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Introduction
Procedure
Technical Details
Risks
An angiogram is a diagnostic test where a contrast dye is injected into the arteries and x-rays are taken in order to visualize blood vessel and any abnormalities associated with them such as an aneurysm (dilation of a blood vessel), stenosis (narrowing of a blood vessel) or blockages. The contrast dye circulating through the blood stream makes the blood vessels appear opaque (darker) on the x-ray image. A side view of a brain angiogram is shown below.
The patient lies back on an x-ray table inside an angiogram suite, similar to the one depicted below.
After appropriate preparations, a small incision is made in the groin and a small catheter is inserted into the femoral (groin) artery. The catheter is then threaded up through the blood vessel into the desired artery at which point contrast dye is injected and a series of x-ray pictures are taken as the contrast circulates inside the blood vessels. The images will appear on a television screen which can be viewed and interpreted by the radiologist. After the desired images have been obtained, the catheter is removed and some pressure will be applied to the insertion site in order to prevent any bleeding. After remaining flat for several hours, the patient can be discharged.
After injection of the contrast material during an angiography scan, x-ray beams are passed through the area of the body to be imaged. The contrast agent will absorb a significant portion of the x-rays, whereas those x-ray beams that do not come in contact with the contrast dye will pass through the body and reach an x-ray detector. Since the beams that encounter the contrast dye in the blood vessels will not reach the detector (will be absorbed), an "x-ray shadow" will be cast on the detector in those areas that correspond to the dye, which is interpreted by the machine in creating images of blood vessels on a television screen.
Angiography machines use ionizing radiations (x-rays) which while relatively harmless at low doses, can potentially increase the risk of certain types of cancers and other problems in chronic or repeated exposure. Furthermore, exposure to x-rays during pregnancy can increase the risk of birth defects. Therefore, all individuals, especially woman who are, or may be, pregnant, should carefully discuss this issue with their physician and radiologist before undergoing an angiogram in order to weigh the benefits of the procedure against its potential risks.
In addition, since the inside of the blood vessel will be manipulated by the catheters that are inserted during the procedure, there is a small risk of formation of blood clots inside of the blood vessel or rupture of the blood vessel, leading to decreased blood supply to a certain part of the body which can potentially lead to problems such as stroke.
Also, contrast agents that contain iodine are injected into the blood stream during this procedure. In rare instances, some patients may be allergic to these chemicals or may have a medical condition or be taking a medication which makes it dangerous to receive these agents. Therefore, patients should discuss their medical history, medications, and any other concerns with their physician and radiologist prior to the procedure.
