Electrical conduction system of heart!
The sinoatrial (SA) node or sinus node is the heart’s natural pacemaker. It’s a small mass of specialized cells in the top of the right atrium (upper chamber of the heart). It produces the electrical impulses that cause your heart to beat.
A chamber of the heart contracts when an electrical impulse or signal moves across it. For the heart to beat properly, the signal must travel down a specific path to reach the ventricles (the heart’s lower chambers).
When the natural pacemaker is defective, the heartbeat may be too fast, too slow or irregular.
Rhythm problems also can occur because of a blockage of your heart’s electrical pathways.
The artificial pacemaker’s pulse generator sends electrical impulses to the heart to help it pump properly. An electrode is placed next to the heart wall and small electrical charges travel through the wire to the heart.
Most pacemakers have a sensing mode that inhibits the pacemaker from sending impulses when the heartbeat is above a certain level. It allows the pacemaker to fire when the heartbeat is too slow. These are called demand pacemakers.