Prolapse of the "floppy" aortic valve as a cause of aortic regurgitation. A clinico-morphologic study.

A clinico-pathologic study was performed in 25 patients undergoing aortic valve replacement because of regurgitation, caused by myxoid degeneration of the valve leaflets. Associated cardiac anomalies were floppy mitral valve (2 cases), floppy mitral valve and idiopathic hypertrophic subaortic stenosis (1), left atrial myxoma (1), and aortic coarctation at the isthmus (1). Three patients died (2 immediately and 1 on the 30th postoperative day). Pathological studies of the explanted valves showed deformities characterized by redundant thin leaflets which appeared soft and gelatinous. On histologic examination the fibrous layer of the leaflets was seen to be infiltrated by myxomatous tissue. Echocardiography showed the aortic root to be dilated in 13 patients and normal in the others. In those with normal aortic root, the histological examination of aortic wall disclosed minimal cystic medial necrosis in two cases. In contrast, more severe forms of cystic medial necrosis were evident in all patients having a dilated aortic root. Aortic valve replacement was performed in all cases. It was accompanied by a Bentall procedure (1 case), repair of ascending aorta dissection (2), replacement of the ascending aorta (1), mitral valve replacement (2), mitral valve replacement and apico-ascending aorta conduit (1) and excision of a left atrial myxoma (1). Our experience suggests that prolapse of the aortic valve due to floppy leaflets is a common degenerative disease which is generally associated with noninflammatory aortic root degeneration. This, together with aortic root dilatation, contributes to valve insufficiency. Nevertheless, the disease, when isolated (with normal aortic root), is liable in itself to produce aortic regurgitation. The need for early diagnosis is stressed, so as to be able to perform valve replacement.