The anomalous septal perforating artery. Its origin from the first diagonal, first marginal, or circumflex artery.

Origin of a septal perforating artery from a proximal portion of the left coronary system other than the left anterior descending artery was seen on coronary angiography in 18 out of 800 patients over a 14-month period. It arose from the first diagonal artery in 12 patients, the proximal circumflex artery in 2, and the first marginal artery in 4. The angiographic appearance and clinical significance of this finding are described.