Dual left anterior descending coronary artery: angiographic description of important variants and surgical implications.

Twenty-three cases of an anatomic variant of the left anterior descending artery (LAD) are described. This variant is termed "dual LAD" and consists of two branches which supply the usual distribution of the LAD. One branch (short LAD) terminates in the proximal aspect of the anterior interventricular sulcus (AIVS). A second, longer branch has a variable course outside the AIVS and returns to the AIVS distally. The long LAD arose from the LAD proper in 21 cases and from the RCA in two cases. The initial course of the long LAD was on the epicardial surface of the left ventricle (17 cases), right ventricle (three cases), or within the interventricular septum (three cases). Recognition of these variants is important for correct surgical identification of the short and long LADs.