In angiography, a contrast dye is injected through a thin, flexible tube (catheter) into selected arteries, and a series of x-rays is obtained. Filled with the dye, these vessels are differentiated from other bodily structures on the x-ray film. Angiography is commonly used to evaluate arteries in the abdomen, kidneys, brain, lower extremities, and adrenal glands, as well as to visualize the coronary arteries and the pulmonary arteries.
Digital subtraction angiography is a technique that is currently used to enhance angiographic images. Continuous x-ray imaging, or fluoroscopy, records images of arteries before and after a contrast dye is injected. A computer converts these images into digital information, and then subtracts the preinjection from the postinjection images, removing bone and soft tissue and leaving an enhanced picture of the contrast-filled blood vessels.
Purpose of the Angiography
- To identify and evaluate narrowing, blockages, and other abnormalities in various arteries, including the femoral arteries in the legs, the carotid arteries in the neck, and the arterial systems of the brain, kidneys, and adrenal glands
- To obtain an accurate picture of the anatomy of specific blood vessels prior to vascular surgery
Who Performs Angiography
- A radiologist or another physician
Special Concerns about Angiography
- Pregnant women should only undergo this test in extreme circumstances because exposure to ionizing radiation may harm the fetus; inform your doctor even if you only suspect that you could be pregnant.
- People with allergies to iodine or shellfish may experience an allergic reaction to iodine-based contrast dyes.
- In people with kidney disorders or chronic dehydration, the contrast dye can worsen kidney function and may cause renal failure. To determine whether the dye can be administered safely, your doctor may perform a blood test to assess your kidney function before the test.
- This test may not be safe in people who have bleeding disorders or unstable cardiac disorders. Coagulation studies may be performed prior to the procedure to ensure that your blood will clot normally.
Before the Angiography
- Inform your doctor if you regularly take anticoagulants or nonsteroidal anti-inflammatory drugs (such as aspirin, ibuprofen, or naproxen). You may be advised to discontinue these drugs for some time before the test.
- Be sure to inform your doctor if you have a known shellfish or iodine allergy or have ever had an adverse reaction to x-ray contrast dyes. You may be given preventive medication before the test, or a noniodinated dye may be used.
- Inform your doctor if you are pregnant or suspect that you may be pregnant.
- Do not eat anything for 4 to 8 hours before the test. You may consume clear liquids.
- At the testing facility, remove any metal objects, including watches, hair clips or jewelry.
- An intravenous (IV) line is inserted into a vein in your arm so that any necessary medications can be administered during the procedure.
- Empty your bladder before the procedure begins. (Because iodinated dye can act as a diuretic, your bladder may feel uncomfortably full during the test. For more prolonged studies, this may require the insertion of a temporary catheter into the bladder.)
- You will be given a mild sedative to help you relax during the test.
- You will undergo routine blood work; you will also have a nervous system examination.
What You Experience
- You will lie on your back on an x-ray table. If blood vessels in the head or neck are being examined, your head is immobilized in a brace (but your face is left uncovered).
- Electrocardiogram (ECG) leads may be taped to your arms and legs to monitor your heart during the test.
- The area where the catheter is to be inserted—usually the femoral artery in the groin—is cleansed with an antiseptic solution and (if necessary) shaved. A local anesthetic is injected to numb the site.
- A needle is inserted into the femoral artery, and a guide wire is passed through the needle. A thin catheter is then inserted over this wire and into the artery, and the wire is withdrawn.
- Under the guidance of fluoroscopic imaging, the catheter is directed to the artery being examined. (To examine the cerebral blood vessels in the brain, the catheter is threaded to arteries of the neck.)
- Next, a contrast dye is injected through the catheter. You may experience a flushing or burning sensation, headache, or a metallic taste briefly after the injection; rarely, some people experience nausea and possibly vomiting.
- As the contrast agent spreads through the arteries, serial x-ray films are obtained in a timed sequence.
- The procedure time varies, ranging from less than 1 hour to 3 hours.
Risks and Complications of Angiography
- Possible serious risks include blood clot formation, bleeding or infection at the catheter insertion site, blood vessel damage, abnormal heart rhythms, and, in rare cases, stroke.
- Some people may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, sneezing, vomiting, hives, and occasionally a life-threatening response called anaphylactic shock. Emergency medications and equipment are kept readily available.
- Renal failure may occur as a result of exposure to the contrast dye, especially in elderly patients with chronic dehydration or mild kidney impairment.
After the Angiography
- The catheter is removed, and pressure is applied until the bleeding stops (up to 30 minutes). A pressure bandage is applied, and a small sandbag may be placed over the puncture site for several hours to prevent bleeding.
- You will rest in a recovery room for about 6 to 8 hours. During this time, you should not move the limb where the catheter was inserted. Nurses will check you periodically to ensure there is no bleeding at the puncture site or other complications.
- You are encouraged to drink clear fluids to avoid dehydration and help flush the contrast dye out of your system.
- Most people may return home after about 5 to 6 hours, though some may require overnight hospitalization. Before you leave, a doctor or nurse will demonstrate how to apply pressure to stop any bleeding at the puncture site.
- Blood may collect and clot under the skin (hematoma) at the puncture site; this is harmless and will resolve on its own. For a large hematoma that causes swelling and discomfort, apply ice initially; after 24 hours, use warm, moist compresses to help dissolve the clotted blood.
- You may resume your normal diet and medications, according to your doctor’s instructions. Avoid heavy lifting and strenuous activities for a few days.
- If bleeding or any other complications develop such as facial weakness, numbness in your leg, slurred speech and vision problems, call your doctor or emergency medical service immediately.
- The doctor will examine the recorded images for signs of significantly narrowed or blocked arteries and any other abnormalities.
- This test usually establishes a definitive diagnosis. Based on the findings, your doctor will recommend a course of medical or surgical treatment.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media