Their job is to allow the blood to flow through the heart in only one direction. To work properly, each valve must open and close completely at the right time. The heart valves can develop problems or disease for many reasons. Sometimes the valves are not normal at birth. Rheumatic fever can cause valve disease.
Bacteria can infect the heart valves.
Injured valves make a sound as the blood passes through them. The sound is called a murmur and is best heard through a stethoscope. Not all murmurs mean that there is a valve problem. A stenotic valve is stiff and cannot open well because it has narrowed. This makes it harder for blood to pass through it.