Mitral Valve Regurgitation

Mitral valve regurgitation, also known as mitral valve insufficiency, refers to blood leaking back through the mitral valve. The mitral valve is one of four valves in the heart and is composed of two leaflets: the anterior leaflet, which has a semi-circular shape, and the posterior leaflet, which has a quadrangular shape. The mitral valve allows blood flow through the left atrium into the left ventricle and to the body. Therefore, a properly functioning mitral valve specifically prevents backflow into the left atrium from the left ventricle. When mitral valve regurgitation occurs, such as when the valve cannot close tightly, blood leaks back through the valve. As a result, the heart must work harder to pump blood forward. 

Mitral valve regurgitation can be acute or chronic. In the former case, the mitral valve suddenly becomes leaky, whereas in chronic conditions, the symptom onset is slow and worsens over time. 

Mitral valve regurgitation can be caused by mitral valve prolapse (MVP), or the bulging of the mitral valve’s two leaflets back into the left atrium during systole, thereby allowing for the backflow of blood into the left atrium. MVP occurs in approximately 2% of the population, and can be caused by genetic defects, long term calcium buildup, or deterioration due to aging. Similarly, coronary artery disease, or the buildup of the plaque in arteries over time, can damage the heart valves. Other chronic causes of MVP include concurrent autoimmune disease, such as rheumatoid arthritis, and heart arrhythmias such as atrial fibrillation. Connective tissue diseases, such as Marfan Syndrome or late-stage Syphilis, may also be associated with mitral valve prolapse. 

Mitral valve regurgitation is diagnosed after a thorough understanding of the individual’s medical history and physical examination. The healthcare provider may check for heart murmurs using a stethoscope. Upon auscultation, mitral regurgitation will produce a holosystolic (pansystolic) murmur, heard best at the apex with the diaphragm of the stethoscope while the patient is in the left lateral decubitus position (i.e., while lying down). In the case of mitral prolapse, this murmur may be heard during midsystole.

Other diagnostic tests include an echocardiogram, specifically a transesophageal echocardiogram, where a probe with an ultrasound transducer is passed through the individual’s esophagus to visualize the structures of the heart. An electrocardiogram (ECG) to assess heart rhythm and magnetic resonance imaging (MRI) of the heart can also be used for diagnosis. Cardiac catheterization may also be performed, where a physician threads a long, thin tube through an artery or vein in the groin, neck, or arm to the heart. This procedure can assist doctors in performing diagnostic tests to measure the pressure in the chambers, and biopsies, or tissue samples of the heart, if necessary. 

Mitral valve regurgitation may not require any treatment if the condition is mild to moderate, but may need to be monitored using echocardiograms over time to ensure that it does not worsen. Certain lifestyle changes, such as a low salt diet and mild to moderate exercise, can help decrease blood pressure and subsequent stress on the heart. A doctor may prescribe medications to reduce blood pressure and workload on the heart (e.g., angiotensin-converting enzyme (ACE) inhibitors and beta-blockers). Diuretic medications, such as furosemide or chlorothiazide, can reduce swelling due to fluid retention from less blood being pumped to the kidneys and thus less filtration. 

For cases of acute and severe mitral valve regurgitation, surgery is usually required. The valve may be replaced with human, porcine or bovine heart tissue, or it may be mechanical and man-made. The surgeon may choose to perform an open heart procedure or use a minimally invasive technique. In cases where the patients are too high-risk for open-heart surgery, a mitral valve clip can repair the damaged valve. A small metal clip is inserted via a vein in the leg and attached to the abnormal part of the valve. The clip tightly closes the affected part of the valve, while allowing the rest of the valve to open and close normally, in order to minimize regurgitation. 

Atrial fibrillation, an irregular and rapid heartbeat, can be a consequence and/or a cause of mitral valve insufficiency. If this occurs, a healthcare provider might prescribe blood thinners, such as dabigatran, rivaroxaban, or apixiban, to prevent blood clots.