Bicuspid Aortic Valve
An aortic valve that has two leaflets instead of the usual three is called a bicuspid aortic valve. It is the most common congenital heart defect, meaning it is present at birth, but symptoms may develop in late childhood or during adulthood.
The heart is made up of four chambers and four valves, which control the flow of blood into the heart, between its chambers, and out of the heart to the rest of the body. One of the valves, known as the aortic valve, regulates the flow of oxygen-rich blood from the heart’s left ventricle to the aorta, a large artery that transports the blood to organs and tissue around the body.
Normally, the aortic valve contains three leaflets that open to allow blood to flow out of the heart and close to prevent blood from flowing backward into the heart. But a bicuspid aortic valve results from the fusion of two of the leaflets.
Between 1 and 2% of babies are born with a bicuspid aortic valve. The condition is two to three times more common in males than females. While bicuspid aortic valves often work normally during childhood and adolescence, they may lead to symptoms later in life. These may include chest pain, shortness of breath, and fainting, among other symptoms. They can also cause serious complications. Fortunately, effective treatments are available.
What is a bicuspid aortic valve?
As blood flows through a normal aortic valve, it exerts pressure on the valve’s three leaflets. But when blood flows through a bicuspid aortic valve, that stress is distributed across only two leaflets, which, over time, can lead to their deterioration. Blood flow into the aorta is also disturbed, which may damage its walls.
People with bicuspid aortic valves may develop the following complications:
- Aortic stenosis, a condition in which the aortic valve narrows, reducing the amount of blood that flows from the heart to the aorta and the rest of the body. Because the heart needs to work harder than normal to pump enough blood to meet the body’s needs, the condition can lead to higher stress on the pumping chamber, a muscle that can fail over time, resulting in heart failure.
- Aortic regurgitation, a condition in which the aortic valve doesn’t close properly, allowing blood to flow backwards into the heart. As with aortic stenosis, people with aortic regurgitation are at risk for heart failure because the heart has to work harder to keep up with the body’s needs.
- Dilation of the aortic root or ascending aorta. The aortic root is the part of the aorta immediately after the aortic valve that connects to the heart; the ascending aorta is the segment beyond the aortic root that moves upward, toward the head. In people with bicuspid aortic valves, these parts of the aorta may become dilated, or enlarged, which can lead to an aortic aneurysm. A dilated aorta or aneurysm is at increased risk of dissection (when the inner wall of the aorta tears) or rupture (when the aorta bursts open), both of which are life-threatening conditions.
- Infective endocarditis, a condition in which the membrane that lines the chambers of the heart and heart valves becomes inflamed, usually due to a bacterial or fungal infection. Infective endocarditis can cause damage to the aortic valve, impair blood flow and lead to heart failure and other heart problems.
What causes a bicuspid aortic valve?
A bicuspid aortic valve is a congenital condition, meaning it is present at birth. As a fetus develops, two of the leaflets of the aortic valve fuse together.
Genetic factors often play an important role. The condition is more prevalent among first-degree relatives of people with bicuspid aortic valves, and mutations in several genes have been associated with the condition.
Other conditions are also associated with bicuspid aortic valves, including:
- Coarctation of the aorta (narrowing of the aorta)
- Marfan syndrome
- Ehlers-Danlos syndrome
- Loeys-Dietz syndrome
- Turner syndrome
- Williams syndrome
- Shone complex
- Supravalvular aortic stenosis
- Ventricular septal defect
- Sinus of Valsalva aneurysm
The condition can also occur sporadically, meaning it can affect people who don’t have a family history of the disease or other conditions associated with it.
What are the symptoms of a bicuspid aortic valve?
People who have a bicuspid aortic valve often don’t have any symptoms. When symptoms are present, they may include:
- Chest pain
- Shortness of breath
- Heart palpitations
- Reduced ability to perform physical activities and exercise
How is a bicuspid aortic valve diagnosed?
To diagnose a bicuspid aortic valve, your doctor will collect and review your medical history, perform a physical exam, and order one or more imaging tests.
Your doctor will ask you about your symptoms, whether you have a family history of bicuspid aortic valve disease, and if you have other medical conditions associated with a bicuspid aortic valve. During the physical exam, your doctor will use a stethoscope to listen to your heart. A bicuspid aortic valve may produce a murmur or “clicking” sound as blood passes through it.
