What is the aortic valve? What is aortic valve stenosis?
The heart has
four chambers. In the lower left chamber (left ventricle), the
aortic valve works like a one-way gate. When the heart pumps, the aortic valve
opens to let oxygen-rich blood flow from the left ventricle into a large blood
vessel called the
aorta. Blood then flows through the aorta to the rest
of the body.
Aortic valve stenosis means that this valve has
narrowed, and it can't open all the way. The heart has to work harder to pump
blood through the smaller opening. The heart can do this for many years, but
over time it gets worn out. It can no longer send out as much blood as your
body needs. If you don't get treatment,
heart failure may develop.
What causes aortic valve stenosis?
Problems that
can cause aortic valve stenosis include:
Calcium buildup on the aortic valve. As you
age, calcium can build up on the valve, making it hard and thick. This buildup
happens over time, so symptoms usually don't appear until after age 65. Many of
the same things that increase your risk for hardening of the arteries (atherosclerosis) make you more likely to have aortic
valve stenosis. They include smoking, being male, or having
high cholesterol,
high blood pressure, or
diabetes.
A heart defect you were born
with (congenital). Some babies are born with an aortic valve that has only two
flaps instead of the normal three. This is called a bicuspid valve, and it
makes a smaller opening for blood to flow through. In this case, symptoms
usually start around age 40.
Aortic valve stenosis is a
slow process. For many years, even decades, you will not feel any symptoms. But
at some point, the valve will likely become so narrow (often one-fourth of its
normal size) that you start having problems.
As aortic valve
stenosis gets worse, you may have symptoms such as:
Chest pain (angina). You
may have a heavy, tight feeling in your chest. Chest pain is often brought on
by exercise, when the heart has to work harder.
Feeling dizzy or
faint, often after you have been active.
Feeling tired and being
short of breath when you are active.
A feeling that your heart is
pounding, racing, or beating unevenly (palpitations).
If you start to notice any of these symptoms, let your
doctor know right away. If you have symptoms, you need treatment. By the time
you have symptoms, your condition probably is serious. If you have symptoms,
you also have a high risk of sudden death.1
How is aortic valve stenosis diagnosed?
Most
people find out they have it when their doctor hears a heart murmur during a
regular physical exam. To be sure of the diagnosis, your doctor may want you to
have an
echocardiogram, which can show moving pictures of your
heart. You may have other tests to help your doctor judge how well your heart
is working.
How is it treated?
If symptoms develop, you will
probably need surgery right away. Surgery to replace the aortic valve is the
best treatment for most people. View a
slideshow on aortic valve replacement surgery. Young people or people who cannot
have open-heart surgery may have another procedure called balloon valvuloplasty
to enlarge the valve opening.
If you do not have surgery after you
start having symptoms, you may die suddenly or develop heart failure. Most
people who have symptoms of severe aortic valve stenosis die within 2 to 5
years if they do not have valve replacement surgery.2
Surgery can help you have a more normal life span.
If you don't
have symptoms, your doctor will see you regularly to check your heart. You
probably will not have surgery. Until you have symptoms, surgery is likely to
be more risky than the disease.3
Medicines do not cure the disease, but they can treat some problems that
aortic valve stenosis can cause. You might need to take medicines that help
control irregular heart rhythms or blood thinners (anticoagulants)
to prevent blood clots.
Most people who have
aortic valve stenosis are born with a normal, healthy
aortic valve but develop
aortic stenosis late in life. Aging and calcium buildup cause the leaflets of
the valve to thicken and harden, preventing the valve from opening properly.
Typically, stenosis develops slowly over many years.
Aortic valve
stenosis also occurs in people who are born with a valve that has two flaps
instead of three (congenital bicuspid valve) or in people who have had
rheumatic fever. In either of these cases, the
leaflets do not open as widely as they should. This creates a smaller opening
and makes it much harder for blood to flow from the
left ventricle into the
aorta.
You probably will not have any symptoms if
you have mild or moderate
aortic valve stenosis, because your heart can make up
for the stenosis. You may begin to notice symptoms if the pressure buildup in
the heart becomes severe or if blood flow to the heart and the rest of the body
is reduced. Symptoms may include:
Chest pain (angina) or
discomfort, often described as a heavy, tight feeling in your chest. You may
also have a burning, choking, or constricting feeling that may spread to your
arms, shoulders, or neck. You may have chest pain when you exercise or do
something strenuous because your heart has to work
harder.
