What is mitral valve prolapse? (a heart abnormality affecting 5-10% population)

[Naveed Yaseen]

Mitral valve prolapse (also known as “click murmur syndrome” and “Barlow’s syndrome”) is the most common heart valve abnormality, affecting five to ten percent of the world population. A normal mitral valve consists of two thin leaflets, located between the left atrium and the left ventricle of the heart. Mitral valve leaflets, shaped like parachutes, are attached to the inner wall of the left ventricle by a series of strings called “chordae.” When the ventricles contract, the mitral valve leaflets close snugly and prevent the backflow of blood from the left ventricle into the left atrium. When the ventricles relax, the valves open to allow oxygenated blood from the lungs to fill the left ventricle.

In patients with mitral valve prolapse, the mitral apparatus (valve leaflets and chordae) becomes affected by a process called myxomatous degeneration. In myxomatous degeneration, the structural protein collagen forms abnormally and causes thickening, enlargement, and redundancy of the leaflets and chordae. When the ventricles contract, the redundant leaflets prolapse (flop backwards) into the left atrium, sometimes allowing leakage of blood through the valve opening (mitral regurgitation). When severe, mitral regurgitation can lead to heart failure and abnormal heart rhythms. Most patients are totally unaware of the prolapsing of the mitral valve. Others may experience a number of symptoms discussed below.

The mitral valve prolapse (MVP) syndrome has a strong hereditary tendency, although the exact cause is unknown. Affected family members are often tall, thin, with long arms and fingers, and straight backs. It is seen most commonly in women from 20 to 40 years old, but also occurs in men.

What are the signs and symptoms of mitral valve prolapse? Most people with mitral valve prolapse have no symptoms, however, those who do commonly complain of symptoms such as fatigue, palpitations, chest pain, anxiety, and migraine headaches. Stroke is a very rare complication of mitral valve prolapse.

Fatigue is the most common complaint, although the reason for fatigue is not understood. Patients with mitral valve prolapse may have imbalances in their autonomic nervous system, which regulates heart rate and breathing. Such imbalances may cause inadequate blood oxygen delivery to the working muscles during exercise, thereby causing fatigue.

Palpitations are sensations of fast or irregular heart beats. In most patients with mitral valve prolapse, palpitations are harmless. In very rare cases, potentially serious heart rhythm abnormalities may underlie palpitations which require further evaluation and treatment.

Sharp chest pains are reported in some patients with mitral valve prolapse, which can be prolonged. Unlike angina, chest pain with mitral valve prolapse rarely occurs during or after exercise, and may not respond to nitroglycerin.

Anxiety, panic attacks, and depression may be associated with mitral valve prolapse. Like fatigue, these symptoms are believed to be related to imbalances of the autonomic nervous system.

Migraine headaches have been occasionally linked to mitral valve prolapse. They are probably related to abnormal nervous system control of the tension in the blood vessels in the brain.

Mitral valve prolapse may be rarely associated with strokes occurring in young patients. These patients appear to have increased blood clotting tendencies due to abnormally sticky blood clotting elements, called platelets.

How is mitral valve prolapse diagnosed and evaluated?

Examination of the patient reveals characteristic findings unique to mitral valve prolapse. Using a stethoscope, a clicking sound is heard soon after the ventricle begins to contract. This clicking is felt to reflect tightening of the abnormal valve leaflets against the pressure load of the left ventricle. If there is associated leakage (regurgitation) of blood through the abnormal valve opening, a “whooshing” sound (murmur) can be heard immediately following the clicking sound.

Echocardiography (ultrasound imaging of the heart) is the most useful test for mitral valve prolapse. Echocardiography can measure the severity of prolapse and the degree of mitral regurgitation. It can also detect areas of infection on the abnormal valves. Valve infection is called endocarditis and is a very rare, but potentially serious complication of mitral valve prolapse. Echocardiography can also evaluate the effect of prolapse and regurgitation on the functioning of the muscles of the ventricles.

Abnormally rapid or irregular heart rhythms can occur in patients with mitral valve prolapse, causing palpitations. A 24-hour Holter monitor is a continuous cassette recording of the patient’s heart rhythm as the patient carries on his/her daily activities. Abnormal rhythms occurring during the test period are captured on tape and analyzed at a later date. If abnormal rhythms do not occur every day, the Holter recording may fail to capture the abnormal rhythms. These patients then can be fitted with a small “event-recorder” to be worn for up to several weeks. When the patient senses a palpitation, an event button can be pressed to record the heart rhythm prior to, during, and after the palpitations.

What is the treatment for mitral valve prolapse?

The vast majority of patients with mitral valve prolapse have an excellent prognosis and need no treatment. For these individuals, routine examinations including echocardiograms every few years may suffice. Mitral regurgitation in patients with mitral valve prolapse can lead to heart failure, heart enlargement, and abnormal rhythms. Therefore, mitral valve prolapse patients with mitral regurgitation are often evaluated annually. Since valve infection, endocarditis, is a rare, but potentially serious complication of mitral valve prolapse, patients with mitral valve prolapse are usually given antibiotics prior to any procedure which can introduce bacteria into the bloodstream. These procedures include routine dental work, minor surgery, and procedures that can traumatize body tissues such as colonoscopy, gynecologic, or urologic examinations. Examples of antibiotics used include oral amoxicillin and erythromycin as well as intramuscular or intravenous ampicillin, gentamycin, and vancomycin.

Patients with severe prolapse, abnormal heart rhythms, fainting spells, significant palpitations, chest pain, and anxiety attacks may need treatment. Beta-blockers, such as atenolol (Tenormin), metoprolol (Lopressor), and propranolol (Inderal), are the drugs of choice. These act by increasing the size of the left ventricle, thereby reducing the degree of prolapse. The calcium blockers verapamil (Calan) and diltiazem (Cardizem) are useful in patients who cannot tolerate beta-blockers.

Although most patients with mitral valve prolapse require no treatment or treatment with oral medications, in very rare cases, surgery (mitral valve replacement or repair) may be required. Patients who require surgery usually have severe mitral regurgitation causing worsening heart failure and progressive heart enlargement. Rarely, rupture of one or more chordae can cause sudden, severe mitral regurgitation and heart failure requiring surgical repair. Mitral valve repair is preferable if possible, to mitral valve replacement as the surgical treatment for mitral valve regurgitation. After mitral valve replacement, lifelong blood thinning medications are necessary to prevent blood from clotting on the artificial valves. After mitral valve repair, these blood thinning medications are unnecessary. Because of the success of valve repair, it is being performed earlier in patients with mitral regurgitation, thus reducing the risk of abnormal heart rhythms and heart failure.

Rare patients with mitral valve prolapse may suffer strokes because of increased blood clotting. These patients can be treated with a combination of a blood thinner (anticoagulant) and a beta-blocker.

Again, although patients with mitral valve prolapse may experience a variety of complications, most have no symptoms and can lead healthy, active, and normal lives.

Mitral Valve Prolapse At A Glance

* Mitral valve prolapse (mitral valve prolapse) is the most common heart valve abnormality.

* Most patients with mitral valve prolapse have no symptoms and require no treatment.

* Mitral valve prolapse can be associated with fatigue and/or palpitations.

* Mitral valve prolapse can often be detected by a doctor during examination of the heart. mitral valve prolapse can be confirmed with an echocardiogram.

* Patients with mitral valve prolapse are usually given antibiotics prior to any procedure which might introduce bacteria into the bloodstream, including dental work and minor sur.

—www.medicinenet.com

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