In angiography, x-rays are used to produce detailed images of blood vessels. It is sometimes called conventional angiography to distinguish it from computed tomography (CT) angiography CT angiography In computed tomography (CT), which used to be called computed axial tomography (CAT), an x-ray source and x-ray detector rotate around a person. In modern scanners, the x-ray detector usually... read more and magnetic resonance angiography Magnetic resonance angiography (MRA) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more (MRA). During angiography, doctors can also treat disorders of blood vessels. Angiography, although invasive, is relatively safe.
Angiography can provide still images or motion pictures (called cineangiography). Cineangiography can show how fast blood travels through blood vessels. (See also Coronary Angiography Coronary angiography Cardiac catheterization and coronary angiography are minimally invasive methods of studying the heart and the blood vessels that supply the heart (coronary arteries) without doing surgery. These... read more and Overview of Imaging Tests Overview of Imaging Tests Imaging tests provide a picture of the body’s interior—of the whole body or part of it. Imaging helps doctors diagnose a disorder, determine how severe the disorder is, and monitor people after... read more .)
Procedure for Angiography
Before the angiography procedure, people are usually asked to refrain from eating and drinking for 12 hours.
For the procedure, people lie on an x-ray table (one that x-rays can easily pass through). Because the table may be tilted, straps may be applied across the chest and legs. X-ray cameras can be positioned as needed. Electrodes are placed on the chest to monitor the heart. Blood pressure and oxygen levels are also monitored.
After injecting a local anesthetic, a doctor makes a small incision, typically in the groin or sometimes in the arm. Then a thin, flexible tube (catheter) is inserted, usually into an artery, and is threaded through blood vessels to the area being evaluated. When the catheter is in place, a radiopaque contrast agent Radiopaque Contrast Agents During imaging tests, contrast agents may be used to distinguish one tissue or structure from its surroundings or to provide greater detail. Contrast agents include Radiopaque contrast agents... read more (a liquid that contains iodine and can be seen on x-rays) is injected. The contrast agent flows through the blood vessels and outlines them. The images appear on a video screen and are recorded. Thus, doctors can assess the structure of blood vessels and identify any abnormalities present.
Before angiography, people are often given a sedative intravenously to help them relax and remain calm, but they remain conscious during the procedure. During the procedure, people may be asked to take deep breaths, hold their breath, or cough. People should report any discomfort they feel.
Angiography may take less than an hour or several hours, depending on the area of the body being evaluated and the type of the examination or procedures being done. It is usually done as an outpatient procedure.
If the catheter is inserted into an artery, the insertion site must be steadily compressed for 10 to 20 minutes after all the instruments are removed. Compression reduces bleeding and bruises. Alternatively, a small closure device may be used to seal the hole in the blood vessel. People may also need to lie flat for several hours after the procedure to help prevent bleeding. Rarely they need to stay overnight in the hospital. For the remainder of the day, they are advised to rest and to drink extra fluids to help eliminate the contrast agent from the body.
Uses of Angiography
Angiography is used to check for abnormalities in blood vessels, usually arteries. Abnormalities may include
Abnormal connections between arteries and veins (arteriovenous malformations)
Bulges ( aneurysms Aneurysms of Arteries in the Arms, Legs, and Heart An aneurysm is a bulge (dilation) in the wall of an artery. (See also Aortic Branch Aneurysms and Brain Aneurysms.) Aneurysms may occur in any artery. Aneurysms are most common in the aorta... read more ) in a weakened blood vessel wall
During angiography, procedures to treat the abnormalities detected can sometimes be done:
Narrowed arteries can be widened.
Blockages can be removed.
A tube made of wire mesh (stent) can be placed to keep an artery open.
Tears or weakened areas in a blood vessel can be repaired.
Blood flow to tumors or arteriovenous malformations can be blocked.
Variations of Angiography
This term refers to imaging of arteries. It is the most common type of angiography.
This term refers to imaging of veins. Ultrasonography has largely replaced venography in the diagnosis of clots in veins ( deep venous thrombosis Deep Vein Thrombosis (DVT) Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins, usually in the legs. Blood clots may form in veins if the vein is injured, a disorder causes the blood to clot... read more ).
Digital subtraction angiography
X-ray images of blood vessels are taken before and after a radiopaque contrast agent Radiopaque Contrast Agents During imaging tests, contrast agents may be used to distinguish one tissue or structure from its surroundings or to provide greater detail. Contrast agents include Radiopaque contrast agents... read more is injected. Then a computer subtracts one image from the other. Images of structures other than arteries (such as bones) are thus eliminated. As a result, the arteries can be seen more clearly.
Disadvantages of Angiography
For some people, the procedure is uncomfortable. In a few people, allergic-type reactions Allergic-type contrast reactions During imaging tests, contrast agents may be used to distinguish one tissue or structure from its surroundings or to provide greater detail. Contrast agents include Radiopaque contrast agents... read more to the contrast agent occur. The injection site may bleed, become infected, or be painful. Rarely, the catheter damages a blood vessel.
Serious complications, such as shock, seizures, kidney damage, and sudden stopping of the heart’s pumping (cardiac arrest), are very rare. Sometimes during cardiac catheterization, the heart skips beats or slows briefly.
The risk of complications is higher in older people, although it is still low.
The dose of radiation Risks of Radiation in Medical Imaging Imaging tests that use radiation, usually x-rays, are a valuable tool in diagnosis, but exposure to radiation has some risks (see also Radiation Injury). Different diagnostic tests require different... read more used in angiography varies depending on the procedure but typically is much higher than in plain x-ray tests. For example, the radiation dose in coronary angiography is 350 to 750 times as much as that used in a single-view plain x-ray of the chest.
Angiography is not always readily available. It must be done by highly skilled doctors.