Spontaneous laceration of the ascending aorta may result in (1) through-and-through laceration causing hemopericardium, (2) limited intramural dissection of blood (incomplete dissecting aneurysm), or (3) classical dissecting aneurysm. The latter is the most common manifestation. Background conditions include either extensive cystic medial necrosis (as may be seen in Marfan's syndrome) or hypertension. The latter condition is universally associated with cystic medial necrosis but classically the medial lesion is of minimal degree. Aortic stenosis may be an underlying cause of spontaneous laceration of the ascending aorta.