Mitral Valve Prolapse

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What is Mitral Valve Prolapse?

The heart has four chambers, two upper chambers called atria and two lower chambers called ventricles. The upper and lower chambers are each connected by a valve in between them, like a common door connecting two separate rooms. The valve between left atrium and left ventricle is called Mitral Valve, which allows blood to flow from the left atrium to the left ventricle. This valve closes during systole (heart contraction) and opens during diastole (heart relaxation). Mitral Valve Prolapse is a condition where the Mitral Valve is prolapsing (bulging) into the left atrium during systole and does not close competently as it should normally do. As a result, it allows some blood to leak from the left ventricle back into the left atrium.

Why does this happen?

The Mitral Valve has two leaflets (flaps) that open and close synchronously with each contraction and relaxation of the heart. (Analogy: a double door, one on each side, that open and close at the center.) The outer periphery of the Mitral Valve is attached the annulus (the opening between the atrium and ventricle), much like a door frame of a double doors where the hinges of the doors are attached one on each side of the frame). The inner edges (central opening) of the two valve leaflets are attached to several strands of evenly spaced chordae tendinae (cords), looking almost like a parachute, where the dome represents the umbrella-shaped leaflets and the chordae tendinae are the cords. These cords are attached to the papillary muscles on the wall of the heart. When the heart contracts, the papillary muscles shorten and pull on the cords, thus opening the valve. When shut, normal leaflets are so approximated no blood leaks through them. However, in the case of Mitral Prolapse, the annulus is dilated (analogy: door frame larger than doors), and/or the leaflets are floppy and redundantly larger than normal (bulging into the left atrium when the heart contracts) and/or the supporting cords are too long, making perfect (liquid-tight) closure not possible. Hence, the leak.

What causes Mitral Valve Prolapse?

Mitral Valve Prolapse, or Mitral Prolapse for short, is also known as MVP, Floppy Valve Syndrome, Click-Murmur Syndrome, Balloon Mitral Valve, Barlow's Syndrome, and Click Chick/Straight Back Syndrome. The exact cause is not known and usually no other heart disease co-exist with it. Microscopically, there are myxomatous tissue degeneration of the valve resulting in thin, flimsy and redundant valve leaflets and elongated chordae. Occasionally, MVP may be associated with disorders causing inflammation of the heart, coronary heart disease, atrial septal defect (congenital hole between the two atria, the upper chambers of the heart).

How common is MVP?

Mitral Valve prolapse varies in prevalence between 1 to 6% in otherwise normal population, predominantly among females. If we extrapolate and took the average, roughly about 2.28 million Filipinos have MVP. The prevalence is higher among persons with Graves' (thyroid) Disease, Marfan's syndrome, atrial septal defect, rheumatic heart disease, Duchenne muscular dystrophy, sickle cell disease, and myotonic dystrophy. About 25 out of a hundred of these patients with MVP have high-arched palate, laxity of the joints, funnel chest, scoliosis and other skeletal adnormalities.

What are the symptoms of MVP?

Most people with MVP are active and healthy, without symptoms whatsoever. Many of them may not even know they have MVP. Among those few who may have, the symptom(s) could be one or a combination of the following: palpitation (skipped beats) and other heart rhythm irregularity, fatigue, dizziness, shortness of breath, chest pains, migraine, orthostatic hypotension (pressure falls when suddenly getting up from a sitting or lying position). In general, people with asymptomatic (symptom-free) MVP do not have to be overly conscious and anxious after diagnosis is made by a physician. It is rare for this condition to be serious or life-threatening. However, those with symptoms should seek medical consultation because the treatment could be as simple and as minimal as taking pills daily to ward off the symptoms.

Can stroke occur among MVP patients?

The probability of stroke or sudden death to take place in persons with Mitral Valve Prolapse is very rare, less than 1%, and usually happens among those with the complete click-murmur syndrome (prolonged QT interval and low or negative T waves in II, III, AVF and the left precordial leads on EKG). This is more of an exception than the rule among MVP patients. The chances of a heart attack or cancer developing among chronic cigarette smokers are much higher than the probability of stroke or death among persons with Mitral Valve Prolapse.

How is MVP diagnosed?

Auscultation (listening to the heart sounds with a stethoscope) is the primary method of diagnosing Mitral Valeve Prolapse. The anatomical deformities of the valve leaflets and chorda tendinae described above create abnormal heart sounds (an opening snap or click, a systolic honk or a whoop). Two-dimensional echocardiography confirms the diagnosis in 95% of cases, and only in 75% of patients when using M-mode echocardiogram. The positive yield is slightly more if the echo is done with the patient on standing position.

Is valve infection a worry?

MVP in itself does not make the mitral valve more susceptible to endocarditis (infection). It is when there is Mitral Regurgitation (leaky valve) that the mitral valve is more prone to endocarditis, in which case prophylactic (preventive) antibiotic is recommended, especially for those undergoing dental procedures or other surgery, or those with infection elsewhere in the body, including skin infection. Unless absolutely sure that there is no mitral valve leak, all patients with MVP, symptomatic or not, are prescribed prophylactic antibiotic under those circumstances.

Can MVP patients engage in sports?

This issue is still controversial. Some cardiologists advise MVP patients with definite click and murmurs to avoid competitive sports to prevent the occasional rupture of chorda tendinae that will lead to severe Mitral Regurgitation and serious heart failure. Others do not restrict their patients from sports activities, even those that require maximum effort. A scientific consensus has not been developed yet. The patient's tolerance (or lack of it) to strenuous physical activities (as evidenced by any symptom present) is one best guide to use in making the final decision. The vast majority of MVP patients enjoy full and active lives with no restrictions

What is the treatment for MVP?

As alluded to earlier, the overwhelming majority of patients with Mitral Valve Prolapse do not have symptoms at all, will have no problem, and do not require any treatment whatsoever. MVP patients with leaky mitral valve may need antibiotics during dental or surgical procedures to prevent endocarditis as mentioned earlier. Those with symptoms listed above may obtain relief and benefit from Beta Blockers, which oral medications also raise the fibrillation (heart quivering) threshold, minimizing the occurrence of fibrillation among patients with dangerous tachycardias (excessively rapid and potentially fatal heart rhythm problem). This is the reason why patients with symptomatic MVP, or who are in doubt that they may have MVP, are advised to seek medical evaluation and care.

When is surgery indicated?

Surgery is seldom indicated for Mitral Valve Prolapse. The operation is reserved for the very rare case where the prolapse is so marked that severe chest pains and/or hemodynamically significant heart rhythm disturbances are medically intractable, and/or Mitral Regurgitation (valve leak) becomes excessively debilitating because of the resultant congestive heart failure.

©2003Raoul R. Diez, M.A.O.D.