Bicuspid Aortic Foundation's Overview of Bicuspid Aortic Valve Disease

What is Bicuspid Aortic Valve Disease (BAVD)?

Bicuspid aortic valve disease is more than a bicuspid aortic valve.

This condition gets its name from the bicuspid aortic valve, which is the most common congenital abnormality of the heart. The bicuspid aortic valve is an important marker of this disease and might be what is first noticed. However, more than the aortic valve is involved. To indicate this, sometimes the term bicuspid aortic disease is used.

Current clinical and scientific studies are revealing that bicuspid aortic valve disease is not a simple valve condition. It increasingly appears to be a genetically based connective tissue disorder. An inclusive definition, listing the major areas of the body possibly affected, is needed. Not everything is understood today, but enough is known to identify several major characteristics of this condition.

BAVD includes the following:

• Bicuspid aortic valve
• Thoracic aortic dilation, aneurysm, or dissection
• Labile hypertension (high blood pressure which changes quickly with stress or exercise)

It may also include:

• Mitral valve leakage
• Coarctation of the aorta
• Kidney or liver cysts
• Near-sighted vision
• Musculoskeletal degenerative changes (scoliosis, degenerative spinal discs, flexible joints, flat feet, etc.)
• Aneurysm of smaller arteries, including head vessels (berry aneurysms)

Not everyone has all of the listed characteristics. However, those diagnosed with a bicuspid aortic valve, who may have wondered why they also have high blood pressure, a leaking mitral valve, or poor eye sight, will recognize themselves in the definition above.

BAVD does not simply mean that some day, when you are older, you may need aortic valve surgery.

In many people, BAVD is not just an abnormally shaped aortic valve that may some day, when they are older, need to be repaired or replaced. A broader description is needed to include those who:
• require aortic valve treatment in infancy, childhood, or as young adults.
• develop an aortic aneurysm.
• develop an aortic aneurysm after their bicuspid aortic valves have been replaced.
• experience dissection of their ascending aorta.
• have mitral valve failure.

The challenge for those who have BAVD is to understand what it means to them individually.

BAVD is different in different people, but there are some patterns.

Bicuspid aortic valve disease is not a uniform condition. It is different in different people. Among those with bicuspid aortic valve disease there are some sub-groups that are beginning to emerge.

• One group includes those who are younger, (in their 20's or 30's), and have aortic valve insufficiency (leakage) and an ascending aortic aneurysm. It appears that this group has more fragile tissue in the heart valves, aorta, and possibly other arteries.

• Another group are those, ranging in age from about 40 to 60, who develop aortic valve calcification and stenosis (narrowing).

• Many develop consistently high blood pressure or high blood pressure that rises and falls quickly (labile hypertension), while a very few have normal blood pressure.

• When more studies and research are done, it should be possible to sort out all of the variations of bicuspid aortic disease.

Not everything is understood about BAVD, but some of the most dangerous sides of it are known.

While not everything is understood about bicuspid aortic disease, some of the most dangerous aspects of it are known. This disease can present the greatest threat to life due to abnormalities that are seen in the heart valves and the aorta.

• As with any heart valve condition, it is important to obtain expert medical care for a bicuspid aortic valve. However, focusing on the aortic valve alone is not enough.

• Ignoring other potential affects of this disease can be dangerous. Aortic aneurysm and dissection are serious, life-threatening conditions.

• It is not safe to think that if the bicuspid aortic valve has been removed, repaired, or continues to work well that everything is all right, because there is still a risk of aortic aneurysm and/or dissection.

The Heart and its Valves

Bicuspid Aortic Valve

The bicuspid aortic valve (BAV) may seem to be a very simple birth defect of the heart. Perhaps this is because it frequently does not require surgical treatment early in life. There is no real way to predict if or when a bicuspid aortic valve will fail due to stenosis and/or aortic insufficiency. A bicuspid aortic valve may develop problems at different stages of life, including infancy. Some bicuspid valves may continue to work well for an entire lifetime, but most will require treatment at some point.

The valves of the heart are like gates. They open and close to direct the flow of blood into and out of the heart and between the chambers inside the heart. The aortic valve is the gate between the main pumping chamber of the heart, the left ventricle, and the main artery of the body, the aorta. The aortic valve is able to open and close because it has leaflets (cusps). In a normal aortic valve there are three leaflets, and because of this it is called trileaflet. The word bicuspid is used to describe an aortic valve that is not normal; it has only two cusps or leaflets.

The highest pressure in the circulatory system is experienced by the left ventricle, aortic valve, and ascending aorta. When the heart muscle of the left ventricle contracts, the aortic valve leaflets separate, making an opening and allowing blood to flow from the heart into the aorta. When the heart muscle relaxes, the leaflets fold back together, closing the opening so that blood cannot flow back into the heart again.

