CT Angiography: Coronary Computed Tomography Angiogram
A coronary computed tomography angiogram is a diagnostic imaging test that uses advanced technology to produce high-resolution, three-dimensional images of the moving heart and its vessels. The scan may be carried out on individuals who have been identified as possessing a high risk for coronary disease. This quick, painless test clearly defines plaque, calcium build up and narrowed arteries, as well as damaged muscle.
How does the test work?
CT Angiography combines the technology of CT scan and traditional angiography. X-rays are used to obtain multiple cross section images or slices, which in turn are reconstructed by a computer into the three-dimensional pictures. Contrast dye is injected into a vein to provide detailed images of the blood vessels and tissues of the heart.
How do I prepare for the test?
Arrive at The Heart Institute in comfortable clothing for your procedure. Be sure to remove all metal objects, jewelry and accessories. If your doctor has specified that contrast dye will be used in your procedure, you will be asked not to eat or drink anything immediately beforehand. As the CT angiography test is considered low-risk and noninvasive you will be capable of driving yourself home after the test and should not experience any discomfort.
What can I expect upon arriving at The Heart Institute?
When you arrive at The Heart Institute you will be shown through to the radiology department. The CT images are taken within a large box-shaped machine with a hole and a short tunnel that contains of a patient examination table. Patients will lie down on the table while it slides in and out of the tunnel.
So that images aren’t blurred by the motion of your heartbeat, a beta-blocker medication may be administered to momentarily decrease heart rate. While the scan takes place, you will be asked to lie very still to ensure the accuracy of images taken of your heart and surrounding tissues.
Your technician will place electrodes on your chest to monitor your heart throughout the test and will talk you through the process via an intercom system. While you are lying on the table, the x-ray tube will move around your chest to capture several angles. You will not see this tube moving but you will hear a whirring sound.
What happens after the test?
Once your CT angiogram is completed you will be able to drive yourself home or, if necessary, immediately return to work. The procedure is generally easy and painless, although some people can find the process slightly stressful or claustrophobic. Your scans will be available shortly after your test is complete and interpreted by a radiologist. Your doctor will go through your results with you and will suggest steps to follow, which may include a follow-up scan, treatment or life-style changes.
Who needs CT Angiography?
This test can be used to check your heart for various conditions, but primarily it is used to diagnose or exclude the presence of coronary artery disease. It can be helpful in patients with an intermediate risk for heart disease with suspicious cardiac symptoms, CT angiography is recommended to patients with chest pain and low risk profiles, as well as people with unclear or inconclusive stress tests and with suspected congenital abnormalities of the coronary arteries.
What are the risks?
You will be exposed to a small amount of radiation during the procedure because of the X-ray technology used. This exposure equates roughly to the amount of radiation the average American is exposed to over a 3-year period. This amount is usually harmless but excessive radiation exposure has been linked to cancer.
Although reactions are rare, some patients may experience allergic reactions to the dye used for heart definition. If you have a known allergy, alert your doctor and alternative dyes may be used or a combination of steroids can reduce the reaction risk.
Pregnant mothers are advised against CT angiograms because of the risk radiation poses to an unborn child. Nursing mothers should not breast feed for 24 hours following the procedure.
What are the benefits?
- Eliminates the need for traditional, invasive angiogram testing in which a thin tube (catheter) is inserted into an artery in your arm or leg. The catheter is then advanced to the area of your heart to be examined. This can be uncomfortable, requiring sedation or general anesthetic.
- Reveals the health of surrounding heart tissues, and screens for general heart abnormalities and venous disease.
- Radiation is NOT stored in the body after the procedure and poses no immediate side effects.
When will the procedure not be performed?
Overweight patients may not be suitable for the procedure due to limitations of the machinery and equipment. The CT scanner has a fixed dimension and general weight restrictions of 450 pounds.
Patients who have had previous reactions to the contrast dye, who have kidney disease or severe diabetes will be advised against the procedure, as the kidneys may not be strong enough to endure the dye.