The left coronary artery (LCA) usually divides into two (anterior interventricular artery [AIA] and left circumflex [LCx] artery) or less frequently into the AIA, LCx, and one or more “additional” terminal branch/es (ATBs). These ATBs of the LCA have no unanimity regarding their anatomical nomenclature. There is a lack of common consensus on the criteria used for their definition, and they are also absent from the current Terminologia Anatomica (1998). This study, therefore, aimed to document the prevalence of the ATBs of the LCA, discuss their clinical importance, and propose an anatomical nomenclature. This study was conducted by reviewing 367 coronary angiograms. The termination patterns of the LCA were classified into 3 categories based on the number of their branches, viz. (a) bifurcation 78.2%, (b) trifurcation 20.4%, and (c) quadrifurcation 1.4%, respectively. The presence of an ATB was recorded in 21.8% of the angiograms. The identification of this vessel may be of clinical importance because the extent of its supply may decrease the effect of occlusion of the LCx artery and AIA on the myocardium. The term “left ramus medianus artery” is proposed as the nomenclature for the ATB of the LCA

Ajayi, N. O.

Lazarus, L.

Satyapal, K. S.

Vanker, E. A.

English

Via Medica Journals

Folia Morphol. Vol. 72, No. 2, pp. 128–131DOI: 10.5603/FM.2013.0021Copyright © 2013 Via MedicaISSN 0015–5659 www.fm.viamedica.plO R I G I N A L   A R T I C L E128Address for correspondence: Prof. K.S. Satyapal, Department of Clinical Anatomy, School of Laboratory Medicine and Medical Sciences,  College of Health Sciences, Westville Campus, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa,  tel: +27 31 260 7899, +27 83 777 8780, fax: +27 31 260 7890, e-mail: satyapalk@ukzn.ac.zaThe prevalence and clinical importance  of an “additional” terminal branch  of the left coronary arteryN.O. Ajayi1, L. Lazarus1, E.A. Vanker2, K.S. Satyapal11Department of Clinical Anatomy, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, Westville Campus, University of KwaZulu-Natal, Durban, South Africa 2Specialist Cardio-Thoracic Surgeon, St Augustine’s Hospital, Chelmsford Medical Centre 3, Durban, South Africa[Received 6 November 2012; Accepted 23 January 2013]The left coronary artery (LCA) usually divides into two (anterior interventricular artery [AIA] and left circumflex [LCx] artery) or less frequently into the AIA, LCx, and one or more “additional” terminal branch/es (ATBs). These ATBs of the LCA have no unanimity regarding their anatomical nomenclature. There is a lack of common consensus on the criteria used for their definition, and they are also absent from the current Terminologia Anatomica (1998). This study, therefore, aimed to document the prevalence of the ATBs of the LCA, discuss their clinical importance, and propose an anatomical nomenclature. This study was conducted by reviewing 367 coronary angiograms. The termination patterns of the LCA were classified into 3 categories based on the number of their branches, viz. (a) bifurca-tion 78.2%, (b) trifurcation 20.4%, and (c) quadrifurcation 1.4%, respectively. The presence of an ATB was recorded in 21.8% of the angiograms. The identification of this vessel may be of clinical importance because the extent of its supply may decrease the effect of occlusion of the LCx artery and AIA on the myocardium. The term “left ramus medianus artery” is proposed as the nomenclature for the ATB of the LCA. (Folia Morphol 2013; 72, 2: 128–131)Key words: left coronary artery, branching pattern, nomenclature, “left ramus medianus artery”INTRODUCTIONThe arterial supply of most of the heart is depen-dent on the patency of the left coronary artery (LCA) [19]. On reaching the atrioventricular groove, the LCA usually divides into 2 (anterior interventricular artery [AIA] and left circumflex [LCx] artery) or less frequently into the AIA, LCx, and one or more “ad-ditional” terminal branch/es (ATBs). It is these ATBs (1 or more) that are the topic of investigation and discussion in this paper. There is great variability in the morphometric and morphologic parameters of the LCA with regard to its length, calibre, angle of division, and branching pattern [7]. Although the description of the LCA and its branches have been the topic of repeated anatomi-cal investigation, it is surprising to find that there is no unanimity in the literature regarding the no-menclature of the ATBs of the LCA (when present). There is also a lack of consensus on the criteria used for their definition [16], and these ATBs are 129N.O. Ajayi et al., Left coronary artery branching patternsabsent from the current Terminologia Anatomica (1998) [9]. Furthermore, the nomenclature of these branches has not been afforded much attention in standard anatomical textbooks [15, 20, 21]. Howe-ver, in anatomical studies these branches have been referred to as the “ramus diagonalis” [3], “median (or intermedian)” branch [8, 19, 24], and “diagonal branch” [17].  