Review of Congenital Mitral Valve Stenosis: Analysis, Repair Techniques and Outcomes

Christopher W. Baird, Gerald R. Marx, Michele Borisuk, Sitram Emani, Pedro J. del Nido

The spectrum of congenital mitral valve stenosis (MS) consists of a complex of defects that result in obstruction to left ventricular inflow. This spectrum includes patients with underdeveloped left heart structures (Fig. 1) to those with isolated congenital MS. The specific mitral valve defects can further be divided into categories based on the relationship to the mitral valve annulus including valvar, supravalvar and subvalvar components. Clinically, these patients present based on the degree of obstruction, associated mitral regurgitation, secondary pulmonary hypertension, associated lung disease and/or associated cardiac lesions. There are a number of factors that contribute to the successful outcomes in these patients including pre-operative imaging, aggressive surgical techniques and peri-operative management. Figure 1 (a) Image representing a parachute mitral valve with a small left ventricular cavity. Supra-mitral ring with a fibrous rim of tissue attaches to the mitral annulus and extends on the surfaces of the mitral leaflets. Stenosing mitral membranes or the thickened fribrotic rim of tissue grows on to the atrial aspects of the mitral leaflets restricting the effective orifice area. This thickened fibrous anterior leaflet tissue can extend down onto the chordae tendenae towards the papillary muscle creating an "arcade" like structure. Additional valvar components include commissural fusion and thickened fibrous leaflets that can lead to restricted leaflet motion. Note the sub-valvar or papillary muscle components of congenital MS including the shortened chordae tendenae, reduced inter-chordal space and tethering of the papillary muscles to the ventricle. (b) Pathologic specimen of a parachute mitral valve with a single papillary muscle.