What is a CT Scan of the Coronary Arteries (CTCA)?
The blood vessels that supply blood to the heart are the coronary arteries (CA). Previously the only accurate way of accessing these was by a conventional coronary angiogram. This is an invasive test which requires hospital admission and a contrast injection through a large needle in an artery in your groin.
Today the coronary arteries for most people can now be accessed using ultra-fast computed tomography (CT) scanners. The benefit is that a CTCA is a less invasive test that involves a contrast injection through a vein in the arm. It is quicker, has less potential complications and has been shown to be as accurate as a conventional coronary angiogram.
What are the Risks?
As with any medical procedure there are some risks associated with the scan:
- Radiation: X-rays are used during the scan. We are proud to use the lowest dose CT scanner. The typical dose is around 0.5mSv – 2mSv depending on the size of the patient and the technique used. At the lower dose this amount of radiation is about 1/4 of the amount of background radiation that you receive ina year from natural sources such as cosmic rays. This dose is S – 20 times LESS than the dose from some other CT scanners.
- Contrast Reaction: Very rarely people experience an allergic reaction to the contrast (dye). This usually manifests as an itchy rash which settles down by itself. Asthmatic patients may experience worsening of their asthma shortly after the injection. Patients with kidney failure require a cautious contrast injection as contrast can (usually temporarily) worsen kidney function. There is a 1 in 250 000 chance of a life threatening (anaphylactic) reaction.
- Contrast leakage: Very rarely the contrast goes into the tissues under the skin in your arm rather than into the vein. This can cause bruising, swelling andmild This usually resolves by itself. We will perform a test injection using saline to help prevent this from happening. In addition, a member of staff will be with you to watch the injection.
What to Expect
- You will change into a gown and have your blood pressure and heart rate monitored. You will be assessed by a radiologist or cardiologist. You may require additional medication.
- You will have a cannula (plastic needle) inserted in the vein near your elbow and ECG leads placed on your chest.
- You may be given GTN (Nitrolingual spray) under the tongue just before the scan to relax your coronary arteries helping us to obtain the best images possible. This may give you a mild headache.
- You may notice a warm sensation and a metallic taste during the contrast injection. This is normal.
- For some scans. you need to hold your breath for up to 15 seconds and to lie flat for about 5-10 minutes.
- Although the scan time is fast – 1/4 second the process is more time consuming. Allow up to 2 hours.
- Allow for post procedure care and monitoring for a short period of time after the completion of the examination. The effects of beta-blockers should wear off after half a day but please consider organising someone else to provide transport home.
- Your referrer will be notified directly of any urgent/ unexpected findings on the day of examination. Routinely test results will take 2-3 days.
- If you have any questions about the test please discuss this with your referring doctor. Also, there are radiographers and radiologists on hand atHeartscan Australia who will be able to address any of your concerns.
Test preparation for Coronary CT – please follow instructions
- PRE-MEDICATION REGIMEN – AIM: HR Equal to or less then 60 bpm
- Metoprolol 50-100 mg night before and 8am morning of CTCA prescribed by referrer
- Chronic beta blocker / calcium channel therapy to heart rate Equal to or less then 60 bpm
- Other preparation
- Take ALL normal morning medications except metformin
- Fast for 4 hours if possible prior to CTCA
- No caffeine, coffee, tea, energy drinks for 24 hours prior to CTCA
- No Cialis, Viagra, Levitra or similar for 36 hours prior to CTCA