In clinical textbooks, these ATBs are named the “ramus medianus artery” [23] or the “ramus interme-dius branch” [22]. The bifurcation of the LCA into the AIA and LCx arteries is the most common branching pattern, while the trifurcation of the LCA into the AIA, LCx artery, and an ATB is described as a variation of its branching pattern [24]. The branching of the LCA into 4 or 5 branches has also been reported in the literature [4, 11]. Some authors define the ATB as the artery loca-ted at the vertex of the angle formed by the AIA and LCx arteries (Figs. 1A, B) [6, 12–14, 19], while the vessels not at this vertex are considered as collate-ral branches of the AIA and the LCx arteries. Other authors used a wider definition and considered the ATB as the vessel that originated in the vertex of the angle formed by the terminal branches of the LCA, including the initial length of the AIA and LCx artery (Fig. 1C) [3]. This study aimed to record the prevalence of ATB of the LCA, discuss its clinical im-portance and propose an anatomical nomenclature based on the origin of the ATB. MATERIALS AND METHODSA total of 407 coronary angiograms were obtained from cardiac catheterisation laboratories in the eThe-kwini Metropolitan area, KwaZulu Natal, South Africa. The coronary angiograms without LCA (with branches originating directly from the left aortic sinus) (n = 39) and 1 of the angiograms with a poor image of the LCA were excluded. Consequently, a total of 367 an-giograms were analysed by 2 independent observers. The branching patterns of the LCA were noted and documented. In this study, the ATB of the LCA was defined as the vessel that originated from the vertex of the angle between the AIA and LCx artery (Figs. 1A, B). RESULTSAfter excluding the coronary angiograms with ab-sent LCA, the remaining angiograms (n = 367) were analysed. The incidences of the branching patterns were (i) 287/367 (78.2%), 75/367 (20.4%), and 5/367 (1.4%) for bifurcation (Fig. 2), trifurcation (Fig. 3), and quadrifurcation (Fig. 4) patterns, respectively (Table 1). DISCUSSIONThere is substantial variation in the incidence of the ATB of the LCA reported in the literature (19–60%) (Table 1). This may be due to the inconsistent definition of the ATB by different authors [19]. In this study, the branching pattern of the LCA into its 2 terminal bran-ches, viz. the AIA and LCx artery, was classified as the bifurcation pattern (n = 287/367 [78.2%]). The presence Figure 1A–C. Schematic diagram illustrating the varying definition of the “additional” terminal branch of the left coronary artery (LCA); A, B. “Additional” terminal branch from the vertex of the angle for-med by the anterior interventricular artery (AIA) and left circumflex artery (LCx); C. “Additional” terminal branch from the vertex of the angle formed by the AIA and LCx and the proximal segments of the AIA and LCx artery; ATB — additional terminal branch. Figure 2. Coronary angiogram in the right anterior oblique projec-tion showing bifurcation of the left coronary artery (LCA) into ante-rior interventricular artery (AIA) and left circumflex (LCx) artery.130Folia Morphol., 2013, Vol. 72, No. 2of an ATB (originating from the vertex of the angle formed by the AIA and LCx artery) was classified either as a trifurcation pattern (n = 75/367 [20.4%] — for 1 ATB) or a quadrifurcation pattern (n = 5/367 [1.4%] — for 2 ATBs). The incidence of 20.4% recorded for the trifurcation pattern of the LCA compared favourably with the range of 14–60% reported in the literature, while an incidence of 1.4% for the quadrifurcation of the LCA in this study was lower than the range of 2–10% recorded in the literature (Table 1). The trifurcation of the LCA usually has no adverse haemodynamic effects and may play a protective role against the development of myocardial ischaemia [1]. However, it may cause technical difficulties in coronary artery catheterisation and therefore be a source of com-plication or misdiagnosis [13]. In