It is usually performed to determine whether your coronary arteries are narrowed or blocked as a result of fatty cholesterol plaque in the artery walls, which could explain the presence of chest pain or other acute or chronic symptoms. The CT coronary angiogram takes dynamic x-ray pictures of the heart. It checks for blockages or narrowing of the coronary arteries, as well as abnormalities of the heart muscle or heart valves. A CT coronary angiogram relies on CT imaging to construct high-resolution, three-dimensional images of your heart and its adjacent coronary arteries after intravenous dye (contrast) is inserted into your arm via an intravenous line. This test is non-invasive, meaning it differs from a traditional invasive coronary angiogram (an invasive coronary angiogram requires a cardiac catheter to be threaded inside the body via the wrist or groin artery until it reaches the coronary arteries of the heart).
Usually, you’ll be asked not to eat anything for four hours prior to the test. You can drink water, but avoid caffeinated beverages for the preceding 12 hours, because they can increase your heart rate, making it difficult to visualise the heart arteries if they are moving too fast.
When you arrive, if your heart rate is above 60 beats per minute, you will likely be given medication called a beta blocker to slow your heart rate, enabling the scan to produce clearer images of the arteries. As you enter the scanner, you will also be given a spray of nitroglycerin under the tongue to dilate your coronary arteries which will allow clearer images to be taken.
The CT technician will place electrodes on your chest to record your heart rate and rhythm. You will lie on a table that slides through a short, “doughnut-shaped” machine. When instructed during the scan, you’ll need to stay still and briefly hold your breath to avoid blurring the images. After the contrast agent is injected, you may feel flushed or have a metallic taste in your mouth. These are common sensations and will subside within a few seconds. If you experience shortness of breath, throat tightening or any unusual symptoms, please immediately alert the CT technologist as they may indicate an allergic reaction to the dye.
Although the actual scanning portion of the test takes only a couple of minutes, it may take up to two hours for the entire process to be completed, especially if you require medication to slow down your heart rate which can sometimes take over an hour to have an effect.
After your CT angiogram is completed, you can return to your normal daily activities and unless you have been given high doses of beta-blocker medication, you will be able to drive yourself. Drink plenty of water for 24 hours after the test to help flush the dye from your system.
Depending on the results of your test, Dr Nasis will discuss with you whether you have a heart condition that needs treatment, what your risk of suffering a heart attack is and the steps you can take to optimise your heart health.