Structural basis for mitral valve dysfunction associated with ostium secundum atrial septal defects.

Mitral valve (MV) specimens obtained at operation from 50 patients with ostium secundum atrial septal defect and associated MV dysfunction were studied macro- and microscopically to evaluate the structural lesions. The functional abnormalities in these patients were isolated mitral stenosis, isolated mitral regurgitation, mitral valve prolapse or mitral stenosis with regurgitation. Post-inflammatory lesions were commonly found in those with mitral stenosis who had a past history of rheumatic fever. Patients with mitral valve prolapse had either post-inflammatory lesions or lesions attributable to haemodynamic stress but different from the extensive lesions seen in floppy MV syndrome.