For proper blood flow, it is important for the valve leaflets to open widely and then close tightly. The bicuspid aortic valve may not function as perfectly as a trileaflet valve, but it could open and close well enough to support normal life and activity for some time.

As the drawings on the left show, a bicuspid aortic valve generally looks different than a trileaflet aortic valve. However, in reality the malformation can be very subtle and not infrequently the BAV is not found by routine echocardiography.

With time, a bicuspid aortic valve may begin to leak (insufficiency, regurgitation), become narrowed (stenosis), or do both of these. Calcification of the leaflets may occur. It is also prone to bacterial infection, which is called endocarditis. These valve-related complications are the part of bicuspid aortic disease that is most well known.

It should be remembered that while the diseased aortic valve is very important, it is only one part of this condition. Repairing or replacing a bicuspid aortic valve addresses the valve issue but not a diseased aorta.

Bicuspid Aortic Valve Regurgitation

When the leaflets of the aortic valve do not come together well, it is possible for blood to flow back or leak into the heart again. This is called regurgitation or insufficiency. This leakage puts a strain on the heart, because it must re-pump some of the same blood again. As a result, the left ventricle becomes over loaded and stretches in diameter (dilated).
In the early stages of this disease, symptoms are apparent during exercise only.

Bicuspid Aortic Valve Stenosis

Some bicuspid aortic valves become stiff, calcified, and narrow. When this happens, it is called stenosis. When the valve opening becomes too small (critical stenosis), the heart must work too hard to pump blood through the small opening. This leads to a very thickened and over-strained left ventricle (concentric LV hypertrophy). As a result of an inefficient left ventricle, progressive diastolic heart failure can occur. The early stages of this condition are only noticeable during exercise (exercise intolerance).

Endocarditis

Endocarditis is an infection of the heart valve. Once it develops, depending on the organism involved, it can be very difficult to treat. Intravenous antibiotics are used, and surgical repair or replacement of the valve also may be necessary.

Those with abnormal heart valves, such as bicuspid aortic valves, and those whose valves have been replaced by a prosthesis are prone to valve infection. It is important that antibiotics be given before dental cleanings, as well as before all invasive procedures.

Mitral and Pulmonary Valves

There may be issues, not just with the aortic valve, but also with other valves in the heart:

• The mitral valve may have weak tissue and begin to leak (myxomatous changes).
• There are also questions about the pulmonary valve, and whether or not its tissue is affected. It is located in a low-pressure position in the right heart and usually continues to function well there.

The Coronary Arteries

What is commonly called heart disease is plaque build up in the coronary arteries. Generally, those with bicuspid aortic valve disease are not prone to this plaque build up, and their coronary arteries remain open. However, bicuspid aortic valve patients who also are smokers or have diabetes, high cholesterol, or atherosclerosis may develop coronary artery blockages.

Other Heart Problems

Sometimes other congenital heart defects may be present, such as an atrial septal defect (an opening in the wall between the collecting chambers of the heart). Also BAVD patients may have conduction abnormalities (electrical conduction, such as an irregular heartbeat). These conditions require appropriate, comprehensive diagnosis and treatment for some BAVD patients.

Aortic Aneurysm and Dissection

At one time it was thought that the abnormal blood flow from a bicuspid aortic valve was the main cause of enlargement of the ascending aorta. However, development of an ascending aortic aneurysm has been observed in the presence of a normally functioning bicuspid aortic valve. Also, the aneurysmal progression of the ascending aorta following replacement of the bicuspid aortic valve indicates the intrinsic aortic wall abnormality present in this syndrome.

Bicuspid aortic disease is increasingly being understood as degeneration of the medial layer of the aorta, resulting in an aortic wall that gradually loses its strength. This condition causes the aorta to over stretch with each beat of the heart, eventually leading to formation of an aneurysm. Secondary to the anatomical nature of the ascending aorta (which is relatively free inside the pericardium), and its exposure to maximal blood flow from the heart, the aortic root and ascending aorta are the most common sites of aneurysm formation.

This weak aortic tissue is prone to dissection and rupture. Given that many of those with bicuspid aortic disease also develop labile hypertension, this combination of high pressure and weak aortic tissue could result in a life-threatening situation.

Blood Pressure

Overall, intelligent systolic blood pressure management could be a hallmark of treatment, providing added safety for those who have bicuspid aortic valve disease.

The majority of those with BAVD have labile hypertension. Often their blood pressure goes up quickly under stress or when exercising. According to the blood pressure classifications published in 2003, normal systolic blood pressure is below 120. However, for those with bicuspid aortic disease, consideration of their fragile aortic tissue is necessary when setting a target blood pressure range. Blood pressure treatment is done on an individual basis, taking into consideration factors such as age, how well someone can function comfortably at a lower blood pressure range, and whether other associated conditions are present. Each person needs guidance and feedback regarding their blood pressure management.

