European Journal of Cardiovascular Medicine

Functionally, Heart is a fused pair of valved muscular pumps circulating blood in series through systemic (left heart) and pulmonary (right heart) circulations. The word “coronary” comes from the Latin “corona” and Greek “koron” that means “crown” covering the heart.(1) Of the two coronary arteries much importance is given to the anatomy of left coronary artery, which is larger in calibre when compared to the Right coronary artery, covers greater volume of myocardium, almost all of left ventricle. The left coronary artery arises from the left posterior aortic sinus which may give off a small atrial ramus and rarely, the sinu-atrial nodal artery.(2) Reaching the atrio-ventricular groove, the left coronary artery  (LCA) bifurcates into its main branches namely, the circumflex ( CA) and anterior interventricular artery or Left anterior descending artery (LAD) in majority of the cases. other anatomical variations like trifurcation, quadrifurcation based on the number of diagonal branches have been widely documented in literature thus warranting detailed survey of these variations.

The present descriptive anatomical study was conducted on 53 formalin-fixed human hearts, irrespective of age and sex, obtained from the Department of Anatomy, SVIMS-SPMC(W), Tirupati, located in the Rayalaseema zone.

Each specimen was carefully dissected to expose the coronary arteries. Observations were recorded, and photographic documentation was performed for each specimen. The collected data were tabulated, statistically analyzed, and compared with findings from previously published literature to identify variations and patterns.

Parameters Studied

1. Origin of the Left Coronary Artery (LCA):

 The site of origin of the LCA from the left posterior aortic sinus (left coronary sinus) was noted.

2. Branching Pattern of the LCA, Left Anterior Descending Artery (LAD), and Left Circumflex Artery (LCx):

The LCA branching pattern was classified as bifurcation, trifurcation, tetrafurcation or pentafurcation based on the number of primary branches arising from the LCA trunk.

    The number and distribution of diagonal branches and ventricular rami of the LAD were observed and recorded.

    The number of marginal branches and auricular branches arising from the LCx were also documented.

3. Termination of the LAD and LCx:

    The LAD was classified based on its level of termination as:

1. a) terminating before the apex,
2. b) at the apex, or
3. c) winding around the incisura apicis cordis.

    The LCx termination was categorized as:

1. a) before the obtuse border,
2. b) at the obtuse border,
3. c) between the obtuse border and the crux, or
4. d) at the crux of the heart.

The variations observed in the origin of LCA from aortic sinus, branching pattern, mode of termination of LCA, same observation is also carried with relevance to LAD and CA.

Branching pattern of LCA: Regarding the branching pattern, generally LCA bifurcates into two branches but sometimes it may bifurcate into three, four or five. In the present study out of 53 specimens, Bifurcation was observed in 24 specimens i.e., 45.3% and Trifurcation was observed in 24 specimens i.e., 45.3% whereas tetrafurcation and pentafurcation was observed in 3(5.7%) and 2(3.8%) respectively.

Termination of LAD : Regarding the termination of LAD, In the present study LAD terminates at apex in 29(54.7%) specimens and it terminates by winding around the apex and anastomosis with the posterior interventricular branch in 14(26.4%) specimens whereas in 10 (18.9%) specimens LAD terminates before apex was observed.

Table-1: Termination of LAD

Diagonal branches of LAD : Regarding the diagonal branches of LAD in the present study, out of 53 specimens we observed that in 29(54.7%) specimens diagonal branch is single and two diagonal branches are observed in 14(26.4%) specimens and three branches are seen in 8(15.1%) specimens and four branches are in 2(3.8%) specimens.

Ventricular rami for right & Left ventricle of LAD : In the present study, regarding to the ventricular rami for right ventricle of LAD, out of 53 specimens, ventricular branches are absent in 2(3.8%) specimens, whereas one branch in 3(5.7%) specimens, two branches in 12(22.6%) specimens, three branches in 18(34%) specimens, four branches in 11(20.8%) specimens, five branches in 6(11.3%) specimens, six branches in 1(1.9%) specimen.

Regarding to the ventricular rami for left ventricular branch of LAD , generally LCA supplies most of the left ventricle. In the present study, out of 53 specimens ventricular rami for left ventricular branch is absent in 2 (3.8%) specimens, whereas two branches in 5 (9.4%) specimens, three branches in 6 (11.3%) specimens, Four branches in 12 (22.6%) specimens, five branches in 9 (17%) specimens, six branches in 10 (18.9%) specimens, seven branches in the 4 (7.5%) specimens, eight branches in 2 (3.8%) specimens, whereas in 1 (1.9%) specimen, nine, ten and eleven branches are observed.

Table-2: Termination of CA

Marginal branches of CA : The main branch of CA is the marginal branch. In the present study out of 53 specimens, one branch is seen in 29 (54.7%) specimens whereas two branches are observed in 20 (37.7%) specimens and three branches are seen 4(7.5%) specimens.

The present study provides valuable insights into the anatomical variations of the left coronary artery (LCA), left anterior descending artery (LAD), and left circumflex artery (LCx). Understanding these variations is crucial for clinicians and cardiac surgeons during diagnostic angiography, coronary interventions, and bypass grafting procedures.

