About What to Expect
About the Risks
What: It is an imaging technique that uses Computed Tomography (CT) scanner to obtain images of the heart and coronary arteries. It will be able to give valuable information of the structures of the heart and of the coronary arteries.
How: The CTCA scanner takes multiple images of your heart and coronary arteries by rotating the scanner around you while you lie on the table. The scanning time takes only less than a second, but you will need to lie on the scanner table for up to ten minutes. The CTCA scanner will then reconstruct the images into a 3D picture of your heart, and will be able to analyse if you have any significant narrowing or blockages in your coronary arteries.
Why would your doctor choose this investigation (CTCA) over the conventional coronary aniography?
- CTCA is a non-invasive investigation whereas the conventional coronary angiography is an invasive test which requires hospital admission and involves insertion of tubes (catheters) via a arterial sheath to insert or “engage” the coronary artery, thereby allowing dye (contrast) to be directly injected into the arteries. (see information on coronary angiography). On the contrary, CTCA only involves injection of contrast through an intravenous cannula (plastic needle or drip line).
- You may still require invasive coronary angiography if there are significant narrowing or blockages in your coronary arteries.
How do I prepare for the scan?
- Your cardiologist will prescribe a heart rate slowing medication to be taken at least one day prior to the scan. Better quality images can be taken if your heart rate is slower, and therefore better identify any significant narrowing and blockages in the coronary arteries
- If you have any significant allergies or asthma, your doctor will prescribe a medication to reduce any significant allergic reaction towards the dye (contrast) or to reduce the chance of an asthmatic attack.
- You can take all your usual medications if you have any except metformin on the day of the scan.
- You will need to fast for 4hours prior to the scan.
- Do not take coffee, tea, energy drinks or any other food and drinks containing caffeine for at least 24hrs prior to the scan.
- Do not take Cialis, Viagra, Levitra or similar medications for 36hrs prior to the scan.
About What to Expect
What can I expect during the scan?
- You will change into a gown and have your blood pressure and heart rate monitored. You will be assessed by your Cardiologist or Radiologist, and may require additional medication as determined by them.
- You will have a cannula inserted in the vein near your elbow and ECG leads placed on your chest.
- You will be given GTN (nitrolingual spray) under the tongue just before the start of the scan in order to relax your coronary arteries so as to obtain the best optimal images. This medication may, however, give u a mild headache.
- You may required to hold your breath for up to 15seconds and to lie flat for 5-10mins during the scan. Although the scan itself takes only less than a second, the whole process time can take up to 2hrs.
- During the injection of contrast, you may notice a warm sensation and a metallic taste. This is normal.
- Following the completion of the scan, we will monitor you for a short period of time before discharging you.
About the Risks
Are there still risks involved in this non-invasive investigation?
There are minimal risks associated with a scan.
- Radiation: The CTCA scanner will use the lowest dose of radiation possible to achieve the best optimal images of your heart and coronary arteries. At a lower dose, this amount of radiation is about ¼ of the amount of background radiation that you may receive in a year from natural sources such as cosmic rays.
- Contrast reaction: Very rarely people experience an allergic reaction to the contrast. It may manifest as an itchy rash which usually settles down by itself. However, 1 in 250,000 may develop a life-threatening (anaphylactic) reaction. Asthmatic patients may also experience worsening of their asthma shortly after contrast injection. Patients with kidney failure may also experience (usually temporary) worsening of their kidney function.
- Contrast leakage: The contrast can very rarely goes into the tissues under your skin and may cause swelling and bruising. This will usually resolves by itself.