Interact CardioVasc Thorac Surg 2005;4:297-298. doi:10.1510/icvts.2005.105965
© 2005 European Association of Cardio-Thoracic Surgery
Case report - Cardiac general |
Two cases of anomalous origins of left coronary artery with a course between the aortic root and the free standing subpulmonary infundibulum on CT coronary angiography
Amogh N. Hegde* and
Shrinivas B. Desai
Department of Radiology, Jaslok Hospital and Research Centre, 15, G Deshmukh Marg, Mumbai 400026, India
Received 10 January 2005;
received in revised form 1 March 2005;
accepted 2 March 2005
*Corresponding author. Tel.: +91 22 5657333,+91 22 26420191; fax: +91 20 25231662.
E-mail address: amogh77{at}yahoo.co.in (A.N. Hegde).
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Abstract
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Two cases of anomalous origins of the left coronary artery have been demonstrated on a CT coronary angiogram. In one case the left main coronary artery arose from the right aortic sinus of valsalva, separate from the right coronary artery. In the second case there was a single coronary artery arising from the right aortic sinus of valsalva. In both these rare cases, the left main coronary artery traversed between the aortic root and the freestanding subpulmonary infundibulum and then divided into its regular branches. These cases show well, the left main artery actually coursing free of the crista supraventricularis portion of the outlet septum. This is contrary to the commonly used classifications and descriptions, which describe the anomalous coronary artery actually traversing through the outlet septum.
Key Words: Anomalous; Single coronary artery; Subpulmonary infundibulum
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1. Case 1
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A 54-year-old asymptomatic female underwent a CT coronary angiography as part of a routine health check up.
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2. Case 2
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A 45-year-old female complaining of vague left sided chest pain and an unequivocal stress test was referred for a CT coronary angiography.
In both cases, the study was performed on a sixteen-slice CT scanner after administration of 100 cc of nonionic contrast at the rate of 4.5 cc per second.
The images were then reconstructed in Volume Rendered (VR), Maximum Intensity Projection (MIP) and Curved Planar Reformat (CPR) formats.
In Case 1, Left Main Coronary Artery (LMA) originated from the right sinus of valsalva. It then coursed dorsal and inferior to the aortic root and traversed in the plane between the aortic root and the subpulmonary infundibulum. Further, it divided into the Left Anterior Descending artery (LAD) and the Left Circumflex artery (LCX) and the intermediate branches (Fig. 1). The Right Coronary Artery (RCA) had a separate normal origin and course.
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Fig. 1. Left Main Coronary artery (LMA) originates from the right sinus of valsalva and traverses between the aortic root and the subpulmonary infundibulum. It then divides into the Left Anterior Descending artery (LAD) and the Left Circumflex artery (LCX) and the intermediate branches.
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In Case 2, there was a single coronary artery, which arose from the right sinus of valsalva, which divided into the RCA and the LMA (Fig. 2). The LMA followed the same course through the plane between the aortic root and the subpulmonary infundibulum as in Case 1 dividing into LAD and LCX branches.
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Fig. 2. A single coronary artery from the right aortic sinus of valsalva with the left main artery passing in the plane between the aorta and subpulmonary infundibulum.
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3. Discussion
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The anomalous origin of the left main coronary artery from the right aortic sinus of valsalva is a rare congenital anomaly. Of the 601 cases of coronary anomalies in a series of 38,703 patients studied by coronary angiograms, this anomaly was noted only in 9 (1.5%) patients [1]. Isolated single coronary artery occurs in about 0.024% to 0.04% of the population [2]. There are various proposed classifications of the Anomlous coronary arteries. Based on their origin they are classified into four types: (1) Both the coronary arteries arising from the pulmonary artery, (2) one coronary vessel arising from the pulmonary artery and the other from the aorta, (3) both the coronary arteries arising from the aorta with an abnormal location of the ostia, and (4) single coronary artery. According to the anatomic pathways of the left main coronary artery en route to the left side of the heart, they are classified as: type A (i.e. anterior to the right ventricular outflow tract), type B (i.e. between the aorta and pulmonary trunk), type C (i.e. through the crista supraventricularis portion of the septum), and type D (i.e. dorsal to the aorta) [3,4].
If the above mentioned classification is followed, in our two cases, the left mainstem artery follows a ‘Type C’ course. However, in each of these cases, the LMA is seen to traverse anteriorly through a plane between the aortic root and the free-standing subpulmonary infundibulum. It has often been mentioned in the past that the left main artery passes through the crista supraventricularis portion of the septum [3,4]. This, however, does not hold true in all cases. Surgeons are well aware of the fact that the pulmonary valvar leaflets are supported entirely by free-standing musculature, having no direct relationship with the ventricular septum. This makes possible the Ross procedure [5].
Our two cases clearly demonstrate the path of the anomalous left mainstem artery adjacent to the subpulmonary infundibulum, free of the crista supraventricularis portion of the septum.
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References
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- Sheldon WS, Hobbs RE, Millit D, Raghavan PV, Moodie DS. Congenital variations of coronary anatomy. Cleve Clinic Q 1980;47:126–130.
- Desmet W, Vanhaecke J, Vrolix M, Van de Werf F, Piessens J, Willems J, de Geest H. Isolated single coronary artery: a review of 50,000 consecutive coronary angiographies. Eur Heart J 1992;13:1637–1640.[Abstract/Free Full Text]
- Roberts WC. Major anomalies of coronary arterial origin seen in adulthood. Am Heart J 1986;111:941–963.[CrossRef][Medline]
- Roberts WC, Shirani J. The four subtypes of anomalous origin of the left main coronary artery from the right aortic sinus (or from the right coronary artery). Am J Cardiol 1992;70:119–121.[Medline]
- Merrick AF, Yacoub MH, Ho SY, Anderson RH. Anatomy of the muscular subpulmonary infundibulum with regard to the Ross procedure. Ann Thorac Surg 2000;692:556–561.
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Abstract
1. Case 1