated before and after ablation. Resting heart rate was increased and AVN effective refractory period was prolonged and sinus node recovery time (SNRT) and corrected SNRT were shortened immediately after ablation. These changes were reverted to preablation level after 1 month. At 1 month, ventricular rate during atrial fibrillation was slowed, atria-His intervals were prolonged, and Cx43 and Cx45 expression in SAN and AVN were downregulated. At 6 months, all changes were reverted to preablation level. The histological characteristics of SAN and AVN did not change. Ablation of ARGP and IRGP has short-term effects on function and structure of SAN and AVN rather than long-term effects, which suggests that ablation of ARGP and IRGP is safe. Atrioventricular conduction dysfunction after ablation may be related to downregulated Cx43 and Cx45 expression in AVN.