Prosthetic heart valves. X-ray, taken diagonally from the right, of a patient with two prosthetic heart valves. The valves (white circles) have replaced the mitral and tricuspid valves. These are the two atrioventricular valves, which control the flow of blood between the chambers of the heart. The tricuspid controls flow between the right atrium (upper chamber) and the right ventricle (lower chamber), while the mitral does the same on the left of the heart. Valve failure can lead to malfunctioning of the heart and death.