Coronary angiography
Coronary angiograms use X-ray pictures to diagnose narrowings and blockages in arteries of the heart, which may cause angina or heart attacks.
CT coronary angiogram
Angiography using a CT scan is a non-invasive, low risk method to examine for narrowings in the coronary arteries. This test is recommended by the National Institute for Clinical Excellence (NICE) for assessment of chest pain in patients without known coronary disease.
The scan takes around 10 minutes during which time X-ray images are taken of the chest, including the heart. An injection of X-ray dye is given, precisely timed to show up the coronary arteries at the instant the pictures are acquired.
CT imaging of the heart arteries also provides some information about the anatomy (but not the function) of the heart muscle, and may detect blood clots within the heart.
A CT scan of the heart arteries may also provide good quality pictures of the lungs and other structures in the chest.
Invasive coronary angiogram
This is the gold standard test for assessing severity of narrowings (“stenoses”) and blockages in the coronary arteries. This is a vital step in planning treatments for angina and other forms of ischaemic heart disease.
During an invasive coronary angiogram, wires and thin flexible tubes called “catheters” are passed from a small, easily accessible artery in the arm or leg, to the arteries of the heart. This allows injections of X-ray dye directly into the coronary arteries. The flow of dye is then captured on short runs of X-ray video.
Angiograms are undertaken in a specialised operating theatre called a catheter laboratory, or “cath lab”. The procedure generally starts with giving a small amount of local anaesthetic to numb the area around the artery to be accessed. Sedative drugs may also be given.
A straightforward coronary angiogram may take as little as 15 minutes from start to finish. Patients are usually discharged from hospital the same day, but may be advised not to drive if sedation has been given.
Invasive coronary angiography does carry a slightly higher risk of complications than CT angiography, but gives a much more accurate impression of the severity of narrowings. It also gives direct access to the coronary arteries, allowing procedures such as angioplasty and stenting to be carried out, usually at the same sitting.