155 THE PATHOLOGY OF CONGENITAL MITRAL STENOSIS

Abstract

This study was undertaken in an effort to clarify the principal pathologic findings of congenital mitral stenosis and to propose an anatomic classification. In a series of 64 autopsied cases, four anatomic types were found: (1) typical congenital mitral stenosis with short chordae tendineae, obliteration of interchordal spaces, and reduction of interpapillary distance (32 cases, 50 percent); (2) hypoplastic congenital mitral stenosis, associated almost always with a hypoplastic left heart syndrome (26 cases, 41 percent); (3) supramitral ring (5 cases, 8 percent); and (4) parachute mitral valve (4 cases, 6 percent). The median ages at death were: parachute mitral valve, 9 11/12 years: supramitral ring, 5 7/12 years; typical congenital mitral stenosis, 7 years; and hypoplastic congenital mitral stenosis, 7 days. Thus, parachute mitral valve had the best natural history and the hypoplastic type had the worst, while that of the other two types was intermediate. Associated malformations were present in 94 percent of cases, those with the greatest frequency being endocardial sclerosis or florid endocardial fibroelastosis in 41 percent, valvular aortic stenosis in 33 percent, hypoplasia of the aortic isthmus in 31 percent, aortic atresia in 23 percent, and coarctation of the aorta in 20 percent of the cases.