CARDIAC CT (Low Dose)

About the Examination

A Computerised Tomography (CT) scan, also known as a computerized axial tomography (CAT) scan uses a mixture of x-rays and computer systems to create virtual ‘slices’ of the body without the need for invasive surgery. During a CT a large, circular scanner spins and moves up and down the body, taking multiple images of internal organs and soft tissue.

What is a cardiac CT?

A cardiac CT, or 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 condition of the heart as well as the surrounding arteries and blood vessels.

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?

A cardiac CTs is a non-invasive procedure, which makes it ideal for checking whether a patient with heart related issues or symptoms has coronary heart 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.

However, 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 lowest radiation doses possible are used, there is a risk that patients may develop cancer. The risk is slightly higher in patients under 40 years of age.

You can find out more about the levels and risks of x-rays from the Patient Dose Information Fact Sheet, published by Public Health England.

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

Low blood pressure
Anaphylactic shock
Cardiac Arrest

Allergic reactions to the x-ray dye are usually mild and can be treated with medication on site.

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

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

High blood pressure
Sleep Apnea
Depression
Diabetes
Heart attack
Arrhythmia
Heart failure

About the Equipment

Equipment specifications of a cardiac CT

The following equipment is used during a cardiac CT procedure:
A high speed CT scanner
Electrocardiogram (EKG) machine
An intravenous drip

What are the benefits of a cardiac CT

A cardiac CT is a safe, non-invasive procedure with detailed results, which are produced quickly.

Alternative for a cardiac CT

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

A coronary angiography
A coronary calcium scan

Preparation for a cardiac CT

What Special Diet is required Before a cardiac CT

You may be instructed to fast and avoid caffeine for up to four hours before your procedure,

What should a patient tell the Radiographer before a cardiac CT

Patients should alert the radiographer if they are pregnant as there is a risk that the radiation from the CT scan could endanger the baby.

You should also tell the radiographer if you are asthmatic, suffer from kidney problems or have any allergies as these conditions increase the risk of a negative reaction to the contrast medium.

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 should also avoid clothes with zippers or metal buttons.

You may 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?

The cardiac CT procedure will typically take between 10-45 minutes to complete.

Cardiac CT Procedure Description

What does a cardiac CT involve?

During a cardiac CT scan the patient will be asked to lay down on a CT table, and a contrast medium is injected into the bloodstream, via an intravenous (IV) line connected to your hand or arm.

Your doctor may also give you medicine to slow your heart rate.

Detail the specific steps during a cardiac CT

After being escorted to the procedure room, you will be asked to lie down on the CT table with your head towards the opening of the machine. The radiographer will then inject the contrast medium, through the IV line, into the back of your hand, or the inside of your elbow.

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

Warmth
Mild burning
A metallic taste or smell
A temporary urge to pass urine

You will also be connected to an electrocardiogram (EKG) machine during the procedure, via small patches placed on your chest. These monitor and record your heart rate.

You will then be told to lie still while the CT scanner spins, moving up and down as it takes images of your body.

Post cardiac CT instructions

What are the Recovery Details?

Your radiologist may ask you 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.

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