Cardiac Computed Tomography Angiography (CCTA)
- Patients with symptoms that could be due to ischemia (including chest discomfort, shortness of breath with activity, a sudden decrease in the ability to do physical activities) who cannot undergo optimal stress testing due to the inability to exercise or due to an abnormal resting electrocardiogram (ECG)
- In addition, those patients who have had a stress test that could not rule out or in a problem with blood flow to the heart may also be candidates
- Patients with an acute onset of possible cardiac symptoms, who need to know if there is coronary disease (usually in the emergency room)
- Those born with possible or known structural defects of the heart, coronary arteries, or the major blood vessels coming from the heart may benefit from CCTA to define the precise anatomy
- Patients with a newly diagnosed cardiomyopathy (weak heart muscle), who need an evaluation of the coronary arteries
- Patients with suspected masses or pericardial (covering around the heart) abnormalities without good enough images from an echocardiogram or MRI
- A patient planning an atrial ablation procedure or placement of a pacemaker lead in the cardiac veins that needs anatomic mapping before the procedure
Who is not a good candidate for CCTA?
The following may not be good candidates:
- Those patients for whom it would be unsafe to have imaging contrast or X-rays: mainly women who are pregnant and patients with abnormal kidney function
- CCTA requires a slow regular heart rate; so those patients with irregular heart rhythms or who have fast heart rates and are unable to take medications that slow the heart are unlikely to have accurate images
- Patients who are not able to lie flat, follow voice instructions, or hold their breath for up to 20 seconds
Are there any dangers?
As stated above, the imaging contrast can be irritating or cause injury to the kidneys; however this is very unlikely in patients with normal kidney function. In addition, some people can have allergic reaction to imaging contrast. In patients who have not had problems with contrast in the past, this is also unlikely. For patients who have had reactions to contrast in the past, medications can be given before the test to protect from repeat reactions.
Other problems are possible, but not likely - such as significant bleeding or infection at the IV site. In addition, if there is a problem with the IV, the contrast can be injected into the skin instead of the vein which can be mildly irritating. Lastly, as we give medicines to slow the heart, the heart could slow too much. We follow carefully developed guidelines and monitor heart rates at all times to help avoid this.
Are there specific instructions prior to testing?
Prior to a CCTA, patients should have nothing to eat four hours prior to the test. Patients can and should drink water four hours prior to the test. We encourage drinking extra water up to test completion as it helps flush the kidneys.
Patients should skip morning diuretic medicines (water pills) until the test is over. Patients taking medicines for diabetes should speak with the nurse in the CCTA preparation (prep) area before the test for instructions.
Medicines that slow the heart rate should be taken normally prior to the CCTA. The most common medicines in this category are metoprolol, atenolol, carvedilol, verapamil, diltiazem and others in the classes of beta-blockers or calcium channel blockers.
How is CCTA performed?
CCTA is performed in both the inpatient and outpatient settings. Outpatients arrive about an hour and a half before the scan to a prep area. In the prep area, patients are connected to a cardiac monitor, and a nurse will place an intravenous (IV) line into a vein in the arm. Medicine is given by mouth and IV as necessary to slow the heart rate.
The patient then goes to the CT scanner room and the following steps are taken:
- The patient is made comfortable on the CT table and the IV is connected to the contrast injector
- Initial pictures of the chest are taken for positioning
- Heart pictures without contrast are taken for a calcium evaluation
- A small dose of imaging contrast is injected and the time it takes for the contrast to get to the heart is measured
- The imaging dose of contrast is injected and CCTA pictures are taken
How long does it take?
From arrival to, and departure from, the prep area, the total time is about two hours. The time of the CCTA itself is 10-20 minutes. The actual time the scanner takes to make the final heart pictures is 5-7 seconds.
How do I get my test results?
In all cases, the results of the CCTA will be sent to the physician who ordered the test. In many cases, we will be able to give you initial results after the test.