Imaging tool reveals early
evidence of coronary artery disease
A doctor aims an electron beam at a patient's heart and discovers early
evidence of calcium deposits on blood vessel walls that 10 years later may
lead to heart attack. That once unlikely scenario is now possible, thanks
to a new imaging machine Emory doctors are using to aid diagnosis of atherosclerosis,
the sometimes deadly buildup of blockages in coronary arteries.
Randolph E. Patterson, director of cardiovascular imaging for the Emory
Heart Center, is serving as medical director for the new Lifetech Cardiac
Imaging Center-the first in Georgia to offer electron beam tomography, a
quick, painless, noninvasive and inexpensive means of imaging the heart.
Lifetech electron beam tomography does not require the physical exertion
that heart tests such as the exercise thallium stress test does. The complete
test requires only five to 10 minutes of the patient's time and involves
no needles, exercise, drugs, X-ray dye or undressing.
The special advantage of electron beam tomography over other noninvasive
cardiac tests is that it detects the atherosclerotic disease process itself
in the coronary arteries, Patterson said. Coronary atherosclerosis grows
progressively over time, like a time bomb with a variable delay detonation
time measured in years. Other noninvasive tests are not conducted until
the disease progresses enough to narrow the openings in the artery by at
least 50 percent-a narrowing that limits the maximum flow of blood through
the artery. When blood flow does not deliver enough blood to supply the
needs of the heart muscle, the heart may develop abnormalities that can
then be detected by ECG or other methods. And unlike most other tests, electron
beam tomography can detect coronary artery disease with equal accuracy in
men and women.
"If we know who has the disease, we can offer very effective treatment,"
Patterson said. "The problem has been that we often don't know who
has coronary atherosclerosis until the person has a heart attack, sudden
death or develops symptoms. At these points, treatment options decrease
or end. The electron beam tomography system provides an accurate test for
coronary artery disease per se-not just its consequences-before symptoms
appear."
The technology is an improvement over other computed tomography scanners
for cardiac imaging because it acquires images more quickly-about 10-14
images per second, Patterson said. The fast scanner is required to "stop
the motion" of the heart and its coronary arteries long enough to create
an accurate picture.
"If a person has coronary athersclerosis, the American Heart Association
recommends more intensive efforts to lower cholesterol levels and decrease
other risk factors. Patients who know they have the disease are more highly
motivated to change their lifestyle through improving diet, exercising and
quitting smoking," Patterson explained.
Chicago resident and former heart patient Jim Dunfee, for instance, credits
electron beam tomography with saving his life. Although he had no symptoms,
the test nonetheless detected advanced coronary artery disease. Dunfee subsequently
underwent six-vessel bypass surgery.
.
Heart disease is by far the leading killer of Americans-far more lethal
than AIDS and all cancers combined. The American Heart Association estimates
about 1.5 million Americans will experience a heart attack this year and
about one-third will die. Coronary artery disease kills six times the number
of women who die of breast cancer.
-Lorri Preston
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