Singapore Med J 2013; 54(1) : 49 O riginal A rticle INTRODUCTION The coronary arteries are the frst vessels that branch from the aorta, normally originating below the junction between the bulbus and the ascending aorta, i.e. at the sinotubular junction. The right and left coronary arteries (RCA and LCA, respectively) arise from the ascending aorta. Patency of the LCA is vital for suffcient perfusion of most of the heart. The LCA is responsible for irrigation of most of the left ventricle and also a considerable proportion of the right ventricle. (1) The LCA arises from the left posterior aortic sinus. Its length is variable, although it is not usually more than a few millimetres. It lies between the pulmonary trunk and the left atrial auricle, emerging into the atrioventricular (AV) groove, in which it turns left. Reaching the AV groove, the LCA usually divides into two main branches: the anterior interventricular artery (AIVA) and the circumfex artery (CA). (2) The AIVA (left anterior descending artery) passes to the left of the pulmonary trunk, travels into the upper portion of the interventricular sulcus and continues toward the apex of the heart. It branches into the anterior ventricular rami (diagonal artery) and septal rami. (3) The CA arises from the left main artery at almost a right angle. Its course nearly mirrors that of the RCA, as it travels under the left atrial appendage in the left AV sulcus around the left acute margin and toward the crux in most hearts, but sometimes it continues as a posterior interventricular artery (PIVA). The CA typically branches into the sinoatrial nodal artery, left marginal artery, and the atrial and ventricular rami. (3) The term ‘dominant’ is used to refer to the coronary artery giving off the PIVA, which supplies the posterior part of the ventricular septum, and often, to a part of the posterolateral wall of the left ventricle. The RCA is usually the dominant artery (60%). Left dominance is when the PIVA arises from the circumfex branch of the LCA. (2) Proficiency in the anatomy of coronary arteries and their variations is vital for proper interpretation of coronary angiographies, as well as for the assessment of complexities and results of coronary insuf fciency and surgical myocardium revascularisation. The LCA presents wide variability in its morphological expression. Thus, this study aimed to determine these variations in the LCA and its branches. METHODS The study was conducted on 30 heart specimens that were used during routine dissection for medical undergraduates in the Department of Anatomy, Kasturba Medical College, Manipal, India. We observed the origin, length and branching pattern of the LCA and its coronary dominance. The length of the LCA was measured using a digital vernier calliper. RESULTS In all the heart specimens (the approximate age was 50–80 years in both genders), the LCA originated normally, i.e. from the left posterior aortic sinus. No other associated variations or anomalies were found during dissection. Applying the criteria of extreme values, (1,4,5) we found a short main LCA trunk in three out of the 30 (10%) specimens and a long main LCA trunk in one (3.3%) specimen (Fig. 1). The length of the LCA trunk in the rest of the specimens (86.7%) was between 6–15 mm. The mean length of the LCA trunks was 8.86 ± 2.96 mm. The most frequent type of division was a bifurcation into two terminal branches (28/30; 93.3%) – the AIVA and CA. Anatomical variations in the left coronary artery and its branches Mamatha Hosapatna 1 , MBBS, MD, Antony Sylvan D’Souza 1 , MBBS, MS, Lokadolalu Chandracharya Prasanna 1 , MBBS, MD, Vijayalakshmi Sitanadhi Bhojaraja 1 , MBBS, Suhani Sumalatha 1 , BAMS, MSc 1 Department of Anatomy, Kasturba Medical College, Manipal University, Karnataka, India Correspondence: Dr Mamatha Hosapatna, Assistant Professor, Department of Anatomy, Kasturba Medical College, Manipal University, Manipal 576104, Karnataka, India. mamatha2010@yahoo.com INTRODUCTION Proficiency in the anatomy of coronary arteries and their variations is important for proper interpretation of coronary angiographies. The left coronary artery (LCA) commonly originates at the level of the left posterior aortic sinus and normally bifurcates into the anterior interventricular artery and circumfex artery. This study aimed to determine the variations in the LCA and its branches. METHODS The study was conducted on 30 heart specimens. We observed the origin, length and branching pattern of the LCA and its coronary dominance. RESULTS We found a short main LCA trunk in three specimens and a long main LCA trunk in one specimen. In two specimens, the division of the LCA led to three branches. With regard to ‘dominance’, one specimen showed left dominance while another showed codominance. CONCLUSION Variations of the LCA are clinically relevant, especially when a perioperative coronary perfusion or coronary arteriography is performed. Keywords: angiography, coronary artery, dominance, variations, vessels Singapore Med J 2013; 54(1): 49–52