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What is CT coronary angiography? 

Computed tomography (CT) coronary angiography is a type of x-ray imaging procedure that uses a contrast dye, a CT scanner and a computer to produce images of the heart and the blood vessels that supply it (coronary arteries).

This test helps determine narrowing and blockages of coronary arteries. It uses an iodine-based contrast dye to ‘light up’ the heart and its blood vessels and clearly define their appearance on the CT images. (Read more: Coronary heart disease)

Coronary arteries may become narrow and blocked due to the build-up of plaque (fat, cholesterol and calcium deposit) along their inner lining.

  1. Who cannot have CT coronary angiography?
  2. Why is CT coronary angiography done?
  3. How should I prepare for a CT coronary angiography?
  4. What is the procedure for a CT coronary angiography?
  5. How does CT coronary angiography feel?
  6. What do the results of CT coronary angiography mean?
  7. What are the risks and benefits of a CT coronary angiography?
  8. What happens after the CT coronary angiography?
  9. What other tests can be done with a CT coronary angiography?
Doctors for CT Coronary Angiography

CT coronary angiography should be avoided in pregnant women, as it can cause harm to the unborn baby. A contrast dye scan is not done in diabetic people or those who have severe kidney disease.

Your doctor may order a CT coronary angiography if you have:

You will be asked to wear loose and comfortable clothes or a hospital gown. Metal objects, including jewellery, hearing aids and removable dental work must be left at home or removed before the test. Your doctor will explain the details of the procedure and will ask you to sign a consent form.

Tell the doctor if you:

  • Are pregnant or nursing
  • Are allergic to any medicines or the contrast dye
  • Have any health problems, like diabetes, asthma or kidney disease
  • Are taking any medication

You may have to avoid eating and drinking for a few hours before the test.

Your doctor may ask you to avoid diet pills, caffeinated beverages and certain medications that can interfere with the test. They may prescribe beta-blocker medicines to be taken a night before the test to lower your heart rate.

The test is performed in the following manner:

  • You will be asked to lie down on the examination table of the scanner, which is a large machine with a tunnel in the centre. 
  • The technologist will place small electrodes (sticky discs) on your chest that will be connected to the electrocardiograph (ECG) monitor to show your heart’s activity.
  • He/she will inject the contrast dye through an intravenous (IV) line placed in your arm. You may also be given a beta-blocker orally or through the same IV line.
  • Another medicine called nitroglycerine, which makes the arteries wider and clearly visible, may also be given as a tablet, a patch on your skin or a spray under your tongue.
  • As soon as the dye reaches your heart, the machine will be turned on.
  • To improve image quality, the technician will ask you to raise your arms over your head during the scan.
  • While the images are being taken, the table will slowly move in and out of the scanner, and you will hear the machine rotate around you.
  • The technologist will go to another room to operate the machine but will be able to see you and communicate with you using a speaker.
  • You will be asked to remain still and hold your breath for five to 15 seconds while the scanner captures images.
  • After the test, the IV line will be removed.

This test is usually completed in 15 minutes but can take longer.

CT coronary angiography is a painless diagnostic test. However, you may feel slightly uncomfortable remaining still for the procedure.

A pinprick may be felt when the needle is inserted into the IV line. Also, you may experience a feeling of warmth, metallic taste in the mouth or a flushing sensation when the dye is injected. 

Beta-blockers may cause lightheadedness and dizziness. You may hear whirring or clicking sounds as the machine rotates around you.

CT coronary angiography detects the presence of blockages in coronary arteries. It provides information on:

  • The number of arteries that are blocked
  • The location of the blockages
  • The severity of the blockages

The benefits of CT coronary angiography are:

  • It is a non-invasive test that provides detailed images of your coronary arteries.
  • No x-ray radiation is left in the body after the test.

The risks of CT coronary angiography are:

  • The contrast dye can be harmful to people with kidney disease.
  • The contrast dye can cause an allergic reaction in some people.

Unless advised otherwise, you can continue with your usual activities after the test. You must drink a lot of water to help flush the dye out of your body.


The following tests may be done with CT coronary angiography:

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