The cardiac electrical conduction system includes several pacemakers of the heart. The sinoatrial (SA) node innervates the atrium of the heart.

 

This pacemaker keeps the heart at a normal rhythm 60-100 beats per minute. The SA node then passes the impulse to the second pacemaker the atrioventricular (AV) node.

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The AV node paces the heart at 40-60 beats per minute. The electrical impulse then passes from the AV node to the bundle of his where it bifurcates into the left and right bundle branches, down to the Purkinje Fibers which distribute the impulse throughout the bottom of the heart’s ventricles and paces the heart at 30-40 beats per minute.

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1st Pacemaker Sino-Atrial Node 60-100 BPM

(sends impulse across the atria)

 

 

2nd Pacemaker Atrio-Ventricular Node 40-60 BPM

(sends impulse to the Bundle of HIS to the Bundle Branches)

 

 

3rd Pacemaker Purkinje Fibers 30-40 BPM

(sends impulse across bottom of the heart’s ventricles)

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