Heart diseases

damaged valves.

Blood moves through the heart in one direction. Valves stop the blood flowing backwards. Such valves are shown on the right.

 
   
 
   
There are two problems that can affect the heart valves. One is that the valve does not close properly, as shown on the right. So blood leaks backwards in the wrong direction. The other is that the valve can become narrow allowing little blood to flow.
   
Valves can be replaced with artificial valves. The heart is stopped and the patient is connected to a heart-lung machine. The surgeon will remove the damaged valve and sew the new one in place.