What is Mitral Valve Disease?
Mitral valve disease is a structural or functional deterioration that occurs in the mitral valve, which is located between the left atrium and left ventricle of the heart. A normally functioning mitral valve ensures that blood flows in the correct direction during the contraction and relaxation of the heart and prevents blood from flowing back from the left ventricle to the left atrium. Mitral valve disease can manifest as the valve not opening completely (mitral stenosis), not closing completely (mitral regurgitation), or a combination of both conditions.
The mitral valve is an important valve located on the left side of the heart, consisting of two leaflets (anterior and posterior). This valve opens during the relaxation phase of the heart, allowing blood to pass from the left atrium to the left ventricle. During the contraction phase, it closes, thus preventing blood from flowing back while it is being pumped from the left ventricle to the main artery. Mitral valve diseases are among the frequently seen valve problems worldwide and become more common with advancing age.
Mitral valve diseases can range from mild conditions to serious problems that can put life at risk. Early diagnosis and appropriate treatment can slow the progression of the disease and reduce symptoms.
What is Mitral Stenosis?
Mitral stenosis is a condition where the mitral valve does not open completely due to thickening, stiffening, or adhesion of the mitral valve leaflets. This creates an obstacle to the passage of blood from the left atrium to the left ventricle and causes the heart to work harder to maintain normal blood flow. Over time, pressure increases in the left atrium, leading to increased pressure in the pulmonary vessels, which can cause symptoms such as shortness of breath and fatigue.
Although mitral stenosis is less common in developed countries today, it occurs more frequently in people who have had rheumatic fever in the past. Rheumatic fever is a disease that develops after an infection caused by group A streptococcus bacteria and can damage heart valves. Other causes of mitral stenosis include congenital anomalies, calcification of the area where the mitral valve sits, some immune system diseases (lupus, rheumatoid arthritis), and calcification after previous heart surgeries.
The severity of mitral stenosis is determined by the size of the valve opening. In mild stenosis, symptoms are generally minimal or nonexistent. In moderate stenosis, symptoms may begin during exercise. In severe stenosis, symptoms are felt even at rest and require treatment. Untreated severe mitral stenosis can lead to serious problems such as heart failure, rhythm disorders, and pulmonary hypertension (high blood pressure in the pulmonary vessels).
What is Mitral Regurgitation?
Mitral regurgitation is a condition where blood flows back from the left ventricle to the left atrium during the contraction phase of the heart due to the incomplete closure of the mitral valve leaflets. Since this requires the heart to pump more blood, it can lead to enlargement of the heart muscle and heart failure over time. Mitral regurgitation is the most common type of mitral valve disease and becomes more prevalent with advancing age. Mitral regurgitation is divided into two main groups according to its cause: primary (structural) and secondary (functional).
Primary mitral regurgitation arises from problems in the valve leaflets, cord-like structures that hold the valve (chordae tendineae), or the muscles that support these structures (papillary muscles). Mitral valve prolapse, endocarditis, rheumatic heart disease, injury, and congenital problems are the main causes of primary mitral regurgitation.
Secondary mitral regurgitation is a condition where the valve cannot close despite being normal due to enlargement or dysfunction of the left ventricle. This is usually caused by enlargement of the heart muscle (dilated cardiomyopathy), coronary artery disease (ischemic heart disease), or long-term hypertension.
The severity of mitral regurgitation is classified as mild, moderate, and severe based on the amount of blood that flows back. Mild mitral regurgitation is usually asymptomatic and does not require treatment. Moderate regurgitation may require medication in some cases. Severe mitral regurgitation is generally treated with surgery or percutaneous interventions. Untreated severe mitral regurgitation can lead to heart failure, cardiac arrhythmias, and pulmonary hypertension (high blood pressure in the pulmonary vessels).
What Causes Mitral Valve Disease?
Mitral valve disease can stem from various causes that affect the structure and function of the valve. The most common causes include rheumatic heart disease, mitral valve prolapse, infective endocarditis, coronary artery disease, congenital problems, and age-related wear and tear. These factors can disrupt the structure of the valve, leading to the development of stenosis or regurgitation.
Rheumatic heart disease is one of the most important causes of mitral valve disease, especially in developing countries. This condition arises from damage to the heart valves caused by rheumatic fever, which develops after a group A streptococcal infection. Defense substances (antibodies) formed during the infection damage heart tissue, causing inflammation, thickening, and adhesion of the valve leaflets. This condition can lead to mitral stenosis, regurgitation, or both over time.
Mitral valve prolapse is one of the most common causes of mitral regurgitation and is seen in approximately 2-3% of the general population. In this condition, the mitral valve leaflets bulge (sag) toward the left atrium during contraction. This condition is harmless in most people, but in some patients, severe mitral regurgitation can develop due to deterioration of the valve leaflets or rupture of the cord-like structures.
Infective endocarditis is the inflammation and damage caused by circulating bacteria settling on the heart valves. The risk is higher especially in people who already have valve disease or have undergone valve surgery. This inflammation can cause holes, tears, or damage to the valve leaflets, leading to mitral regurgitation.
