A new test is available to diagnose coronary artery disease. In the past, noninvasive functional tests of the heart were used, such as treadmill tests and nuclear studies, to indirectly assess if there were blockages in thecoronary arteries. The only way to directly look at the coronary arteries was via a cardiac catheterization and coronary angiogram.
CT scans have been used to look at various anatomic regions, but have not been useful for the heart because the heart is continuously in motion. CT is very effective in looking at "static" areas, such as the brain, abdominal cavity, and extremities. Most early CT scanners take 1-8 pictures (slices) a minute, much slower than the rate of the heart. Just as taking a picture of a moving object with a camera results in a blurry picture, conventional CT scans of the heart are not helpful. A new generation of CT scanners which can take 64 pictures a minute is now available; with the use of a little medication to slow the heart rate to less than 64, CT images of the coronary arteries are now possible.
How is CT coronary angiogram performed and what are the risks of the procedure?
This procedure use intravenous dye which containsiodine and CT scanning to image the coronary arteries. While the use of catheters is not necessary (thus the term "noninvasive" test applies to this procedure), there are still some risks involved. In people allergic to iodine, pretreatment with medications is necessary to prevent allergic reactions to the dye. In people with abnormal kidney function and/or diabetes, the dye may worsen kidney function. Finally, there is radiation exposure which is similar to, if not greater than, that received with a conventional coronary angiogram. Nonetheless, this is generally a very safe test for most people, but should only be undergone when ordered by a physician familiar with the patient and their underlying medical condition.