Heart valve replacement. Coloured chest X-ray of a female patient (side view), showing an artificial heart valve (pink loop, centre left) in the heart (red). The valve is seen behind the sternum (breastbone). The sternum runs down the centre of the chest and has here been repaired (dark loops) following its opening to access the heart during open- heart surgery to fit the valve. Heart valves act to control blood flow into and out of the heart, as well as between its chambers. Valve failure can lead to malfunctioning of the heart and death. The spine (down right) is seen, as well as the branching airways of the lungs.