Pathology
Mitral valve prolapse refers to a defect in the bileaflet (two-part) mitral valve that is strongly hereditary in some families, but most often occurs at random. With mitral valve prolapse, the valve becomes increasingly elastic. Healthy valve tissue has both elastic and collagen tissue. Elastic tissue provides flexibility, allowing the valve to move rapidly from open to closed at differing heart rates. Collagen gives the valve a durable mechanical quality. As a valve becomes more elastic, it starts to flop or bulge into the left atrium.

Normally, a closed mitral valve prevents blood from returning to the left atrium from the left ventricle. In the case of mitral valve prolapse, the valve makes a clicking sound as it flops backwards, separating the anterior and posterior portions of the mitral valve. During that separation, blood can reverse course and flow back into the atrium, a more severe condition known as mitral regurgitation.

Mitral valve prolapse is the most common valvular disease among adults. Approximately two to three percent of the general population has the condition, and it is more common among women than men. Only a small portion of people with mitral valve prolapse will ever require either medication or surgery. In most cases, prolapse patients have a similar longevity to the general population. While family history is a risk factor, for most patients the condition stems from a random event in their development. Rheumatic heart disease may also cause mitral valve prolapse with regurgitation, but ultimately progresses to stenosis in most cases.

Diagnosis and Treatment
Often asymptomatic, mitral valve prolapse is frequently detected during a routine physical examination by stethoscope. The physician may pick up a click (the sound of the valve bulging back), a murmur (the blood leaking into the atrium), or a combination of a click followed by a murmur. Patients may experience chest pain or palpitations, though not necessarily due directly to the prolapse. Patients who have mitral regurgitation may experience shortness of breath. As blood leaks back into the atrium, it creates an enlargement or swelling of the heart. This swelling in turn increases the pressure in the atrium and causes retention of fluid in the lungs, making it harder to breathe.

Mitral valve prolapse can cause fainting spells if the patient experiences a sudden change in blood pressure—for example, by standing up quickly. That quick, excessive drop in pressure is a sign of autonomic dysfunction. Fainting spells may also occur when the patient has both mitral valve prolapse and an irregular heart rhythm, such as ventricular tachycardia, ventricular fibrillation, or atrial fibrillation.

Physicians can best diagnose mitral valve prolapse using an echocardiogram or ultrasound. The characteristic changes appear as an increasingly floppy, thick-looking valve that bulges well into the left atrium. The leaflet may bulge in the anterior or posterior portion of the valve, or both.

Depending on their ailment, patients undergoing valve surgery may either have their own valve repaired, or they may receive a tissue or mechanical valve replacement.

Most patients with mitral valve prolapse have only a mild version of the condition. Physicians may choose to treat more moderate conditions with medical therapies, especially in the presence of hypertension. Certain preventive measures, such as taking antibiotics before dental procedures and other surgeries so as to avoid a possible infection of the valve tissue, have recently been discontinued for most people. Patients with artificial heart valves, congenital defects, or prior heart valve infections will still need to follow some protective regimen with antibiotics. Dental procedures are still the most likely to pose a bacterial risk overall.

For patients who have severe cases of mitral valve prolapse, the large volume of blood reversing course (regurgitation) can begin to decrease their normal heart performance. Physicians can treat severe mitral valve prolapse surgically by replacing the valve. Increasingly, however, patients are opting instead to have surgery to repair the valve. Often only a discrete portion of the valve causes the problem. The surgeon can, in essence, perform plastic surgery on the valve, removing the damaged portion and supporting the remainder of the valve with an implantable ring device. These repairs are now possible using surgical tools attached to catheters. Mitral valve repair has proven to be an effective therapy that offers durable results.