What is mitral valve insufficiency?
Heart valves are door-like structures that allow blood to pass in only one direction. They open with the driving force of blood flow and close when the driving force of the blood decreases. In this way, they prevent the backflow of blood. The mitral valve is one of the four valves in the heart. It is located between the two chambers on the left side of the heart. It separates the left atrium from the left ventricle. When the mitral valve cannot close completely, blood leaks back into the chamber it came from, namely the left atrium. The leaking blood is then not delivered to the body. This leakage is called “mitral valve regurgitation” or simply “mitral regurgitation.” Insufficiency or leakage can also be used instead of regurgitation; these are synonyms. Mitral valve regurgitation is the most common valve disease.
How many types of mitral valve insufficiency are there?
Mitral valve regurgitation is divided into two types based on the cause of the leak and the mechanism of its formation. This classification is significant in terms of treatment selection:
- Primary (degenerative) mitral valve regurgitation: The problem lies within the mitral valve itself. Examples: Rheumatic mitral valve, mitral valve prolapse…
- Secondary (functional) mitral valve regurgitation: The valve is actually intact, but there is a problem with the heart tissue to which the valve is attached. The valve leaks blood because it lacks adequate support. Examples: Tethering of the valve due to heart attack damage, enlargement of the left ventricle due to heart failure, or enlargement of the left atrium due to a heart rhythm disorder.
What are the causes of mitral valve regurgitation?
- Mitral valve prolapse (MVP; mitral valve collapse): In the case of mitral valve prolapse, one or both of the mitral valve leaflets bulge toward the left atrium each time the heart contracts. This may prevent the mitral valve from closing tightly and cause blood to leak backward. Sometimes the cause of the bulging is the leaflets themselves being soft (myxomatous), while sometimes it is the thin strands (chordae) holding the leaflets that are soft. Spontaneous rupture of these strands can also cause leakage. All of these are of genetic origin. However, it may take many years for them to progress and cause problems.
- Congenital: Defective valves are present from birth.
- Age-related calcification: In some people, calcification may be more than expected, hardening the valve and preventing it from closing properly.
- Damage caused by infection: Bacterial infections can damage the heart valves either directly (infective endocarditis) or indirectly, as in the disease called rheumatic fever. Rheumatic mitral valve regurgitation appears years after pharyngitis or tonsillitis experienced in childhood and is almost always accompanied by mitral valve stenosis.
- Heart attack: If damage develops in the areas of the heart muscle holding the mitral valve due to a heart attack, leakage may develop as the valve’s support decreases. If the damage resulting from a heart attack is large, it can cause sudden and severe leakage. Leakage can also develop gradually over time.
- Genetic diseases of the heart muscle: The mitral valve is ultimately a structure attached to the heart muscles. Disorders in the heart muscle (for example, hypertrophic cardiomyopathy) naturally affect the valve as well.
- Radiation therapy: Rarely, radiation therapy (radiotherapy) applied for cancers in the chest area affects the valve and impairs its structure. Often, the deterioration in the valve becomes apparent 15-20 years later.
- Atrial fibrillation: In this type of rhythm disorder, the mitral annulus to which the mitral valve is attached dilates, the valve tips move away from each other, and leakage develops. Conversely, atrial fibrillation (AF) can develop when the left atrium enlarges in someone who already has mitral regurgitation. That is, mitral regurgitation can cause atrial fibrillation; and atrial fibrillation can cause mitral regurgitation.
- Heart failure: If heart failure develops for any reason and the left ventricle enlarges, the mitral annulus dilates, the valve tips move away from each other, and leakage develops. This is one of the most common types of mitral regurgitation. As mitral regurgitation progresses, heart failure also progresses, creating a vicious cycle. That is, advanced (primary) mitral valve regurgitation can cause heart failure, just as heart failure developed due to another reason can subsequently cause (secondary) mitral valve regurgitation. In some types of heart failure, left bundle branch block developing in the heart’s electrical conduction system disrupts the simultaneous contraction of the heart’s right and left walls. This is a different mechanism that leads to the development of mitral regurgitation. In this case, the implantation of pacemakers called CRT can correct mitral regurgitation by ensuring the simultaneous operation of the heart walls.
What are the stages of mitral valve insufficiency?
- We know that even under a sturdy and properly functioning room door, there is a small amount of air passage, and this is normal. By the same logic, it is normal to have a very tiny leak even if there is no problem with the mitral valve. This trace amount of leakage present in most people is called a physiological leak. A physiological leak does not cause any symptoms. Instead of physiological, the words trace and minimal can also be used. Since they are not indicators of disease—meaning they are considered completely normal—these terms are usually not written in the “conclusion” section of an echo report to avoid unnecessary anxiety. In summary: Physiological = Trace = Minimal
- Abnormal (pathological) leaks are divided into three grades according to the amount of leaking blood: Mild, moderate, and severe. Most doctors prefer to further divide the moderate grade into mild-to-moderate and moderate-to-severe. Instead of severe, the words advanced or critical can also be used. Alternatively, numerical grading from 1 to 4 can be performed in increasing order of severity. However, numerical classification is not a widely preferred method today. In summary: Grade 1 = Mild, Grade 2 = Mild-to-moderate, Grade 3 = Moderate-to-severe, Grade 4 = Severe = Advanced = Critical
What are the symptoms of mitral valve regurgitation?
