Left main coronary trunk compression by dilated main pulmonary artery in a patient with atrial septal defect

A 12-year-old girl with atrial septal defect combined with pulmonary hypertension and 90% stenosis of the left main coronary artery caused by dilated pulmonary artery was scheduled for atrial septal closure and coronary artery bypass graft under general anesthesia. During the echocardiographic examination to evaluate the anatomical relationship between the pulmonary artery and left main coronary trunk, bradycardia and a depression of ST-segment on electrocardiogram appeared suddenly when the operator compressed the pulmonary artery with a probe of echocardiography from the operative field. The circulatory collapse and ischemic change on electrocardiogram might have been caused by a further reduction of blood flow to the left main coronary trunk narrowed originally by dilated pulmonary artery. Although various etiologies, such as atherosclerosis, syphilis, and congenital abnormalities are widely known to cause stenosis of the left main coronary trunk, external compression by dilated pulmonary artery has not been widely known. Malignant arrhythmias from coronary artery compression with subsequent ischemia could contribute to an incidence of sudden death. Coronary angiography and magnetic resonance imaging are useful for the preoperative evaluation. Careful management is needed to protect such a patient from ischemic event in the perioperative period.