Fish mouth is a pathomorphological variant of rheumatic narrowing of the left atrioventricular orifice, in which the valve leaflets are thickened at the edges and fused together over a significant extent. As a result, the valve takes on a funnel-shaped shape, reminiscent of a fish's mouth.
With fish mouth, a pronounced hemodynamic disturbance is observed - the flow of blood from the left atrium to the left ventricle during diastole is difficult. This leads to increased pressure in the pulmonary circulation and the development of pulmonary hypertension. Clinically, fish mouth is manifested by shortness of breath, weakness, and fatigue. The diagnosis is made based on echocardiography data. Treatment consists of valve replacement.