What is coronary angiography?
Coronary angiography is an X-ray procedure used to examine the coronary arteries – the blood vessels that supply blood to your heart muscle. During the procedure, an image (called an angiogram) is displayed on a monitor, showing the doctor what your coronary arteries look like.
Although ‘angiogram’ is the name of the image and ‘angiography’ is the name of the procedure, many people refer to the test as an angiogram.
Types of coronary angiography
Traditionally, coronary angiography is done using a technique called cardiac catheterisation. This involves using a thin, flexible tube (a catheter) to reach your heart’s blood vessels. As well as showing what your coronary arteries look like, this procedure can also be used to measure blood pressure within the chambers of your heart, and to check the functioning of your heart valves.
CT coronary angiography (CTCA)
Another way of doing coronary angiography, developed in more recent years, uses a technique called computed tomography (CT) – the same technology used to produce ‘CT scans’ of other parts of the body. Called CT coronary angiography (CTCA), this method produces multiple 2-dimensional images that provide a very detailed view of your coronary arteries and nearby structures.
Because the newer method of CT coronary angiography doesn’t involve inserting a catheter, it is sometimes referred to as ‘non-invasive’ coronary angiography.
Why is coronary angiography done?
The main reason for doing coronary angiography is to check the health of your coronary arteries and see if there are any blockages or areas of narrowing. The procedure may also show up some problems with the way the valves and muscular walls of your heart are working, or may show a cardiac aneurysm (a bulging of the heart wall) or a birth defect such as a hole in the inner wall (septum) separating the chambers of the heart.
As well as being used to diagnose problems with the coronary arteries, coronary angiography can be used to treat certain conditions, if done using the technique of cardiac catheterisation. For example, a procedure known as angioplasty can be done, where narrowed or blocked coronary arteries are dilated by inflating a tiny balloon on the tip of the catheter, often followed by the placement of a stent (a tiny wire mesh tube that helps keep the artery open). These types of procedures can’t be done during CT coronary angiography, because this doesn’t involve the use of a catheter.
Who should have coronary angiography?
You may be advised to have coronary angiography if:
- your doctor considers you to be at risk of coronary artery disease and wants to evaluate the condition of your coronary arteries and/or you develop symptoms such as chest pain (angina).
Other reasons you may need coronary angiography include:
- evaluation of congenital heart disease (heart defects you have been born with)
- to assess the valves in your heart
- to look for weakness or bulging in the walls of the heart
- to map your coronary arteries to prepare for bypass surgery or for angioplasty – where your arteries are stretched with a tiny balloon and may have a stent (wire mesh tube) put in
- to follow up after bypass surgery or angioplasty to see if the treated vessels are still open
- to check the health of your coronary arteries before you have general surgery.
Australian guidelines recommend that traditional coronary angiography be used for people at high risk of coronary artery disease, or who are known to have coronary artery disease, while the newer method of CT coronary angiography is suitable for people at low-to-moderate risk.
If you already have a stent, a normal coronary angiography won’t be able to show what’s happening inside the stent, but a CTCA may be able to show whether it is becoming narrowed or blocked up.
CTCA is also very good for ruling out the presence of atherosclerosis (where the artery wall thickens due to the build-up of plaque) in the coronary arteries.
CTCA is not suitable for pregnant women and people who have reduced kidney function.
Will I be admitted to hospital for coronary angiography?
If you are not already a patient in a hospital, you will usually be admitted as a day patient (outpatient) on the morning of the day you are scheduled to have your angiography. You will most likely go home the same day of the test, although in some circumstances you may need to stay overnight.
How do I prepare for the angiography?
Before you have coronary angiography, you may have other tests done first, such as blood tests, an electrocardiogram (ECG), a chest X-ray and possibly an exercise test (‘stress test’).
If you normally take medication, your doctor will advise whether you should continue this before your test, so it is a good idea to provide a list of all your medications, including those you take only occasionally and any complementary or alternative medicines. You should also bring all your medications with you into hospital in their original bottles.
It is very important to tell the doctors and nurses looking after you if you have diabetes, asthma, any allergies or any problems with your kidneys, as special precautions may be necessary.
Your doctor or cardiologist will advise you what food and drink you may have before the angiography. If you are having traditional angiography done, you usually won’t have anything to eat or drink after midnight on the day before your test.
However, if you are having CT coronary angiography, you only need to fast from about 4 hours before the test. It is advised that you don’t have any coffee, tea, cola or other stimulants before the test as this may raise your heart rate.
In addition, many people having a CT coronary angiography will need to take medication to slow down their heart rate.
Where is coronary angiography done?
Coronary angiography using catheterisation is done in the hospital’s cardiac catheterisation laboratory (‘cath lab’). A number of nurses, X-ray staff and cardiac technicians will be present. You will be taken there from the ward on a wheelchair or a movable bed. Once you are in the laboratory you will be moved onto an examination table. This is directly under an X-ray camera through which the angiography procedure can be viewed.
