The mitral valve is the valve that separates the two chambers on the left side of the heart, the left atrium and ventricle, from each other. The left side of the heart is stronger than the right side because it pumps blood out from the lungs to the rest of the body, while the right side pumps blood only to the lungs. Mitral valve prolapse, also called Barlow’s syndrome, floppy valve syndrome, or click-murmur syndrome, occurs when one or both of the two leaflets (flaps composing the mitral valve) bulge backwards (prolapse) into the left atrium when the left ventricle contracts. In the majority of cases, the mitral valve is still perfectly functional, but sometimes the valve can allow blood to leak backwards, a condition called mitral valve regurgitation.
Mitral valve prolapse can occur in a structurally normal valve, in which case the cause is often difficult to determine, though the condition has strong hereditary tendencies. When the prolapsing valve has an abnormal structure, the reason the valve bulges backwards is usually that the mitral valve closes unevenly due to leaflets that are too large or chordae tendinea that are too long. Chordae tendinea are chords that attach the mitral valve to muscles on the wall of the heart, and, combined with the muscles to which they attach (papillary muscles), the two leaflets, and the hole in which the valve sits (mitral annulus) compose what doctors call the mitral apparatus. A process called myxomatous degeneration can cause this apparatus to become redundant (too large or long) because of the abnormal formation of a protein called collagen. Sometimes, mitral valve prolapse can be attributed to a genetic disorder like Marfan syndrome or associated with an imbalance of the autonomic nervous system, the portion of the nervous system controlling involuntary functions.
When mitral valve prolapse is not associated with an abnormal valve structure, the condition is usually benign and has few symptoms. Even when the valve’s structure is abnormal, the condition is still likely not to have any symptoms or complications, but blood clots can be more likely to form in the heart and mitral regurgitation can lead to congestive heart failure. When patients have symptoms, they can often be difficult to explain or psychological problems like anxiety, panic attacks, and depression. These symptoms may be related to an imbalanced autonomic nervous system. Other symptoms include palpitations; dull, lasting chest pain; fatigue; dizziness; and shortness of breath.
Doctors can identify a prolapsing mitral valve by the characteristic clicking sound heard in the middle of the heart’s contraction (mid-systolic click) followed by a whooshing sound heard during the end of contraction (late systolic murmur). An echocardiogram can help a doctor confirm his diagnosis.
The majority of patients with mitral valve prolapse do not require treatment, but because they are more susceptible to an infection in the heart (endocarditis), doctors often prescribe antibiotics to patients with the condition before a procedure that might expose them to bacteria in the bloodstream. Patients with severe prolapse or regurgitation may require medication or surgery. Beta-blockers can help by reducing the strain on the left ventricle so that the mitral valve will be less likely to prolapse. Aspirin and blood thinners like Coumadin can help prevent blood clots from forming and may be especially necessary if a patient has had a stroke.
If a patient’s mitral valve is causing his heart to fail or enlarge, he may need to have the valve surgically repaired or replaced. Mitral valve repair can involve a catheter-based procedure like valvuloplasty or annuloplasty to change the shape of the mitral valve or open surgery to reconnect leaflets and remove excess tissue. The mitral valve may be beyond repair and need to be replaced by an artificial mechanical or biological replacement valve. Mechanical valves usually last longer than biological replacements, but they are more likely to promote blood clotting. Biological valves may need to be replaced again, because they usually do not last as long as their mechanical counterparts, but they are less likely to cause blood clotting problems.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.