[DeBakey type 2 Aortic Dissection Failed to Diagnose by Enhanced Computed Tomography;Report of a Case].

An 81-year-old woman presented with dyspnea and chest pain. A plain chest X-ray revealed widening of the mediastinum and a contrast-enhanced chest computed tomography showed dilatation of the ascending aorta without any specific findings of aortic dissection. Transesophageal echocardiography revealed severe aortic regurgitation (AR). We planned an aortic valve replacement on the 34th day after admission because of the severe AR. During the operation, we found an entry in the intima of the ascending aorta 5 mm above the aortic valve and she was diagnosed with DeBakey type II aortic dissection. Therefore, we decided to perform Bentall's operation and the operation was successful.