Dizziness, fainting, or loss of consciousness, often after
periods of activity.
Signs of
heart failure, such as fatigue and shortness of breath
with activity.
Certain medical problems or
conditions make it more likely that you will develop
aortic valve stenosis:
Calcium buildup. Aging can cause calcium buildup
around the aortic valve, which can make the normally thin and flexible valve
flaps thick and stiff. This is also called calcific aortic valve stenosis. It
is unclear why some people develop calcium buildup while others don't. This
calcium buildup may be related to the same process that causes atherosclerosis,
or hardening of the arteries. In fact, many of the things that increase the
risk of atherosclerosis and heart disease are the same for aortic valve
stenosis. They include smoking,
high cholesterol,
high blood pressure,
diabetes, and being male.4, 5
Birth defect. Sometimes a person is born with a
bicuspid aortic valve that has two flaps instead of the normal three. Over time,
the valve becomes damaged and calcium builds up. As the valve narrows, less
blood can flow through it.
Infection.Rheumatic fever
can cause scar tissue to build up at the edges of the valve. The scar tissue
binds the corners of the flaps together, limiting their ability to open fully.
The most common cause of rheumatic fever is strep throat that has not been
treated. Because antibiotics have been widely used to treat strep throat,
rheumatic fever has been uncommon in the United States since the 1970s.
Artificial valve. Aortic valve disease also may
develop in an artificial aortic valve that is made from human or animal
tissue.
Other things that increase the risk for aortic valve
stenosis include:
Being male. Men are at higher risk than
women.
Atherosclerosis. In some studies, the
buildup of plaque in the arteries has been associated with aortic valve
stenosis.
Kidney failure.
Smoking.
When to Call a Doctor
If you experience any of the
symptoms of
aortic valve stenosis, such as chest pain, fainting,
or shortness of breath, call your doctor immediately.
Aortic valve stenosis generally does not cause symptoms until the condition has
become quite severe. The longer you try to live with symptoms of stenosis and
its complications without seeking medical attention, the more you risk getting
heart failure.
The table below explains
why these symptoms occur.
Aortic valve stenosis
Symptom
What happens
Why you should see a
doctor
Chest pain
You feel pain or pressure in your chest that
may move down the inside of your left arm. At the same time, you may feel as if
you are suffocating.
Angina occurs because your heart muscle is
not getting enough blood. Angina can be caused by severe aortic stenosis and
coronary artery disease (CAD).
Fainting
Fainting or blacking out is usually preceded
by lightheadedness.
By reducing the heart's ability to pump
blood, aortic stenosis can prevent the brain from receiving enough oxygen-rich
blood.
Shortness of breath
Shortness of breath can occur during
physical exertion or suddenly during the night.
Shortness of breath may be a sign of heart
failure, which is the main complication of aortic valve stenosis.
Palpitations
An uncomfortable awareness of the heart
beating rapidly or irregularly. Some people report a vague "fluttering" in
their chest or the feeling of a "skipped beat," while others note a "pounding
sensation" or feel that their hearts are "jumping out of their
chest."
If palpitations occur with fainting, near
fainting, or lightheadedness, they may be a sign of a heart problem such as an
irregular heartbeat (arrhythmia).
Watchful waiting
Watchful waiting is a
"wait-and-see" approach that is not appropriate if you have chest pain,
shortness of breath, palpitations, or fainting. Contact your doctor
immediately.
If you have been diagnosed with aortic valve stenosis
but you do not have symptoms, you and your doctor should discuss a plan to
check your heart regularly. You may have mild stenosis and have no symptoms for
many years. You may never develop symptoms. There is some debate about whether
people who don't have symptoms should have valve replacement surgery.
But even if you don't have symptoms, if tests show your left ventricle is
not working right or you have an exercise stress test that is abnormal, your
doctor may recommend valve replacement.
Who to see
Your
family doctor may diagnose aortic valve stenosis
during a routine checkup. Other health professionals who also may discover
aortic valve stenosis during a physical exam include:
If you have any of the symptoms of aortic valve stenosis
or heart failure but have not been diagnosed with aortic valve stenosis, you do
not necessarily need to see a heart specialist (cardiologist) immediately. Your
family doctor can evaluate your symptoms. If your doctor thinks that you do
have stenosis, the doctor will likely have you take an
echocardiogram.
