Mitral regurgitation (MR)

Mitral regurgitation (MR) is a heart disorder, sometimes referred to as mitral insufficiency or mitral incompetence. The mitral valve is part of the structure of the heart that connects the upper and lower left heart chambers (the left atrium and left ventricle). Valves help to pump blood and direct blood flow using small flap-like openings, known as leaflets or cusps, that open and close during the beating of the heart. In mitral valve regurgitation, the flaps of the mitral valve cease to close tightly enough, allowing some blood to leak backwards. In mild cases, mitral valve regurgitation may lead to an irregular heartbeat or to feelings of fatigue or breathlessness. In more severe cases, it may contribute to serious damage to the heart and related organs, or heart failure. Surgery may be required to fix or replace faulty mitral valves.

Background

The heart is an organ essential for keeping blood circulating throughout the body. The heart is tasked with pumping blood as well as maintaining the flow of blood in the proper direction. To accomplish this, the heart includes a system of chambers, valves, and flaps that help to push and direct the blood.

Four valves important for this purpose are the aortic, mitral, pulmonary, and tricuspid valves. Each of these valves has small flaps, known as cusps or leaflets. Every time the heart beats, the flaps open to allow blood to pass, and then close to stop the flow of blood. Although quite small, these valves are crucial for the workings of the body.

Serious disorders may occur when these flaps cease to function properly. If the valves cannot hold and move the blood in a controlled and timely manner, circulation will be disrupted throughout the body. One of the main heart conditions involving disrupted blood flow is called mitral valve regurgitation.

Overview

For blood to circulate properly through the body, it must first pass in a particular sequence through the chambers and valves of the heart. Sometimes, malfunctions occur between the upper and lower left heart chambers, known as the left atrium and left ventricle. The valve connecting these chambers, the mitral valve, does not shut completely at each heartbeat.

This valve failure allows some of the blood that has been pumped from the left atrium into the left ventricle to leak back into the left atrium. This condition is generally known as mitral valve regurgitation. (It is also sometimes called mitral insufficiency or mitral incompetence.) Mitral valve regurgitation can be a serious problem because it restricts the fast and efficient circulation of blood, and can leave the body feeling exhausted or breathless.

In less-serious cases of mitral valve regurgitation, the patient may never notice symptoms, or only notice symptoms after many years. The condition is often mild at first, but frequently grows in severity over time until its effects are noticeable and problematic. Some of the most common symptoms include fatigue, or chronic tiredness, and shortness of breath that usually occurs during exercising or when lying down.

Other symptoms of mitral valve regurgitation occur near the heart itself. These include heart murmur and heart palpitations, or fluttering heartbeats. A heart murmur is an unusual sound, audible through a stethoscope, created by irregular beating of the heart. Sometimes, the symptoms occur due to the inefficient pumping of the blood, even far away from the heart. One of the most common such symptoms is that the ankles or feet will swell.

Mitral valve regurgitation is most commonly diagnosed either through severe and sudden symptoms, or when doctors discover a heart murmur. When mitral valve regurgitation is suspected, doctors may refer patients to cardiologists. These heart specialists may conduct a test called an echocardiogram to study the pattern of heartbeats and the motion of the heart and blood.

A wide variety of factors may cause or worsen mitral valve regurgitation. One of the main contributing factors is a condition known as mitral valve prolapse. In this condition, when the heart beats, the flaps of the mitral valve suck back into the left atrium chamber. When this occurs, the seal between the chambers is not tight enough and some blood can drain back. This condition may cause mitral valve regurgitation. It may also worsen the condition by putting strain on the tissues that hold the flaps in place.

Many other factors may damage the mitral valve and nearby parts, potentially causing or worsening mitral valve regurgitation. An infection of the heart called endocarditis can damage the lining of heart valves, including the mitral valve. Heart attacks may also damage the mitral valve and surrounding areas. Mitral valve regurgitation brought about by heart attacks may be sudden and severe. High blood pressure and other conditions may gradually swell the left ventricle, making its valves seal less tightly and causing mitral valve regurgitation.

Most people who develop mitral valve regurgitation are adults, although some cases are caused by congenital defects in the heart valves. Trauma to the chest and heart area, such as accidents or violence, can damage the valves as well. So, too, can the use of certain drugs, and sicknesses such as rheumatic fever. Rheumatic fever is uncommon in developed countries but still occurs frequently in many regions.

Just as mitral valve regurgitation has many possible causes, it also has many potential effects. In many cases, the defect and its results are mild. They may not be serious enough to treat, and may be hardly noticeable. However, some cases are severe, and sometimes mild cases intensify.

In cases of severe mitral valve regurgitation, patients may face a range of problematic effects. These include pulmonary hypertension, a heightened blood pressure affecting the lungs. Another possible effect is atrial fibrillation, or irregular heart rhythm in the upper chambers of the heart. This latter condition is known to potentially create dangerous blood clots. Severe cases of mitral valve regurgitation may also lead to heart failure, the inability of the heart to process blood as needed.

Although mitral valve regurgitation can become serious, even life-threatening, patients have treatment options. Mild cases may not require treatment. More serious cases may require heart surgery to fix faulty mitral valves, or to install replacement valves into the heart. In general, the prognosis is best when the disorder is discovered early, before it has time to worsen or contribute to other problems.

Bibliography

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