Anatomic study of the morphologic relationship between the proximal left and right coronary arteries.

Abstract

Arising from the aorta, the right (RCA) and left (LCA) coronary arteries provide the arterial supply to the heart. An extensive literature review revealed that most studies have either evaluated the morphology of the RCA or the LCA independently. This study aimed to document the relationship between the morphology of the RCA and LCA using coronary angiograms and fetal dissections. In addition, variations such as split or double RCA and absence of the LCA was documented. A review of 500 coronary angiograms and a fetal dissection of 41 heart specimens was conducted. The RCA and LCA were classified according to their branching patterns and arterial dominance. The embryologic relationship between the RCA and the LCA was also documented including their lengths and diameters. The angiographic review showed that the most prevalent branching pattern of the LCA was bifurcation in 65.8%, while trifurcation and quadrifurcation occurred in 20.4% and 1.6%, respectively. The splitting of the RCA and absence of the LCA occurred in 4.2% and 11.8%, respectively. A significant correlation was found between the split RCA and absent LCA showing that the split RCA was more prevalent in the absence of the LCA. The dissection of the fetal heart specimens (age range 13.13 - 26.95 weeks) found that the RCA arose from the right aortic sinus and provided arterial dominance in all the specimens. The LCA was classified into types according to their branching pattern. The bifurcation, trifurcation and quadrifurcation of the LCA occurred in 68.3%, 29.3% and 2.4% of hearts, respectively. The mean lengths of the RCA and LCA were 0.98 ± 0.54mm and 1.83 ± 0.77mm, respectively. The mean diameters of the RCA and LCA were 0.38 ± 0.12mm and 0.49 ± 0.17mm, respectively. A significant correlation was found between the RCA and LCA length and the fetal age indicating changes in the development of the coronary vasculature with fetal development. A knowledge of the distribution of the RCA and LCA assists in providing information on the area of the myocardium supplied. With the advent of coronary angiography, a comprehensive understanding of coronary arterial anatomy and their variations is necessary.