faulty heart valves

• the valves in the heart can be damaged or weakened by heart attacks, infection or old age
• the damage may cause the valve tissue to stiffen, so it won't open properly
• a valve may become leaky - allowing blood to flow in both directions, this means that the blood doesn't circulate as effectively as normal
• severe damage can be treated by replacing the valve
• replacement valves can be ones taken from humans or other mammals - these are biological valves
• valves can also be man-made - mechanical valves
• replacing valves is a much less drastic procedure than a whole heart plant transplant
• fitting artificial valves is still a major surgery and there can still be problems with blood clots