Editorial note Pathogenesis of aortic regurgitation

Causes of isolated aortic insufficiency in an urban population in the 1990s a review of 56 surgical pathology cases

Until recently, the cause of isolated aortic insufficiency (AI) was usually thought to be inflammatory or rheumatic in most cases. However, at our institution we have noted a high prevalence of myxomatous degeneration (MD) in aortic valves removed for AI. In this study we report anatomic observations on valves from 56 consecutive patients with isolated AI undergoing aortic valve replacement surgery. Fifty-six consecutive aortic valves removed at our institution from 1994 to 1996 for isolated AI and/or aortic aneurysm were reviewed. Anatomic features were compared with clinical history and echocardiographic data. The anatomic results were also compared to 22 age-matched control aortic valves obtained at autopsy. In 13/56 cases (23%), a specific valvular cause of AI was determined (infectious endocarditis, seven cases; chronic rheumatic disease, four cases; congenital bicuspid valve, two cases). Of the remaining (idiopathic) 43 cases, 18 (42%) had severe isolated MD defined as >50% expansion of the spongiosa and disruption of the fibrosa by the deposition of acid mucopolysaccharides in the absence of severe calcification, fibrosis, or other pathologic findings. Only 1/22 aortic valves from the autopsy controls had severe MD. Eighteen of the 56 patients also had a clinical history of aortic dilatation/aneurysm of which 12 were confirmed to be dilated by echocardiographic criteria. Of these 12, five (42%) had MD of the aortic valve only, three (25%) had both MD and cystic medial degeneration (CMD) of the aorta, two (17%) had CMD of the aorta only, and two (17%) had no specific diagnosis. Isolated MD of the aortic valve is the most common cause of isolated AI in our patient population. Furthermore, in a subset of non-Marfan's patients with both AI and dilatation of the aortic root/aortic aneurysm the incidence of MD is even higher (67%). These results suggest that there is overlap between MD and CMD in non-Marfan's patients and that both entities may be part of a spectrum of a generalized connective tissue disorder.

Non-inflammatory aortic root disease and floppy aortic valve as cause of isolated regurgitation: a clinico-morphologic study

A clinico-morphologic study was performed on 1120 patients who underwent aortic valve replacement at the Department of Medical and Surgical Cardiology, 2nd University Medical School of Naples, Naples, Italy, from January 1981 through December 1991. In 69 cases the aortic valve was incompetent due to a non-inflammatory aortic root disease such as myxomatous infiltration of the cusps and or aortic root dilatation. Among these patients males were prevalent (male/female ratio = 2.2). The mean age was 37 +/- 7.5 years. A floppy mitral valve was diagnosed in 16 cases while in one a left atrial myxoma was found. The patients were divided into 3 groups: Group 1-29 patients with aortic root dilatation and normal cusps; Group 2-25 patients with aortic root dilatation and myxomatous infiltration of aortic cusps (floppy aortic valve); and Group 3-15 patients with floppy aortic valve and undilated aortic root. At the gross examination the cusps of the patients in Groups 2 and 3 were redundant, thin, soft and gelatinous. The histology showed myxomatous infiltration with disruption of the fibrous layer. In patients with aortic root dilatation the histology of the aortic root fragments showed a cystic medial necrosis. Deep correlation was found between the root dilatation and the grade of aortic wall cystic medial necrosis. Cusp's diastasis was the cause of aortic regurgitation in patients with aortic root dilatation, while cusp prolapse caused aortic incompetence in presence of the floppy aortic valve and undilated aortic root.(ABSTRACT TRUNCATED AT 250 WORDS)

The clinical and pathological features of isolated aortic regurgitation in relation to its etiology

Chronic isolated aortic regurgitation (AR) caused by degenerative, rheumatic, and Marfan etiologies were compared in a study of 87 patients. There were three hospital deaths in the Marfan group, but none in the rheumatic and degenerative groups. The late postoperative survival rates at 5 and 10 years were 98% and 94%, respectively, in the rheumatic group; 84% and 84%, respectively, in the degenerative group; and 85% and 78%, respectively, in the Marfan group. An analysis of the late complications disclosed a higher incidence of aortic dissection and paravalvular leakage in the degenerative and Marfan groups than in the rheumatic group. In the degenerative group, 4 of the 32 patients developed acute aortic dissection within 3 years following aortic valve replacement. The aortic root diameter in these 4 patients was more than 40 mm at the time of surgery, whereas it was less than 40 mm in the remaining 28 patients. In conclusion, considering the progressive nature of myxomatous degeneration, patients with a severely dilated aortic root diameter should be monitored carefully with echocardiography after surgery.