Types of division of the left coronary artery and the ramus diagonalis of the human heart.

The surgical, clinical and radiological importance of the diagonal artery in the human heart and the extreme variability in its description prompted us to undertake its study. The investigation was performed in 150 hearts, dissected after injection of colored substance in the coronary arteries. The following results were obtained: The left coronary artery presented 3 types of division: bifurcation (54.7%), trifurcation (38.7%) and quadrifurcation (6.7%); the latter 2 patterns produced a diagonal artery. The trunk of the left coronary artery bifurcated more frequently in hearts of female Caucasians (57.1%) and male Caucasians (54.9%). It trifurcated more frequently (60%) in hearts of female non-Caucasians. The ramus diagonalis was found in 45.3% of the hearts. The incidence of a ramus diagonalis did not differ significantly between male Caucasians (45%), male non-Caucasians (42.8%) and female Caucasians (37%). However, it occurred more frequently in female non-Caucasians (66.5%). The length of the ramus diagonalis varied from 20.1 to 50 mm (79.3%) and its relative length varied from 21 to 50% of the length of the left ventricle (75.3%). The ramus diagonalis was classified as short, medium and long types, the former 2 types were most frequent.