The purpose of a coronary angiogram is to obtain a clear picture of the coronary arteries and blood vessels around the heart to assess the severity and location of any narrowing and blockages. It can also help show how well your heart muscle and valves are working.
To enable the clear viewing of the blood vessels, once the cardiologist or technician has threaded the catheter through your arteries, guided by a video monitor, a contrast agent – usually iodine – is injected into the catheter. This dye shows up clearly on an X-ray film enabling a clear view of the state of the blood vessels and heart. This can otherwise be difficult to see in fine detail on an X-ray. The dye is then excreted naturally by the body.
You will normally be referred for an angiogram if your symptoms or initial tests such as an ECG, exercise stress test, echocardiogram and/or chest X-ray reveal that you may have coronary artery blockage.
The findings of the angiogram will help guide decisions about your treatment.
An angiogram is usually carried out as a day or emergency procedure in a hospital catheterisation lab. In some hospitals if you’re admitted through the emergency department with unstable angina or signs of a heart attack, this may be done within minutes after basic tests such as an ECG and serum troponin (blood test for heart muscle damage) are performed.
Usually, you’ll be given a local anaesthetic at the site of the incision in your wrist or groin, which may also be shaved, along with some sedation that will relax you while still allowing you to stay partially aware for the procedure, although you may not remember it clearly afterwards.
The procedure can take from 20 minutes to an hour or so, depending on its complexity. During this time you’ll lie on a table with an X-ray machine positioned over your chest and connected to a heart monitor that records your heart rate and rhythm.
Using a needle, the doctor will make a hole in your blood vessel and insert a fine plastic tube called a sheath into it. Next, a fine, flexible wire will be inserted into the sheath and threaded through your blood vessel into your heart. The catheter is then put through the sheath over the wire to your heart.
When the catheter has reached the right spot, the guide wire will be removed and the contrast agent injected. X-ray films will be taken as the dye flows through your blood vessels and heart.
Depending on the situation and what informed consent has been agreed to, you may have consented to the specialist opening up a blocked artery there and then and inserting a stent (a metal scaffolding to keep the artery open). However, some people may be better off having surgery for their blockage and that should have been discussed before the procedure.
Once complete, the catheter and sheath will be removed. Pressure will be applied to the incision site and, often, a small collagen plug inserted to help seal the blood vessel. This usually dissolves in 60 to 90 days.
After the procedure, you’ll be asked to lie flat for several hours. This will allow the sedation to wear off and help the blood vessel to seal properly.
By revealing in fine detail the degree and location of the narrowing and blockages in your arteries, an angiogram can guide you and your doctors on your best treatment options.
These options might include relying on lifestyle changes and medication to control your condition; having a procedure called an angioplasty, or having a more major operation known as a coronary artery bypass graft, also known as open heart or bypass surgery
Angiography is associated with a small risk of allergic reactions, especially to one of the components of the contrast agents used. For this reason, it’s important to let your doctor or technician know of any allergies you have, especially to seafood or iodine. There is also a small risk of impaired kidney function, infections, and bleeding.
An angiogram can also cause a heart attack or death, but this risk is relatively small when angiography is performed in a non-emergency situation.Top of page
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Last published 31 October 2011