Mitral Regurgitation

Mitral Regurgitation, also known as mitral valve regurgitation, mitral insufficiency or mitral incompetence, is an abnormal reflux of blood from the left ventricle into the left atrium during ventricular systole (contraction of the left and right ventricles). This condition may result from a dilatation of the left ventricle, a dilatation of the mitral annulus or an abnormal joining of the two valve leaflets.

Mitral Valve, also known as bicuspid valve, is a membranous fold that separates the left atrium from the left ventricle. It consists of 2 cusps (or leaflets) having a miter-shaped when open. The role of the leaflets is to ensure proper closing and opening of the valve during contraction of the ventricles (ventricular systole). Mitral regurgitation occurs when, due to certain pathological conditions, the mitral valve is unable to close tightly.

Mitral regurgitation affects millions of people around the world, which makes it the most common heart valve disease in developed countries. It is estimated that more than 8 million people in the United States and Europe suffer from mitral valve regurgitation, with an increase of approximately 600 000 new cases each year.

Causes and Risk Factors

The mitral valve provides permeability between the left atrium and left ventricle during systole and diastole. It is a membranous fold located between the left atrium and left ventricle. Its main role is to prevent blood from flowing back, mostly reflux of blood from the left ventricle into the left atrium. A healthy mitral valve opens during the filling of the left ventricle to facilitate the passage of blood coming from the left atrium. Then, during ventricular contraction (contraction of the muscles of the left and right ventricles), the mitral valve closes to prevent blood from backflowing into the atria.

Sometimes, however, the mitral valve can be affected by certain disorders preventing it from closing properly; this lead to a leakage of blood backward through the mitral valve when the heart contracts; this condition is called mitral valve regurgitation.  Many disorders can cause valve regurgitation; most common include:

• rheumatic fever
• mitral valve prolapse
• previous heart attack
• chronic high blood pressure
• congenital heart defects
• structural valve deterioration
• Infection of the lining of the heart (endocarditis).

Mitral regurgitation is a multifactorial medical condition; some of the common factors that can lead to its development include:

Age – age does not cause mitral regurgitation; however, as you get older, your mitral valve tends to get deteriorated. This natural deterioration can lead to mitral regurgitation in some people.

Previous heart attack – heart attack can damage the structure of the heart muscle, including the function of the mitral valve.

Rheumatic fever – chronic or untreated rheumatic fever can damage the leaflets of the mitral valve leading to narrowing or abnormal function of the valve.

Endocarditis – infection or inflammation of the inside lining of the heart chambers (endocardium) increases the risk of mitral valve regurgitation if left untreated.

Taking certain drugs – taking certain medications such as pergolide (used for the treatment of Parkinson’s disease) and ergotamine (used for the treatment of migraine) increase the risk of developing mitral regulation. In addition, certain diseases such as atherosclerosis, Buerger’s syndrome, coronary artery disease, hepatic disease, Raynaud’s syndrome, and renal disease can be responsible for the development of mitral valve regurgitation.

Mitral valve prolapsed – when the valve that separates the upper and lower chambers of the left side of the heart does not close properly, the blood flows backward during heart beats; this condition can lead to mitral valve regurgitation.

Congenital heart disease – Congenital heart defect (CHD) refers to a number of different problems affecting the heart, including but not limited to an abnormality in the mitral valve anatomy.

Mitral Regurgitation Symptoms

Most people with mitral valve regurgitation can spend years without developing any symptoms. When finally emerge, symptoms tend to vary depending on the severity of the disease. Although it can manifest all the symptoms of an acute mitral regurgitation, chronic mitral regurgitation tends to be asymptomatic, even during exercise. An acute mitral regurgitation can be associated with:

• shortness of breath
• lightheadedness
• nocturnal cough
• swollen feet or ankles
• heart murmur
• excessive urination during day and night
• unreasonable fatigue, during times of activity
• rapid or sudden development of heartbeat
• respiratory distress that awakens you from sleep
• Accumulation of fluid in your lungs – a sign indicating complications.

Complications

Most of the times, mitral valve regurgitation is not associated with complications; the disease is kept under control with appropriate medications or surgical therapies. However, in rare cases, some patients may experience the following life threatening conditions:

• endocarditis
• atrial fibrillation
• heart failure
• pulmonary hypertension
• Sudden death.

Diagnosis

Your cardiologist will begin the diagnosis by asking you questions about your medical history and the symptoms you experience. After which, a physical examination will be performed to listen to the sound of your heart with stethoscope. During the exam, your doctor will also try to detect other clinical signs related to the disease. However, these procedures are not sufficient to confirm the presence of a mitral regurgitation in your heart; other examinations such as chest x-ray, electrocardiogram (ECG), cardiac catheterization and other imaging techniques are needed to confirm the diagnosis.

Nuclear Heart Scan – this is a precordial examination (cardiac exam) that allows your cardiologist to evaluate the health of your heart. During the procedure, a radioactive material called tracer is used to examine your left and right ventricular functions. Doctors recommend this test to see if the heart normally pumps blood through different parts of the heart muscles. Because, most of the times, left ventricular function is impaired in individual with valve regurgitation.

