Figure 18b. Assessment of a 43-year-old man with a history of aortic dissection who presented to the emergency department with recurrent chest pain. Original nongated CT study was inconclusive for aortic dissection. (a) Axial ECG-gated image of the aortic root shows aortic dissection, with the posterior dissection flap involving the origin of the left coronary artery (arrow). (b) Axial CT scan obtained superior to a shows involvement of the origin of the right coronary artery (arrow). Because of these findings, the patient’s LIMA and saphenous vein grafts were dissected before coronary bypass in anticipation of coronary revascularization. Dissection involving the native coronary arteries was confirmed at surgery, and coronary artery bypass was performed.