Cardiac CT / Coronary CT Angiography

We are proud to offer comprehensive state-of-the-art cardiac CT and coronary CT angiography testing. Walter Reed Bethesda is recognized internationally as a center of excellence in coronary CT angiography where we perform these tests using the latest generation, most advanced CT scanner technology. Our highly trained CT imaging cardiologists work together with Walter Reed radiologists specifically trained in cardiac CT imaging.

Coronary CT angiography is a quick, non-invasive test that uses computed tomography (CT) to look at blood vessels that supply the heart muscle (the “coronary arteries”). Coronary CT angiography allows your physician to see whether or not plaque has developed in the coronary arteries that may result in “blockages” that could cause symptoms or increase your risk of a future heart attack.

If your doctor has ordered a coronary CT angiography test, there are important instructions that you should follow prior to arriving for your scan. Please see the links to the left which outline the potential benefits of coronary CT angiography, how the test is performed, where to arrive for your test and how to prepare for the test.

1. What is Coronary CT Angiography?
   1. Coronary CT angiography is a quick, non-invasive, highly accurate test that uses computed tomography (CT) to visualize the coronary arteries (arteries that supply the heart muscle). Coronary CT angiography allows your physician to see whether or not plaque has developed in the coronary arteries that may result in “blockages” and be the cause of your symptoms or increase your risk of a future heart attack. Coronary CT angiography has been shown to be a highly accurate test when performed by trained, experienced providers.
2. Potential Benefits of Coronary CT Angiography?
   1. Coronary CT angiography is especially useful to decide that the coronary arteries are not the cause of chest discomfort or shortness of breath (“rule-out a heart problem”). Also, coronary CT angiography is able to find both severe blockages, as well as plaque buildup in the coronary arteries that may not be causing severe narrowing at present, but may lead to heart problems in the future.
3. When is Coronary CT Angiography Used?
   1. Coronary CT angiography is generally considered best for individuals with symptoms that may be caused by coronary artery blockage but who have no prior history of coronary artery disease (no prior heart attack, stent or bypass surgery). It is also a very useful test for individuals who have unclear findings from a stress test. In certain cases, coronary CT angiography may be considered appropriate for patients who have previously experienced a heart attack or have undergone coronary stent placement or coronary artery bypass surgery. Numerous other possible indications exist for coronary CT angiography, which may be further explained by your doctor.
4. How is Coronary CT Angiography Performed?
   1. CT is a non-invasive technique that uses x-rays to obtain images of the body. An electrocardiogram, or measure of a patient’s heart rhythm, is recorded during the coronary CT angiogram so that images can be matched with the motion of the heart. During the coronary CT angiogram, contrast (iodine dye) is injected into a vein in the arm so that the coronary arteries can be seen. Some patients may feel a “warm” sensation when the contrast is injected. Allergic reactions to the contrast dye occur very rarely.
5. How to Prepare for a Coronary CT Angiography
   1. Based upon your condition, the reason for testing and the doctor performing the coronary CT angiogram, you may be asked to do the following – always check with your doctor for your preparation before the test:
      1. Take a beta-blocker medication to lower your heart rate. You will typically be prescribed a beta-blocker, such as metoprolol that you will take approximately one hour prior your scheduled arrival time for your coronary CT angiography. This medication is generally very safe and well-tolerated.
      2. You must have your blood drawn to check your kidney function by the lab if they have not been checked recently. Women of childbearing potential may be required to have a pregnancy test done on the day of the scan. Individuals with mild kidney disease may still receive injected contrast but may require additional medications and IV fluids before or after the test.
      3. Avoid caffeinated drinks or foods (e.g. coffee, tea, sodas, energy drinks, and chocolate) for 12-24 hours prior to your test.
      4. Do not eat for 4 hours or drink for 1 hour prior to the test, unless otherwise instructed by your doctor.
      5. Drink plenty of water the day before your test. Drink plenty of fluids after your CT scan, as well.
      6. Do not take certain medications such as Viagra, Cialis or Levitra for at least 72 hours prior to your coronary CT angiogram test.
