ANATOMY

Detailed explanation-1: -The sinus node is sometimes called the heart’s “natural pacemaker.” Each time the sinus node generates a new electrical impulse; that impulse spreads out through the heart’s upper chambers, called the right atrium and the left atrium (figure 2).

Detailed explanation-2: -The SA node is considered the pacemaker of the heart. Its electrical signals normally cause the atria of an adult’s heart to contract at a rate of about 60 to 100 times a minute. Disturbance anywhere along this electrical pathway can cause irregular heartbeats (arrhythmia).

Detailed explanation-3: -The SA node is the pacemaker of the heart and has an intrinsic rate of 60 – 100 bpm. If the SA node does not fire, the next pacemaker in hierarchical order is the AV node. This intrinsic rate of the AV node is 40 – 60 bpm.

Detailed explanation-4: -SA node likes to pace at 60-100bpm. atrial foci normally have an intrinsic rate of 60-80bpm.

Detailed explanation-5: -The sinoatrial node (SA node) is a specialized myocardial structure that initiates the electrical impulses to stimulate contraction, and is found in the atrial wall at the junction of superior caval vein and the right atrium (Mikawa and Hurtado, 2007).