If your valve has stenosis, it means the flaps of the valve have thickened or stiffened, narrowing the opening and restricting the flow of blood. If you have valve regurgitation, it means your valve is leaking. Sometimes this is called mitral valve prolapse. Both stenosis and regurgitation put a strain on your heart. Valves that do not function properly sometimes produce a sound that your physician can hear. This is called a heart murmur. Some heart valve diseases may not cause you any problems. Others are more serious and may lead to heart failure, stroke, blood clots, or sudden cardiac arrest.