|
The coronary computed tomography angiogram (CTA) is revolutionizing
cardiology by revealing coronary artery blockages within minutes and for about
one-tenth of the cost of invasive catheterization.
Studies have shown that early detection of calcium deposits in the arteries
can help predict whether a patient is likely to have a heart attack. Usually a
patient arriving in the emergency room with chest pains is admitted for 24-hour
observation and diagnostic testing, including X-rays and scans. Images produced
by the coronary CTA illustrate whether there are calcium deposits in the
arteries.
"The speed, processing and quality of images compared to other cardiac
imaging, such as ultrasound, cardiac catheterization or MRI, are superior,"
explains Mario Garcia, M.D., Co-director of the Center for Integrated
Noninvasive Cardiovascular Imaging. The CTA scan produces 64 images in about
five to 10 seconds.
Just before the scan, technicians administer a beta blocker to slow down the
patient’s heartbeat. Using an electrocardiogram, the scan is timed to
photograph the heart at the same point in the pumping cycle for six or seven
beats. Once the image is received on the computer screen, technicians use tools
similar to those found in graphics editing software to isolate the coronary
arteries.
"We can determine if soft, unstable or calcified deposits are present in
the arteries," says Dr. Garcia, adding that those results determine how a
cardiologist can treat the patient - with close monitoring and lifestyle
changes, use of statin drugs, angioplasty, surgery or some combination of those
treatments.
The coronary CTA is not without its downside, namely that it requires
training and expertise to maximize its effectiveness. "It’s more common
for physicians untrained in this technology to see things that aren’t
there," explains Dr. Garcia. "Training is crucial." Cardiologists
also are concerned that the coronary CTA could be overused and lead to incorrect
diagnoses and unnecessary surgical treatments.
Patients need to be aware that, as with most computed tomography scans, it
involves higher doses of radiation exposure. In addition, some patients may be
allergic to the contrast dye used. The technology’s limitations also make it
unsuitable for extremely obese patients and those with irregular heart rhythms.
|
