Valve replacement in an infant with congenital mitral stenosis--report of a case which showed hemodynamics similar to that of hypoplastic left heart syndrome in neonatal period

In the neonatal period, the patient showed severely hypoplastic left ventricle, severe mitral stenosis, patent foramen ovale and patent ductus arteriosus with right-to-left shunting, which resulted in the hemodynamics similar to that of hypoplastic left heart syndrome. However, progressive left ventricular growth was recognized after spontaneous closure of the foramen ovale, and the cardiac catheterization at the age of 6 months revealed almost normal left ventricular volume and systolic forward flow from the left ventricle to the descending aorta. The operation was performed at the age of 7 months under cardiopulmonary bypass with moderate hypothermia and cardiac arrest. The mitral leaflets were thickened and dysplastic, two short papillary muscles were hypertrophic and very closely related, and the chordae were extremely short and fused each other making the interchordal space obstructed. Because the mitral annular diameter (13 mm) was too small for conventional valve replacement, the prosthetic valve (CarboMedics #16) was sewn to the left atrial wall 5 to 10 mm above the mitral annulus. The ductus arteriosus was ligated. The postoperative cardiac catheterization showed residual pulmonary hypertension, but pulmonary vascular response to oxygen-inhalation was recognized. We consider that there were two important hemodynamic factors which led to successful biventricular repair in this case. First, early spontaneous closure of the foramen ovale accerelated the left ventricular growth and prevented right ventricular failure resulting from increased pulmonary blood flow. Second, considerable part of the systemic output was supplied through a large ductus arteriosus, and thus over-systemic pulmonary hypertension was avoided.