Bicuspid Aortic Valve

Definition

Definition of Bicuspid Aortic Valve
A bicuspid aortic valve (BAV) is most commonly a congenital condition of the aortic valve where two of the aortic valvular leaflets fuse during development resulting in a valve that is bicuspid instead of the normal tricuspid configuration. Normally the only cardiac valve that is bicuspid is the mitral valve (bicuspid valve) which is situated between the left atrium and left ventricle. Cardiac valves play a crucial role in ensuring the unidirectional flow of blood from the atrium to the ventricles, or the ventricle to the aorta or pulmonary trunk.

Symptoms

Symptoms of Bicuspid Aortic Valve
Although bicuspid aortic valve disease is present at birth, it usually is not diagnosed until adulthood because the defective valve can function for years without causing symptoms. Rarely, the disease is so severe at birth that the baby develops congestive heart failure early in life. More commonly, patients will have a history of having a childhood murmur and symptoms develop in mid-life as the valve ages.

Calcium deposits on and around the leaflets eventually cause the valve to stiffen and narrow, a condition known as stenosis. As stenosis develops, the heart must pump increasingly harder to force the blood through the valve. Symptoms of a stenotic valve include chest pain, shortness of breath and dizziness or fainting caused by inadequate blood flow to the brain.

If the bicuspid valve does not close completely, blood can flow backwards into the heart. This is regurgitation, also called aortic valve insufficiency. The heart then must pump that same blood out again, causing strain on the heart’s lower left chamber, the left ventricle. Over time, the ventricle will dilate, or over-expand. The main symptom of aortic valve regurgitation is shortness of breath during exertion, like walking up stairs.

As the disease progresses, these symptoms start occurring more frequently, even without exercise. When a physician listens to the person's heart, characteristicmurmurs can be heard.

Causes

Causes of Bicuspid Aortic Valve
The actual cause of bicuspid aortic valve disease is not completely clear. We do know that the two-leaflet valve develops in the early stages of pregnancy, and the defect is present at birth. About 2% of the population has BAVD, and it is twice as common in males as in females.

Diagnosis

Diagnosis of Bicuspid Aortic Valve
The condition can be associated with a heart murmur located at the right second intercostal space. Often there will be differences in blood pressures between upper and lower extremities. The diagnosis can be assisted with echocardiography (EchoCG) or magnetic resonance imaging (MRI).

Treatment

Treatment of Bicuspid Aortic Valve
In the most severe cases, when symptoms are present at birth or in early infancy, surgical repair of the valve must be performed immediately. In other cases, people can go their whole lives without knowing they have BAVD.

About 80 percent of people with BAVD will require surgical treatment to repair or replace the valve and part of the aorta, usually when they are in their 30s or 40s. Cleveland Clinic specialists can determine the best time to do the surgical repair and whether multiple repairs to the valve and aorta can be done at the same time if needed. As of December 2008, they have operated on 3,700 patients with BAVD, the largest experience in the world in treating this disease.

For the patient who has stenosis and symptoms, the preferred treatment is to replace the valve with a mechanical or biological valve. The mortality rate for this procedure at Cleveland Clinic is less than 1%.

When regurgitation is present, the aortic valve can be repaired successfully. Cleveland Clinic is one of only a handful of centers in the world to repair bicuspid aortic valves, and 91% of patients who undergo the procedure here do not need another valve operation for at least 10 years. After repair, if failure does occur, it will take place in the first year to 18 months after surgery - but thereafter the risks of re-operation are low. However, because the valve is abnormal,it is likely that it will need to be replaced after a few decades.

An aorta that is enlarged and forming an aneurysm can be repaired, but at Cleveland Clinic we more often replace the damaged section with a section of plastic tubing that is sewn into position. The timing for repair of an aortic aneurysm is critical. When the valve is faulty and the aorta has enlarged to greater than 4.5 cm, we repair the aorta at the same time we repair or replace the valve. If the aorta has enlarged but the valve is still good, the optimal time to repair the aorta varies. At Cleveland Clinic, we have developed a special mathematical formula we use to determine this, based on the patient’s height and weight and the size of the aorta - surgery is usually recommended when the aortic cross sectional area in square centimeters, divided by the patient's height in meters is more than 10.

Prognosis

Prognosis of Bicuspid Aortic Valve
How well the baby does depends on whether complications of bicuspid aortic valve are present, and how severe they are.

The presence of other physical problems at birth also can affect how well a baby does.

Most babies with this condition have no symptoms, and the problem is not diagnosed until they are adults. Some people never find out that they have this problem.

Prevention

Prevention of Bicuspid Aortic Valve
Bicuspid aortic valves run in families. If you know of this condition in your family, speak to your health care provider before becoming pregnant. There is no known way to prevent the condition.