With mild cases of
stenosis, only regular monitoring may be necessary, in which case you may be
able to continue seeing your family doctor. If you have (or develop) more
severe stenosis, your doctor can help you to decide when to involve a
cardiologist in your treatment.
Considerations for children
If a
pediatrician detects a heart murmur in a child or
teen, the murmur may be a sign of a heart defect that has been present since
birth, such as a
bicuspid aortic valve (which has two valve flaps instead of three). In most
cases, a pediatrician will recommend an echocardiogram, which can identify a
defect. A pediatrician may refer your child to a pediatric cardiologist for
further evaluation and treatment.
Exams and Tests
A physical exam and review of your
medical history are important first steps in diagnosing
aortic valve stenosis. If you have stenosis but no
symptoms, your doctor will likely find the condition during a routine exam or a
checkup for another health problem. A distinctive heart murmur is usually the
first clue that leads a doctor to suspect aortic valve stenosis.
During the physical exam, the doctor will:
Take your blood pressure. Low blood pressure may
mean that not enough blood is getting through the narrowed aortic valve.
Check your pulse. A weak pulse may mean there is
narrowing of the heart valve.
Listen to your heart and lungs for abnormal sounds. A soft whooshing or humming sound (murmur) heard through a
stethoscope is an important finding that often indicates heart valve disease.
Abnormal sounds in the lungs can indicate fluid buildup in the lungs that is
caused by heart valve disease.
Look at your legs and feet. Swelling in the legs
and feet may be a sign of
heart failure.
After the exam
Your doctor may want to do an echocardiogram to confirm that your
symptoms and the results of your exam are caused by aortic valve stenosis. The
echocardiogram will also tell your doctor:
How severe the stenosis is.
How
wide your aortic valve can open.
The difference in pressure between
the heart and the aorta, resulting from blood being forced through the narrowed
valve.
The size of your left ventricle.
How well your
left ventricle is working.
Whether there are problems with other
valves.
Tests for aortic valve stenosis
Echocardiogram (echo). If you have aortic valve stenosis, an echocardiogram may show
thickened aortic valve leaflets that aren't moving normally.
Stress echocardiogram. A stress echocardiogram can
show how severe your aortic valve stenosis is and how it affects how much you
can exercise.
Electrocardiogram (EKG or ECG). An
electrocardiogram may show abnormalities in heart rhythm or lower left heart
chamber (ventricle) thickness.
Chest X-ray.
A chest X-ray may show calcium buildup in the valve, an enlarged left
ventricle, or fluid buildup if you have developed heart failure. In some cases,
the
aorta may be enlarged just beyond the aortic
valve.
Brain natriuretic peptide (BNP) test. A
BNP test may help show how well your heart is working and if you have heart
failure.
In most cases, if you
have symptoms, the risk of not treating aortic valve stenosis is higher than
the risk of having surgery. Most people who have symptoms of severe aortic
valve stenosis die within 2 to 5 years if they do not have valve replacement
surgery.2
Doctors may prefer
balloon valvuloplasty for teens, young adults in their
20s, or people for whom valve surgery is too great a risk. This treatment
involves inserting a tiny balloon into the aortic valve and expanding it to
open the valve. While this is less risky than valve surgery, it is usually only
a temporary treatment in anyone other than young people.
For most
people, valve replacement is the only effective treatment. You and your doctor
need to decide whether to replace the aortic valve at the time you are
diagnosed or delay until later. Depending on the results of your tests, you may
also require additional heart surgery during your valve replacement surgery,
such as
coronary artery bypass grafting. For more information
about valve replacement surgery, see:
You may need medicine to prevent or treat a heart infection
or
heart failure. If you have surgery to receive an
artificial valve, you also may have to take blood thinners (anticoagulants) to prevent blood clots from forming.
For more information, see the Medications section of this topic.
Aortic valve stenosis can be an easy condition to miss. In its mild form, you may not
even realize that you have it, because it has not yet begun to cause symptoms.
The condition may not be found unless you have tests for another possible heart
condition.
If you do not yet have symptoms, you may go a long time
without having them. This phase can last for 10 years or more. During this
phase, you may have an
echocardiogram every 6 months to every few years to
check the condition of your valve.
