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.