[Stanford Type A Acute Aortic Dissection Localized in the Aortic Root with Difficulty in a Definitive Diagnosis:Report of a Case].

A 39-year-old man presented with sudden onset of chest pain. The initial computed tomography angiography (CTA) showed a small amount of pericardial effusion and a soft tissue density localized in the aortic root, but no intimal flap was identified in the aorta. Aortic dissection was suspected, and the patient was hospitalized at the intensive care unit for close monitoring. On the day of admission, repeated non-contrast computed tomography (CT) showed no significant changes in the aorta or pericardial effusion. Electrocardiography-gated, thin-slice contrast-enhanced CTA revealed an intimal flap localized at the sinotubular junction. Intraoperative transesophageal echocardiography showed a flap at the sinotubular junction. An ascending aorta was successfully replaced using a vascular graft. An aortic wall submitted to the pathology showed no evidence of connective tissue disorders. The postoperative course was uneventful.