Congenital mitral stenosis is when an infant is born with a narrowing of the opening of the mitral valve. The mitral valve is made of leaf-like flaps and is situated between the upper left chamber (atrium) and lower left chamber (ventricle) of the heart. Congenital mitral stenosis reduces the blood flow from the left atrium to the left ventricle. Individuals born with congenital mitral stenosis also often have other congenital heart defects.

Symptoms of congenital mitral stenosis may include feeling tired upon exertion, chest pain, shortness of breath, coughing, rapid breathing, bluish or greyish color of skin, lips, and fingernails, trouble eating or gaining weight (failure to thrive), swelling of body tissue or organs, abnormal heart rhythms, such as palpitations or other arrhythmias, pulmonary hypertension (high blood pressure), fluid build-up in the lungs, and heart failure.

Treatment for congenital mitral valve stenosis depends on its severity and may include diuretics to lessen fluid build-up in the lungs, blood thinners (anticoagulants), such as heparin, warfarin, aspirin, and fibrinolytics, such as tissue plasminogen activator (tPA), to prevent blood clots, drugs to control the heart rhythm (antiarrhythmics, beta blockers, and calcium channel blockers), and surgical repair or replacement of the mitral valve.