Concealment of Preexisting Aortic Regurgitation by the Intimal Flap in Acute Type A Aortic Dissection.

Aortic regurgitation (AR) frequently accompanies acute type A aortic dissection (ATAAD); however, the underlying mechanism is not always apparent preoperatively. We describe a rare case in which the intimal flap concealed preexisting AR, leading to underestimation of the severity until after surgical repair. A 50-year-old man presented with ATAAD and underwent total arch replacement under moderate hypothermic circulatory arrest. Preoperative and intraoperative transesophageal echocardiography demonstrated only trivial AR. After replacement of the dissected aorta and removal of the intimal flap, severe AR became evident. Long-axis imaging suggested prolapse of the right coronary cusp as the underlying cause. Aortic valve replacement was subsequently performed, and the patient had an uneventful recovery. This case illustrates that the intimal flap can mask the severity of AR in acute dissection, potentially leading to intraoperative diagnostic pitfalls. Careful echocardiographic evaluation, including consideration of valve morphology and jet direction, is crucial for accurate assessment and surgical planning in such patients.