Combined aortic and mitral stenosis in mucopolysaccharidosis type I-S (Ullrich-Scheie syndrome)

Abstract

The genetic mucopolysaccharidosis syndromes (MPS) are autosomal recessive inborn errors of metabolism. Heart valve involvement in MPS is not uncommon but only a few case reports of successful cardiac surgery are available. In particular, reports of combined aortic and mitral stenosis associated with MPS type I-S are very rare. Both type I and type VI MPS are associated with significant left sided valvar heart disease that requires surgical valve replacement because of irregular valve thickening, fibrosis, and calcification. A 35 year old man had severe mitral valve stenosis after successful surgical replacement of a stenotic aortic valve. Valvar heart disease was investigated by cardiac ultrasound and left heart catheterisation. Histomorphological characterisation of the affected mitral valve was performed. The case illustrates typically associated clinical features of cardiac and extracardiac abnormalities found in MPS type I-S.

Figure 1

(A) Cross sectional echocardiogram in a right anterior oblique equivalent view (left) and superimposed colour Doppler (right) showing irregular thickening and calcification of the mitral valve and the subvalvar apparatus. Decreased opening of the thickened mitral leaflets led to typical flow acceleration through the stenotic mitral valve. (LV, left ventricle; LA, left atrium.) (B) Excised mitral valve with severe compromise of the central lumen by deposits of mucopolysaccharides. Note the severe thickening of the papillary muscles, chordae tendineae, and the nodular deposition of material along the annulus and leaflets. Some but not all chordae tendineae show severe thickening, calcification, and fusion with neighbouring chordae. (Bar = 1 cm.) (C) Electron micrograph of peroxidase acid Schiff (PAS) positive material depicted in D. Note the vacuolar change of the lysosomes containing fluffy, poorly stained material, and the lamellar structures of lipid leaflets. (Bar = 1 µm.) (D) Mitral valve leaflet, distended by deposition of PAS positive material and dystrophic calcification. The transverse section through the mitral valve leaflet shows pronounced deposition of irregular masses of PAS positive material resulting in thickening and irregular bulging of the leaflet surface. Also, the leaflet shows extensive dystrophic calcification. (Bar = 100 µm.)