coronary artery disease
Coronary artery disease (CAD), also called coronary heart disease,
occurs when the arteries that supply blood
to the heart muscle (the coronary arteries)
become hardened and narrowed. The arteries harden and narrow due to buildup
of a material called plaque on their inner walls. The buildup of plaque
is known as atherosclerosis. As
the plaque increases in size, the insides of the coronary arteries get narrower
and less blood can flow through them. Eventually, blood flow to the heart
muscle is reduced, and, because blood carries much-needed oxygen, the heart
muscle is not able to receive the amount of oxygen it needs. Reduced or
cutoff blood flow and oxygen supply to the heart muscle can result in:
Over time, CAD can weaken the heart muscle and contribute to:
- Angina. Angina is
chest pain or discomfort that occurs when the heart does not get enough
- Heart attack.
A heart attack happens when a blood clot develops at the site of plaque
in a coronary artery and suddenly cuts off most or all blood supply
to that part of the heart muscle. Cells in the heart muscle begin to
die if they do not receive enough oxygen-rich blood. This can cause
permanent damage to the heart muscle.
CAD is the most common type of heart disease. It is the leading cause of
death in the United States in both men and women.
- Heart failure.
In heart failure, the heart can't pump blood effectively to the rest
of the body. Heart failure does not mean that the heart has stopped
or is about to stop. Instead, it means that the heart is failing to
pump blood the way that it should.
are changes in the normal beating rhythm of the heart. Some can be quite
What causes coronary artery disease?
Coronary artery disease (CAD) is caused by atherosclerosis (the thickening
and hardening of the inside walls of arteries). Some hardening of the arteries
occurs normally as a person grows older.
In atherosclerosis, plaque deposits build up in the arteries. Plaque is
made up of fat, cholesterol, calcium,
and other substances from the blood. Plaque buildup in the arteries often
begins in childhood. Over time, plaque buildup in the coronary arteries
- Narrow the arteries. This reduces the amount of blood and oxygen that
reaches the heart muscle.
- Completely block the arteries. This stops the flow of blood to the
- Cause blood clots to form. This can block the arteries that supply
blood to the heart muscle.
|An artery with normal blood flow (figure A) and an
artery containing plaque buildup (figure B). Credit: National Institutes
Plaque in the arteries can be:
- Hard and stable. Hard plaque causes the artery walls to thicken and
harden. This condition is associated more with angina than with a heart
attack, but heart attacks frequently occur with hard plaque.
- Soft and unstable. Soft plaque is more likely to break open or to
break off from the artery walls and cause blood clots. This can lead
to a heart attack.
Who is at risk for coronary artery disease?
About 13 million people in the United States have coronary artery disease
(CAD). It is the leading cause of death in both men and women. Each year,
more than half a million Americans die from CAD. Several factors increase
the risk of developing CAD. The more risk factors you have, the greater
chance you have of developing CAD. Some CAD risk factors, such as age, can't
be modified, but others can.
Risk factors that cannot
- Age. As you get older, your risk for CAD increases.
- In men, risk increases after age 45.
- In women, risk increases after age 55.
- Family history of early heart disease
- Heart disease diagnosed before age 55 in father or brother.
- Heart disease diagnosed before age 65 in mother or sister.
Risk factors that can be modified
Other potential risk factors
Scientists continue to study other potential risk factors for developing
According to some research studies, high blood levels of a substance called
C-reactive protein (CRP) may be associated with an increased risk of developing
CAD and having a heart attack. CRP is a protein in the blood that shows
the presence of inflammation. Inflammation
is the body's response to injury or infection. CRP levels rise when there
is inflammation. The inflammation process appears to contribute to the growth
of plaque in arteries.
Research is underway to find out if reducing inflammation and lowering CRP
levels can also reduce the risk of developing CAD and having a heart attack.
What are the signs and symptoms
of coronary artery disease?
The most common symptoms of coronary artery disease (CAD) are:
The severity of symptoms varies widely. Symptoms may become more severe
as coronary arteries become narrower due to the buildup of plaque (atherosclerosis).
- Chest pain or chest discomfort (angina) or pain in one or both arms
or in the left shoulder, neck, jaw, or back
- Shortness of breath
In some people, the first sign of CAD is a heart
attack. A heart attack happens when plaque in a coronary artery breaks
apart, causing a blood clot to form and block the artery.
How is coronary artery disease diagnosed?
There is no single test to diagnose coronary artery disease (CAD). Your
doctor will ask about your medical history and your family's medical history,
assess your risk factors, and do a physical exam and several tests. These
procedures are used to:
Based on the results of these procedures, your doctor may order one or more
of the following tests:
- Decide if you have CAD
- Determine the extent and severity of the disease
- Rule out other possible causes of your symptoms
Your doctor may also order the following blood
- EKG (electrocardiogram).
