Congenital Mitral Valve Anomalies

Congenital mitral valve anomalies are malformations of the valve between the two chambers on the left side of the heart that are present in an infant at birth. Luckily, these defects are generally not serious health issues.

Normal heart structure

The heart has four chambers: two smaller ones on top called the atrium and two larger ones on the bottom called the ventricles.

The four chambers work together to pump blood to the lungs and the rest of the body. Heart valves sit between each atrium and ventricle to keep blood flowing in the right direction through the heart.

The mitral valve has two cusps or flaps and is attached to a ring of tissue called the annulus, which is attached to chordae (strings) that connect to the heart muscle. The heart acts like this:

1. The left side of the heart accepts oxygenated blood from the lungs into the left artium.
2. The mitral valve opens between pumps to allow blood to enter the left ventricle.
3. The valve closes when the heart pumps to prevent blood from returning to the atrium.
4. The left ventricle pumps blood into the body.

The defects

Mitral valve anomalies occur when the valve between the left atrium and the left ventricle is too big, too tight, too loose, or has an unusual shape.

Mitral valve prolapse. In mitral valve prolapse, one or both valve cusps are too big or not shaped correctly, and the valve bulges backward into the atrium when closed. Often, mitral valve prolapse does not cause symptoms or does not become a problem until adulthood. Mitral valve prolapse can turn into mitral valve insufficiency.

Mitral valve insufficiency. In mitral valve insufficiency, the valve cusps are too loose; they don’t close tightly enough, may bulge backward (mitral valve prolapse), and allow blood to leak back into the atrium. Mitral valve insufficiency is also called mitral valve regurgitation.

Mitral valve stenosis. In mitral valve stenosis, the valve cusps are too tight, fused, or unable to open efficiently due to structural damage. Blood can't flow from the atrium into the ventricle easily, and the heart must work harder to pump blood out to the body. You can have both mitral valve stenosis and mitral valve regurgitation.

Mitral valve atresia. In mitral valve atresia, the valve is absent or has no opening.

Causes

Mitral valve abnormalities may be congenital heart defects, meaning the mitral valve does not form correctly while the baby is developing before birth.

Some issues that may occur include flaps that:

• Are too thick or stiff.
• Are deformed.
• Are fused.
• Are missing chords.
• Have chords that are too short or thick.
• Have chords that are attached to the heart muscle instead on the annulus.

Problems with the heart tissue or muscle near the valve or a double orifice valve (more than one opening where the mitral valve is) can also cause problems.

Mitral valve anomalies can appear alone or with other congenital heart defects.

Surgery on the mitral valve or inflammatory conditions such as endocarditis (infection in the heart) or rheumatic fever can also lead to mitral valve issues.

Symptoms

Symptoms can appear at any age, or not at all.

Infants with severe mitral valve defects may have cyanosis (bluish hue to the lips, nail beds, or skin) and difficulty breathing.

Less severe symptoms include:

• Cough.
• Fatigue.
• Transient chest pain/
• Dizziness or lightdeadedness.
• Irregular heartbeat (arrhythmia).
• Shortness of breath with exertion.
• Frequent respiratory and lungs infections.
• Heart palpitations (skipping beats or beating fast).

The heart valves closing is what creates the sound of your heartbeat, and a malformed valve can sometimes be heard through a stethoscope as a heart murmur, so this may be the first symptom that is detected.

Diagnosis

Your doctor will ask you about your symptoms, medical history, and family history and check your heart for a murmur.

If a heart defect is suspected, your doctor may order tests such as:

• A chest x-ray to see the heart's anatomy.
• En ECG (EKG) to assess the heart rhythm.
• An echocardiogram to see the heart's structure and the blood flow through the heart.
• A transesophageal echocardiogram if your doctor needs more information.

Treatment

Treatment for mitral valve anomalies depends on the severity of the defect and the symptoms.

You and your doctor may decide to only monitor the defect.

You may need blood pressure medication to reduce your heart’s workload or control a heart arrhythmia.

Usually, mitral valve defects do not affect everyday activities, and children can generally play sports if they do not have symptoms of mitral valve regurgitation.

For a stiff valve, balloon valvuloplasty may be an option. Your doctor will insert a catheter into your bloodstream, thread it into the heart and through the valve, open a balloon to stretch the stiff valve, and then remove the balloon and the catheter.

An infant may need surgery urgently, later in life, or not at all. Your doctor may want to perform surgery to:

• Patch holes.
• Reconnect cusps.
• Separate fused cusps.
• Reinforce or tighten the annulus ring.
• Reshape the heart muscle around the valve.
• Remove extra valve tissue to allow the cups to close tightly.
• Lengthen, shorten, disconnect, or replace the chords supporting the valve.

The valve may also need replacing at some point. Your doctor may recommend replacing the valve with a pig, cow, human, or mechanical valve. If a mechanical valve is the best option, you will need to be on medication to prevent blood clots for the rest of your life, and if you choose an organic valve (pig, cow, or human) you may need further surgeries to repair it.

Talk to your doctor about which treatment is right for you or your child.