atrioventricular bundle

例句：

1. 1.The atrial flutter is a common cause of arrhythmias.
   房性心动过速是心律失常的常见原因。
2. 2.The atrial septum is the thin partition between the atria and ventricles.
   房间隔是心房和心室之间的薄分隔。
3. 3. During the atrial contraction, the atria contracts while the ventricles relax.
   在心房收缩期间，心房收缩而心室放松。