subsidiary atrial pacemaker

sub·sid·i·ar·y a·tri·al pace·mak·er

secondary source for rhythmic control of the heart, available for controlling cardiac activity if the sinoatrial pacemaker fails; usually located within the crista terminalis and atrial free wall near the inferior vena cava.

sub·sid·i·ar·y a·tri·al pace·mak·er

(sŭb-sid'ē-ar-ē ā'trē-ăl pās'māk-ĕr)
Secondary source for rhythmic control of the heart, available for controlling cardiac activity if the sinuatrial pacemaker fails; located within the crista terminalis and atrial free wall near the inferior vena cava.