Holter monitor – a Holter is a portable diagnostic machine that allows you to recording a continuous ECG for hours or days. The device can record many symptoms associated with mitral valve regurgitation: palpitations, chest pain, abnormal heart rhythm, etc.

Cardiac stress test – also called exercise stress test, cardiac stress test is an examination done by a cardiologist as a part of heart disease diagnosis. During the test, you will be recommended to do intense effort, which allows your physician to detect and measure your heart rate and certain cardiovascular problems: imbalance of blood flow to your heart, abnormal blood pressure, shortness of breath, etc. The cardiac stress test helps your cardiologist to prescribe appropriate treatment or recommend other more specialized tests such as coronary angiography or myocardial scintigraphy.

Coronary CT angiography – Angiography is a medical imaging technique used to study your blood vessels that are not visible on standard X-rays.  When the test used to explore your arteries, it is called arteriography; phlebography when it is performed to explore your veins.

Echocardiogram – This painless exam allows to your cardiologist, using sound waves, to view your heart in motion on a screen. The images show if your heart muscle is working well or not. Echocardiogram also provides anatomic information of your heart such as size and shape.

Electrocardiogram (ECG) – ECG is a graphic representation of electric potential that controls the activity of your heart muscle. This painless test can be performed in a doctor’s office, hospital or at home. However, its interpretation remains complex and requires a health care professional.

Magnetic resonance angiography (MRA) – MRA is the study of the vascular wall and blood flow using radiowaves and a magnetic field. It is done through techniques based on dynamic hemodynamic properties and different physical and chemical properties of your blood. The magnetic resonance angiography (MRA) has become a reliable exploration of vascular disease in recent years.

Mitral Regurgitation Treatment

Mitral regurgitation treatment depends on its characteristic or its severity. The treatment aims at normalizing the function of the heart and eliminating or reducing the symptoms.

A moderate, asymptomatic mitral regurgitation does not require treatment but regular monitoring, usually every 1 or 2 years. While under surveillance, it is important to prevent infective endocarditis, and detect or treat all forms of atrial fibrillation. Even when you feel good, medical observation is necessary; infective endocarditis and/or supraventricular arrhythmia can occur and lead to sudden deterioration or complications.

Medications

Your cardiologist can prescribe you diuretic drugs and blood pressure medications as symptomatic treatment. The diuretics aim at preventing or reducing fluid accumulation in your lungs, which can lead to major complications. High blood pressure medications can also be used to lower or keep your blood pressure at normal levels. The drugs, however, do not treat or attack the root of the problem, which is the incomplete closing of the mitral valve; they keep the symptoms of the disease under control, and help you live a better life.

Surgical treatment

If the regurgitation is accompanied by symptoms, whether the blood leaking is acute or chronic, surgery must be performed, in case there is no contraindication. The surgery can be performed to replace or repair the heart valve.

Mitral valve repair – In case the valve diseased is not too damaged to be repaired, your cardio-surgeon may perform a mitral valve repair. Mitral valve replacement consists of removing excess valve tissue, tightening or replacing the ring of tissue around the valve. Unlike the valve replacement, this method allows your health care provider to preserve your own valve, thus preventing implantation of prosthesis and taking of anticoagulant drugs. In fact, this method is the best option for most patients with mitral regurgitation. Mitral valve repair ensure a better long-term survival and a faster recovery than the valve replacement. In addition, the repair presents a lower risk of stroke and endocarditis (infection or/and inflammation of the inside lining of the heart chambers and heart valves).

Heart valve replacement – valve replacement is performed when all other alternatives do not work. The goal of the replacement is to improve or eliminate symptoms and reduce the risk of impact on the function of your heart. The operation must be performed, under general anesthesia, in a cardiac surgery center after completion of a preoperative evaluation indicates that there is no contraindication for the intervention.

This is an open-heart surgery which involves opening the chest, using a section of the sternum, which allows direct access to the heart. The diseased valve is removed and replaced by a healthy one. The type of valve replaced varies depending on your age, your general condition, and other medical conditions. The valve may be biological or mechanical. A mechanical valve usually lasts longer, but requires taking of anticoagulants medications permanently.

Mitral Regurgitation Prevention

There is no known method to prevent mitral regurgitation; however, to reduce your risk of having mitral regurgitation and all other cardiovascular disease, you need to:

• excise regularly
• lose weight (if you are obese or overweight)
• stop smoking (including second hand smoke).

In addition, you need to avoid fast foods and adopt a healthy diet.

• Increase your intake of antioxidants
• Avoid saturated acids, mainly from animal fats, pastries, margarine, etc.
• Increase your intake of carbohydrates and fiber; they play an important role in increasing the levels of good cholesterol
• Reduce bad cholesterol: egg yolk, organ meats (brain, kidney, liver), nuts, almonds, lobster, shellfish, fish eggs, etc.
• Consuming polyunsaturated fatty acids such as omega-6 (sunflower oil) omega 3 (flax seed oil, fish oil), they lower the bad LDL cholesterol and prevent the formation of a blood clot.
• Eat plenty fruits (2 to 3 per day), vegetables (3 to 4 servings per day), polyphenols (moderate consumption of wine and green tea) and phyto-oestrogens: soy, green tea, chickpeas, lentils, beans, grains, carrots, fennel, onions, garlic, etc.

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