Myxoid degeneration of the aortic valve and isolated severe aortic regurgitation.

Clinical and pathologic data were reviewed in 55 patients who had valve replacement for pure aortic regurgitation (AR) during a 6-year period. The clinical histories established the cause for AR in 34 cases: 11 rheumatic, 13 infective endocarditis, 4 congenital, 4 associated with aortic aneurysms and 2 the Marfan syndrome. In the valves from the other 21 patients, 13 had myxoid degeneration, defined as significant disruption of the valve fibrosa and its replacement by acid mucopolysaccharides and cystic change. Myxoid degeneration was also the primary pathologic abnormality in the 2 patients with the Marfan's syndrome, in 3 patients with a history of rheumatic disease and in 1 patient with a history of infective endocarditis. The patients with myxoid degeneration of uncertain origin were predominantly elderly (average age 63 years), had a long-standing history of systemic hypertension (77%) and had coronary artery disease (46%); 85% were male. In these patients the replacement valves were not larger than those of the other groups studied, indicating that dilatation of the aortic anulus was not a significant factor in the pathogenesis of the valve disease. These findings indicate that myxoid degeneration of the aortic valve is common (36% of all valves examined) and, in many cases, may be secondary to long-standing systemic hypertension.