Bicuspid Aortic Valve Disease
What is bicuspid aortic valve disease?
The aortic valve is a one-way valve between the heart and the aorta, the main artery from the heart that distributes oxygen-rich blood to the body. Normally, the aortic valve has three small flaps or leaflets that open widely and close securely to regulate blood flow, allowing blood to flow from the heart to the aorta and preventing blood from flowing backwards into the heart.
In bicuspid aortic valve disease (BAVD), the valve has only two leaflets. With this deformity, the valve doesn’t function perfectly, but it may function adequately for years without causing symptoms or obvious signs of a problem.
The latest studies suggest that bicuspid aortic valve disease is caused by a connective tissue disorder that also causes other circulatory system problems. People with bicuspid aortic valve disease also may have abnormal coronary arteries, aortic aneurysm or an abnormal thoracic aorta (the portion of the aorta that passes through the upper chest) and unstable (labile) high blood pressure.
What are the symptoms and signs of BAVD?
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, characteristic murmurs can be heard.
What causes bicuspid aortic valve disease?
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.