Mild and moderate regurgitation does not cause any symptoms and does not require treatment. However, if more than half of the incoming blood flows back, it is clear that the condition has reached an advanced stage. When severe mitral valve insufficiency develops, the amount of blood pumped to the body decreases significantly. As a result, the heart has to work harder, leading to shortness of breath, fatigue, palpitations, or swelling in the legs. In the most advanced stage, it causes heart failure. Quality of life is impaired, and even performing daily routine activities becomes difficult.
How is mitral valve regurgitation diagnosed?
- ECHO (Echocardiography; heart ultrasound): ECHO is the most important test used in the diagnosis of valve diseases. With this device, which works via sound waves, images of the heart are obtained, and it can easily be determined whether there is a leak in the valve. Sometimes, to obtain clearer images, an ECHO (transesophageal echocardiography; TEE) performed through the esophagus may be required.
- ECG (Electrocardiography): ECG measures the electrical activity of the heart. It is used to detect heart rhythm problems related to mitral regurgitation.
- Chest X-ray: It shows the status of the heart and lungs. Although it can indicate that the heart is enlarged, it is not a direct diagnostic test.
- MRI (Magnetic Resonance Imaging): It is a highly effective diagnostic method used when a diagnosis cannot be made with ECHO.
- Cardiac catheterization: Another method used when a diagnosis cannot be made with ECHO. It is similar to heart angiography.
Is mitral valve insufficiency dangerous?
Mild or moderate mitral valve regurgitation does not require treatment; it is sufficient to remain under a doctor’s supervision with ECHO performed at regular intervals. In some cases, the degree of regurgitation may progress over time, though in most cases it does not. However, if severe mitral valve regurgitation has developed and is left untreated, atrial fibrillation (a serious heart rhythm disorder), pulmoner hypertension (high blood pressure in the lung arteries), and heart failure may develop, which can ultimately lead to death.
Does the mitral valve regenerate?
Unfortunately, the mitral valve cannot regenerate itself.
How is mitral valve insufficiency treated?
As mentioned above, only severe mitral valve regurgitation requires treatment. Since the cause and mechanism of the leak are different for each of these patients, the treatments also vary. In treatment, either valve surgery is performed or non-surgical methods are applied. In surgery, the valve is repaired if possible. However, repair is not suitable in every case, or the physician may not have sufficient experience in this regard. In such cases, the mitral valve is replaced with an artificial valve. Non-surgical methods are applied to patients who are too high-risk for surgery. The most frequently performed of these is reducing the mitral valve leak by placing a clip (MitraClip / Pascal).
Prof. Dr. Şükrü Akyüz is an interventional cardiologist. His area of expertise is the treatment of heart diseases using non-surgical methods. The clip method is included in these treatments.
What medications are used to treat mitral valve regurgitation?
Medications are used to alleviate the patient’s symptoms rather than to treat the valve itself, and to treat additional conditions that could potentially damage the valve.
- Diuretics: These are heart medications that help remove excess fluid—which causes swelling in the lungs or other parts of the body, particularly the legs—and excrete it through urine.
- Blood thinners: If atrial fibrillation (AF) develops due to mitral valve disease, you may need to take blood thinners to prevent blood clots. These medications significantly reduce the risk of stroke.
- High blood pressure medications: High blood pressure (hypertension) increases the load on the mitral valve, leading to even more severe regurgitation. Keeping high blood pressure under control can reduce the amount of regurgitation.
- Heart rhythm medications: Mitral regurgitation can cause irregular heart rhythms, or conversely, irregular heart rhythms can cause mitral regurgitation. In other words, the two can trigger each other. Correcting the rhythm—or at least controlling a high heart rate—can reduce the amount of regurgitation.
It is very important to control the patient’s blood pressure and heart rate with medication. For example, a leak that was thought to be severe on an echocardiogram performed while blood pressure was high or the heart rhythm was irregular may actually be found to be moderate on a subsequent echocardiogram after blood pressure has been normalized and the rhythm controlled. This helps prevent unnecessary early heart surgery.
References
- Otto CM, Nishimura RA, Bonow RO, et al. ACC/AHA Guideline for the management of patients with valvular heart disease. J Am Coll Cardiol. 2021 Feb 2;77(4):e25-e197.
- Vahanian A, Beyersdorf F, Praz F, et al. ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2022;43(7):561-632.
- Sorajja, Sato H, Bapat VN, et al. Contemporary anatomic criteria and clinical outcomes with transcatheter mitral repair. Circ Cardiovasc Interv. 2023;16:e012486.
- Libby P, Bonow RO, and Mann DL, eds. Braunwald’s heart disease: A textbook of cardiovascular medicine, 12th ed. Philadelphia PA: Elsevier; 2022.