What is an angiogram?
Angiography is a procedure in which a liquid contrast agent is injected into the bloodstream to make blood vessels visible on a scan. The image produced by the scan is called an angiogram. Angiography can be used to look at blood vessels in the heart, lungs, brain, kidneys or other parts of the body. It is usually done in hospital.
As well as being used for diagnosis, angiography can also be used to guide procedures that treat some abnormalities of the blood vessels, such as narrowing or clots. For example, narrowed arteries may be treated by inserting a tiny metal tube called a stent to keep the artery open.
Why is an angiogram done?
Angiograms help doctors detect and sometimes treat abnormal blood vessels, clots and other problems, such as narrowing or blockage of blood vessels.
Coronary angiograms show the blood vessels that supply the heart. They can show if you have narrowing of the coronary arteries, which may be causing you symptoms.
Pulmonary angiograms show blood vessels in the lungs and can be used to see if there is narrowing of a blood vessel, or to look for blood clots in the lungs.
Before the test
Some angiogram procedures require you to fast (have no food or drink) for 4 to 6 hours before the angiogram. Other procedures need you to drink a lot of fluids before the test. Your doctor or radiology provider will give you clear instructions beforehand.
You will need to arrange someone to help you get home, especially if you are going home the same day, as you may be drowsy from medication used in the test.
Your doctor should discuss the procedure and any potential risks. This is a good time to ask questions or discuss any concerns. You should tell your doctor or nurse:
- about any medicines you take, including over the counter or complementary ones
- about any allergies you have
- if you have ever had an allergic reaction to a contrast medium previously
- if you have kidney disease, diabetes, or other health conditions
What happens during an angiogram?
What happens during the angiography procedure depends on whether you are having a conventional angiogram or CT angiogram.
CT angiography uses a CT scanner to take images of your blood vessels.
CT angiography can only be used for diagnosis. Treatment is not possible during a CT angiogram.
CT angiography involves having the contrast agent injected into a vein in your arm. The contrast agent is a liquid that works to make anatomical structures, like your blood vessels, visible on scans. The images of your blood vessels are taken by the CT scanner.
You will lie on the CT scan bed, which is moved into the scanner by remote control.
You may be given medicine to slow your heart rate and reduce blood flow, so that the images are clearer. You may be asked to hold your breath for short periods while each scan is done.
CT coronary angiograms (CTCA) look at the coronary arteries while the heart is beating. CT pulmonary angiograms (CTPA) look at the blood vessels that run from the heart to the lungs (the pulmonary arteries) and smaller blood vessels in the lungs, for clots and abnormalities.
Conventional angiography uses x-rays and contrast agent to produce the angiogram pictures.
Unlike CT angiography, if the doctor or radiologist finds a blockage or clot during a conventional angiogram, they may be able to treat the problem during the procedure. This is possible because in conventional angiography, a thin tube called a catheter is inserted into the blood vessel.
If you are having a conventional angiogram, you will be given a local anaesthetic in your arm or your groin to numb the area where the catheter will be inserted. You may also be given a sedative to help you relax.
A thin tube known as a catheter will be inserted into a large blood vessel in your arm or groin, and fed in to reach the area being examined. You will not feel anything.
Contrast medium (the liquid that helps show up the blood vessels) is injected through the catheter and x-rays are taken. You will be asked to stay very still or hold your breath while the images are being taken. When the contrast medium goes in, you might feel temporary warmth or a hot flush. Some people feel nauseous or have chest discomfort, but this doesn't generally last long. Let your doctor know if you are experiencing these or other symptoms.
What happens after the angiogram?
After an angiogram, if a catheter was used, it will be carefully removed. The doctor or nurse will probably put pressure on the wound to reduce the risk of bleeding. You will be asked to lie flat for a few hours.
If you have had a sedative, you must not drive or use public transport for 24 hours afterwards. You should also have someone with you for that 24 hours.
The contrast medium will pass out of your body in the urine. It is colourless, so you won't be able to see it.
Angiogram risks and side effects
There is a small risk that you will be allergic to the contrast medium. This can result in itching, rash or more severe reactions, such as breathing difficulties. It's important to mention any previous allergic reactions you have had to tests, to the doctor or nurse before the procedure. Also mention if you have any strong allergies to other things, such as foods or dust.
There is a small risk of bruising or bleeding, where the catheter was put in. There is also a small risk of bleeding or infection at the injection site.
Beta-blocker medicines are sometimes used to slow the heart during the procedure. These can cause narrowing of the airways and breathing difficulties in people who have asthma.
Conventional angiography uses x-rays, but the doses of radiation are very small. However, angiograms are not generally carried out on pregnant women because of the radiation dose to the unborn baby.
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Last reviewed: September 2021