The exact cause of mitral valve prolapse (MVP) isn't known. Most people who have the condition are born with it. MVP tends to run in families. Also, it's more common in people who are born with connective tissue disorders, such as Marfan syndrome.
In people who have MVP, the mitral valve may be abnormal in the following ways:
- The valve flaps may be too large and thick.
- The valve flaps may be "floppy." The tissue of the flaps and their supporting "strings" are too stretchy, and parts of the valve flop or bulge back into the atrium.
- The opening of the valve may stretch.
These problems can keep the valve from making a tight seal. Some people's valves are abnormal in more than one way.