Coarctation of the Aorta

Aortic coarctation means that a section of the aorta is narrow, usually the part of the descending aorta just past the arch. Some with BAVD have this congenital aortic condition. It is often found and treated in the early years of life.
It is possible to reach adulthood without symptoms, because other blood vessels take over some of the blood flow that would normally go through the aorta (collateral circulation). However, because blood is trying to flow through a narrow opening, pressure may still build up. This increased pressure in the ascending aorta and its branches to the brain may cause a break in a fragile vessel in the brain, resulting in bleeding and stroke. The heart muscle (left ventricle) may also thicken as it pumps against the resistance due to the narrowed aorta, and could potentially cause diastolic dysfunction or heart failure. Surgery should be planned before complications such as this happen.

Brain Aneurysm

Some people with BAVD have been found to have not only a weakness in the aorta, but also in the blood vessels of the head and neck. This weakness may result in brain aneurysm or dissection. One school of thought is that the vessels in the head and neck are formed from the same cells as the aortic valve and aorta, and therefore share the same abnormal tissue. Additional statistics and research in this area are needed to further understand the frequency with which this may happen. As screening and follow up are done on more people with BAVD, more information will become available.

Miscellaneous Areas of the Body

Other areas of the body may also be affected in those with BAVD. One area is the spine, where scoliosis or premature degeneration of the discs may occur. Hernias, hiatal hernias, and cysts in the liver and kidneys are other examples. Near-sighted vision is also present in some individuals.

Who Has Bicuspid Aortic Valve Disease?

Many people, up to 2% of the population, have it.

The simple answer is that anyone may have bicuspid aortic valve disease. You, your family members, friends, neighbors, or someone you know at work could have it. It is found through out the world in all races and affects both men and women, although it is found more often in men.

Out of every 100 people, it is very possible that two of them have bicuspid aortic valve disease, because this condition is estimated to exist in about two per cent of the population. In the United States alone, this represents a very large group of people.

• The US population, from the US Census Bureau as of July 1, 2003, was 290,809,777.
• Assuming that 2% of the US population has bicuspid aortic valve disease, that is 5,816,196 people.

Currently, it is estimated that about 5% of those with bicuspid aortic valve disease will experience aortic dissection.

• If 5% of them dissect, this means 290,810 people.
• Given these figures, this condition may represent the most frequent cause of aortic dissection.

It is also estimated that more than one third of those with bicuspid aortic disease will have a serious complication of some type due to their condition.
• Using the same US Census Bureau figure, more than 1,919,345 people will have serious complications.
• The actual figure is unknown.

At this point in time, many in the baby boomer generation have reached their 50's and 60's. Since it is very typical for a male with BAVD to require treatment for the bicuspid aortic valve and/or aorta at this age, the number of men currently at risk of complications from this condition could at this time be reaching an all time high.

Can BAVD be found just by looking at someone?

By just looking, it is not possible to tell if someone has this condition. Unlike some other connective tissue disorders, there are no strikingly obvious outward characteristics of this disease. Those with BAVD may be short, average in height, or tall. They may have a slight, average, or large body size.

Listening to their chest sometimes provides an important clue. If the blood makes an unusual sound as it flows through the bicuspid aortic valve, this sound or heart murmur can be heard. However, blood may also flow quietly through the bicuspid aortic valve, without a murmur.

Many people with BAVD are good athletes and enjoy exercise and work outs at the gym. It is understandably difficult for those who have BAVD to reconcile this contradiction in their body: strong, healthy muscles and flexible joints along with a defective aortic valve and very fragile aortic tissue.

Is BAVD inherited?

This condition also appears to be inherited within families, although not everyone in a family will have it. It is important to consider the entire family when one person is found to have BAVD. Since it may not appear in every generation, going beyond the immediate family (father, mother, brothers, sisters) to include grandchildren, nieces, nephews, and cousins when checking for BAVD is wise.

Generally, the bicuspid aortic valve has been the main identifier of this form of aortic disease.
• However, as entire families are studied, aortic aneurysms have been found in family members with normal appearing aortic valves.
• It is possible that the two aortic valve leaflets are fused only slightly, and that this cannot be seen by diagnostic tests.
Until more is known, it is wise to monitor the aorta of family members of those with bicuspid aortic valves, even if their aortic valve appears to be normal.

When did they get this disease? It is a condition from birth.

Those with BAVD had it when they were born. Something happened before birth, as their hearts, blood vessels, and other parts of their bodies were forming.

