Background - Sinus node (SN) dysfunction is common in patients with atrial tachyarrhythmias including atrial fibrillation (AF), but underlying mechanisms remain poorly understood. This study was performed to evaluate the effect of atrial tachyarrhythmia on SN function and ion channel expression in canine model.
Methods and Results - Five mongrel dogs (20 to 25 kg) were instrumented with a pacemaker programmed to provide atrial pacing of 300 bpm for 4 weeks. Sinoatrial conduction time (SACT) and corrected sinus node recovery time (cSNRT) were assessed at baseline, 2 and 4 weeks. SN region, RA free wall and LA appendage tissue samples were collected at 4 weeks for analysis of ion channel expression. Both cSNRT and SACT were significantly prolonged 2 weeks after rapid atrial pacing, but interestingly slightly recovered at 4 weeks. Ion channel expression data will be presented at the meeting.
Conclusions - SN dysfunction was observed in canine model with atrial pacing of 300 bpm at 2 weeks and slightly recovered in 4 weeks. These findings suggest that there might be protective electrical remodeling against atrial tachyarrhythmia in SN.