Coronary angiography in a patient with an inferior wall infarction shows the posterior descending artery arising from the distal left circumflex artery and running in the posterior interventricular groove. How should this coronary anatomy be classified, and which vessel supplies the AV node in this patient?

• A Left dominant, AV nodal artery from the left circumflex artery ✓
• B Right dominant, AV nodal artery from the right coronary artery
• C Balanced (codominant), AV nodal artery from both arteries
• D Left dominant, AV nodal artery from the left anterior descending artery

Explanation

Dominance is defined by which artery gives the posterior descending artery. In about 10 percent of individuals the left circumflex gives the PDA, defining left dominance, and in such hearts the AV nodal artery arises from the distal circumflex at the crux. Right dominance occurs in roughly 85 percent, with the AV nodal artery from the RCA. An inferior infarction can occur in any dominance pattern, so the angiographic finding decides the answer.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.