What Is Mitral Valve Disease?

Overview

The heart consists of four chambers, two atria (upper chambers) and two ventricles (lower chambers), and four valves: the tricuspid, pulmonary, mitral, and aortic valve. The valves guard the chambers to stop the backward flow of blood. Mitral valve disease is a condition affecting the valve located between the two left heart chambers (left atrium and left ventricle). These two chambers of the heart contain oxygen-rich blood from the lungs and pump the blood towards the rest of the body. The normal function of the mitral valve is to let the blood flow from the left atrium to the left ventricle, but not back up from the ventricle to the atrium. The valve has very small flaps of skin called leaflets, that open and close, like doors, with every heartbeat.

When the mitral valve becomes diseased or damaged it affects the normal function of the valve. Mild damage may cause no symptoms, but severe damage can harm the heart over time and lead to heart failure. 

Types of mitral valve disease

There are three types of mitral valve disease: 

• Mitral valve stenosis - the valve between the two left chambers becomes narrowed and it reduces or blocks the flow of blood from the atrium to the ventricle⁵
• Mitral valve prolapse - also known as Barlow syndrome, where the flaps (called leaflets or cusps) of the mitral valve become stretched or enlarged. These enlarged flaps bulge or prolapse into the left atrium as the heart contracts during each heartbeat⁴ 
• Mitral valve regurgitation - also known as mitral insufficiency, the flaps do not close properly and cause the blood to flow back up from the ventricle to the atrium²

Causes of mitral valve disease

There are many conditions that can cause mitral valve disease: 

• Congenital heart defect - congenital heart disease is a condition where a heart defect occurs in the womb before the baby is born. In this condition, the valves may not be formed properly, or there may be holes between the chambers of the heart. In many cases, it is a minor defect that does not need treatment however, in some conditions medication or heart surgery may be needed.
• Connective tissue disorders - connective tissue is made up of two different proteins known as collagen and elastin. Collagen is found in ligaments, skin, tendons, cartilage, bone, and blood vessels. Elastin is found in ligaments and the skin. When these connective tissues are affected, it affects the surrounding areas of the body. This is known as a connective tissue disorder. There are different types of connective tissue disorders, including Marfan syndrome and Ehlers-Danlos syndrome.
• Endocarditis - a high-risk, fatal inflammation of the lining of the heart valves and chambers. This is caused when infection or germs reach the bloodstream and attack the lining of the heart. Endocarditis is also known as bacterial endocarditis or chronic bacterial endocarditis.
• Cardiomegaly - a condition where the heart is enlarged more than its usual size.  It is caused when the heart is forced to use more strain to circulate the blood, causing it to increase its size to produce enough force

Signs and symptoms of mitral valve disease

The symptoms of mitral valve disease depend on which type of defect has occurred. In many cases, symptoms only occur in severe forms of the disease. Some of the symptoms include: 

• Chest pain 
• Cough
• Coughing up blood 
• Dizziness or fainting
• Fatigue
• Heart palpitation 
• Migraine 
• Mitral facies (malar flush) - an abnormal flushing of the cheeks that occurs in severe mitral valve stenosis, causing low blood flow from the heart.
• Orthostatic hypotension (postural hypotension) - a condition where there is a sudden drop in blood pressure when standing up from a sitting or lying position.
• Shortness of breath 
• Swelling of the leg

Management and treatment for mitral valve disease

Mitral valve disease treatment depends on the severity and type of the condition. Initial treatment includes monitoring and regular follow-up of the condition. This could include following a healthy lifestyle and taking medications such as diuretics, beta-blockers, or blood thinners to reduce the risk of blood clots. There are several interventions available depending on the cause of the disease. These may include:  

• Balloon valvotomy - A catheter with a balloon attached at the end, is inserted in the blood vessels in the groin region and directed into the heart chambers. The cardiologist makes an incision in the wall between the upper chambers of the heart to view the left atrium. The catheter with the balloon is positioned inside the narrowed valve and is inflated and deflated several times to widen the valve opening. The catheter is removed after the valve is widened enough. The cardiologist may perform an echocardiogram to get a better picture of the mitral valve.
• Mitral valve clip - A catheter with a clip at the end is entered through an artery in the groin area and passed through to the mitral valve. The clip helps to fix the torn or leaky area of the mitral valve leaflet. This procedure is done in a severe case of mitral valve regurgitation or in someone whose body cannot withstand open heart surgery.