This test measures the rate and regularity of your heartbeat.
- Echocardiogram. This
test uses sound waves to create a moving picture of your heart. Echocardiogram
provides information about the size and shape of your heart and how
well your heart chambers and valves are functioning. The test also can
identify areas of poor blood flow to the heart, areas of heart muscle
that are not contracting normally, and previous injury to the heart
muscle caused by poor blood flow.
There are several different types of echocardiograms, including a stress
echocardiogram. During this test, an echocardiogram is done both before
and after your heart is stressed either by having you exercise or by
injecting a medicine into your bloodstream that makes your heart beat
faster and work harder. A stress echocardiogram is usually done to find
out if you have decreased blood flow to your heart (coronary artery
- Stress test. Some heart
problems are easier to diagnose when your heart is working harder and
beating faster than when it's at rest. During stress testing, you exercise
(or are given medicine if you are unable to exercise) to make your heart
work harder and beat faster while heart tests are performed.
During exercise stress testing, your blood pressure and EKG readings
are monitored while you walk or run on a treadmill or pedal a bicycle.
Other heart tests, such as nuclear heart scanning or echocardiography,
also can be done at the same time. These would be ordered if your doctor
needs more information than the exercise stress test can provide about
how well your heart is working.
If you are unable to exercise, a medicine can be injected through an
intravenous line (IV) into your bloodstream to make your heart work
harder and beat faster, as if you are exercising on a treadmill or bicycle.
Nuclear heart scanning or echocardiography is then usually done.
During nuclear heart scanning, radioactive tracer is injected into your
bloodstream, and a special camera shows the flow of blood through your
heart and arteries. Echocardiography uses sound waves to show blood
flow through the chambers and valves of your heart and to show the strength
of your heart muscle.
Your doctor also may order two newer tests along with stress testing
if more information is needed about how well your heart works. These
new tests are magnetic
resonance imaging (MRI) and positron
emission tomography (PET) scanning of the heart. MRI shows detailed
images of the structures and beating of your heart, which may help your
doctor better assess if parts of your heart are weak or damaged. PET
scanning shows the level of chemical activity in different areas of
your heart. This can help your doctor determine if enough blood is flowing
to the areas of your heart. A PET scan can show decreased blood flow
caused by disease or damaged muscles that may not be detected by other
- Chest X-ray. A chest X-ray
takes a picture of the organs and structures inside the chest. These
include the heart, lungs, and blood vessels.
- Cardiac catheterization.
A thin, flexible tube is passed through an artery in the groin or arm
to reach the coronary arteries. The tube allows your doctor to examine
the inside of your arteries to see if there is any blockage. Your doctor
also can determine the pressure and blood flow in the heart's chambers,
collect blood samples from the heart, and examine the arteries of the
heart by X-ray.
- Coronary angiography.
This test is usually performed along with cardiac catheterization. A
dye that can be seen by X-ray is injected through the catheter into
the coronary arteries. The doctor can see the flow of blood through
the heart and the location of blockages.
- Nuclear heart scan.
This test provides your doctor with moving pictures of the blood passing
through your heart's chambers and arteries and shows the level of blood
flood to the heart muscle. A small amount of a radioactive tracer is
injected into your bloodstream through a vein, usually in your arm.
A special camera is placed in front of your chest to show where the
tracer lights up in healthy heart muscle and where it doesn't light
up (in heart muscle that has been damaged or has a blocked artery).
There are different types of nuclear heart scans. Most scans have two
phases—taking pictures of the heart at rest and while it is beating
faster (called a stress test), although sometimes only a rest scan is
done. Many heart problems show up more clearly when your heart is stressed
than when it is at rest. By comparing the nuclear heart scan of your
heart at rest to your heart at "stress," your doctor can determine if
your heart is functioning normally or not.
- Electron beam computed tomography. This test identifies and
measures calcium buildup in and around the coronary arteries.
- A fasting glucose test to check your blood
- A fasting lipoprotein profile to check your cholesterol levels
How can coronary artery disease be prevented
Preventing or delaying coronary artery disease (CAD) begins with knowing
which risk factors you have and taking action. Remember, your chances of
developing CAD increase with the number of risk factors you have.
Know your family history of health problems related to CAD. If you or someone
in your family has CAD, be sure to tell your doctor. Make sure everyone
in your family gets enough exercise and maintains a healthy body weight.
By controlling your risk factors with lifestyle changes and medicines, you
may prevent or delay the development of CAD.
CAD can cause serious complications, but by following your doctor's advice
and changing your habits, you can prevent or reduce the chance of:
If you have any other health conditions, it is important that you follow
your doctor's directions to treat those conditions. By staying as healthy
as possible, you can lower your risk of developing CAD and its complications.
