Effects of different intensity of atrial pacing on atrial electrophysiology and nerve remodeling

Background and Objective Atrial fibrillation (AF) could be induced by different intensity of atrial pacing, however the detail information during these processes have not been fully explored. The aim of this study was to evaluate the effects of different intensity of atrial pacing on atrial electrophysiology. Methods Twenty-four dogs were randomly subjected to 16 hours atrial pacing at 500 beats/min (bpm) or 1000 bpm as follows: no stimulation (control, n = 8), 500 bpm stimulation (500 bpm, n = 8) and 1000 bpm stimulation (1000 bpm, n = 8). Programmed and burst atrial pacing were performed at baseline and at the end of every 2 hour to determine AF inducibility, sustained time of AF and atrial effective refractory period (ERP). Moreover, the electrical activities of vagus nerve including discharge frequency, signal area were also recorded. In addition, serum acetylcholine (Ach) was determined by ELISA to explore the relationship with AF and vagus nerve features. Results Increased AF inducibility, sustained time of AF and ERP were found in dogs from 1000 bpm group compared to 500 bpm group. Moreover, increased discharge frequency and signal area of vagus nerve were also found in dogs from 1000 bpm group compared to 500 bpm group. Correlation was found between the serum Ach and AF. Conclusions Our results demonstrated that different intensity of atrial pacing exerted different effects on atrial electrophysiology and nerve remodeling, while high-frequency electrical stimulation are more prone to autonomic nervous activity induction.