If you have aortic valve
stenosis, you are at risk of getting
iron deficiency anemia due to a condition called
angiodysplasia. With angiodysplasia, you have gastrointestinal bleeding and
symptoms of anemia. Be aware that the symptoms of anemia are similar to some of
the symptoms of aortic valve stenosis.
If you have aortic valve
stenosis, you cannot prevent it from getting worse or causing symptoms,
including chest pain (angina), fainting, and shortness of
breath.
After symptoms of stenosis develop, you must decide with
your doctor whether to have valve replacement surgery. This surgery is the only
effective treatment. Without it,
heart failure will likely develop and shorten your
life.6 View a
slideshow on aortic valve replacement surgery.
Most people who have
symptoms of severe aortic valve stenosis die within 2 to 5 years if they do not
have valve replacement surgery.2 With surgery, you may
reach a normal life expectancy. For more information about valve replacement
surgery, see:
As aortic valve stenosis progresses,
it often causes
complications that can have a serious impact on your
overall health. Heart failure is the most common and potentially the most
life-threatening complication. Other complications include chest pain,
fainting, irregular heartbeat, and heart infection. In rare cases, aortic valve
stenosis can cause sudden death before you have symptoms. Sudden death is more
common in people who have
bicuspid aortic valves.
Living With Aortic Valve Stenosis
How you will feel
and how
aortic valve stenosis will affect your life will vary
greatly depending on whether you have symptoms and the treatment decisions you
make.
If you have no symptoms
You may be surprised when
you first learn that you have aortic valve stenosis, because you may not have
symptoms. In fact, you may even have quite severe stenosis and still not feel
any symptoms or show physical signs. But even if you feel fine, there are still
many things you will have to keep in mind.
It is important that
you watch closely for any signs of chest pain, lightheadedness, fainting, or
shortness of breath. See your doctor promptly if you develop these symptoms or
others that concern you. You are more likely to have symptoms while exercising
or doing other strenuous activity than at other times. Discuss with your doctor
what kinds of exercise are safe for you. There is no way to predict when
symptoms will develop.
You can keep your heart healthy and lower
your risk of
coronary artery disease with a heart-healthy diet and
lifestyle such as not smoking, staying at a healthy weight, being active, and
managing diabetes, high blood pressure, and high cholesterol.
You
also will need to have an
echocardiogram every 6 months to 1 year for severe
stenosis and every 1 to 5 years for mild to moderate stenosis.
If
you have severe stenosis, avoid strenuous physical activity. In rare cases,
sudden death can occur if enough blood cannot get to your heart muscle during
strenuous physical activity.
Conditions that increase your risk for sudden death if you have aortic valve stenosis
Condition
What it means
Hypotension
You have abnormally low blood pressure.
Left ventricular systolic dysfunction
Your left ventricle is the chamber of
your heart that pumps blood from your heart into the rest of your body.
Systolic function refers to the ventricle's ability to contract and pump blood
out of the ventricle and into the rest of the body. Systolic dysfunction means
that the ventricle is not contracting properly, which can lead to a range of
problems including not enough blood getting to your organs and
tissues.
Marked left ventricular hypertrophy
The muscles of the left ventricle become
thick.
Severe aortic stenosis
Your aortic valve has narrowed
considerably.
Severe coronary artery disease (CAD)
The combination of aortic valve stenosis and CAD, or
blockages in the arteries that send blood to the heart is a serious condition.
Your doctor may recommend surgery to fix both problems at the same time.
If you have symptoms
After symptoms of stenosis
appear, you'll need to decide whether to have valve replacement. Because it is
the only effective long-term treatment, valve replacement surgery is
recommended unless you are in such poor health the surgery would be too risky
or you have other reasons not to have it. For more information about valve
replacement surgery, see:
If you do not have surgery, you will likely develop
severe
heart failure, which will shorten your life. But you
can make lifestyle changes to manage heart failure, including:
Eating a low-sodium diet and being careful
about how much fluid you drink.
Taking medications for heart
failure. For more information, see the topic
Heart Failure.
Being active with walking
or other mild exercise. You should discuss with your doctor what type of
exercise is safe for you.
Quitting smoking.
Limiting
activities that may strain you, such as travel and sex.
If you choose to have surgery, you should know that it
will likely involve a long recovery. On average, people who have valve
replacement take 3 to 6 weeks off from work. In some cases, full recovery may
take several months.
