Angiography is an X-ray technique in which dye is injected into the chambers of the heart or the coronary arteries supplying the heart. The test allows measurement of blood flow and blood pressure in the heart chambers and can reveal whether the coronary arteries are blocked or not.

How does it work?

The doctor performs a cardiac catheterisation procedure in which a long, thin tube (called a catheter) is put into an artery or vein in the groin and threaded into the heart. Once the catheter is correctly positioned, a dye is injected through the catheter and into the heart. The dye allows doctors to see how the heart chambers and coronary arteries are working, and the movement of the dye is recorded as an angiogram and viewed on a monitor.

The procedure

The patient cannot eat or drink anything after midnight the night before the test. If the patient has diabetes, he or she should talk to the doctor about their food and insulin intake, because not eating can affect blood sugar levels.

The patient should talk to his or her doctor about any drugs they are taking, since medication might need to be stopped before the test can be done. The patient should make a list of his or her medication and bring it with them, so that the doctors know exactly what drugs the patient is taking and in what quantity. Blood tests, an electrocardiogram (ECG) and a chest X-ray might also need to be done before the procedure.

In the catheterisation laboratory, the patient will see television monitors, heart monitors and blood-pressure machines. The patient will lie on an examination table, which is usually near an X-ray camera.

Small metal disks called electrodes will be placed on their chest. These electrodes have leads, which hook up to an ECG machine that monitors the patient’s heart rhythm during the test.

To prevent infection, the patient will be cleaned and shaved (if necessary) around the area of the groin where the catheter will be inserted.

A needle with a tube connected to it—called an intravenous line (or IV)—will be put in the patient’s arm. The patient will be given a mild sedative through the IV to aid relaxation during the test.

An anaesthetic medicine will also be given subcutaneously to numb the area where the catheter will be inserted, which could cause the patient some mild discomfort. Next, a small incision will be made in the skin and doctors will introduce the catheter into the leg artery or vein. The patient should not feel pain during this part of the procedure.

The catheter is gently threaded through the artery and into the heart. If doctors want to measure blood pressure in the left ventricle (the heart's main pumping chamber), they will move the catheter to this position and record the pressure with small sensors.

Alternatively, if doctors want to examine the blood flow through the coronary arteries, then the catheter will be positioned at the opening of each of the arteries and dye pumped into them. The dye allows doctors to see whether the patient has blockages in a main artery or its branches, and the information is recorded on a monitor. After doctors have all the information they need, the catheter and IV will be removed. Firm pressure will be applied to the site where the catheter was inserted to prevent bleeding. The patient’s groin will be bandaged and they will be moved to another room to rest for a few hours. The patient may feel a little sleepy until the sedative has worn off. He or she should try to lie still and not bend their knee too much. Nurses will monitor the patient to ensure that their heart rate and blood pressure are normal. After resting, the patient will be able to go home.


Angiography is a technique that is used to find an exact anatomical diagnosis for cases of acquired and congenital heart disease, and is used to determine an adequate medical or surgical treatment.

Value and limitations of the method

Angiography is a safe test, although pregnant women should not be examined because of the radiation. When contrast dye is needed, the thyroid and renal function have to be considered. Allergic reactions to the contrast dye occur infrequently and rarely require medical treatment.

Author(s): Montse Mireles
Last updated: 2008-09-23