A computed tomography scan — commonly called a CT scan or CAT scan — is a test that uses X-rays to view specific areas of your body. These scans use safe amounts of radiation to create detailed images of the body, which can help your doctor to detect any problems. A heart, or cardiac, CT scan is used to view your heart and blood vessels.
During the test, a specialized dye will be injected into your bloodstream. The dye is then viewed under a special camera in a hospital or testing facility.
A heart CT scan may also be called a coronary CT angiogram if it’s meant to view the arteries that bring blood to your heart. The test may be called a coronary calcium scan if it’s meant to determine whether there is a buildup of calcium in your heart.
Your doctor may order a heart CT scan to look for certain conditions, including:
- birth defects in the heart (congenital heart disease)
- buildup of a hard substance known as lipid plaque that may be blocking your coronary arteries
- defects or injury to the heart’s four primary valves
- blood clots within the heart’s chambers
- tumors in or on the heart
A heart CT scan is a common test for people experiencing heart problems, since it allows your doctor to explore the structure of the heart and the adjacent blood vessels without making any incisions.
A heart CT scan carries very few risks. Most of the dyes used for CT scans contain iodine, which is later flushed from the body by the kidneys. If your kidneys have been impacted by disease or infection, such as diabetes, you may need to drink extra fluids after the test to help your kidneys remove the dye. However, newer dyes carry much less risk to the kidneys.
As with any X-ray, there is some exposure to radiation. While typically harmless, this is an important issue for women who are pregnant or could be pregnant. The levels of radiation are considered safe for adults — there have been no documented side effects from low levels of radiation — but not for a developing fetus.
Your doctor will typically ask you to fast for four to eight hours before the scan. You’ll be able to drink water. However, avoid caffeinated drinks since caffeine can affect your heart rate.
You will be required to lie down on a table during the exam, so you may want to wear loose, comfortable clothing. You will also need to remove any jewelry and other metal items from your body, such as piercings.
After the test, you will be able drive yourself home. There is no need to arrange for transportation.
A heart CT scan is performed in a hospital’s radiology department or a clinic that specializes in diagnostic procedures.
You may be given a beta-blocker before the scan. This medication will slow down your heart so that clearer pictures can be taken. You’ll also be given an IV so that the technician can inject the radioactive dye into your arm. Small, sticky discs called electrodes will be placed onto your chest to record the scan.
At the start of the scan, you’ll lie down on a bench. The technician may want you to lie in a specific position. He or she may use pillows or straps to ensure that you stay in the correct position for long enough to get a quality image. You may also have to hold your breath during brief individual scans, which last only 10 to 20 seconds.
To start the scan, the technician will move the table — via a remote from a separate room — into the CT machine. A CT machine looks like a giant doughnut made of plastic and metal. You will most likely go through the machine several times. Although you will be in the room by yourself, the technician will be able to talk to you via an intercom.
After a round of scans, you may be required to wait for a few minutes while the technicians review the images to ensure they are clear enough for your doctor to read. The whole test should take no longer than 10 minutes.
After the procedure, you’ll be able to leave and go about your day. The dye will naturally work its way out of your body. Drinking more water will help speed up this process.
Getting the results from your heart CT scan doesn’t take long. Your doctor or the technician will go over the results with you.
Depending on what the images show, your doctor will advise you of any lifestyle changes, treatments, or procedures that need to be done.