      7. Temporarily stop taking Glucophage (Metformin) for 48 hours AFTER the test.
      8. Inform your doctor of any medications you are taking – including over-the-counter pain medications such as Advil or Motrin.
      9. If you have an allergy to iodine contrast agents, you may be given medications to prevent a serious reaction. These medications may include Benadryl (diphenhydramine). If you are given Benadryl (diphenhydramine) prior to your CT scan you will need to arrange for someone to drive you home as this medication can make you drowsy and it unsafe for you to operate a vehicle.
      10. Women should avoid wearing bras with under wires or large metallic clasps; a sports bra is an acceptable alternative.
      11. LOCATION: arrive on the AM of your scan to the Multidisciplinary Procedures Area of the Cardiology Clinic, 2nd Floor, in the Arrowhead Building (Bld. 9) - “Procedures Check-in”, room 2825.
      12. If you have questions, please call 301-295-0390 and ask for the CT Fellow or CT Staff.
6. What Will Happen During and After the Coronary CT Angiogram?
   1. A nurse or technologist may ask you to remove your clothes above the waist and wear a hospital gown. You may be asked to remove metal objects such as jewelry, which can affect your CT images.
   2. An intravenous line (IV) will be inserted into a vein in your arm.
   3. The CT scanner is a machine with a large ring-like or doughnut-like structure that has a sliding bed in its center. You will be asked to lie on your back on the scanner bed. While you may lie on this table for approximately 10-30 minutes, most of the time will involve preparation. The actual scan images are acquired in a few seconds.
   4. The technologist or nurse will apply sticky patches called electrodes on your chest. These will be used to monitor your heart beats during the exam. Excessive hair on the chest may be shaved to allow for adequate electrode placement.
   5. You may be given additional doses of beta blocker medications (e.g., metoprolol) in order to obtain a lower heart rate. Coronary CT angiograms are typically of better image quality when your heart rate is below 65 beats-per-minute.
   6. You will be asked to lie still and you will receive instructions to hold your breath for short periods of time (less than 15 seconds) while pictures are taken. It is very important to be absolutely still and to not breathe, move or swallow while the pictures are being taken.
   7. During some steps of the test, contrast dye will be injected through the IV line. This may cause a warm feeling all over your body, which usually disappears within a minute or so.
   8. Following your coronary CT angiogram, you will be transported back to the preparation and recovery area for a period of brief observation or released directly from the CT scanner area after you have been observed. Your IV will be removed and you will be allowed to get dressed and leave the hospital.
      1. Unless otherwise instructed, you may resume your usual activities after the scan is performed.
      2. The results of the scan are generally read and sent to the doctor that ordered your test on the day of your scan.
      3. In addition to evaluating the coronary arteries, the doctors performing and interpreting your coronary CT angiogram may occasionally visualize abnormalities in other areas, outside of the heart. These findings will also be provided in your coronary CT angiogram report and to your doctor.
   9. The total duration of time that you are at the hospital for your cardiac CT may vary and take up to 3 hours. Please plan accordingly.
7. Coronary Artery Calcium Scan
   1. In some cases, your doctor may order a coronary artery calcium scan. This study is typically ordered for patients who do not experience any symptoms. The results of this test may provide you and your doctor with more information regarding plaque build-up in your heart arteries and information about your future risk of having a heart attack.
   2. While there are many similarities between a coronary CT angiogram, the coronary artery calcium scan does not require an injection of contrast dye or the use of an IV line in your vein.
   3. Coronary artery calcium scans can be use to show hardened (calcified) plaque build-up in the coronary arteries, which allows your doctors to estimate the risk of future heart attacks. However, unlike a coronary CT angiogram, a coronary artery calcium scan cannot show blockages in the coronary arteries.
   4. In some cases, your doctors may perform a coronary artery calcium scan prior to performing a coronary CT angiogram. This is done to assist your providers in the proper performance of the coronary CT angiogram (how best to image your coronary arteries).
8. Useful Links and information
   1. WRNMMC Printable Patient Instructions for Coronary CT Angiography
   2. SCCT