Health Care Imaging

Cardiac CT

What part of the anatomy is examined by a cardiac CT?

A Computerised Tomography (CT) scan, uses x-rays and computer systems to create a three dimensional image of different areas of the body. During a CT scan the patient lies on an x-ray bed which moves in and out of a large, circular scanner, taking multiple images of the area being scanned.

What is a cardiac CT?

A cardiac CT, or CT Coronary Angiogram, is a specialised non-invasive procedure which uses a mixture of x-ray technology, computer systems and a contrast medium to produce detailed three dimensional images of the heart, arteries and blood vessels.

What part of the anatomy is examined by a cardiac CT?

Cardiac CTs are used specifically to examine the heart.

What conditions can be diagnosed by a cardiac CT?

Cardiac CTs are typically used to detect and aid in the diagnosis of coronary heart disease.

Why is a cardiac CT required instead of a Coronary Angiogram?

A cardiac CT is a non-invasive procedure, which makes it ideal for checking whether a patient with low risk heart-related issues or symptoms has a coronary artery disease. Doctors also use cardiac CTs to check for blockages and damage to the coronary arteries. Doctors may also require patients to get a cardiac CT scan before or after other coronary procedures.

What are the Risks and Complications of a cardiac CT?

A cardiac CT is a relatively low risk procedure as it is non-invasive, the contrast is injected through a cannula in the arm.

During a cardiac CT, patients are exposed to more radiation than in a typical x-ray as multiple images are taken of the heart, although the dose is typically lower than a standard Coronary Angiogram. Although the lowest radiation doses possible are used, any radiation slightly increases the risk of developing cancer later in life. The risk is slightly higher in younger patients.

Some people can be allergic to the contrast, and this is more likely if you have other multiple severe allergies. Allergic reactions to the x-ray dye are usually mild and can be treated with medication.

There is a very minor risk that patients may suffer from a severe reaction to the contrast medium and experience:

  • Low blood pressure
  • Anaphylactic shock
  • Cardiac Arrest

What consequences are there if the suspected condition is undiagnosed or untreated?

Coronary artery disease is a serious illness, which if left untreated can lead to the development of other serious conditions including:

  • Heart attack
  • Arrhythmia
  • Heart failure
  • Death

What are the pros of a cardiac CT?

  • A CT coronary angiogram is non-invasive
  • Fast, with little recovery time needed
  • Lower radiation dose than a standard coronary angiogram

What are the cons of a cardiac CT?

  • If the heart rate is too high the scans may not be diagnostic, or may be less diagnostic
  • If a problem is found, and a stent needs to be inserted, a standard coronary angiogram will need to be performed as well.

Alternative for a cardiac CT

There are two procedures which are similar to a cardiac CT:

  • A coronary angiography
  • A coronary calcium score

What should you tell us when making a booking for a cardiac CT?

  • If you are pregnant
  • If you are diabetic
  • If you have kidney problems
  • If you have multiple severe allergies, or a previous allergy to IV contrast

You will usually be asked to have a blood test to check your kidney function before the test, and definitely if you are diabetic.

What Special Diet is required Before a cardiac CT?

You may be instructed to fast after breakfast and avoid any caffeine for up to 24 hours before your procedure.

What to bring for a cardiac CT?

Your doctor may ask you to bring any previous scans or x-rays to the procedure, along with any medications you’re currently taking.

What to wear for a cardiac CT?

You will be asked to remove any metallic items, such as jewellery, watches, eyewear and belts, as these items can show up on the CT scans.

You will be asked to remove any clothing obstructing the area to be scanned and given a medical gown to wear instead, so you should try and wear something that is comfortable and easy to remove.

How long will a cardiac CT take?

Before the CT Coronary angiogram can be performed, your heart rate will be measured and unless it is normally very low, you will be given medication to lower and stabilize your heart rate. This gives much better images and thus a better chance of diagnosing any problems. This process may take a few hours. The actual CT scan will usually only take 10-15 minutes.

What does a cardiac CT involve?

After arrival at the Radiology Department, you will be placed on a trolley to have your heart rate (HR) measured. If it is too high to perform the test, you will be given medications to lower your HR, and it will be rechecked after 1/2 – 1 hour. Once your HR is at a good level, a nurse, doctor or radiographer will put a cannula in your arm, usually in the inside of the elbow. You will be taken to the CT Scan room and asked to lay on the CT bed. The radiographers will connect you to the CT Scan ECG and explain the next part of the test to you. You will be asked to hold your breath during all of the scans – this is very important. A couple of preliminary scans will be done and then the radiographer will start the injection of contrast, and the CT Coronary scan will start shortly after that.

You may experience the following sensations as the contrast agent moves through the body:

  • Warmth or heat
  • Mild burning
  • A metallic taste or smell
  • A feeling as though you have passed urine

What are the Recovery Details?

You may be asked to stay in the hospital for up to an hour after the cardiac CT, to ensure that there are no side effects or reactions to the contrast medium or the medications given to lower your HR.

After the procedure you will be able to return to normal activity the next day. The results of the scan will be sent to your doctor, who will discuss them with you during your next appointment.

Can I Drive Home?

You should bring someone to drive you home after the procedure.


Mayo Clinic Staff. (May 15, 2014). CT coronary angiogram. In Tests and Procedures. Retrieved from This Website

National Heart Blood and Lung Institute. What is a cardiac CT? In Health Topics. Retrieved from This Website

NHS Choices. (July 24, 2015). CT Scan. In Health A-Z. Retrieved from This Website

WebMD. (May 16, 2014). Diagnosing Heart Disease With Cardiac Computed Tomography (CT). In Heart Disease Health Centre. Retrieved from This Website

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