Cardiac Imaging: Coronary CTA

WebMD Live Events Transcript

New imaging techniques are giving doctors a clearer picture of the heart and allowing them to better manage heart disease. A Coronary CTA is a heart-imaging test to determine if either fatty deposits or calcium deposits have built up in the coronary arteries, which supply blood to the heart muscle. We discussed the latest noninvasive cardiac imaging techniques with Richard White, MD, and Mario Garcia, MD, from the Cleveland Clinic Heart Center. They joined us on Aug. 16, 2005.

The opinions expressed herein are the guests' alone and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.

MODERATOR:
Welcome to WebMD Live, Dr. White and Dr. Garcia. Thank you for joining us today.

GARCIA:
Thank you. It's a pleasure to join you.

WHITE:
Thank you for the invitation to be here.

MODERATOR:
Please explain the role of imaging in diagnosing heart disease.

GARCIA:
There are different tests that we have to do in order to characterize the nature of a patient's symptom or the likelihood of that patient having a cardiac problem based on their reflectors. The most common imaging tests that we use in cardiovascular medicine are echocardiography or ultrasound of the heart, nuclear profusion imaging, cardiac magnetic resonance, or MRI, and most recently, cardiac CT, computer tomography.

WHITE:
Imaging could be said to have begun even with an X-ray of the chest, and the fundamental purpose is to get some direction as to the key problem at hand and then add on with more sophisticated or more targeted diagnostic imaging to delve further into it. And in many ways, it's to give the user who might be a surgeon -- or whoever is administering care to the patient -- something in their mind's eye which has direct benefits, such as reduced exploratory surgeries.

MODERATOR:
Let's talk about the advantages and disadvantages of noninvasive heart procedures for diagnosis.

WHITE:
The one disadvantage of the noninvasive imaging techniques is they do not provide the opportunity of a measurement of a pressure or to sample the blood directly, so we are not provided direct measures of the ability of the blood to carry oxygen or the pressure generated by a pumping chamber, although we can surmise some of these things indirectly through noninvasive imaging. The advantage is in the title; it is noninvasive.

GARCIA:
The invasive diagnostic methods in many cases are more accurate. Nevertheless, they do carry a significantly higher cost and in general, a higher risk to the patient.

MODERATOR:
When would you decide to use noninvasive vs. invasive procedures?

GARCIA:
Depends on the information that we are trying to achieve but in general, we like to use noninvasive diagnostic methods as a start and only recur to invasive methods when we need additional information.

MEMBER QUESTION:
Are there times when you would go straight to the cath lab to see what is going on?

WHITE:
Yes. Certainly catheterization of the heart is the backbone of understanding coronary disease and indicating its treatment, whether it be by a catheter based or a surgery, so I think it's expected a patient would go directly there if there is a high suspicion of a narrowing of the arteries which would need such intervention, but the suspicion may be preceded by a noninvasive indicator.

MODERATOR:
Can you please explain how coronary CTA works?

WHITE:
The basic principles of CT involve a rotating X-ray beam with the detection, on the other side of the patient, of the ability of the different tissues to absorb the X-ray. And because it's viewing the body from multiple different angles and can be done over a long portion of the body, you end up with a three-dimensional column of information that can be viewed in multiple directions.

MODERATOR:
What is involved from a patient's perspective?

GARCIA:
The patient can have this procedure done in the hospital setting or in an outpatient setting. The preparation required is minimal. An intravenous catheter is placed in a vein in the arm. A drug is typically used to control or slow down the heart rate, and contrast is injected into the vein. Then the procedure is performed typically over a few seconds. The patient can get dressed and drive back home immediately, practically after the procedure.

MODERATOR:
How long does it take to get results?

WHITE:
From start to finish the cardiac CT examination takes approximately 10 minutes. The information is made available to the noninvasive imager immediately. Depending on the presence or absence of disease and the extent of disease, the interpretation might take anywhere from five minutes to 15 minutes.