CT Angio of the Coronary Arteries
CT of the coronary arteries is only possible with a high-end multi-detector CT (MDCT) scanner. This new technology (currently available at 8 of our branches) makes it possible to compile an exquisite angiographic picture of the coronary arteries without the risks of an invasive procedure. An iodine-based contrast agent is injected intravenously followed by a saline injection, which allows a bolus of the contrast medium to be concentrated in the arterial system of the heart at the time of the scan.
The examination requires a high-level of skill and our staff undergoes special training to be able to scan the heart and process the images to create angiographic and 3D images of the heart and coronary vessels.
When you arrive your heart rate and blood pressure will be monitored. If your heart rate is above 80bpm a beta-blocker tablet will be given, after consultation with the radiologist or cardiologist. The heart rate is monitored again 45 minutes later and if it has slowed sufficiently the radiographer will start the scan. If your heart rate is still not optimal, you may be given another tablet and will be asked to wait another 30 minutes.
Your co-operation is critical to ensure the success of the scan. The radiographer will give you special breathing instructions and a breathing exercise will be performed a number of times to monitor the heart rate during a breath hold. An intravenous line will be inserted for the contrast injection. A vasodilator will be sprayed under the tongue just before the scan to dilate the cardiac vessels for the scan. This may cause a slight headache, which resolves rapidly.
Two scans will be done. The first will identify any calcified plaque in the coronary arteries. The number and size of these plaques are used to calculate the Agatston Calcium score, which quantifies the relative risk for cardiac disease.
The second scan uses the intravenous contrast agent and utilizes special technology that enables the scanner to acquire images at the same instant in every heartbeat, creating an angiographic image without movement. This is very useful to identify and diagnose the following conditions:
• Abnormal coronary artery origins or courses
• Narrowing/occlusion of the coronary arteries
• Patency of arteries after coronary stenting
• Electro-Anatomical Mapping of the left atrium prior to ablation therapy
If significant pathology is identified you may be referred for a conventional cardiac angiogram. The Cardiac CT Angiogram, however, remains a non-invasive, low-risk first investigation in patients at risk for cardiac disease.
The total time spent in our department can be 1 – 2 hours.
After the scan, the post-processing is done with great care to ensure accuracy and the radiologist carefully reviews the images. The images and a detailed report by our specially trained radiologist will be sent to your referring doctor.
Special preparation for a CT of the Coronary Arteries:
This examination is highly specialized and relies on your co-operation. Please ensure that you advise the receptionist and radiographer of the following conditions at the time of booking the appointment so that precautions can be taken:
• Renal disease
• Heart disease
You will be asked to avoid intense activity, any caffeine and not smoke on the day of the scan.