In certain cases, a more serious surgical intervention is necessary. This may include:

Mitral valve repair

An open heart surgery where anaesthesia is given so the patient will be in deep sleep during the procedure. The patient is connected to a cardiopulmonary bypass machine which works for the heart and the lungs during the surgery so that the heart can be temporarily and safely stopped. The surgeon makes an incision down the middle of the chest (full sternotomy), and small incisions in different points between the ribs. Some different techniques used for mitral valve repair include:

• Annuloplasty - The surgeon inserts an annuloplasty ring around the valve, which  acts like a washer that supports the valve and helps to return it to normal shape. The ring may be flexible or rigid, and it helps the repair to last a long time.
• Triangular or quadrangular resection -This technique is used mostly in cases of posterior leaflet prolapse. The surgeon removes the damaged parts of the leaflet and sews the remaining edges together.
• Chordal repair -This method is used to repair the anterior leaflet prolapse. The surgeon removes the ruptured or elongated chords, which are tough, fibrous strings that support the mitral valve. They create and attach new chords. In some cases, the surgeon creates new chords out of tough, synthetic material, or surgeons may take healthy chords from another area and replace them with the damaged ones. This is called chordal transportation, or chordal transfer.
• Mitral valve replacement - the cardiologist will give the person anaesthesia so the patient will be asleep throughout the surgery. The person will be connected to a cardiopulmonary bypass machine which will work for the heart and lungs, as the heart will be temporarily and safely stopped during the surgery. There are two types of replacement valves, mechanical valves made of carbon and steel, and biological (bioprosthetic) valves which are made with tissues from pigs, cows, and rarely humans.

The surgeon makes the incision in the chest in the left atrium to reach the mitral valve. They will preserve all the healthy tissue, remove the damaged tissue, and sew the new valve in place. They will make sure that the valve leaflet can move freely and they will sew the left atrium.^1,6

Diagnosis

Diagnosis includes a physical examination, where the doctor can hear any heart murmurs using a stethoscope, which is a sign of mitral valve disease.

Additional tests may include: 

• Echocardiogram - sound waves are used to produce video images of the heart in motion
• Electrocardiogram (ECG) - can detect enlarged chambers of the heart, irregular rhythm, and heart disease, using the electrical signals from the heart
• Chest X-ray - can show the enlargement of the heart and the condition of the lungs
• Exercise or stress test - involves walking on a treadmill while the heart is monitored, to show how the heart responds to physical activity and whether any valve disease symptoms occurred
• Cardiac catheterization - a catheter is inserted through a blood vessel in the arm or groin and passed to the heart. A dye is injected, so that the arteries are clearly shown in the X-ray

Risk factors

• Older age - with age, calcium deposits slowly build up on the heart valves, meaning that they do not work as well
• Rheumatic fever - if untreated, this may lead to heart valve damage
• Using certain medicines or usage of drugs
• Radiation therapy - people who are exposed to radiation to the chest have a higher risk of valve damage

Complications

There are several complications that are associated with mitral valve disease. These complications include: 

• Atrial fibrillation - irregular and rapid increase of heart rate
• Pulmonary hypertension - high blood pressure in the blood vessels of the lungs
• Heart failure - heart failure where the heart muscle doesn’t pump enough blood
• Stroke - a life-threatening condition where the blood supply to the brain is cut off

FAQs

How can I prevent mitral valve disease?

In many cases, mitral valve disease cannot be prevented, but you can reduce your risk by maintaining a healthy diet, scheduling regular check-ups, taking medications to address related conditions, and avoiding the use of tobacco, alcohol, and other drugs. 

How common is mitral valve disease?

Mitral valve disease can affect people of all ages. Mitral valve prolapse is more common in people assigned female at birth (AFAB).

What can I expect if I have mitral valve disease?

If left untreated, mitral valve disease can cause atrial fibrillation (irregular and rapid increase of heartbeat), an increase in blood pressure in the lungs, and can lead to heart failure.

When should I see a doctor?

During the early onset of symptoms, it is advised to consult a doctor for prompt diagnosis and treatment to avoid further complications.

Summary

Mitral valve disease is a condition in which the valve located between the left heart chambers (left atrium and left ventricle) is damaged or does not function properly. These two chambers of the heart contain oxygen-rich blood from the lungs and pump it towards the rest of the body. The normal functioning of the mitral valve is to let the blood flow from the left atrium to the left ventricle and prevent backflow between the two. When the mitral valve becomes diseased or damaged, it affects the normal function of the valve. Mild damage may cause no symptoms, but severe damage can harm your heart over time and lead to serious problems like heart failure.