Mitral valve in secundum atrial septal defects

SUMMARY The mitral valve in 15 of 16 adult hearts with unclosed secundum atrial septal defects showed a consistent abnormality consisting of thickening of the medial half of the anterior cusp and some fusion of adjacent chordae. Histologically the lesion is a surface fibrosis without vascularisation or myxomatous change to suggest a rheumatic or floppy valve. The high frequency and morphological appearances suggest abnormal cusp movement and resultant valve trauma rather than a primary valve abnormality. The functional abnormality leading to secondary valve changes is presumably related to increased flow and altered left ventricular geometry but cannot be studied in the dead heart. The name of Lutembacher ' has become attached to mitral valve stenosis when associated with secundum atrial septal defects. In retrospect it seems likely that this was no more than a fortuitous association and it was the pathophysiological results of the combined lesions that engendered the clinical interest. Numerous papers subsequently recorded cases of rheumatic disease in association with secundum defects'4 creating th