The right coronary artery (RCA) in most individuals (right dominant) gives rise to the posterior descending artery (PDA). Occlusion of the mid-RCA proximal to the sinoatrial nodal artery would cause infarction of:

• A Anterior wall and anterior interventricular septum
• B Lateral wall and posterior papillary muscle of mitral valve
• C Right ventricular outflow tract only
• D Inferior wall, posterior interventricular septum, and potentially the SA and AV nodes ✓

Explanation

The right coronary artery (right dominant, ~70% of population) supplies the right ventricle via acute marginal branches, the SA node (60% via the SA nodal artery from the proximal RCA), the AV node (via the AV nodal artery, a branch of the PDA), and the inferior wall of the left ventricle via the PDA. Proximal RCA occlusion (before the SA nodal artery origin) therefore threatens the inferior LV wall, posterior interventricular septum, right ventricle, SA node (sinus arrest, sinus bradycardia), and AV node (complete heart block). This explains why inferior STEMI classically presents with bradyarrhythmias. The anterior wall and septum are supplied by the LAD.

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

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Written and medically reviewed by the StethoPrep medical team.