Anatomia, Histologia, Embryologia
ORIGINAL ARTICLE
Absent Left Main Coronary Artery with Variation in the Origin of its Branches in a South African Population N. O. Ajayi1, L. Lazarus1, E. A. Vanker2 and K. S. Satyapal1* Addresses of authors: 1 Department of Clinical Anatomy, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa; 2 Chelmsford Medical Centre 3, St Augustine’s Hospital, 107 Chelmsford Rd, Durban 4001, South Africa
*Correspondence: Tel.: + 27 31 260 7899, + 27 83 777 8780; fax: + 27 31 260 7890; e-mail: [email protected] With 5 figures and 2 tables Received March 2013; accepted for publication January 2014 doi: 10.1111/ahe.12109
Summary Coronary artery anomalies are traditionally classified into anomalies of origin, course and termination. One of the anomalies of origin is absence of the left main coronary artery (LMCA), where the left anterior descending (LAD), the circumflex (Cx) and the ramus medianus (RM) (when present) arteries originate directly from the left aortic sinus. The study aimed to document the prevalence of absent LMCA, discuss its possible embryogenesis and clinical relevance. A review of 407 coronary angiograms performed by cardiologists of three private hospitals in the eThekwini Municipality area of KwaZulu-Natal, South Africa, was performed. The LMCA was absent in 9.6% (39/407) of the coronary angiograms. The LAD and Cx arteries originated directly from the left aortic sinus with a single ostium in 8.6% (35/407) and separate ostia in 1% (4/407) of the angiograms. In four of the angiograms with absent LMCA, a RM artery was recorded originating directly from the left aortic sinus in addition to the LAD and the Cx arteries. Angiographic detection of the anomalies of the coronary arteries is essential in the determination of the significance of such findings and their management.
Introduction Coronary artery anomalies have been classified traditionally into anomalies of origin, course and termination (Majid et al., 2011). Clinically, coronary artery anomalies have also been classified as either lifethreatening or not (Danias et al., 2001) depending upon their prognosis (Yamanaka and Hobbs, 1990). The anomalies of origin include multiple ostia, single coronary artery, absence of the left main coronary artery, anomalous origin of the coronary artery from the pulmonary artery and origin of the coronary artery or branch from the opposite or non-coronary sinus or from the subclavian artery (Monro et al., 1978; Safi et al., 2001; Khanna et al., 2005; Kim et al., 2006; Li et al., 2011). The anomalies of course include myocardial bridging and duplication of arteries, and the anomalies of termination include coronary artery fistula, coronary arcade and extra cardiac termination (Kim et al., 2006). The anatomy of the coronary vasculature should be adequately evaluated preoperatively for the presence of © 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85
coronary artery anomalies to avoid transsection, ligation or iatrogenic obstruction of vessels (Hobbs et al., 1981). As noted earlier, one of the anomalies of origin is the absence of the left main coronary artery (LMCA), where the left anterior descending artery (LAD) (also called the anterior interventricular artery), the circumflex (Cx) artery and ramus medianus (RM) artery (when present) originate directly from the left aortic sinus. This anomaly is sometimes not recognized at the time of catheterization, and the LAD or Cx artery may be misinterpreted as totally obstructed, atretic or congenitally absent (Yamanaka and Hobbs, 1990; Cankaya et al., 2009). The absence of the LMCA has no adverse hemodynamic consequence (Kosßar et al., 2009), but may cause technical difficulties in coronary artery catheterization and result in misdiagnosis (Cankaya et al., 2009) or may be a source of complication during diagnostic, interventional and surgical procedures (Kosßar et al., 2009). The absence or early bifurcation of the LMCA may cause perioperative occlusion of a main branch of the
81
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N. O. Ajayi et al.
