Mitral Valve Prolapse
What is mitral valve prolapse (MVP)?
Mitral valve prolapse, also known as click-murmur syndrome, Barlow's syndrome, balloon mitral valve, or floppy valve syndrome, is the bulging of one or both of the mitral valve flaps (leaflets) into the left atrium during the contraction of the heart. One or both of the flaps may not close properly, allowing the blood to leak backward (regurgitation). This regurgitation may result in a murmur (abnormal sound in the heart due to turbulent blood flow). Mitral regurgitation (backward flow of blood), if present at all, is generally mild.
It is estimated that mitral valve prolapse occurs in around 3 percent of the population.
What is the mitral valve?
The mitral valve is located between the left atrium and the left ventricle and is composed of two flaps. Normally the flaps are held tightly closed during left ventricular contraction (systole) by the chordae tendineae (small tendon "cords" that connect the flaps to the muscles of the heart). In MVP, the flaps enlarge and stretch inward toward the left atrium, sometimes "snapping" during systole, and may allow some backflow of blood into the left atrium (regurgitation).
What causes MVP?
The cause of MVP is unknown, but is thought to be linked to heredity. Primary and secondary forms of MVP are described below.
Primary MVP. Primary MVP is distinguished by thickening of one or both valve flaps. Other effects are fibrosis (scarring) of the flap surface, thinning or lengthening of the chordae tendineae, and fibrin deposits on the flaps. The primary form of MVP is seen frequently in people with Marfan's Syndrome or other inherited connective tissue diseases, but is most often seen in people with no other form of heart disease.
Secondary MVP. In secondary MVP, the flaps are not thickened. The prolapse may be due to ischemic damage (caused by decreased blood flow as a result of coronary artery disease) to the papillary muscles attached to the chordae tendineae or to functional changes in the myocardium. Secondary MVP may result from damage to valvular structures during acute myocardial infarction, rheumatic heart disease, or hypertrophic cardiomyopathy (occurs when the muscle mass of the left ventricle of the heart is larger than normal).
What are the symptoms of MVP?
Mitral valve prolapse may not cause any symptoms. The following are the most common symptoms of MVP. However, each individual may experience symptoms differently. Symptoms may vary depending on the degree of prolapse present and may include:
Palpitations. Palpitations (sensation of fast or irregular heart beat) are the most common complaint among patients with MVP. The palpitations are usually associated with premature ventricular contractions (the ventricles beat sooner than they should), but supraventricular rhythms (abnormal rhythms that begin above the ventricles) have also been detected. In some cases, patients may experience palpitations without observed dysrhythmias (irregular heart rhythm).
Chest pain. Chest pain associated with MVP is different from chest pain associated with coronary artery disease and is a frequent complaint. Usually the chest pain is not like classic angina, but can be recurrent and incapacitating.
Depending on the severity of the leak into the left atrium during systole (mitral regurgitation), the left atrium and/or left ventricle may become enlarged, leading to symptoms of heart failure. These symptoms include weakness, fatigue, and shortness of breath.
The symptoms of mitral valve prolapse may resemble other medical conditions or problems. Always consult your doctor for a diagnosis.
How is MVP diagnosed?
People with MVP often have no symptoms and detection of a click or murmur may be discovered during a routine examination.
MVP may be detected by listening with a stethoscope, revealing a "click" (created by the stretched flaps snapping against each other during contraction) and/or a murmur. The murmur is caused by some of the blood leaking back into the left atrium. The click or murmur may be the only clinical sign.
In addition to a complete medical history and physical examination, diagnostic procedures for MVP may include any, or a combination, of the following:
Electrocardiogram (ECG or EKG). A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and can sometimes detect heart muscle damage.
Echocardiogram (also called echo). 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 the heart. Echocardiography is the most useful diagnostic test for MVP.
In some situations where symptoms are more severe, additional diagnostic procedures may be performed. Additional procedures may include:
Stress test (also called treadmill or exercise ECG). A test that is performed while a patient walks on a treadmill to monitor the heart during exercise. Breathing and blood pressure rates are also monitored.
Cardiac catheterization. With this procedure, X-rays are taken after a contrast agent is injected into an artery to locate any narrowing, occlusions, or other abnormalities of specific arteries. In addition, the function of the heart and the valves may be assessed.
Cardiac MRI. This is a noninvasive test that produces comprehensive images of the heart. It may be used as a complement to echo for a more precise look at the heart valves and heart muscle, or in preparation for heart valve surgery.
How is MVP treated?
Specific treatment for mitral valve prolapse will be determined by your doctor based on:
Your overall health and medical history
Extent of the disease
Your signs and symptoms
Your tolerance for specific medications, procedures, or therapies
Expectations for the course of the disease
Your opinion or preference
Treatment is not usually necessary as MVP is rarely a serious condition. Regular checkups with a doctor are advised.
People with rhythm disturbances may need to be treated with beta blockers or other medications to control tachycardias (fast heart rhythms). In most cases, limiting stimulants, such as caffeine and cigarettes, is all that is needed to control symptoms.
If atrial fibrillation or severe left atrial enlargement is present, treatment with an anticoagulant may be recommended. This can be in the form of aspirin or warfarin (Coumadin) therapy.
For the person with symptoms of dizziness or fainting, maintaining adequate hydration (fluid volume in the blood vessels) with liberal salt and fluid intake is important. Support stockings may be beneficial.
If severe mitral regurgitation resulting from a floppy mitral leaflet, rupture of the chordae tendineae, or extreme lengthening of the valve should occur, surgical repair may be indicated.
What is the prognosis for MVP?
This condition is usually harmless and does not shorten life expectancy. Healthy lifestyle behaviors and regular exercise are encouraged.