Angiography is the use of a solutionvisibleon X-ray to obtain a contrast X-ray picture o fthe interior of blood vessels. Angiography of arteries (also called arteriography) may be used to detect obstruction due to clots or foreign matter in the bloodstream, or distortions of the vessel wall due to arteriosclerosis, atheroma or aneurysm. The contrast solution is introduced via a catheter (fine tube) that is inserted into a large artery, such as the femoral artery in the groin or the carotid in the neck, and guided through it with X-ray monitoring until it reaches the branch to be examined. X-ray-visible solution is then injected into the branch and a series of X-ray pic-tures taken.

• Coronary angiography is used to determine how much the blood supply to the heart has been affected by coronary artery disease, and to locate narrowed coronary vessels. It is often performed when coronary bypass surgery or balloon angio- example parts of micro-organisms. or tissues from plasty (a procedure, to restore flow through arteries) is considered. Preparation includes physical examination and ElECTROCARDlOGRAPH (ECG),and a 6-hour fast before the procedure. CARDIAC CATHITERISATION is performed, When the catheter reaches the left sIde of the heart, a small amount of X-ray- visible solution is injected. X-rays are taken as the solution passes through the coronary arteries.
• Pulmonary angiography enables a study of blood circulation from the right side of the heart to the lungs. An X-ray-visible solution is injected after the cardiac catheter has been guided, usually from a leg vein, to the right side of the heart and into the pulmonary artery.
• Digital subtraction angiography uses computer technique to produce images of the vessels being examined and to remove images of surrounding tissues.

The techniques of angiography may be used for treatment of some blood vessel disorders, and for the administration of drugs directly to particular organs or parts of the body.

Angiography is generally carried out in hospital. Apart from the prick when the catheter is inserted, the procedure is painless. The patient may feel faint or nauseated as the catheter is moved through the artery, and will usually notice a brief flushing sensation as the X-ray-visible, solution is injected. There is a small risk of adverse effects such as, allergy to the solution and damage to the artery when the catheter is inserted and moved.

Angiography can detect the development of clumps of new vessels and other abnormal patterns that suggest tumours, cysts, congenital defects or an injury to any internal organ. Coronary angiography is done to find a blockage in the coronary arteries, which can lead to heart attack. It may be done if you have unstable angina, atypical chest pain, aortic stenosis, or unexplained heart failure. Angiography is used to look at the liver to localise abnormalities, including tumours. This can be particularly useful when planning surgery. This procedure is used to get more exact information after something abnormal has been detected by an CT scan of the head. An example of such abnormality would be bleeding within the brain. During angiography, physicians inject streams of contrast agents or dyes into the area of interest using catheters to create detailed images of the blood vessels in real time. Catheter angiography should be done very cautiously – if at all – in patients who have a tendency to bleed.

Types of angiographs

• Cerebral angiography.
• Visceral angiography (the abdominal organs, or viscera ).
• Coronary angiography.
• Right heart ventriculography.
• Lymphangiography ( lymph vessels ).
• Left heart ventriculography.
• Retinal angiography.

When is angiography used?

• An angiogram was once commonly used to check the condition of blood vessels.
• Angiography may reveal aneurysms (a bulge on an artery caused by a blood vessel wall becoming weaker).
• It may be used if the doctor is considering surgery, because it shows a clear picture of the blood vessels.
• Angiography is used to look at the coronary arteries that send blood to the heart. The test is used to show if the arteries of the heart have narrowed.
• Demonstrate a source of bleeding, such as a stomach ulcer.
• Angiography is used to look at the liver to localise abnormalities, including tumours. This can be particularly useful when planning surgery.

Is angiography dangerous?

• A small minority of patients are allergic to the liquid dye, mainly due to the iodine content of the dye. Anyone who has previously experienced such reactions should mention this to the doctor.
• There is a small risk of the catheter damaging the blood vessels that it was inserted through.
• Pregnant women should enquire about the risks of the fluoroscopy harming their baby.
• Patients suffering from severe liver, heart or kidney diseases may be at greater risk, and should seek advice from the specialist.

How long does coronary angiography take?

• It usually takes about 30 minutes.
• In most cases it is done as a day-case procedure.

Precautions

• Patients who have blood-clotting problems, have a known allergy to contrast media, or are allergic to iodine may not be suitable candidates for an angiography procedure.
• Because x rays carry risks of ionizing radiation exposure to the fetus, pregnant women are also advised to avoid this procedure.

What the risks are

Risks of the procedure include the following:

• Heart attack.
• Cardiac arrhythmias.
• Stroke.
• Trauma to the artery caused by hematoma.
• Low blood pressure.