cases of myocardial in-farction, failure to recognise the occlusion of an ATB may cause misinterpretation of coronary angiograms [10].The blood supply to the sterno-costal surface of the left ventricle may be through an ATB [16]. It may also give off 1 or more anterior septal arteries and su-pply the anterior papillary muscle of the left ventricle. In certain cases, and depending on its distribution, the ATB may be an important source of collateral circulation [16, 24]. The identification of this vessel may be of clinical importance because the extent of Figure 3. Coronary angiogram in the right anterior oblique projec-tion showing trifurcation of the left coronary artery (LCA) into ante-rior interventricular artery (AIA), left circumflex (LCx) artery, and an “additional” terminal branch (ATB).Figure 4. Coronary angiogram in the left anterior oblique projection (caudal view) showing the quadrifurcation of the left coronary arte-ry (LCA) into the anterior interventricular artery (AIA), left circum-flex (LCx) artery, and 2 “additional” terminal branches (ATBs).Table 1. Incidence of the branching patterns of the left coronary artery Author (year) Sample size  Number of branches and percentage       2 (%) 3 (%) 4 (%)  Crainicianu (1922)* 200 38 60 2    Kalbfleisch and Hort (1976)*  41 53 –    Baptisa et al. (1991) [3] 150 54.7 38.7 6.7    Lujinović et al. (2005) [14] 120 71 29 –    Kilic and Kiriki (2007) [12] 50 86 14 –    Ballesteros and Ramirez (2008) [2] 154 52 42.2 5.8    Kosar et al. (2009) [13] 700 69 31 –    Christensen et al. (2010) [6] 105 81 19     Fazliogullari et al. (2010) [8]  50 46 44 10    Present study 367 78.2 20.4 1.4  *Cited by Rieg and Petit (2004)131N.O. Ajayi et al., Left coronary artery branching patternsits supply may decrease the effect of occlusion of the AIA and LCx artery on the myocardium [18].Cademartiri et al. [5] recorded a prevalence of 21.9% for the ATB of the LCA. They reported an asso-ciation of the presence of ATB with decreased num-ber of diagonal branches of the AIA and stressed the importance of the ATB in the vascular supply of the myocardium. The present study found the presence of ATBs of the LCA present in 21.8% (trifurcation [20.4%] and quadrifurcation [1.4%] patterns) of the angio-grams. Therefore, the division of the LCA into more than 2 terminal branches is not an infrequent bran-ching pattern. Consequently, based on these findings, the term “left ramus medianus artery” is proposed as the nomenclature for the additional branches of the LCA. This is based on the fact that these additional branches of the LCA are regarded as median branches (i.e. they originate from the vertex of the angle formed by the AIA and LCx artery) of the LCA. Furthermore, in cases where there are more than one ATB, they may be distinguished by adding the suffix I, II, and III for the third, fourth, and fifth branches of the LCA, respectively, starting from the vessel closest to the AIA. CONCLUSIONSThis study illustrated that the presence of the ATBs (21.8% [trifurcation and quadrifurcation]) is not an unusual branching pattern of the LCA. These ATBs may be a source of complication or misdiagnosis. The term “left ramus medianus artery” is recommended to be applied to the one or more ATBs as this may be helpful in standardising the nomenclature of this important additional branch of the LCA.REFERENCES1.  Abuchaim DCS, Spera CA, Faraco DL, Ribas Filho JM, Malafaia O (2009) Coronary dominance patterns in the human heart investigated by corrosion casting. Rev Bras Cir Cardiovasc, 24: 514–518.2.  Ballesteros LE, Ramirez LM (2008) Morphological expres-sion of the left coronary artery: a direct anatomical study. Folia Morphol, 67:135–142.3.  Baptista CA, Di Dio LJ, Prates JC (1991) Types of division of the left coronary artery and the ramus diagonalis of the human heart. Jpn Heart J, 32: 323–335.4.  Bhimalli S, Dixit D, Siddibhavi M and Shirol VS (2011) A study of variations in coronary arterial system in cada-veric human heart. World J Sci Tech, 1: 30–35.5.  Cademartiri F, La Grutta L, Malagň R, Alberghina F, Meij-boom W, Pugliese F, Maffei E et al. 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The prevalence and clinical importance of an “additional” terminal branch of the left coronary artery

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The prevalence and clinical importance of an “additional” terminal branch of the left coronary artery

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