what is the primary pacemaker of the heart?
The pacemaker of the heart is a bundle of cells that tells the  heart when to beat. These cells are connected to the rest of the  cells of the heart and communicate with theâ¦m through electrical  signals. The pacemaker cells set the pace (or rate) of the  heartbeat.    The actual structure that serves as the heart's primary pacemaker  is called the sinoatrial node (SA node).