What is Angiography?
Literally speaking, ‘angiography’ translates to ‘imaging of blood vessels.’ Four major blood vessels provide the blood supply of the brain. These are the right and left carotid arteries and the right and left vertebral arteries.
Why is this test performed?
Angiography is performed in order to evaluate the health of the cerebral blood vessels (the carotid and vertebral arteries as well as their branches.) Your neurologist may request this test if you have any of the following conditions:
Unexplained hemorrhage in the brain (intra-cerebral or subarachnoid hemorrhage)
Blockage of one or more of the arteries supplying the brain (stenosis or occlusion)
Thinning of the wall of a blood vessel resulting in weakening and bulging with subsequent possible rupture (cerebral aneurysm)
Ripping of the inside lining of one or more blood vessels (dissection)
Inflammation of the blood vessels in the brain (vasculitis)
Abnormal blood vessel formations (AVMs – arteriovenous malformations)
As a preoperative procedure in order to define the anatomy
Primary or metastatic brain tumors
Certain cases of stroke
Other (rare) conditions
How to prepare for the test?
You must inform your doctor before hand if you have any allergies. Allergy to shellfish or a prior allergic reaction to dye (iodine-based contrast material) must be reported. You must inform your doctor if you are pregnant or suspect that you may be pregnant. You will be instructed not to ingest any food or fluids for at least 4 hours and preferably a little longer, prior to the procedure.
A neurological examination is usually conducted prior to the procedure, either at your physician’s office or in the hospital. Certain routine blood tests will be requested in order to exclude any bleeding tendency and to assure adequate hydration and kidney function. A consent form will have to be signed prior to the procedure.
Where is the procedure performed?
Angiography is usually performed in the ‘angio’ suite of the radiology department in a hospital and may be completed as a same day procedure.
How is the procedure performed?
You will be asked to lie on a firm examination table. In order to obtain an image of the blood vessels, a contrast agent (dye) is injected into the arteries via a catheter and then X-rays are taken.
The area where the catheter is to be inserted is initially shaved and cleansed. A local anesthetic agent is then injected under the skin. A needle is then inserted into an artery (usually in the groin) through which a catheter (a long flexible tube) is threaded all the way up to the carotid or vertebral arteries in the neck. Through fluoroscopy (an X-ray technique whereby intermittent injections of dye material allow your physician to monitor the procedure on a screen) your physician can assure proper placement of the catheter.
In order to visualize the blood vessels under study, the dye material is injected and the arteries (and also the veins) can be photographed. During the procedure you will be continuously monitored. ECG leads monitor your cardiac rhythm while vital sign are recorded every few minutes.
At the end of the procedure the catheter is withdrawn and pressure is applied to the site in order to prevent bleeding. Then a tight bandage (and at times a heavy weight) is applied to further minimize the risk of any bleeding. You will then be observed in the hospital for several hours before you are allowed to leave.
How the test will feel
The room is usually kept cool. The local anesthetic agent may produce a mild burning sensation and the needle may cause a brief sharp painful sensation when it punctures the artery. As the catheter is advanced you may feel a pressure-like sensation. When the dye is injected you may experience a warm sensation throughout your body. This quickly subsides. Some may experience transient flushing or a headache. If you experience any other phenomena, you must inform your physician immediately.
At the end of the procedure, you will experience slight tenderness and bruising at the site of the injection.
What are the possible complications?
There is a possibility of an allergic reaction to the dye material. Mild reactions may include nausea, vomiting and lightheadedness. More serious reactions are quite rare and occur at a frequency of about 1:100,000
Patients who are dehydrated, have underlying kidney disease or are at risk for kidney damage (such as those with diabetes mellitus) require close monitoring since dye material can result in significant kidney damage.
Any invasive procedure carries a risk of infection. Angiography is performed under sterile conditions and therefore this risk is minimal.
During the procedure, heparin (a blood thinning agent) is injected to maintain the catheter open and to prevent clotting. This however can result in unwanted bleeding at the injection site after the procedure. You must report any oozing of blood or any hematoma (a collection of blood under the skin) formation to your physician.
Rarely, the leg through which the catheter was inserted may become cold and numb due to clotting of the artery that was punctured thus preventing blood from reaching your leg. Should this occur you must immediately notify your physician since this represents an emergency that requires prompt surgical intervention in order to restore blood flow.
When the catheter is inserted, it may disrupt clots on the inside walls of the blood vessels. The clot thus becomes dislodged and travels upwards to block a distal vessel possibly resulting in a stroke. This is an uncommon complication. The catheter may also cause a tear in the wall of the blood vessel (a dissection) which may also result in a stroke. This too is a rare complication
Stroke is the most feared complication of this procedure. It occurs at a frequency of less than 0.5% (less than 1:200).