After you recover from surgery, you will
still need to take
antibiotics when necessary to guard against an
infection in your heart (endocarditis). You may also need to
take a blood thinner (anticoagulant) to prevent blood clots,
depending on the type of valve you have. If you have a mechanical valve, you
will have to take blood thinners as long as you have the valve.
Most people who have symptoms
of severe aortic valve stenosis but do not have valve replacement surgery die
within 2 to 5 years.2 For this reason, it is important
to consider end-of-life issues.
If you choose not to have
surgery, your doctor will prescribe medications to make you comfortable. As you
get sicker, you may be unable to make decisions about your medical care. You
may want to consider the type of care you wish to receive in case you are
unable to make your wishes known. For more information, see the topic
Care at the End of Life.
You may need to take medicines to
prevent and treat complications of
aortic valve stenosis.
If you have
valve replacement surgery with a man-made (mechanical) valve, you also will
need to take blood-thinning (anticoagulant) medication (such as
heparin or warfarin [for example, Coumadin]) for the rest of your life. These
medicines prevent blood clots from forming around the valve.
Some
doctors also recommend taking low doses of aspirin in addition to warfarin. If
you receive a biological (tissue) replacement valve instead of a mechanical
valve, you may need to take anticoagulants for only a few months. After that
time, you may be able to take aspirin alone.
If an infection develops
in your heart, your doctor will prescribe high-dose antibiotics for a much
longer period of time than if you were trying to prevent an infection.
If aortic valve stenosis leads to irregular heartbeats (arrhythmias), you may need to take medicines that help
control irregular heart rhythms until surgery can be done.
If you
develop
heart failure, you may be able to take medicines such
as diuretics, digoxin, vasodilators, or beta-blockers to help your heart pump
blood more effectively. For more information, see the topic
Heart Failure.
Your doctor will likely recommend valve
replacement surgery if you have symptoms of
aortic valve stenosis, unless you have other
conditions that make surgery too risky. Symptoms such as chest pain, fainting,
and shortness of breath indicate that you have severe narrowing of your aortic
valve. If you do not have surgery to replace the valve, you will have a much
shorter life span. In rare cases, you could die suddenly.
Most of
the time, valve replacement surgery is a straightforward procedure with a high
rate of success and a low risk of complications.
Aortic valve replacement
Aortic valve replacement is either an open-heart procedure or a
minimally invasive procedure. In an aortic valve
replacement surgery, the damaged valve is removed and replaced with an
artificial valve (mechanical or tissue). View a
slideshow on aortic valve replacement surgery. Several different types of
replacement valves are available. For more information about types of
replacement valves, see:
In rare cases, the aortic valve may be replaced with one
of your other heart valves. Usually the pulmonic valve is used. This valve is
located between the lower right heart chamber and the opening to the artery
that goes to the lungs. An artificial valve is used to replace the pulmonic
valve. This type of valve surgery may be used in people younger than 25 who
stand to benefit the most from this difficult surgery. The pulmonic valve is
more durable, grows with the person, and has a lower risk of infection.
Valve replacement surgery is high-risk for people who either have a
failing left ventricle,
coronary artery disease, or have had a
heart attack.
Medical experts debate whether valve replacement
surgery should be done for aortic valve stenosis that is not causing symptoms.
Although no current research supports this approach, some doctors believe that
repair or replacement surgery should be done as soon as severe stenosis is
found because of the small risk of sudden death.
Other doctors
believe surgery isn't necessary until symptoms develop. These doctors believe
that the risk of sudden death is less than the risks of surgery. If surgery is
delayed, regular follow-up exams (including
echocardiograms) are needed to monitor changes in the
valve structure and heart function. These tests may indicate when surgery is
needed.
In most cases, if you have symptoms, the risk of not
replacing the valve is higher than the risk of having surgery. The majority of
people who have symptoms of severe aortic valve stenosis die within 2 to 5
years if they do not have valve replacement surgery.2
The risk of surgery is higher than average for people who have
severe aortic valve stenosis, failure of the left ventricle, and a low
ejection fraction. But one study has found that even
people in this higher-risk group benefit from valve replacement. Valve
replacement surgery is also high-risk for people who have
coronary artery disease or have had a
heart attack.
Before having valve
replacement surgery, your doctor may suggest you have a
coronary angiogram/catheterization test. This test can
show if you have blockages in your
coronary arteries (as part of coronary artery
disease). If you have serious blockages, your doctor may want to do a
coronary artery bypass surgery at the same time as the
valve replacement surgery.
