CASE REPORT
A 6- month-old male child weighing 3.5 kg presented with failure to thrive and oxygen saturations of 75% on room air. Echocardiography confirmed d-transposition of great arteries with a subpulmonic ventricular septal defect (VSD). Single origin of coronary arteries with separate ostia from sinus 1 (Leiden Convention: 1R,LCx) was suspected and the child was scheduled for arterial switch operation and closure of VSD.
Standard median sternotomy was followed by harvest of a patch of pericardium that was promptly treated with 0.0625% glutaraldehyde solution for five minutes. Following heparinization, cardiopulmonary bypass was instituted with distal ascending aortic and bicaval venous cannulation. The temperature of the perfusate was cooled to 28⁰C. Cold cardioplegic (Del Nido) arrest was achieved and the VSD was closed through the trans right atrial route using the previously harvested patch of pericardium and a continuous suture of 6 0’ polypropylene. Following this, the aorta and main pulmonary arteries were transected at appropriate levels above the respective sinotubular junctions.
Inspection of the aortic sinuses confirmed the coronary anatomy pattern to be different from that previously described: Sinus 1 gave origin to a right coronary artery (RCA) supplying the anterior wall of the right ventricle. In addition, a separate ostium from the same sinus gave origin to the left coronary artery that divided after a short course into anterior descending and circumflex coronary arteries (Figure 1). Sinus 2 was also found to contain two coronary arteries arising through separate ostia; an RCA running in the right atrioventricular groove and an additional circumflex coronary artery coursing posterior to the pulmonary artery (posterior looping) to gain the posterior and lateral walls of the left ventricle (Figure 2).
The coronary anatomy pattern can therefore be described 1R,LCx-2R,Cx as per the Leiden Convention (Figure 3).
Two coronary buttons were excised separately as in the standard switch procedure including the respective ostia in either button. Following adequate mobilization (particularly for the RCA from sinus 1), the left sided button (sinus 1) was transferred to the neo aortic root. The coronary branches on the right sided button (sinus 2) required wider mobilization. Due to the posterior looping of the corresponding circumflex artery from sinus 2, this button was implanted higher up (two thirds of the button extending into the ascending aorta). There was significant size discrepancy between the neo aortic root and the ascending aorta; an incision into the ascending aorta to accommodate the right sided button helped to equalize this discrepancy.
The right ventricular outflow tract was reconstructed as in the standard switch procedure using the treated pericardium as a “pantaloon patch”. The child was rewarmed and weaned off bypass uneventfully. He was weaned off the ventilator after 48 hours.