Table-3: Comparison of our study with other studies

In the current study, the bifurcation pattern of the LCA was observed in 45.3% of specimens, which is closely consistent with the findings of Surucu H.S. et al.(3) who reported a similar distribution. The trifurcation pattern observed in 45.3% of specimens also correlates well with previous studies by Surucu H.S., L.E. Ballesteros, and Lakshmiprabha S.,(3,4,10) where trifurcation occurred in approximately 40–50% of cases. Less frequent branching patterns, such as tetrafurcation and pentafurcation, were observed in 5.7% and 3.8% of specimens respectively, which align with the studies of L.E. Ballesteros,(4) P. Darmendra, Julius A.(5) Ogeng’o, and Vandana Ravi,(9) who also documented rare occurrences of higher-order branching. These findings underscore the wide anatomical variability of the LCA trunk, which has significant implications in interventional cardiology — particularly in identifying the precise origin of the diagonal, marginal, and septal branches during angiographic evaluation.

In the present study, the LAD terminated at the apex in 54.7% of specimens, wound around the apex and anastomosed with the posterior interventricular branch in 26.4%, and terminated before the apex in 18.9%. These findings are in close agreement with those of Nagaraj Mallashetty et al.(8), who observed that the LAD terminated at the apex in 50% of specimens, wound around the apex in 46.67%, and terminated before the apex in 3.33% of specimens. Such variations in LAD termination are clinically significant, as they influence the extent of myocardial perfusion and the area at risk during occlusive coronary events. A longer LAD that wraps around the apex provides additional collateral circulation to the inferior interventricular region, thereby reducing ischemic risk in inferior wall infarctions.

The LCx terminated between the crux and obtuse border in 77.35% of specimens, followed by termination at the crux in 13.2%, at the obtuse border in 7.54%, and before the obtuse border in 1.88%. These findings are comparable to the results of Nagaraj Mallashetty et al. (8), who reported that the LCx terminated between the crux and obtuse margin in 60% of cases, and to Lakshmiprabha S. (10), who described similar termination levels. The termination level of the LCx is functionally important, as it determines coronary dominance. A LCx extending to or beyond the crux suggests a left-dominant circulation, influencing both myocardial perfusion distribution and risk stratification in coronary artery disease.

The observed anatomical variations reinforce the importance of preoperative imaging and intraoperative awareness during coronary artery bypass grafting (CABG) and angioplasty. Variability in LCA branching or LAD termination may alter the interpretation of coronary angiograms and the placement of grafts or stents. Therefore, understanding these patterns not only aids in anatomical orientation but also minimizes procedural complications.

After detailed analysis and meticulous comparison with literature, In contrast to earlier studies showing a predominance of the bifurcation pattern, the present study revealed that bifurcation and trifurcation patterns occurred with nearly equal frequency. Although the present study is not exhaustive, it highlights important aspects of coronary artery branching patterns and their variations, which may provide valuable insight into coronary circulation. Awareness of anatomical variants helps clinicians anticipate complications, choose appropriate revascularization strategies, and improve patient outcomes

1. Standring S, ed. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st ed. London: Elsevier; 2016. p. 997–1020.
2. Dutta AK. Essentials of Human Anatomy (Thorax and Abdomen). 9th ed. Kolkata: Current Books International; 2010. p. 81–86.
3. Surucu HS, Karahan ST, Tanyeli E. Branching pattern of the left coronary artery and an important branch—the median artery. Saudi Med J. 2004;25(2):177–81.
4. Ballesteros LE, Ramirez LM, Quintero ID. Morphological expression of the left coronary artery: a direct anatomical study. Folia Morphol (Warsz). 2008;67(2):135–42.
5. Dharmendra P, et al. Clinically significant anatomical variations of the left coronary artery in human cadaveric hearts. Int J Curr Res Rev. 2013;5(12):1–6.
6. Hosapatna M, et al. Anatomical variations in the left coronary artery and its branches. Singapore Med J. 2013;54(1):49–52.
7. Ogeng’o JA, Olabu BO, Gatonga PM, Mwachaka PM. Variant termination of the left coronary artery: pentafurcation is not uncommon. Eur J Anat. 2014;18(2):98–101.
8. Mallashetty N, et al. The study of branching pattern and variations in the left coronary artery in human heart with a unique case of crossing of coronary arteries—a cadaveric study. Indian J Clin Anat Physiol. 2017;4(1):48–50.
9. Ravi V, et al. Anatomical variation in branching pattern and dominance in coronary arteries: a cadaveric study. Int J Anat Res. 2017;5(1):3611–17.
10. Lakshmiprabha S, et al. Variations in the anatomical and branching pattern of the left coronary artery: a cadaveric study. Int J Res Med Sci. 2018;6(4):1235–40.
11. Manickavasuki AK, et al. Anatomical study of left coronary artery and its variations—a cadaveric study. J Clin Diagn Res. 2018;12(1):AC06–AC09