What is angiography?
Angiography is an x-ray study of the blood vessels. An angiogram uses a radiopaque substance, or dye, to make the blood vessels visible under x ray.
Why is an angiography done?
Angiography is used to detect abnormalities or blockages in the blood vessels throughout the circulatory system and in some organs. The procedure is commonly used to identify atherosclerosis; to diagnose heart disease; to evaluate kidney function and detect kidney cysts or tumours; to detect an aneurysm (an abnormal bulge of an artery that can rupture leading to haemorrhage), tumour, blood clot, or arteriovenous malformations in the brain; and to diagnose problems with the retina of the eye. It is also used to give surgeons an accurate ‘map’ of the heart prior to open-heart surgery, or of the brain prior to neurosurgery.
What happens during the procedure?
Angiography is performed at a hospital by a trained radiologist and assisting technician or nurse. Angiography requires the injection of a contrast dye that makes the blood vessels visible to x-ray. The dye is injected by an arterial puncture. The puncture is usually made in the groin area, armpit, inside elbow, or neck. Depending on the type of angiography procedure being performed, the contrast medium is either injected by hand with a syringe or is mechanically injected with an automatic injector connected to the catheter. An automatic injector is used frequently because it is able to propel a large volume of dye very quickly to the angiogram site. The patient is warned that the injection will start, and instructed to remain very still. The injection causes mild to moderate discomfort. Possible side effects or reactions include headache, dizziness, irregular heartbeat, nausea, warmth, burning sensation, and chest pain, but they usually last for a short time.
Throughout the dye injection procedure, x-ray pictures and/or fluoroscopic pictures (or moving x rays) are taken. Because of the high pressure of arterial blood flow, the dye will dissipate through the patient's system quickly, so pictures are taken in rapid succession. Once the x-rays are complete, the catheter is slowly and carefully removed from the patient. A pressure bandage is then applied.
In a coronary angiography, the arterial puncture is typically given in the femoral artery, and the cardiologist uses a guide wire and catheter to perform a contrast injection and x-ray series on the coronary arteries. The angiogram procedure takes several hours, depending on the complexity of the procedure.
How to prepare for an angiography?
Patients undergoing an angiography are advised to stop eating and drinking eight hours prior to the procedure. If the arterial puncture is to be made in the armpit or groin area, shaving may be required. A sedative may be administered to relax the patient for the procedure. An IV line will also be inserted into a vein in the patient's arm before the procedure begins in case medication or blood products are required during the angiogram. Prior to the angiography procedure, patients will be briefed on the details of the test, the benefits and risks, and the possible complications involved, and asked to sign an informed consent form.
What happens after the procedure?
Because life-threatening internal bleeding is a possible complication of an arterial puncture, an overnight stay in the hospital is sometimes recommended following an angiography procedure, particularly with cerebral and coronary angiograms. If the procedure is performed on an outpatient basis, the patient is typically kept under close observation for a period of at least six to 12 hours before being released. Pain medication may be prescribed if the patient is experiencing discomfort from the puncture, and a cold pack is applied to the site to reduce swelling. It is normal for the puncture site to be sore and bruised for several weeks. Angiography patients are also advised two to three days of rest and relaxation after the procedure in order to avoid placing any undue stress on the arterial puncture site. Patients who experience continued bleeding or abnormal swelling of the puncture site, sudden dizziness, or chest pains in the days following an angiography procedure should seek medical attention immediately. Patients undergoing a fluorescein angiography should not drive or expose their eyes to direct sunlight for 12 hours following the procedure.
What are the risks associated with the procedure?
Because angiography involves puncturing an artery, internal bleeding or haemorrhage are possible complications of the test. As with any invasive procedure, infection of the puncture site or bloodstream is also a risk, but this is rare. A stroke or heart attack may be triggered by an angiogram if blood clots or plaques on the inside of the arterial wall are dislodged by the catheter and form a blockage in the blood vessels or artery. The movement of the catheter through its chambers may also irritate the heart during pulmonary and coronary angiography procedures, and arrhythmias may develop. Patients with kidney disease or injury may suffer further kidney damage from the contrast mediums used for angiography. Patients who have blood clotting problems, have a known allergy to contrast mediums, or are allergic to iodine, a component of some contrast mediums, may also not be suitable candidates for an angiography procedure. Because x-rays carry risks of ionising radiation exposure to the fetus, pregnant women are also advised to avoid this procedure.