Primary myxomatous degeneration of cardiac valves. Clinical, pathological, haemodynamic, and echocardiographic profile.

Four hundred and ninety-nine surgically excised valves were examined for pathological evidence of myxomatous degeneration. Thirty-six valves (7%) had myxomatous degeneration as a major pathological finding. Fourteen valves (3%) had significant myxomatous degeneration of the pars fibrosa, a finding which we define as "primary myxomatous degeneration". Echocardiographic findings and catheterisation results were correlated with the clinical course, surgical results, and follow-up in these 14 patients. Echocardiograms in 10 of the 11 patients who had them (91%) showed abnormalities suggesting the presence of primary myxomatous degeneration. Echocardiography was more helpful than angiography in diagnosis. The histological pattern of primary mitral myxomatous degeneration appears to be identical to that seen in patients with mitral valve prolapse and five of six patients with mitral lesions had echocardiographic evidence of prolapse. None of the patients with primary myxomatous degeneration of the aortic valve had syphilis of Marfan9s syndrome. While the aetiology of primary myxomatous degeneration of cardiac valves is not known, a link to a more generalised disorder is suggested.