Myocardial ischemia after arterial switching operation in transposition of great arteries associated with the upstairs-downstairs relationship of the ventricles and abnormal coronary distribution.

A 3-month-old boy was diagnosed with transposition of the great arteries and an upstairs-downstairs relationship of the ventricles. He experienced ischemic heart failure and complete atrioventricular block following arterial switch operation. Selective coronary angiography revealed stenosis in the right coronary artery, supplying the entire right ventricle and a wide portion of the left ventricle. This stenosis in the right coronary artery was the cause of the prolonged reduction of left ventricular ejection fraction, while the flow in the left coronary artery remained preserved. Coronary artery bypass grafting from right internal thoracic artery to right coronary artery was performed and significantly improved the ischemic heart failure. Learning objective: A comprehensive assessment of the peripheral coronary artery is essential before the implementation of arterial switch operation in transposition of great arteries cases with upstairs-downstairs relationship of the ventricles, and the inclusion of cusp shot or selective coronary angiography should be contemplated. Furthermore, despite a small body size, coronary artery bypass grafting can be employed to restore adequate coronary perfusion in a case with coronary artery stenosis.