What is a CT Angiography Scan?
A coronary CT scan (CT angiography) is a test used to visualize the heart vessels in three dimensional images. The CT scanner rotates around the body and takes a series of x-rays scans. A computer program processes and re-assembles the images to create cross sectional 3-D images of the heart. The test provides your physician with images of the heart used to evaluate the arteries for blockages, fatty deposits and calcium build-up.
Instructions Before the Test.
You will need to drink plenty of fluids the day before the test (64 ounces is recommended). Avoid stimulants such as caffeine and nicotine the day of your test and do not eat or drink anything one hour prior to the test. In order for the CT scanner to obtain clear images, it is important for the patient's resting heart rate to be at 70 beats per minute or less. If your physician knows that your resting heart rate is greater than 70, you may be prescribed an oral beta-blocker to take the night before and the morning of your test to help slow your heart rate. If you are not given an oral beta blocker and your heart rate is above 70 beats per minute at the time of your test you may be given an intravenous (IV) beta-blocker to slow your heart rate, which may take 15 to 30 minutes to take effect.
A contrast dye will be used during the test. Please notify your physician if you've had an allergic reaction to contrast dye or if you have kidney disease. You can take your daily medications the day of the test except for oral diabetic medications. If you take Viagra, Levitra or Cialis, avoid taking these medications for several days before the test.
What Happens During the Test?
When you arrive for the test, leads will be placed on your chest and connected to an EKG machine to monitor your heart rate throughout the test. You will be asked to lie on your back on the scanner table. An intravenous (IV) line will be placed in your arm for injection of contrast dye, which is used to help visualize the structure of the heart during the test. When the dye is administered, you will feel a warm flushing sensation throughout the body which will pass quickly. When scanning is ready to begin, you will be asked to keep your arms above your head on the scanner table. The table will glide through the CT scanner several times to record the images. You must take a deep breath and hold it while the table passes through the scanner. A technician will tell you when to take a deep breath and when to expel your breath. The longest you will be asked to hold your breath will be 20 seconds. Holding your breath is important because breathing motion can make the images unusable.
What Happens After the Test?
After the test, your IV will be removed and your heart rate and blood pressure will be monitored for about 20 minutes if you've had IV beta blockers. You will then be free to leave. You should drink plenty of fluids after the test to flush out the contrast dye. The actual scan only takes a few minutes, but you should allow about 45 minutes for the preparation, scan and observation time after the test.