Reported cases of uni-leaflet mitral valve (MV) were related to the absence or dysplasia of the posterior mitral leaflet with ample anterior mitral leaflet. We present here a new entity of uni-leaflet MV where the MV appears as a membrane-like structure with a single slit-like orifice at its lateral part with no commissures. CASE REPORT: Continuous Doppler flow revealed a mean pressure gradient of 19 mmHg across the mitral valve indicating severe mitral stenosis. In 3D images from the left atrial view, the MV appeared like a membrane with a single orifice in its lateral part toward the left atrial appendage, the area of this orifice by 3D was 0.52 cm2, there were no commissures or even any residual lines at the site where commissures should be. The diagnosis of congenital severe mitral stenosis due to acommissural MV was confirmed. During surgery, the surgical appearance of the MV confirmed our diagnosis by 3D. CONCLUSION: Isolated congenital severe mitral stenosis presenting in adulthood is rare, uni-leaflet MV as a cause is only reported in a few cases. MV replacement is usually indicated due to the abnormal anatomy of MV leaflets and the subvalvular apparatus.<Learning objectives: How to diagnose uni-leaflet congenital mitral stenosis and how to differentiate it from other causes of congenital mitral stenosis.>.
Reported cases of uni-leaflet mitral valve (MV) were related to the absence or dysplasia of the posterior mitral leaflet with ample anterior mitral leaflet. We present here a new entity of uni-leaflet MV where the MV appears as a membrane-like structure with a single slit-like orifice at its lateral part with no commissures. CASE REPORT: Continuous Doppler flow revealed a mean pressure gradient of 19 mmHg across the mitral valve indicating severe mitral stenosis. In 3D images from the left atrial view, the MV appeared like a membrane with a single orifice in its lateral part toward the left atrial appendage, the area of this orifice by 3D was 0.52 cm2, there were no commissures or even any residual lines at the site where commissures should be. The diagnosis of congenital severe mitral stenosis due to acommissural MV was confirmed. During surgery, the surgical appearance of the MV confirmed our diagnosis by 3D. CONCLUSION: Isolated congenital severe mitral stenosis presenting in adulthood is rare, uni-leaflet MV as a cause is only reported in a few cases. MV replacement is usually indicated due to the abnormal anatomy of MV leaflets and the subvalvular apparatus.<Learning objectives: How to diagnose uni-leaflet congenital mitral stenosis and how to differentiate it from other causes of congenital mitral stenosis.>.