A study of the distribution of the left coronary artery - clinical importance

The left coronary artery was seen originating in relation to the left posterior aortic sinus in 100% of the specimens. The incidence of bifurcation of the left coronary artery was found in 64% and trifurcation in 36%. In 26% of hearts the circumflex branch of the left coronary artery crossed the crux, in 20% the SA Nodal artery, and in 24% the AV Nodal artery was seen as a branch of the circumflex artery. 2% incidence of retroaortic course of the left circumflex artery was observed. The left coronary artery and its branches are responsible for the irrigation of most of the left ventricle and part of the right ventricle. In case of trifurcation, where the left diagonal artery takes origin directly from the left coronary artery, the size of infarct on occlusion of the left anterior descending artery would be reduced. The left circumflex artery taking origin from the right sinus of Valsalva is an anomaly which may remain clinically silent, but at times it has been known to get compressed during valve replacement surgery, if not detected preoperatively. In hearts where both SA and AV nodal arteries originated from left coronary artery (8%), occlusion of the left coronary artery could severely affect the conducting system.