- Dying suddenly from cardiac problems
- Having a heart attack and permanently damaging your heart muscle
- Damaging your heart because of reduced oxygen supply
- Having irregular heartbeats (arrhythmias)
How is coronary artery disease
Treatment for coronary artery disease (CAD) may include lifestyle changes,
medicines, and special procedures. The goals of treatment are to:
- Relieve symptoms
- Slow or stop atherosclerosis by controlling or reducing the risk factors
- Lower the risk of having blood clots form, which can cause a heart
- Widen or bypass clogged arteries
Making lifestyle changes can help treat CAD. For some people, these changes
may be the only treatment needed:
- Eat a healthy diet to prevent or reduce high blood pressure and high
blood cholesterol and to maintain a healthy weight
- Quit smoking, if you smoke
- Exercise, as directed by your doctor
- Lose weight, if you are overweight or obese
- Reduce stress
In addition to making lifestyle changes, medicines may be needed to treat
CAD. Some medicines decrease the workload on the heart and relieve symptoms
of CAD. Others decrease the chance of having a heart attack or dying suddenly
and prevent or delay the need for a special procedure (for example, angioplasty
or bypass surgery).
Several types of medicine are commonly used to treat CAD.
- Cholesterol-lowering medicines help to reduce your cholesterol
to a doctor-recommended level.
- Anticoagulants help to
prevent clots from forming in your arteries and blocking blood flow.
- Aspirin, and other antiplatelet
medicines, help to prevent clots from forming in your arteries and blocking
blood flow. Blood contains small cells called platelets which clump
together to form clots. Antiplatelet medicines reduce the ability of
platelets to form clots. Aspirin may not be appropriate for some people
because it increases the risk of bleeding. Discuss the benefits and
risks with your doctor before starting aspirin therapy.
- ACE (angiotensin-converting
enzyme) inhibitors help to lower blood pressure and reduce strain
on your heart. They also may reduce the risk of a future heart attack
and heart failure.
- Beta blockers slow your
heart rate and lower your blood
pressure to decrease the workload on your heart. Beta blockers are
used to relieve angina and may also reduce the risk of a future heart
- Calcium channel blockers
relax blood vessels (arteries and veins) and lower your blood pressure.
These medicines can reduce your heart's workload, help widen coronary
arteries, and relieve and control angina.
- Nitroglycerin widens
the coronary arteries, increasing blood flow to the heart muscle and
relieving chest pain. Long-acting nitrates are similar to nitroglycerin
but are longer acting and can limit the occurrence of chest pain when
used regularly over a long period.
- Glycoprotein IIb-IIIa inhibitors are very strong antiplatelet
medicines that are used in hospitals during and after angioplasty or
to treat angina.
- Thrombolytic agents dissolve the clots that can occur during
a heart attack. Thrombolytic therapy is administered in the hospital.
Thrombolytic therapy and other treatments for heart attack are more
effective the sooner they are given after a heart attack starts. You
need to get to a hospital as soon as possible if you think you are having
a heart attack.
Angioplasty or bypass surgery may be used to treat CAD if:
- Angioplasty. This procedure
opens blocked or narrowed coronary arteries. It can improve blood flow
to your heart, relieve chest pain, and possibly prevent a heart attack.
Sometimes a device called a stent is placed in the artery to keep the
artery propped open after the procedure.
- Coronary artery
bypass surgery. In this procedure arteries or veins from other
areas in your body are used to bypass your narrowed coronary arteries.
Bypass surgery can improve blood flow to your heart, relieve chest pain,
and possibly prevent a heart attack.
Some people may need to have angioplasty or bypass surgery on an emergency
basis during a heart attack to limit damage to the heart.
- Medicines and lifestyle changes have not improved your symptoms.
- Your symptoms are getting worse.
Your doctor may prescribe cardiac rehabilitation (rehab) for angina or after
bypass surgery, angioplasty, or a heart attack. Cardiac rehab, when combined
with medicine and surgical treatments, can help you recover faster, feel
better, and develop a healthier lifestyle.
Almost everyone with CAD can benefit from cardiac rehab.
Cardiac rehab often begins in the hospital after a heart attack, heart surgery,
or other heart treatment. Rehab continues in an outpatient setting after
you leave the hospital.
The cardiac rehab team may include:
Rehab has two parts:
- Your family doctor
- A heart specialist
- A surgeon
- Exercise specialists
- Physical therapists and occupational therapists
- Psychologists or other behavior therapists
- Exercise training. This helps you learn how to exercise safely,
strengthen your muscles, and improve your stamina. Your exercise plan
will be based on your individual ability, needs, and interests.
- Education, counseling, and training. This helps you understand
your heart condition and find ways to reduce your risk of future heart
problems. The cardiac rehab team will help you learn how to cope with
the stress of adjusting to a new lifestyle and to deal with your fears
about the future.
Source: U.S. National Heart,
Lung and Blood Institute