The case is reported of a 72-year-old patient with a mobile aortic valve lesion discovered incidentally by echocardiography performed in the setting of coronary artery bypass graft (CABG) surgery. Definitive identification of this lesion was not possible by transthoracic echocardiography or transesophageal echocardiography alone. Pathological examination of the excised aortic valve led to a diagnosis of aortic valve fenestration (AVF) bridging strand rupture. AVFs are common, usually asymptomatic, and of little clinical significance. However, rupture of a bridging strand can produce aortic insufficiency and require surgical correction.