Heart valve replacement is a surgical procedure to remove these diseased valves and replace them with artificial valves to restore normal heart function in some patients with heart valve lesions, usually stenosis or incomplete closure, and the resulting set of symptoms. A heart valve is a device that functions like a one-way valve in order to ensure the unidirectional flow of blood; once narrowed, it can cause poor blood flow, while a poorly closed valve can produce backflow of blood. Both of these results can cause enlargement of the heart and consequent impairment of cardiac function. The current treatment is still primarily surgical, with medical treatment providing only temporary relief.