LMCA by a balloon-tipped perfusion cannula with resultant myocardial infarction, and in such cases, separate cannulation of the LAD and Cx arteries is recommended (Fox et al., 1973). Accurate identification and documentation of coronary artery anomalies during coronary angiography are essential to determine the significance of such findings and to avoid therapeutic complications (Wilkins et al., 1988). This study aimed to record the prevalence of absent LMCA and discuss its possible embryologic basis and clinical import. Materials and Methods A review of 407 coronary angiograms (males = 266, females = 141) performed by cardiologists of three private hospitals in the eThekwini Municipality area of KwaZuluNatal, South Africa, was performed. To protect the identities of the patients whose angiograms were used, their names and hospital numbers were not documented. The mean age of the study population was 59 years (range = 27–91 years). The sample size according to different race groups was as follows: African 7.6% (31/407), White 22.1% (90/407) and Indian 70.3% (286/407) (Table 1). The angiograms were carried out on patients who presented with the following clinical problems: history of atypical chest pain, abnormal ECG changes, multiple coronary artery disease risk factors and a family history of coronary artery disease. The left coronary arterial tree was closely examined, and the presence or absence of the LMCA and the origin of its main branches (LAD and Cx arteries) were noted and documented. The presence or absence of the LMCA was determined by examining the angiogram in the left anterior oblique (LAO) projection caudal view (‘spider’ view), and this view shows the presence of the LMCA (and its division into its branches) or its absence clearly. The right coronary artery (RCA) was also examined for any obvious anomaly. In addition, the presence of the RM artery was recorded. The RM artery is regarded as an additional terminal branch (originating from the vertex of the angle formed by the LAD and Cx arteries) of the LMCA. The Pearson’s chisquare test of association was used to evaluate the effect of sex or race on the absence of the LMCA. Analysis was
performed using the Statistical Package for the Social Sciences (SPSS) version 21 for Windows (IBM SPSS, NY, USA). Ethical clearance (Ethics no BE 103/11) was obtained from the relevant institutional committee. Results The LMCA was present (Fig. 1) in 90.4% (368/407) and absent (Fig. 2) in 9.6% (39/407) of the coronary angiograms (males = 26/266, females = 13/141). The sex and race distribution of the angiograms with absent LMCA was as follows: 9.8% (26/266) of males; 9.2% (13/ 141) of females: 6.5% (2/31) of Africans; 8.9% (8/90) of White; and 10.1% (29/286) of Indians (Table 1). Pearson’s chi-square test showed there was no significant association between sex (P = 0.86) or race (P = 0.18) on the absence of the LMCA. This study identified two types of origin for the main branches of the LMCA directly from the left aortic sinus in its absence, viz. (1) with different ostia and (2) with the same ostium. The LAD and Cx arteries originated directly from the left aortic sinus with a single ostium (Fig. 2) in 8.6% (35/407) and separate ostia (Fig. 3) in 1% (4/407) of the angiograms. In 1% (4/407) of the angiograms reviewed, a RM artery in addition to the LAD and Cx arteries was recorded originating directly from the left aortic sinus (Fig. 4). Left coronary dominance was recorded in 15.9% of the total sample examined, and left coronary arterial dominance was recorded in 51.3% (20/39) of the angiograms with
Table 1. Prevalence of absent left main stem in different race groups
Race groups
% of the race groups (n = 407)
Prevalence of absent left main stem% (n = 39)
African White Indian
7.6 (31) 22.1 (90) 70.3 (286)
6.5 (2) 8.9 (8) 10.1 (29)
82
Fig. 1. Coronary angiogram in the right anterior oblique projection showing bifurcation of the left main coronary artery (LMCA) into left anterior descending (LAD) and Cx artery.
© 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85
N. O. Ajayi et al.
Fig. 2. Coronary angiogram in the left anterior oblique projection (caudal view) showing absence of the left main coronary artery (LMCA).
Fig. 3. Coronary angiogram in the left anterior oblique projection (caudal view) showing absence of the left main coronary artery (LMCA) with separate ostia for the left anterior descending (LAD) and Cx.
the absence of the LMCA. The early splitting of the RCA (bifurcation of the RCA shortly after originating from the right coronary sinus) was recorded in 20.5% (8/39) of the angiograms with absent LMCA (Fig. 5). © 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85
Coronary Artery Anomalies
Fig. 4. Coronary angiogram in the right anterior oblique projection showing absence of left main coronary artery (LMCA) and the presence of the ramus medianus artery.
Fig. 5. Coronary angiogram in the left anterior oblique projection (caudal view) showing the early splitting of the RCA.
Discussion The prevalence of absent LMCA reported in the literature reviewed ranged between 0.4% and 4.1% (Table 2). The present study documented a prevalence of 9.6% for the absent LMCA which is much higher than the values
