Which coronary artery infarct is most associated with bradycardia and heart block?

• A. Left anterior descending artery
• B. Circumflex artery
• C. Right coronary artery
• D. Posterior descending artery

Answer: (C)

The right coronary artery (RCA) is most commonly associated with bradycardia and heart block due to its role in supplying blood to the right atrium, the sinoatrial (SA) node, and the atrioventricular (AV) node in the majority of individuals, especially those who are right-dominant in their coronary circulation. When the RCA is occluded or infarcted, the blood supply to these critical areas can be compromised, leading to disturbances in electrical conduction.

Bradycardia frequently results from impairment of the SA node's ability to generate impulses or from AV block due to ischemia affecting the conductive pathways. Specifically, if the RCA is blocked, not only can the heart rate decrease due to decreased impulse generation from the SA node, but blockages can also cause a delay in the signals from the atria to the ventricles due to the compromised blood flow to the AV node.

In contrast, the left anterior descending artery primarily supplies the anterior wall of the left ventricle and does not significantly impact the conduction system's nodes. The circumflex artery mainly provides blood to the lateral and posterior walls of the left ventricle and has a lesser role in supplying the conduction system. The posterior descending