A patient undergoes coronary angiography which shows complete occlusion of the right coronary artery just after the origin of the posterior descending artery (PDA). Which areas of the heart are at risk of infarction?

• A Anterior wall and interventricular septum
• B Lateral wall of left ventricle and posterior papillary muscle
• C Posterior wall of left ventricle, posterior one-third of interventricular septum, and SA + AV nodes ✓
• D Right atrium and entire right ventricle

Explanation

In a right-dominant coronary circulation (85% of individuals), the right coronary artery (RCA) gives the posterior descending artery (PDA), which supplies the posterior one-third of the interventricular septum and posterior walls. The RCA also supplies the SA node (55–60% of cases via the SA nodal artery from RCA) and the AV node (90% of cases via the AV nodal artery from the PDA of RCA). Occlusion after the PDA origin will infarct the posterior left ventricular wall, posterior septum, and potentially the AV node, causing complete heart block. The lateral wall is supplied by the obtuse marginal from LCx.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.