Cardiac CT Angiography

Cardiac CT Angiography is a diagnostic imaging test of the heart used to help diagnose coronary artery disease. CT scanning is fast, painless, non-invasive and accurate.

What is Cardiac CT Angiography

Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical test that, unlike traditional x-rays, produces multiple images of the inside of the body. The “slices” generated during a CT scan are reviewed on a computer monitor. 

Using cardiac CT, the heart and the coronary arteries which supply oxygen and blood to the heart muscles, can be accurately shown. This allows us to see atherosclerotic plaque and any blockage or narrowing of the blood vessels around the heart. In some cases, CT angiography may prevent the need for more invasive procedures. 

 

  • While CT coronary angiography should not be used as a "screening" test in the general population, it is a major new tool in the diagnosis of coronary artery disease. This test can be used to detect narrowing or blockage of these vessels that supply the heart in the following situations:
     
    1. Patients at high risk of developing coronary disease (cigarette smokers, those with genetic risk, high cholesterol levels, hypertension, or diabetes),
    2. Patients who have unclear results with treadmill or other testing.
    3. Patients who have symptoms suspicious of coronary disease.
     
    In these situations if the CT scan is normal or only mildly abnormal, it makes the likelihood of a severe blockage of the coronary arteries extraordinarily small. However, if the CT scan is significantly abnormal, other tests such as cardiac catheterisation and angiography may be necessary.
     
    Cardiac CT Angiography can also be used in people who have suspected abnormal anatomy of the coronary arteries or who have had bypass surgery. In this setting it can be very effective at evaluating the patency of the bypass grafts. 

What will I experience during my scan?

CT exams are generally painless, fast and easy. With multi-detector CT, the amount of time that the patient needs to lie still for is reduced. These scanners now allow fast imaging making it possible to acquire images that are not blurred by movement of the heart.
 
When you enter the CT scanner room, special light lines may be seen projected onto your body, and are used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds as the CT scanner's internal parts, not usually visible to you, revolve around you during the imaging process.
 
We will place electrodes (small sticky patches connected to leads) on your chest. The electrodes are connected to a monitor that records the rhythm and electrical activity of your heart. Our Radiographer can then trigger the scanner to take a picture at a certain point during your heartbeat. This gives us high quality images of your heart and arteries.
 
You will be alone in the examination room during the CT scan, unless due to specific circumstances you require someone present.The Radiographer will always be able to see, hear and speak with you through a built-in intercom system.
 
Intravenous contrast material is used for this examination. This is a special dye that is injected into a small vein in your arm so that we can see your heart and arteries clearly. You will feel a pin prick when the needle is inserted into your vein. You will likely have a warm, flushed sensation during the injection of the contrast material and a metallic taste in your mouth that lasts for at most a minute or two. You may also experience a sensation like you have to urinate; however, this is actually a side effect of the contrast material and subsides quickly. 
 
It can be difficult for us to get a clear picture if your heart is beating too quickly. Therfore, we will check your heart rate when you arrive and, if it is faster than the ideal rate, we may give you some medication to slow it down. This may be in the form of a tablet or an injection and can take up to an hour to work effectively.  As soon as your heart rate is beating at the right pace, we will perform the scan. To help us get a clear picture of your heart, we will ask you to hold your breath for a few seconds during the scan. We will discuss this with you before your scan so you know exactly what to do.
 
After the CT exam, the intravenous line used to inject contrast material will be removed. If you received medication to slow your heart rate during the scan, you may be transferred to the recovery area. A Nurse will monitor your heart rate, oxygen level and blood pressure for 30 minutes. You then will be given discharge instructions. If you only received medicine under your tongue or a small amount of medication during the test, you will be assessed by our nursing staff after the examination and may be able to leave the hospital as soon as the scan is complete.
 
The medication used can make you a little drowsy for up to a few hours after the scan. Please arrange for a lift home, as driving may not be allowed following such an examination.