Aberrant penetrating posterior descending artery from proximal right coronary artery.

We report a rare variant of the posterior descending artery (PDA) in a 51-year-old African-American male discovered in coronary CT angiography. Arising from the proximal right coronary artery near its ostium, the anomalous PDA penetrated posteriorly toward the atrioventricular junction septum, exited through the inferior pyramidal space into the posterior interventricular groove and continued in the groove as a short PDA. Along its course it gave rise to small branches to the medial wall of the right atrium, the atrioventricular node region, and the inferoseptal wall of the right ventricle.