Coronary artery disease, especially after a heart attack (myocardial infarction), can result in deterioration or rupture of the muscles that hold the valve (papillary muscles). This can lead to damage to the support structures of the mitral valve and secondary mitral regurgitation. Additionally, left ventricular enlargement due to heart failure can lead to enlargement of the ring to which the valve is attached (mitral annulus) and regurgitation.
Congenital problems are abnormalities present in the mitral valve structure at birth. Abnormal development of the valve leaflets, disorders of the muscles and cord-like structures that hold the valve, or enlargement of the valve ring are examples of congenital mitral valve diseases. Additionally, calcification and stiffening of the valve leaflets with aging can also cause age-related mitral valve disease.
What are the Symptoms of Mitral Valve Disease?
The symptoms of mitral valve disease vary depending on the type of the disease (stenosis or regurgitation), its severity, and the rate of progression. Mild cases generally do not show symptoms, but as the disease progresses, the heart’s pumping capacity is affected, and complaints begin. Symptoms of mitral stenosis and mitral regurgitation can differ.
Symptoms of mitral stenosis include shortness of breath, fatigue, palpitations, cough, and inability to exercise. Shortness of breath develops due to fluid accumulation in the lungs as blood backs up from the left atrium to the lungs. Shortness of breath, initially seen during exercise, can also be seen during rest as the disease progresses. Cough and expectoration can become more pronounced, especially at night. In mitral stenosis, rhythm disorders, especially atrial fibrillation, can often develop, leading to palpitations. As left atrial pressure increases, complaints such as cough and fatigue become more pronounced.
The most common symptoms in mitral regurgitation include shortness of breath, palpitations, fatigue, waking up at night unable to breathe, and swelling in the ankles (edema). Shortness of breath occurs due to blood flowing back from the left atrium to the left ventricle as a result of the heart’s reduced pumping power. Shortness of breath, initially felt only during exercise, can also be experienced during moments of rest as the disease progresses. Fatigue results from the heart’s inability to pump enough blood to the body. Palpitations are seen with the irregularity of the heart rhythm, especially in cases of atrial fibrillation. Swelling in the ankles and legs occurs due to fluid accumulation when heart failure develops.
In advanced stages, mitral regurgitation can also bring with it symptoms of heart failure. In this case, problems such as frequent urination at night, loss of appetite, and weight loss can be experienced.
How is Mitral Valve Disease Treated?
The treatment of mitral valve disease is determined based on the type and severity of the disease, the presence of symptoms, and the patient’s general health condition. Treatment methods include medication, surgery, and percutaneous interventions. The main goal of treatment is to reduce symptoms, prevent complications, and improve quality of life.
Patients with mild mitral valve disease who have no symptoms generally do not require treatment, but it is important that they are regularly monitored. These patients may be advised to use antibiotics before dental procedures and surgeries to reduce the risk of infective endocarditis. Additionally, healthy lifestyle changes (balanced diet, regular exercise, avoiding smoking and alcohol, reducing salt) are recommended.
Medication therapy is generally used to alleviate symptoms, reduce the burden on the heart, and prevent complications. In patients with mitral valve regurgitation, blood pressure-lowering medications (ACE inhibitors, ARBs, beta-blockers) can reduce the load on the left ventricle. In patients with heart failure, diuretics help eliminate excess fluid in the body. In cases where the heart beats irregularly (atrial fibrillation), rhythm-regulating medications and blood thinners can be used.
Surgery is generally the most effective treatment option for patients with mitral valve disease who have moderate to severe symptoms. The surgical approach can be repairing the valve (mitral valve repair) or replacing it (mitral valve replacement). Preserving and repairing the valve is preferred whenever possible, as this method yields better results and does not require blood-thinning therapy. However, if the valve structure is too deteriorated or repair is not possible, replacement can be done using mechanical or biological prosthetic valves.
Percutaneous interventions can be considered as an alternative, especially for patients with high surgical risk. Percutaneous mitral balloon valvuloplasty is a suitable option for patients with mitral stenosis. In this procedure, the narrowed valve is opened using a balloon catheter. For mitral regurgitation, percutaneous valve repair can be performed using devices such as MitraClip. In this procedure, the valve leaflets are joined together to try to reduce regurgitation.
The treatment decision should be personalized according to the patient’s condition and evaluated by a team. The patient’s age, other diseases, severity of symptoms, degree of valve disease, and heart functions are important factors in the treatment decision.
Patients with mitral valve disease should also be regularly monitored after treatment. Regular check-ups are important, especially in patients who have undergone valve repair or replacement, to check the functioning of the prosthetic valve, to adjust blood-thinning therapy, and for early diagnosis of possible problems. Additionally, good oral and dental health and the use of antibiotics before dental procedures and surgeries are recommended to reduce the risk of infective endocarditis.
Reference: Mitral Valve Disease
