Subsinosal interventricular branch

The subsinuosal interventricular branch arises from the circumflex branch of the left coronary artery in species with left coronary dominance*.

It originates at the level of the coronary groove on the atrial (caudal) surface of the heart and enters the subsinuosal interventricular groove. From there, it runs toward the apex along this groove, which lies between the left and right ventricles on the atrial surface.

Along its course, the subsinuosal interventricular branch gives off numerous collateral branches. These include ventricular branches that supply the adjacent walls of both ventricles, and septal branches that penetrate the interventricular septum. The septal branches anastomose with those arising from the paraconal interventricular branch, contributing to the vascular network of the septum.

*The coronary dominance of a heart refers to the coronary artery (LCA or RCA) that perfuses the majority of the myocardial tissue and variable methods to determine this have been reported including which coronary artery supplies the subsinuosal interventricular branch, which coronary artery extends beyond the crux of the heart, the relative lengths and number of branches of the LCA or RCA, and the origination and layout of the arteries at the apex of the heart. The dog normally displays a left dominant coronary circulation , the cat is less studied but appears variable with a majority of cases indicating right coronary dominance, the rabbit is variable with predominately left coronary dominance, and the goat, swine, horse and donkey, cow, camelids, and 90% of humans are right dominant. In the mouse and rabbit, the subsinuosal interventricular branch is reported to be absent [1].