Within the cells of the body, exactly what happened, why it happened, and what currently is happening remain open questions. Genetic studies are currently underway in various centers, seeking to understand the origin of this disease. Much more research is needed. However, today we recognize and have solutions for the most potentially devastating aspects of this disease: bicuspid aortic valve failure, aortic aneurysm, and aortic dissection.

Medical and surgical advances have extended the lives of those with bicuspid aortic valve disease. As they live longer, it is not known if and how this condition will continue to progress. Follow up care from aortic disease experts is needed throughout their lives.

BAVD ranges from those who may live their entire life without ever knowing they have it, to those who need a procedure in infancy for severe narrowing of their bicuspid aortic valve. These are the two extremes. In between, there are many who will need:
• their aortic valve repaired or replaced
• their ascending aorta replaced
• other procedures, such as repair or replacement of their mitral valve.

Until more studies are done and more statistics are available, we do not know all that may or may not happen to those with bicuspid aortic disease. This includes just how many of them may with time develop aneurysms elsewhere, including the brain. Screening for brain aneurysms and following bicuspid aortic disease individuals on a long-term basis will shed more light on the frequency with which brain aneurysms occur.

Some day, research will unlock the mysteries of this condition. But for now, since BAVD is still not fully understood, it is important to keep an open mind regarding this condition and its affects on those who have it.

How is BAVD Found?

Often, it is first identified when a bicuspid aortic valve is found. Sometimes an ascending aortic aneurysm is detected, and as this is being investigated, a bicuspid aortic valve is also noticed. The aorta, as well as the aortic valve and other heart valves, all are evaluated as part of the screening for this condition.

Echocardiography, which creates images of the heart with sound waves, is often the first test done that identifies a bicuspid aortic valve. This may be done because a heart murmur has been heard, or because there is another reason to evaluate the heart valves and chambers. The ascending aorta may also be imaged this way, and any enlargement noted. Echocardiography does not always detect a bicuspid aortic valve, especially if the fusion of the leaflets is subtle.

CT or MRI scans are used to obtain the most accurate images of the aorta. A spiral CT scan with contrast or an MRI with contrast both produce images of the entire aorta. MRI technology is advancing rapidly and some centers now have expertise that allow imaging of the heart valves and heart as well as the aorta.

Please see the Patients and Families page for additional information about diagnostic testing.

How is BAVD Treated?

For all those with bicuspid aortic disease, medical treatment is focused primarily on blood pressure optimization. The bicuspid aortic valve and aorta are monitored, and may require surgery at some point. In addition, the existence of any other congenital heart defects, issues with other heart valves, and any heart arrhythmias are also identified and treated as appropriate. The potential for brain aneurysm development is also recognized. All of these areas may be included when planning the course of treatment for an individual.

Systolic Blood Pressure Management

Blood pressure medications are aimed at possibly preventing aortic dissection or rupture, slowing the progression of an aortic aneurysm, and reducing bicuspid aortic valve leakage. These medications generally reduce the pressure and stress on the aorta and any other potentially weak blood vessels, such as those in brain.

Medications from the following categories may be used:

•beta blockers
•ACE inhibitors
•ARBs
•calcium channel blockers
•alpha blockers
•diuretics

When the blood pressure is naturally low in the presence of bicuspid aortic valve leakage and an enlarged aorta, it usually indicates more fragile aortic tissue. However, these individuals may still use smaller doses of blood pressure medication.

Heavy weight lifting is known to raise systolic blood pressure and is a risk for aortic dissection. Therefore, heavy weight lifting is prohibited.

Diagnostic Testing

Testing is done to determine the function and/or size of the:
• bicuspid aortic valve
• aorta
• other heart valves
• chambers of the heart.

The possibility of other heart conditions, such as arrhythmias or coronary artery disease, will also be evaluated. Screening is also available for vascular abnormalities or aneurysms in the brain.

Testing, when performed or evaluated in an experienced aortic center, will result in an accurate baseline picture of the heart and aorta. Once accurate information is available, a determination will be made regarding the need for surgery. If surgery is not needed, on an ongoing periodic basis, the valves, heart, and aorta are checked for any significant changes.

Please see the Patients and Families page for additional information about diagnostic testing.

Surgery for the Bicuspid Aortic Valve and Aorta

For those with bicuspid aortic valve disease, a big picture look at their overall condition is needed to determine the best course of treatment for each individual. There are specific criteria that will be used to determine if the bicuspid aortic valve and/or aorta require surgical intervention. Valve repair and replacement is a complex topic, and options for the aortic valve in those with BAVD require careful thought.

• Repair/replacement of the aortic valve and ascending aorta preferably is done in the same surgery.
• If only the ascending aorta requires surgery, a bicuspid aortic valve that functions well may be left in place.

Please see the Aortic Aneurysm and Dissection page for additional information about the aortic aspects of bicuspid aortic valve disease.

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