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Coronary Artery Anomalies
N. O. Ajayi et al.
Table 2. Prevalence of absent left main stem in the literature
Author(s)
Type of study
Sample size
Prevalence (%)
Kurjia et al. (1986) Angelini et al. (1999) Reig and Petit (2004) Cademartiri et al. (2008) Kosßar et al. (2009) Present study
Cadaveric dissection Coronary angiography Cadaveric dissection Coronary angiography
119 1950 100 543
0.8 0.67 4 4.1
Coronary angiography Coronary angiography
700 407
0.4 9.6
reported in the literature reviewed (Table 2). The high prevalence in our study may be due to inter-population differences (Kurjia et al., 1986) and the fact that absent LMCA is often not reported (Danias et al., 2001). According to Angelini et al. (2002), any morphological feature observed in >1% of an unselected population is normal, while an alternative, relatively unusual, morphological feature seen in >1% of the same population is a normal variant, and a morphological feature seen in
ORIGINAL ARTICLE
Absent Left Main Coronary Artery with Variation in the Origin of its Branches in a South African Population N. O. Ajayi1, L. Lazarus1, E. A. Vanker2 and K. S. Satyapal1* Addresses of authors: 1 Department of Clinical Anatomy, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa; 2 Chelmsford Medical Centre 3, St Augustine’s Hospital, 107 Chelmsford Rd, Durban 4001, South Africa
*Correspondence: Tel.: + 27 31 260 7899, + 27 83 777 8780; fax: + 27 31 260 7890; e-mail: [email protected] With 5 figures and 2 tables Received March 2013; accepted for publication January 2014 doi: 10.1111/ahe.12109
Summary Coronary artery anomalies are traditionally classified into anomalies of origin, course and termination. One of the anomalies of origin is absence of the left main coronary artery (LMCA), where the left anterior descending (LAD), the circumflex (Cx) and the ramus medianus (RM) (when present) arteries originate directly from the left aortic sinus. The study aimed to document the prevalence of absent LMCA, discuss its possible embryogenesis and clinical relevance. A review of 407 coronary angiograms performed by cardiologists of three private hospitals in the eThekwini Municipality area of KwaZulu-Natal, South Africa, was performed. The LMCA was absent in 9.6% (39/407) of the coronary angiograms. The LAD and Cx arteries originated directly from the left aortic sinus with a single ostium in 8.6% (35/407) and separate ostia in 1% (4/407) of the angiograms. In four of the angiograms with absent LMCA, a RM artery was recorded originating directly from the left aortic sinus in addition to the LAD and the Cx arteries. Angiographic detection of the anomalies of the coronary arteries is essential in the determination of the significance of such findings and their management.
Introduction Coronary artery anomalies have been classified traditionally into anomalies of origin, course and termination (Majid et al., 2011). Clinically, coronary artery anomalies have also been classified as either lifethreatening or not (Danias et al., 2001) depending upon their prognosis (Yamanaka and Hobbs, 1990). The anomalies of origin include multiple ostia, single coronary artery, absence of the left main coronary artery, anomalous origin of the coronary artery from the pulmonary artery and origin of the coronary artery or branch from the opposite or non-coronary sinus or from the subclavian artery (Monro et al., 1978; Safi et al., 2001; Khanna et al., 2005; Kim et al., 2006; Li et al., 2011). The anomalies of course include myocardial bridging and duplication of arteries, and the anomalies of termination include coronary artery fistula, coronary arcade and extra cardiac termination (Kim et al., 2006). The anatomy of the coronary vasculature should be adequately evaluated preoperatively for the presence of © 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85
coronary artery anomalies to avoid transsection, ligation or iatrogenic obstruction of vessels (Hobbs et al., 1981). As noted earlier, one of the anomalies of origin is the absence of the left main coronary artery (LMCA), where the left anterior descending artery (LAD) (also called the anterior interventricular artery), the circumflex (Cx) artery and ramus medianus (RM) artery (when present) originate directly from the left aortic sinus. This anomaly is sometimes not recognized at the time of catheterization, and the LAD or Cx artery may be misinterpreted as totally obstructed, atretic or congenitally absent (Yamanaka and Hobbs, 1990; Cankaya et al., 2009). The absence of the LMCA has no adverse hemodynamic consequence (Kosßar et al., 2009), but may cause technical difficulties in coronary artery catheterization and result in misdiagnosis (Cankaya et al., 2009) or may be a source of complication during diagnostic, interventional and surgical procedures (Kosßar et al., 2009). The absence or early bifurcation of the LMCA may cause perioperative occlusion of a main branch of the
