Mitral Valve Prolapse
What is mitral valve prolapse?
Mitral valve prolapse (MVP) is the bulging (or prolapse) of one or both of the mitral valve flaps into the left atrium when the heart contracts. When the flaps do not close properly, blood leaks backward. This is called regurgitation. Regurgitation may result in a heart murmur, an abnormal sound in the heart caused by turbulent blood flow. When regurgitation is present, it’s generally mild although it can progress into a more serious condition over time.
The mitral valve is located between the left atrium and the left ventricle and has 2 flaps. Normally the flaps are tightly closed by small tendon or “cords” that connect the flaps to the muscles of the heart. This closure prevents blood from flowing backwards. In MVP, the flaps enlarge and stretch inward toward the left atrium, sometimes “snapping” during heart contraction. This may allow some backflow or regurgitation of blood into the left atrium.
MVP usually does not need to be treated because it is rarely a serious condition, and it does not damage the heart. However, regular checkups with a doctor are advised.
What causes MVP?
The cause of MVP is unknown, but it’s thought to be inherited. There are 2 forms of MVP: primary and secondary.
Primary MVP means the mitral valve is abnormal because of one or more of these changes:
- One or both of the flaps are too large and thick
- The flap surfaces are scarred
- The tendon cords are thinner or longer than they should be
- There are fibrin deposits on the flaps
Primary MVP is seen in people with Marfan syndrome and other inherited connective tissue diseases. But, it’s most often found in people with no other form of heart disease.
In secondary MVP, the flaps are not thickened but rather prolapse occurs for other reasons. The prolapse or bulging may be due to:
- Damage caused by decreased blood flow (due to coronary artery disease) to the muscles attached to the tendon cords
- Functional changes in the heart muscle
- Damage to valve structures caused by heart attack, rheumatic heart disease, valve infection, or hypertrophic cardiomyopathy (this is when the left ventricle of the heart is larger than normal)
Who is at risk for MVP?
MVP affects both sexes and people of all ages. Factors that may increase the risk of MVP include:
- Graves disease (a condition that affects the thyroid gland)
- Certain connective tissue disorders, such as Marfan syndrome
- Scoliosis and other skeletal problems
- Some types of muscular dystrophy
What are the symptoms of MVP?
MVP may not cause any symptoms. Symptoms may vary depending on the degree of prolapse present. The presence of symptoms does not necessarily match the severity of MVP.
These are the most common symptoms of MVP:
- Palpitations (fast or irregular heartbeats). This may be the result of irregular heartbeats or just the sensation of the valve closing when the heart rhythm is normal.
- Chest pain. Chest pain associated with MVP is different from chest pain associated with coronary artery disease. Usually the chest pain is not like classic angina, such as pain with exertion, but it can happen often, can be very uncomfortable, and can affect your quality of life.
- Exercise intolerance
Depending on the severity of the mitral regurgitation or leak, the left atrium or left ventricle may become enlarged, leading to symptoms of heart failure. These symptoms include weakness, tiredness, dizziness, and shortness of breath.
The symptoms of mitral valve prolapse may look like other medical conditions or problems. Always see a doctor for a diagnosis.
How is mitral valve prolapse diagnosed?
You may have no noticeable symptoms. Your doctor may hear a click or murmur during a routine physical exam. The “click” is created by the stretched flaps snapping against each other during contraction. The murmur is caused by the blood leaking back into the left atrium. This may be the only sign of MVP.
Along with a complete medical history and physical exam, your doctor may order these tests to diagnose MVP:
- Electrocardiogram (ECG). This test records the strength and timing of the electrical activity of the heart. It shows abnormal rhythms and can sometimes detect heart muscle damage. Small sensors are taped to your skin to pick up the electrical activity.
- Chest X-ray. An X-ray may be done to check your lungs and see if your heart is enlarged.
- Echocardiogram (echo).This is a noninvasive test that uses sound waves to evaluate the heart’s chambers and valves. The echo sound waves create an image on the monitor as an ultrasound transducer is passed over your chest above the heart. Echocardiography is the most useful diagnostic test for MVP.
For more severe symptoms, other tests may be done. These may include:
- Stress test (also called treadmill or exercise ECG).This ECG is done while you walk on a treadmill to monitor the heart during exercise. Breathing and blood pressure rates are also checked.
- Cardiac catheterization. With this procedure, X-rays are taken after a contrast agent (dye) is injected into an artery to look for any narrowing, blockages, or other changes in certain arteries. The function of the heart and the valves may be checked, too.
- Cardiac MRI. This is an imaging test that takes detailed pictures of the heart. It may be used to get a more precise look at the heart valves and heart muscle, or to prepare for heart valve surgery.