Single Coronary Artery with the Absence of a Left Anterior Descending Artery
- Volume 17 - Issue 11 - November, 2005
- Posted on: 8/1/08
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Discussion. The single coronary artery was first described in 1903 by Banchi.5 The single coronary artery refers to the origination of both the the left and right coronary arteries from a single aortic sinus, without the origin of a coronary artery from the pulmonary trunk. In a study of 142 patients with a single coronary artery,6 the single coronary artery arose from right aortic sinus in 49% of patients, and from the left aortic sinus in 45% of patients. It also included some patients with a single coronary artery originating from the pulmonary trunk. Yamanaka et al. reported a single coronary artery arising from the right sinus of Valsalva in 0.019% of the population in a large series of 126,595 patients undergoing coronary arteriography.7
The combination of a single coronary artery originating from the right sinus of Valsalva and an absent left anterior descending (LAD) artery is an extremely rare abnormality. However, in our case, this rare anomaly was seen in a patient with a secundum-type atrial septal defect — an association that makes this an exceptional case report. It seems that this coexistence is a coincidental finding, as was also reported by Antonelli et al.8
Classification. The single coronary artery has been classified according to three different systems that include the classification systems of Smith, Ogden-Goodyear and Lipton.
Smith (1950). In 1950, Smith9 classified the single coronary artery into three groups.
(I) Single coronary artery that follows the course of the right coronary artery (RCA), then continues into the left circumflex (LC) artery, which then continues as the LAD, or a single left main (LM) artery that branches into the LAD and the LC, the latter of which extends across the crux to form the RCA.
(II) After its origin, the main trunk divides into the right and LM arteries, or into a RCA, LAD and LC, which then reach their standard locations.
(III) The single coronary artery branches so atypically that there is little similarity to the coursing of the three major arteries.
Ogden and Goodyear (1970). Ogden and Goodyear,6 in 1970, classified the single coronary artery into five types (depending upon the anatomic distribution of the branches), subdivided by the letters “R” and “L” to indicate the side of the ostial origin.
Lipton (1979). Lipton et al.,10 in 1979, proposed a classification system using features of both Smith and Ogden and Goodyear. Lipton’s system offered a better explanation for angiographers. The anomalous coronary artery is first designated with letter the “L” or “R”, depending upon whether the ostium is located in the left or right sinus of Valsalva, respectively. It is then designated a group according to Smith’s classification. The final designation describes the relationship between the anomalous artery, the aorta and the pulmonary artery with the letters “A”, “B” and “P”, referring to “anterior”, “between” and “posterior” patterns. However, in our patient, the anatomy does not follow any of the classifications mentioned because of the absence of the LAD, along with the presence of a single coronary artery (Figure 4).