What to Expect During a Coronary CTA
A nurse will insert an I.V. into a vein in your arm to administer contrast material (dye) during your procedure. You may be given beta blocker medication through the same I.V. or orally.
The technologist will clean three small areas of your chest and place small, sticky electrode patches on these areas. Men can expect to have their chest partially shaved to help the electrodes stick. The electrodes are attached to an electrocardiograph (ECG) monitor, which charts your heart’s electrical activity during the test.
While lying on the scanning table, you may be asked to raise your arms over your head for the duration of the exam.
The table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine as the actual CT scanning is performed.
You may be asked to hold your breath during the scanning. Any motion, whether breathing or body movements, can lead to artifacts on the images. This is similar to the blurring seen on a photograph taken of a moving object. You also may be given a spry of nitroglycerin under your tongue to dilate your vessels for better visualization of the coronary arteries.
Inform your doctor if you have problems in holding your breath for 10 to 15 seconds. Breathing during the scan creates artifacts on the images.
When the examination is completed, you will be asked to wait until the technologist verifies that the images are of high enough quality for accurate interpretation.
Your I.V. will be removed.
Most CT exams are painless, fast and easy. With coronary CTA, the amount of time that the patient needs to lie still is reduced.
Though the scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes. If you have a hard time staying still, are claustrophobic or have chronic pain, you may find a CT exam to be stressful. The technologist or nurse, under the direction of a doctor, may offer you a mild sedative to help you tolerate the CT scanning procedure.
If an intravenous contrast material is used, you will feel a slight prick when the needle is inserted into your vein. You may have a warm, flushed sensation during the injection of the contrast materials and a metallic taste in your mouth that lasts for a few minutes. Some patients may experience a sensation like they have to urinate but this subsides quickly.
The medication given to slow the heart rate has been known to cause some patients to feel dizzy when they stand suddenly. The dizziness is slight and only happens rarely.
You will be alone in the exam room during the CT scan. However, the technologist will be able to see, hear and speak with you at all times.
Limitations of Coronary CTA
A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table.
Patients who are extremely overweight or who have abnormal heart rhythms also tend not to be suitable candidates for this test because imaging quality is compromised.
Although coronary CTA examinations are growing in use, coronary angiograms remain the preferred method for detecting coronary artery stenosis, which is a significant narrowing of an artery that could require catheter-based intervention (such as stenting) or surgery (such as bypassing). Unlike CTA which is only a diagnostic test, coronary angiography can provide both diagnosis and treatment in a single session. Patients with a high likelihood of coronary artery disease and typical symptoms should therefore directly undergo coronary angiography.
Coronary CTA also is of limited use in patients with extensive areas of old, calcified (hardened) plaque, which is often the case in older patients.