Other aortic valve surgery
Balloon valvuloplasty may be an option for some younger people who have aortic
valve stenosis. Although the heart valve is not replaced, the narrowed opening
is made larger during this procedure.
Contact the American College of Surgeons for the names of vascular
surgeons in your area.
American Heart Association (AHA)
7272 Greenville Avenue
Dallas, TX 75231
Phone:
1-800-AHA-USA1 (1-800-242-8721)
Web Address:
www.americanheart.org
Call the American Heart Association (AHA) to find your
nearest local or state AHA group. AHA can provide brochures and information
about support groups and community programs, including Mended Hearts, a
nationwide organization whose members visit people with heart problems and
provide information and support. AHA's Web site also has information on
physical activity, diet, and various heart-related conditions.
Texas Heart Institute
P.O. Box 20345
Houston, TX 77225-0345
Phone:
1-800-292-2221 (Heart Information Service hotline) (832) 355-4011 (general line)
E-mail:
his@heart.thi.tmc.edu (Heart Information Services)
Web Address:
www.texasheartinstitute.org
The Texas Heart Institute's national telephone hotline is staffed
by medical professionals who can answer heart-related health questions. The Web
site provides information on a wide range of heart topics, including common
disorders and prevention programs.
Bonow RO, et al. (2006) ACC/AHA 2006 guidelines for
the management of patients with valvular heart disease. A report of the
American College of Cardiology/American Heart Association Task Force on
Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the
Management of Patients with Valvular Heart Disease). Circulation, 114(5): e84-e231.
Stewart WJ, Carabello BA (2007). Aortic valve disease.
In EJ Topol et al., eds., Textbook of Cardiovascular Medicine, 3rd ed., pp. 366-388. Philadelphia: Lippincott Williams and
Wilkins.
Aikawa K, Otto C (2001). Timing of surgery in aortic
stenosis. Progress in Cardiovascular Diseases, 43(6):
477-493.
Rajamannan NM, et al. (2003). Calcific aortic
stenosis: From the bench to the bedside-Emerging clinical and cellular
concepts. Heart, 89: 801-805.
Pohle K, et al., (2004). Association of cardiovascular
risk factors to aortic valve calcification as quantified by electron beam
computed tomography. Mayo Clinic Proceedings, 79 (10):
1242-1246.
Carabello BA (2002). Aortic stenosis. New England Journal of Medicine, 346(9): 677-681.
Other Works Consulted
Carabello BA (2002). Evaluation and management of
patients with aortic stenosis. Circulation, 105:
1746-1750.
Nishimura RA, et al. (2008) ACC/AHA 2008 guideline
update on valvular heart disease: Focused update on infective endocarditis: A
Report of the American College of Cardiology/American Heart Association Task
Force on Practice Guidelines: Endorsed by the Society of Cardiovascular
Anesthesiologists, Society for Cardiovascular Angiography and Interventions,
and Society of Thoracic Surgeons. Circulation, 118(8):
887-896.
Rahimtoola SH (2004). Aortic valve disease. In V
Fuster et al., eds., Hurst's The Heart, 11th ed., vol.
2, pp. 1643-1667. New York: McGraw-Hill.
This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.
Bonow RO, et al. (2006) ACC/AHA 2006 guidelines for
the management of patients with valvular heart disease. A report of the
American College of Cardiology/American Heart Association Task Force on
Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the
Management of Patients with Valvular Heart Disease). Circulation, 114(5): e84-e231.
Stewart WJ, Carabello BA (2007). Aortic valve disease.
In EJ Topol et al., eds., Textbook of Cardiovascular Medicine, 3rd ed., pp. 366-388. Philadelphia: Lippincott Williams and
Wilkins.
Aikawa K, Otto C (2001). Timing of surgery in aortic
stenosis. Progress in Cardiovascular Diseases, 43(6):
477-493.
Rajamannan NM, et al. (2003). Calcific aortic
stenosis: From the bench to the bedside-Emerging clinical and cellular
concepts. Heart, 89: 801-805.
Pohle K, et al., (2004). Association of cardiovascular
risk factors to aortic valve calcification as quantified by electron beam
computed tomography. Mayo Clinic Proceedings, 79 (10):
1242-1246.
Carabello BA (2002). Aortic stenosis. New England Journal of Medicine, 346(9): 677-681.
