A pacemaker(AOO) was implanted to the right atrial appendage in each of the dogs. The dogs in atrial pacing group were paced at 400 beats per minute for 6 weeks while those in the sham-operated group were not paced.

• 均开胸于右心耳缝植AOO型起搏器,快速起搏组以400次/min起搏6周,假手术组不起搏。