You are taking care of a newborn following the arterial switch operation for D-transposition of the great vessels. Several hours into the postoperative course, the patient develops persistent tachycardia, decreased urine output, persistent lactic acidosis, and left atrial hypertension. A point of care echocardiogram reveals moderately depressed global left ventricular systolic function with mild mitral regurgitation. An electrocardiogram shows a normal sinus rhythm, ST segment depression, and diffuse T wave abnormalities in unipolar and bipolar leads. Despite these findings, you are appropriately concerned that coronary artery flow may be impaired.