WHAT IS MITRAL VALVE REGURGITATION?
Initially, the body and the heart cope with this backward flow of blood. However, to maintain the forward flow of blood, the ventricle has to pump harder. Over a period of time, this causes enlargement of the left atrium and eventually the left ventricle, setting in motion the progressive downward spiral toward serious and potentially life-threatening complications such as congestive heart failure.
Complications from Mitral Regurgitation
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Congestive Heart Failure (CHF)
CHF occurs when increased pressure in the atrium causes fluid accumulation (congestion) in the lungs, or when the reduced forward flow of blood from the ventricle to the body deprives organs of the proper circulation of blood. The left ventricle may dilate and weaken, contributing to heart failure.
Atrial Fibrillation, stroke and other complications
The increased blood pressure in the left atrium increases blood pressure in the veins leading from the lungs to the heart (pulmonary veins) and causes the left atrium to enlarge to accommodate the extra blood leaking back from the ventricle. An extremely enlarged atrium often beats rapidly in an irregular pattern, a disorder called atrial fibrillation. This condition reduces the heart's pumping efficiency because the fibrillating atrium is quivering rather than pumping. Consequently, blood does not flow through the atrium normally, and blood clots may form inside the chamber. If a clot breaks loose (becoming an embolus), it is pumped out of the heart and may block an artery, possibly causing a stroke or other damage.
Symptoms of Mitral Regurgitation
Mild Mitral Regurgitation (MR) may not produce any symptoms. When regurgitation is more severe or when there is atrial fibrillation, people may have palpitations (an awareness that their heart beat has changed rhythm) or unexplained shortness of breath. People with heart failure may have cough, shortness of breath during exertion or at rest, and swelling in the ankles..
Causes of Mitral Regurgitation
In North America, Western Europe, and Australasia, the most common cause of MR is a heart attack or ischemic heart disease (restricted blood flow within the heart). A heart attack can damage the ventricular muscular structures that support the mitral valve. Coronary artery disease may also diminish the blood supply to the ventricular muscle below the mitral valve, affecting it indirectly. Another common cause of MR is myxomatous degeneration, a hereditary connective tissue disorder that causes weakness in the tissue of the valve. As a result, the heart valve gradually becomes floppy and does not close properly.
Rheumatic fever —A childhood illness that sometimes occurs after untreated strep throat or scarlet fever, used to be the most common cause of MR. The severity of this condition provided the impetus for the early work in heart surgery. The first successful valve replacements were for rheumatic mitral valve disease, performed in 1960 by Dr Starr. Today, rheumatic fever is rare in North America, Australasia, Western Europe, and other regions where antibiotics are widely used to treat infections such as strep throat. In these regions, MR results from rheumatic fever only among older people who did not have the benefit of antibiotics during their youth, or among people who have moved from regions where antibiotics are not widely used. In some developing nations and regions without consistent access to healthcare, rheumatic fever is still common and thus commonly causes mitral stenosis or regurgitation, sometimes 10 years or more after the initial infection. Repeated attacks of rheumatic fever hasten valve deterioration.
Diagnosis of Mitral Regurgitation
MR is usually diagnosed based on the characteristic heart murmur heard through a stethoscope. The murmur is a distinctive sound produced by blood leaking backward into the left atrium when the left ventricle contracts. The disorder is sometimes diagnosed when a doctor hears this murmur during a routine physical examination.
Electrocardiography (ECG) and chest x-rays show that the left ventricle is enlarged. If MR is severe, the chest x-ray may also show fluid accumulation in the lungs. Echocardiography, which uses ultrasound waves to produce an image of the heart structures and blood flow, provides the most information. This procedure can show the size of the atrium and ventricle and the amount of blood leaking so that the severity of the regurgitation can be determined.
Treatment of Mitral Regurgitation
If regurgitation is mild, no specific treatment is required; however, the person may need to be evaluated periodically and may need to take antibiotics before dental and medical procedures to prevent the risk of infection.
Treatment options for heart valve disease include medication with angiotensin-converting enzyme (ACE) inhibitors, surgical repair or replacement of the valve. In some cases, medication alone is successful in the treatment of heart valve disease if detected early..
Surgery is necessary for those with severe regurgitation and recommended for moderately severe regurgitation, if the cause is ischemic. Surgery must be performed before the left ventricle becomes irreversibly enlarged and weakened. Surgery may involve repairing the valve or replacing it with an artificial (prosthetic) valve. Repairing the valve eliminates regurgitation or reduces it enough to make the symptoms tolerable and prevent further damage to the heart. For heart valve repair or replacement, the procedure is performed with the support of the heart-lung machine and with the open heart surgery.
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Surgery: Valve Repair
Repairing the valve is preferable to replacing it, if possible, because a repaired valve preserves the native architecture within the heart. The damaged valve is repaired and tightened with a prosthetic ring called annuloplasty ring. Repair usually functions better than replacement with a mechanical or bioprosthetic valve and the person may not require lifetime anticoagulation therapy.
Surgery: Valve Replacement
A damaged mitral valve may be replaced with a mechanical valve (a bileaflet valve made of pyrolite carbon in a stainless steel housing) or with a bioprosthetic valve made of heart valve tissue (usually from pigs) mounted on a synthetic ring. Replacing the valve is more irreversible and while reducing regurgitation, it carries additional risks. Replacement imposes an artificial device or prosthesis in the blood stream, which is prone to tissue reaction, clot formation and infection.
Choice of a valve depends on many factors, including characteristics of the valve. A mechanical valve lasts longer than a bioprosthetic valve but requires that anticoagulants be taken indefinitely to prevent the formation of blood clots on the valve. A bioprosthetic valve rarely requires the use of anticoagulants but has a life of 12 to 15 years. Whether the patient can take anticoagulants may determine which valve is selected. For example, anticoagulants may not be appropriate for women of childbearing age because anticoagulants cross the placenta and may affect the fetus. Other considerations include the person’s age, activity level, relative heart function..
During replacement surgery, the valve is partially removed, and the replacement valve is sewn in place. The incisions are closed, the heart-lung machine is disconnected, and the heart is restarted. The operation takes from 2 to 5 hours. For some individuals, mitral valve can be replaced using a less invasive procedure (without cutting through the sternum) available at some medical centers. The length of the hospital stay varies from person to person. Full recovery may take 6 to 8 weeks.
Precautions for individuals with Heart Valve Disease
Damaged heart valves are susceptible to a serious infection by bacteria (infective endocarditis). People with a damaged or an artificial valve should take antibiotics before surgical, dental, or medical to reduce the risk of an infection on a valve, even though this risk is small. Atrial fibrillation, if present, may require treatment, including use of anticoagulants to prevent clots.
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