Imaging tests, such as an ultrasound of the heart or a transthoracic echocardiogram (TTE), are necessary to confirm the diagnosis. The latter test uses sound waves to produce an image of the heart. Other imaging tests may include a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of the heart. In some cases, your doctor may order a CT angiogram or aortic magnetic resonance angiogram, both of which show blood flow through the heart and blood vessels.
Because bicuspid aortic valves often don’t cause symptoms, they are frequently diagnosed incidentally, when doctors order imaging tests for other heart problems. They are frequently diagnosed in children presenting with a murmur and sometimes can be diagnosed in a fetus on a prenatal ultrasound or fetal echocardiogram.
How is a bicuspid aortic valve treated?
Treatment for bicuspid aortic valves may include:
- Surveillance. If a bicuspid aortic valve is working well, isn’t causing any symptoms, and doesn’t show signs of complications, treatment isn’t necessary. In these cases, patients are closely followed by their heart doctors (cardiologists) who typically monitor the condition using regular echocardiograms, sometimes with additional imaging tests such as MRI or CT scans.
- Medications. For people with high blood pressure, medications that help lower blood pressure are typically part of treatment.
- Exercise and physical activity. People who have a well-functioning bicuspid aortic valve can safely exercise and participate in physical activities, including high-intensity sports. If a patient has a dilated, or enlarged, aorta, they may need to limit or avoid participation in certain types of sports and physical activities such as weight lifting. Your cardiologist will modify their recommendations at every visit based on the echocardiograms.
- For people with a poorly functioning bicuspid aortic valve who do not also have a widening of the aorta, surgery may be needed to repair or replace the bicuspid aortic valve. The valve may be replaced with an artificial one, made of manmade materials or a tissue valve taken from a deceased animal or human donor. In some cases, surgeons may perform a Ross procedure, a surgery in which the bicuspid aortic valve is replaced with their own pulmonary valve.
- For people with a dilated aorta but whose aortic valve is functioning well, a surgeon may repair the aorta and leave the aortic valve in place. This is called a valve-sparing aortic root surgery.
- For people with a poorly functioning bicuspid aortic valve and dilated aorta, surgery may be necessary repair or replace the aortic valve and repair the aorta.
- Balloon valvuloplasty. This procedure may be used to treat people with aortic stenosis. A doctor inserts a catheter (a thin, flexible tube) with a balloon on its tip into a blood vessel (usually in the groin) and guides it to the aortic valve. Once it’s in place, the balloon is inflated, then deflated and removed. This procedure widens the narrowed valve, allowing more blood to flow from the heart to the aorta. Valvuloplasty is often used to treat bicuspid aortic valves in children and adolescents.
- Transcatheter aortic valve replacement (TAVR). TAVR may be an option for people with aortic stenosis. It’s a minimally invasive procedure in which a surgeon replaces the poorly functioning bicuspid aortic valve with a prosthetic one.
What is the prognosis for people with a bicuspid aortic valve?
Bicuspid aortic valves often don’t cause any symptoms in children and adolescents. Over time, however, valves may narrow, impairing blood flow into the aorta and to the rest of the body, or it may become leaky, allowing blood to flow back into the heart. People with bicuspid aortic valves are also at increased risk for dilation or enlargement of the aorta. These complications can be life-threatening and should be treated and monitored by a heart specialist.
The outcome for people with a bicuspid aortic valve can vary greatly depending on whether complications develop, as well as their severity. Some people with the condition never develop symptoms, while others develop serious complications. With treatment, the prognosis for people with bicuspid aortic valves is good and life expectancy is similar to that of the general population.
What makes Yale Medicine unique in its approach to bicuspid aortic valves?
“Yale Medicine offers a multifaceted approach with a wide range of programs to care for patients with bicuspid aortic valves across all age groups,” says Yale Medicine pediatric cardiologist Ruchika Karnik, MBBS. “The youngest patients receive excellent care through the services of the Children’s Heart Center with pediatric cardiologists, interventional cardiologists, a cardio-genetics program, and congenital cardiac surgeons. The Adult Congenital Heart Program offers these patients a smooth transition into adulthood with lifelong care, and the Yale Aortic Institute brings in world-class and highly experienced cardiac surgeons to perform complex aortic surgeries along with a multidisciplinary team of cardiologists, anesthesiologists, cardiac nurses, and advanced practitioners.”