CT coronary angiography is usually done in either the radiology department of the hospital, or in an outpatient facility.
What happens during coronary angiography?
What happens during the procedure depends on the type of coronary angiography being done.
If you are having coronary angiography using catheterisation, an area of your arm or groin will be cleaned, shaved and draped with sterile towels. You will then be given a local anaesthetic and a catheter will be inserted into an artery and threaded all the way through to the aorta (the main artery through which the heart pumps blood to the body). This is the area where the main coronary arteries arise. You will have some electrodes attached so your heart can be continuously monitored throughout the procedure.
A special substance called contrast medium or dye is injected through the catheter into the artery. This is to make the blood inside your heart and coronary arteries visible on X-ray. As the blood containing the contrast medium flows through the arteries and chambers of the heart, the doctor can see how these areas look and how they are working. A series of X-ray pictures is recorded digitally or on film. The doctor may need to make several injections of contrast medium so the coronary arteries can be filmed from different angles. This involves rotating the camera or moving you.
The pressure in the chambers of your heart and blood vessels may also be measured, and blood samples may be taken for testing. Your heart function and blood pressure will be continuously monitored throughout the procedure. If the angiography shows you have one or more blockages in your arteries, you may have a procedure done then and there to address the issue, such as angioplasty.
CT coronary angiography (CTCA)
If you are having the newer technique of CT coronary angiography done, no catheter is used. Instead, an intravenous line will be placed in your hand or arm, through which the dye that makes the blood show up on X-ray will be injected.
Before the test, you may be given a medication (a beta blocker) to slow your heart rate and provide the best images of your heart during the X-ray.
The actual X-ray only takes a matter of seconds, and is done as you lie on a table that slides through the CT machine. The machine is controlled by a technician in another room, who you will be able to talk to via intercom.
Is angiography painful?
If you are having CT coronary angiography, the area where the intravenous line is placed will be numbed beforehand, so you shouldn’t feel any pain.
If you are having angiography done using catheterisation, you will be given a local anaesthetic, similar to that used by a dentist, to numb the area in your arm or groin into which the catheter is inserted. This stings a little before the numbness sets in. Only a small nick in the skin is needed to insert the catheter and you may not even realise that the catheter has been introduced. You will not feel it being moved to the heart, as there are no nerves in the arteries.
There is no pain when the contrast fluid is injected into the catheter but it can cause a sensation of warmth, flushing or tingling which lasts about 20 or 30 seconds. You will be warned when to expect this.
You may experience slight angina, but it should subside rapidly.
After the procedure is over, you may feel some pain where the catheter was inserted. If you feel any discomfort, ask the nurse or doctor for some pain relief. There may also be some bruising there, which will gradually disappear. However, if the discolouration spreads, you see blood coming through the dressing, or you have undue discomfort in the groin, leg or arm, tell a nurse or doctor immediately.
Will I be awake during the procedure?
You will need to be awake to assist your doctor during the test. You may be given a sedative before the test starts to help you relax, but this will not put you completely to sleep. General anaesthetic is only used for small children having assessment of congenital heart disease.
While the X-ray films are being taken, you may be told to take a deep breath and hold it for about 10 seconds. After this you may be asked to cough and then resume normal breathing.
How long will angiography take?
Coronary angiography usually takes less than an hour to do. However, if any other procedures such as angioplasty need to be done, more time may be needed.
If you have had coronary angiography using a catheter, you may need to stay in hospital for a number of hours to recover. If you have had non-invasive CT coronary angiography, no recovery time is needed.
Risks and complications of coronary angiography
Like any medical procedure, coronary angiography has some risks associated with it, and occasionally causes complications. However, in skilled hands these are rare.
The main risk of the procedure is that you could have an allergic reaction to the dye used. Occasionally, people develop hives, itching or other reactions, which if they happen will be treated immediately. If you have a history of allergies or asthma, or if you have had an allergic reaction to dye used in X-rays before, tell the doctor before the test.
There is also a slight risk of damage from the radiation you are exposed to during the X-ray, although the dose used is relatively small and is unlikely to be a problem unless you are pregnant, in which case the procedure is not suitable.
If a catheter is used, there is also a small risk of damage to the artery the catheter went into, excessive bleeding, or infection. Other potential problems that could develop during the procedure include heart attack or stroke, an arrhythmia (irregular heart beat), and a tear in your heart or artery.
The doctor performing the investigation will discuss any risks and potential complications with you before the test. Feel free to bring up any concerns or questions you have then.
What do coronary angiography results show?
Coronary angiography will show if your coronary arteries are narrowed or blocked, and if so, where the blockages are. At these points, blood cannot flow through the arteries freely, and this can cause angina. CT coronary angiography can show the location of plaques in the arteries, even if there is no obstruction to blood flow.
When angina is severe and angiography has shown significant narrowing or blockage of one or more arteries, your doctor may recommend surgery or other treatments to relieve the condition.
In other cases, the angiogram may show that there are no serious problems.