81
Coronary Artery Anomalies
N. O. Ajayi et al.
LMCA by a balloon-tipped perfusion cannula with resultant myocardial infarction, and in such cases, separate cannulation of the LAD and Cx arteries is recommended (Fox et al., 1973). Accurate identification and documentation of coronary artery anomalies during coronary angiography are essential to determine the significance of such findings and to avoid therapeutic complications (Wilkins et al., 1988). This study aimed to record the prevalence of absent LMCA and discuss its possible embryologic basis and clinical import. Materials and Methods A review of 407 coronary angiograms (males = 266, females = 141) performed by cardiologists of three private hospitals in the eThekwini Municipality area of KwaZuluNatal, South Africa, was performed. To protect the identities of the patients whose angiograms were used, their names and hospital numbers were not documented. The mean age of the study population was 59 years (range = 27–91 years). The sample size according to different race groups was as follows: African 7.6% (31/407), White 22.1% (90/407) and Indian 70.3% (286/407) (Table 1). The angiograms were carried out on patients who presented with the following clinical problems: history of atypical chest pain, abnormal ECG changes, multiple coronary artery disease risk factors and a family history of coronary artery disease. The left coronary arterial tree was closely examined, and the presence or absence of the LMCA and the origin of its main branches (LAD and Cx arteries) were noted and documented. The presence or absence of the LMCA was determined by examining the angiogram in the left anterior oblique (LAO) projection caudal view (‘spider’ view), and this view shows the presence of the LMCA (and its division into its branches) or its absence clearly. The right coronary artery (RCA) was also examined for any obvious anomaly. In addition, the presence of the RM artery was recorded. The RM artery is regarded as an additional terminal branch (originating from the vertex of the angle formed by the LAD and Cx arteries) of the LMCA. The Pearson’s chisquare test of association was used to evaluate the effect of sex or race on the absence of the LMCA. Analysis was
performed using the Statistical Package for the Social Sciences (SPSS) version 21 for Windows (IBM SPSS, NY, USA). Ethical clearance (Ethics no BE 103/11) was obtained from the relevant institutional committee. Results The LMCA was present (Fig. 1) in 90.4% (368/407) and absent (Fig. 2) in 9.6% (39/407) of the coronary angiograms (males = 26/266, females = 13/141). The sex and race distribution of the angiograms with absent LMCA was as follows: 9.8% (26/266) of males; 9.2% (13/ 141) of females: 6.5% (2/31) of Africans; 8.9% (8/90) of White; and 10.1% (29/286) of Indians (Table 1). Pearson’s chi-square test showed there was no significant association between sex (P = 0.86) or race (P = 0.18) on the absence of the LMCA. This study identified two types of origin for the main branches of the LMCA directly from the left aortic sinus in its absence, viz. (1) with different ostia and (2) with the same ostium. The LAD and Cx arteries originated directly from the left aortic sinus with a single ostium (Fig. 2) in 8.6% (35/407) and separate ostia (Fig. 3) in 1% (4/407) of the angiograms. In 1% (4/407) of the angiograms reviewed, a RM artery in addition to the LAD and Cx arteries was recorded originating directly from the left aortic sinus (Fig. 4). Left coronary dominance was recorded in 15.9% of the total sample examined, and left coronary arterial dominance was recorded in 51.3% (20/39) of the angiograms with
Table 1. Prevalence of absent left main stem in different race groups
Race groups
% of the race groups (n = 407)
Prevalence of absent left main stem% (n = 39)
African White Indian
7.6 (31) 22.1 (90) 70.3 (286)
6.5 (2) 8.9 (8) 10.1 (29)
82
Fig. 1. Coronary angiogram in the right anterior oblique projection showing bifurcation of the left main coronary artery (LMCA) into left anterior descending (LAD) and Cx artery.
© 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85
N. O. Ajayi et al.
Fig. 2. Coronary angiogram in the left anterior oblique projection (caudal view) showing absence of the left main coronary artery (LMCA).
Fig. 3. Coronary angiogram in the left anterior oblique projection (caudal view) showing absence of the left main coronary artery (LMCA) with separate ostia for the left anterior descending (LAD) and Cx.
the absence of the LMCA. The early splitting of the RCA (bifurcation of the RCA shortly after originating from the right coronary sinus) was recorded in 20.5% (8/39) of the angiograms with absent LMCA (Fig. 5). © 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85
Coronary Artery Anomalies
Fig. 4. Coronary angiogram in the right anterior oblique projection showing absence of left main coronary artery (LMCA) and the presence of the ramus medianus artery.
Fig. 5. Coronary angiogram in the left anterior oblique projection (caudal view) showing the early splitting of the RCA.
Discussion The prevalence of absent LMCA reported in the literature reviewed ranged between 0.4% and 4.1% (Table 2). The present study documented a prevalence of 9.6% for the absent LMCA which is much higher than the values
83
Coronary Artery Anomalies
N. O. Ajayi et al.
Table 2. Prevalence of absent left main stem in the literature
Author(s)
Type of study
Sample size
Prevalence (%)
Kurjia et al. (1986) Angelini et al. (1999) Reig and Petit (2004) Cademartiri et al. (2008) Kosßar et al. (2009) Present study
Cadaveric dissection Coronary angiography Cadaveric dissection Coronary angiography
119 1950 100 543
0.8 0.67 4 4.1
Coronary angiography Coronary angiography
700 407
0.4 9.6
reported in the literature reviewed (Table 2). The high prevalence in our study may be due to inter-population differences (Kurjia et al., 1986) and the fact that absent LMCA is often not reported (Danias et al., 2001). According to Angelini et al. (2002), any morphological feature observed in >1% of an unselected population is normal, while an alternative, relatively unusual, morphological feature seen in >1% of the same population is a normal variant, and a morphological feature seen in
