Coronary
Artery Disease and CT Imaging of the Heart
This
question-and-answer guide will help you understand the
test and let you know what to expect before, during
and after the procedure.
Brigham and Women's Hospital (BWH) has been at the forefront
of CT scanning since its introduction. In fact, BWH
had the first state-approved body CT scanner and has
been performing CT scans since 1977.
BWH now possesses four state-of-the-art CT scanners,
each of which can perform "spiral" CT, giving the latest
technology for the best patient care. |
Frequently
Asked Questions
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Other Investigational CT Scan Procedures:
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1.
What is coronary artery disease? |
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The coronary arteries are the vessels that supply the
heart with blood, which carries oxygen and nutrients.
Coronary artery disease is, simply, the narrowing of
these vessels. This narrowing is caused by a three-step
process:
1. Cholesterol and other fatty materials are deposited
on the walls of the vessels, and the body naturally
surrounds these foreign materials with scar tissue.
This scar-covered deposit—literally forming a
lump on the inside of the vessel—is called “plaque.”
2. The plaque continues to build up over time. New deposits
form around the uneven texture of existing plaques.
The process causes the affected section of the artery
to lose flexibility and become hard. This is called
“atherosclerosis.”
3. Eventually, plaque reduces the interior diameter
of the vessel and restricts the flow of blood. Sometimes,
the deposits completely occlude—block—the
artery.
When blood flow is reduced, less oxygen is carried to
the heart muscle. Lack of oxygen may cause pain (“angina
pectoris”) or even the destruction of a portion
of the heart muscle (myocardial infarction or “heart
attack”).
Coronary artery disease is the leading cause of death
in the United States. Each year more than 750,000 Americans
experience a myocardial infarction; this heart attack
is often the first sign of their coronary artery disease.
The annual costs associated with caring for patients
with coronary artery disease are a tremendous burden
to the healthcare system. |
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2.
Am I at risk of getting coronary artery disease?
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The risk factors linked to coronary artery disease are
well known. They include high cholesterol (and other
blood lipids), high blood pressure, and a family history
of coronary artery disease, among others. If you have
any of these conditions, you have an increased risk
of having or getting coronary artery disease. Smoking
cigarettes is also an important risk behavior. If you
smoke, you are far more likely than a non smoker to
have or develop coronary artery disease. |
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3.
What should I do to prevent coronary artery disease?
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The most important factor in determining your risk for
having or developing coronary artery disease is your
lifestyle. The best prevention against coronary artery
disease is to quit smoking, to eat a healthy, balanced
diet, and to exercise on a regular basis. If these steps
are insufficient to reduce your cholesterol or blood
pressure to normal levels, medications may also be helpful.
If you are affected by factors that put you at a higher
risk of having or getting coronary artery disease (see
above), you should consult with a cardiologist, internist
or family practitioner. These physicians can help you
make lifestyle changes to protect your health. |
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4.
CT Imaging of the Heart and Coronary Calcium Screening
- what can it do for me? |
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Computed tomography (CT) scanning—also known
as computed axial tomography, or CAT scanning—is
being investigated as a method of detecting coronary
artery disease early. The CT scanner consists of a
patient couch and an open ring that rotates around
the patient during the test. Advanced x-ray equipment
is mounted on the ring. As the ring rotates around
the patient, the x-ray “cameras” acquire
cross-sectional images of the heart and surrounding
arteries. In our institution, only cutting-edge CT
scanners are used for imaging of the heart and coronary
arteries. These state of the art scanners acquire
high-resolution images in the shortest possible length
of time. In fact, each individual image is obtained
so quickly that it appears motion-free, even as the
heart continues to beat normally. The procedure is
painless. Since it is a type of x-ray procedure, however,
there is some radiation exposure during the exam.
By using only high-speed scanners and low-dose technology,
we are able to minimize that exposure. In our facility,
a patient undergoing CT screening for coronary artery
disease will be exposed to approximately the same
amount of radiation he or she would normally absorb
from background sources—such as the sun—in
one year.
CT scanning can be used to assess a person’s
risk for coronary artery disease in two ways. The
first approach is called “coronary calcium screening.”
In this procedure, the CT scanner is used to detect,
count and measure calcifications—deposits of
calcium—within the coronary arteries. These
deposits of calcium are known to indicate atherosclerosis.
Unusual amounts of calcifications may be the first
sign of developing coronary artery disease; they can
often be found before symptoms occur and even before
other tests such as an EKG or treadmill testing (so-called
“stress testing”) indicate the presence
of the disease.
If you are over the age of 60 years, do not smoke
and have normal amounts of calcification in your coronary
arteries on CT coronary calcium screening, your likelihood
of having coronary artery disease is extremely low.
Most patients over 60 do have some degree of calcification
in their coronary arteries. Only abnormally high levels
of coronary calcium would indicate an increased risk
of coronary artery disease. If abnormal calcification
is found on your CT images, it may lead your physician
to evaluate you or treat your symptoms more aggressively.
In some instances, coronary artery disease may be
present without calcifications. If you are under the
age of 60 and have other risk factors (for example,
if you are an active smoker or have high cholesterol
or a family history of coronary artery disease), you
could have coronary artery disease without calcifications.
In these cases, contrast-enhanced CT images of the
coronary artery walls can help doctors find noncalcified
(“soft”) plaque. A “contrast agent”
is a substance that shows up very clearly and very
distinctly on the CT image. Images taken when a contrast
agent is in the bloodstream can show irregularities
in the artery walls and stenoses (narrow areas), which
may indicate the presence of soft plaques. This procedure
is under active investigation at this time.
If you experience symptoms of coronary artery disease,
such as chest pain when resting or exercising, you
should talk to your primary care physician. He or
she will determine what diagnostic tests may be appropriate
for you. |
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