Interventional Angiography.

20-12-2006Back to Article

What is Angiography?

The study of filling a blood vessel with a contrast to highlight its lumen (inside) along its full course or in part and taking an image of this process by passing an X-Ray from outside the body is called Angiography. This process can be done for various parts of blood vessels of the body, like heart (called cardiac angiography), brain (Cerebral Angiography), Belly (Abdominal Angiography), kidneys (renal angiography) Limbs – Legs or hands (Peripheral Angiography) , so as to determine whether the vessels are diseased, narrowed, enlarged or blocked altogether.

What is Invasive Catheter Angiography?
The study done after passing a flexible catheter through an artery or vein leading to the specific vessel as mentioned above (body area of interest), a contrast material is injected to highlight the vessels when x-rays are taken. When such a procedure is done by incerting a catheter after cutting a small opening either from the hand (radial artery) or from the leg (femoral artery) and pushing this catheter till the heart through inside these vessels and images are taken after passing a die into the vessel is called Invasive Coronary Angiography. This is mostly indicated in patients proven to have significant coronary artery disease (block of the vessels of the heart) so that treatment by means of – Angioplasty (removal of the block by a balloon and insertion of a medicated or non-medicated stent in that place can be placed to prevent it from collapsing or again getting blocked immediately).
Today, many catheter angiographic studies have been replaced by less invasive methods, such as computed tomography (CT) angiography and magnetic resonance (MR) angiography, that do not require that a catheter be inserted. Catheter angiography still is widely used in patients who may undergo surgery, angioplasty, or stent placement.

What are some common uses of the procedure?
Common reasons to do catheter angiography are to detect narrowing or blockage of a blood vessel, identify abnormally dilated blood vessels, and determine the site of internal bleeding. The procedure is able to:

• Show atherosclerotic disease in the carotid artery of the neck, which may limit blood flow to the brain and even cause a stroke.
• Demonstrate an intracranial aneurysm or other disorders of the blood vessels in the brain.
• Indicate disease in the renal artery or help prepare for a kidney transplant.
• Determine the state of the aorta and detect an aneurysm of this vessel.
• Demonstrate a source of bleeding, such as a stomach ulcer.
• Help prepare for surgery on diseased blood vessels in the legs of patients who have severe leg pain when walking.
• Showthe extent and severity of atherosclerosis in the coronary arteries.

Surgeons sometimes use angiography to plan an operation, like coronary bypass surgery, or to decide on the best surgical procedure. Using catheter angiography as an aid to see inside blood vessels, surgeons can repair diseased vessels from within using tiny instruments and inserting a stent to keep the vessel open.

How should I prepare for the procedure?

If you are to have a sedative during the procedure, you may be asked not to eat or drink anything (except sips of water to take pills) for four to eight hours ahead of time. Some hospitals, however, allow clear fluids until shortly before the examination. Be sure that you have clear instructions from your health care facility. You will probably receive an intravenous (IV) sedative in preparation for angiography, and you should not drive for 24 hours afterward. Because an observation period is necessary before you can leave, you may be admitted to the hospital for an overnight stay if you live more than an hour away.
If you will be going home the same day, you should arrange alternative transportation. After removing jewelry and donning a hospital gown, you should empty your bladder. A small amount of blood will be drawn before starting the procedure to make sure that your kidneys are working and that your blood will clot normally, and an IV line will be set up.
Before the procedure you will have to give your consent. This usually involves a face-to-face talk with a physician, but in some cases you will read a brief description of angiography or view a videotape instead. If you have any allergies, you should tell the physician before the exam begins. Also, the radiology staff should know if there is a possibility that you may be pregnant.

What does the angiography equipment look like?

The angiographic catheter is a long plastic tube about as thick as a strand of spaghetti. The equipment is mounted on a C-shaped with the x-ray tube itself beneath the table on which the patient lies. Over the patient is an image intensifier that receives the x-ray signals after they pass through the patient, amplifies them and sends them to a TV monitor.

How does the procedure work?
The basic idea of catheter angiography is the same as a regular x-ray. The x-rays passed through the patient's body are absorbed to different degrees by various tissues, and each type of tissue has its own distinctive appearance. A stream of dye, or contrast material, is injected into the catheter to obtain a detailed picture from inside the blood vessel. X-ray images are stored in a computer or captured on film. In this way, the procedure can be viewed like a movie and played over as often as necessary.

How is the procedure performed?
A small dose of sedative is usually given through the IV line, not to make the patient sleep but to lessen their anxiety during the procedure. Local anesthesia is injected into the skin at the site of puncture, which is most often at the top of the leg at the site of the femoral artery. A small incision is made after cleaning and shaving the skin at this site in order to introduce the catheter into the artery. The radiologist threads the catheter through the arterial system to the desired location and then injects the contrast material. Usually several sets of x-rays are taken and, after the procedure is completed, the catheter is removed and the puncture site closed by compressing it for about 10 minutes (or by using a special closure device). You will have to lie flat for two to six hours after angiography, depending on the reason for the exam, the catheter size, and the type of device used to close up the artery. During this time, you should inform the nurse if you notice any bleeding, swelling or pain at the site where the catheter entered the skin. The entire procedure may take less than an hour or as long as several hours.

What will I experience during the procedure?
Injecting a local anesthetic may sting briefly but makes the rest of the procedure pain-free. You will not feel the catheter in your artery, but when contrast material is injected you may have a feeling of warmth or, occasionally, a slight burning sensation. The most difficult part of the procedure may be lying flat for several hours.

Who interprets the results and how do I get them?
The radiologist will examine all of the images. In some instances, he or she will discuss the findings with you. Otherwise, he or she will report the findings to your physician, who in turn will discuss them with you.

What are the benefits vs. risks?

• Benefits
  
• Catheter angiography presents a very detailed, clear and accurate picture of the blood vessels. This is especially helpful when a surgical procedure or some percutaneous intervention is being considered.
• By selecting the arteries through which the catheter passes, it is possible to assess vessels in several specific body sites. In fact, a smaller catheter may be passed through the larger one into a branch artery supplying a small area of tissue or a tumor; this is called "superselective angiography."
• Unlike computed tomography (CT) or magnetic resonance (MR) angiography, use of a catheter makes it possible to combine diagnosis and treatment in a single procedure. An example is finding an area of severe arterial narrowing, followed by angioplasty and placement of a stent.
• The degree of detail displayed by catheter angiography may not be available with any other noninvasive procedure.

• Risks
  
• You may have an allergic reaction to the dye, and this could lead to a skin reaction, a drop in blood pressure, difficulty breathing or even loss of consciousness.
• There is a small risk that blood will form a clot around the tip of the catheter, blocking the artery and making it necessary to operate to reopen the vessel.
• If you have diabetes or kidney disease, the kidneys may be injured when contrast material is eliminated through the urine.
• Rarely, the catheter punctures the artery, causing internal bleeding. It also is possible that the catheter tip will separate material from the inner lining of the artery, causing a block "downstream."
• Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.

What are the limitations of Catheter Angiography?
Patients with impaired kidney function, especially those who also have diabetes, are not good candidates for this procedure. Patients who have previously had allergic reactions to x-ray contrast materials are at risk of having a reaction to contrast materials that contain iodine. If angiography is essential, a variety of methods is used to decrease risk of allergy. You may be given one or more doses of a steroid medication ahead of time. Contrast material without iodine may be used instead of standard x-ray dye. Catheter angiography should be done very cautiously—if at all—in patients who have a tendency to bleed.