Home
Profile
Enquiry
Interventional Angiography Vs Catheter Angiography
Back to Article
What is Catheter Angiography?
Angiography is a type of x-ray that is done to image blood vessels in various parts of the body, including the heart, brain and kidneys, so as to determine whether the vessels are diseased, narrowed, enlarged or blocked altogether. After passing a catheter through an artery leading to the body area of interest, a contrast material is injected to highlight the vessels when x-rays are taken. Today, many catheter angiographic studies have been replaced by less invasive methods, such as computed tomography (CT) angiography and magnetic resonance (MR) angiography, that do not require that a catheter be inserted.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.
- Show the 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 x-ray equipment is mounted on a C-shaped gantry 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 tcontrast 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.
Nuclear medicine is a healthcare specialty involving the use of radioactive compounds to perform diagnostic imaging examinations that can lead to the effective treatment of many diseases. Although nuclear medicine is often considered an independent discipline, it is closely related to radiology in that radiation is used to develop images of human anatomy. Cardiac nuclear medicine refers to these diagnostic tests that are used to examine the anatomy and function of the heart.
What are some common uses of the procedure?
Cardiac nuclear medicine tests are indicated for individuals with unexplained chest pain or chest pain brought on by exercise (called angina) to permit the early detection of heart disease. The most common cardiac nuclear medicine procedure, called myocardial perfusion scanning, enables the visualization of blood-flow patterns to the heart walls. The test is important for evaluating the presence and extent of suspected or known coronary artery disease (blockages) as well as the results of previous injury to the heart from a heart attack, called a myocardial infarction. It also can be done to evaluate the results of bypass surgery or other percutaneous revascularization procedures designed to restore the blood supply to the heart. Heart-wall movement and overall heart function can be evaluated with cardiac gating, a technique that synchronizes the images of the heart with different parts of the cardiac cycle (contracting or relaxing) as determined by an electrocardiogram (ECG), which records the electrical currents that activate the heart muscle and cause it to pump.
How should I prepare for the procedure?
You should avoid caffeine (coffee, tea, etc.) and smoking for 48 hours before the examination. You should not eat or drink anything after midnight before the procedure, but continue taking medications with small amounts of water unless your physician says otherwise. Wear comfortable, walking shoes and loose-fitting clothes for your procedure. Tell the technologist and supervising physician if you have asthma or a chronic lung disease or have problems with your knees, hips or keeping your balance, which may limit your ability to perform the exercise needed for this procedure.
What does the equipment look like?
The imaging equipment, called a gamma camera or scintillation camera, consists of specialized detectors enclosed within a metal housing. The detector portion of the camera can be changed to a variety of positions to obtain images of the body from different directions. A nearby computer console, possibly in another room, is used to develop the images of the heart.
How does the procedure work?
Coronary arteries are best evaluated by determining the changes in blood flow to the heart due to exercising. Consequently, you will undergo a stress test—most commonly through physical exercise—to make your heart work harder than normal. Then you will be given a radioactive compound, called a radiopharmaceutical agent or tracer. This compound will collect in parts of your heart with good blood flow and will give off gamma rays. The gamma camera detects the rays. Subsequently, a computer following a set of complicated mathematical formulas will construct images of the heart based on the detected gamma rays.
How is the procedure performed?
For the stress part of the examination, you will exercise by either walking on a treadmill or pedaling a stationary bicycle for a few minutes. While you exercise, the electrical activity of your heart will be monitored by electrocardiography (ECG), and your blood pressure will be measured frequently. Before you stop exercising, you will be given the radiopharmaceutical through an IV leading into a vein in your arm. The compound is given when the blood flow to the heart is at its peak because of your exercising. This provides the best opportunity to identify regions of the heart that are not receiving adequate blood flow. One minute later, you will stop exercising. Approximately one half-hour later, as you lay on an examining table, the compound will have collected in your heart. The gamma camera will then be used to obtain images. The gamma camera likely will move slowly and automatically in an arc over the front of your chest after it is positioned initially by the technologist. The images obtained after exercise must usually be compared with images of your heart obtained after injection of the same radiopharmaceutical while you are resting. This may be performed before or after the exercise part of the examination, depending on the protocol used. Comparison of the exercise and resting images is done to determine whether coronary blood flow has changed once you have rested and to check for coronary artery disease. If you are unable to use a treadmill or bicycle, you will not exercise, but you will be given a drug that will cause your heart to work as hard as if you had exercised. You will then be given the radiopharmaceutical. Immediately after the procedure, a diagnostic radiologist with specialized training in nuclear medicine will check the quality of the images to ensure that an optimal diagnostic study has been performed.
What will I experience during the procedure?
You may experience some minor discomfort from the intravenous injection of the radiopharmaceutical.
You will be asked to exercise until you are either too tired to continue or short of breath, or if you experience chest pain, leg pain, or other discomfort that causes you to want to stop.
If you are given a medication to increase blood flow because you are unable to exercise, the medication may induce a brief period of feeling anxious, dizzy, nauseous, shaky or short of breath. In rare instances, if the side effects of the medication are severe or make you too uncomfortable, other drugs can be given to stop the effects.
Most patients can resume regular activities immediately after the procedure. The radioactivity in your body will decrease due to the natural process of radioactive decay. In addition, radioactivity will decrease because the radiopharmaceutical passes out of the body in the urine or stool.
Who interprets the results and how do I get them?
Generally, patients undergo a nuclear medicine examination because a referring physician has recommended it. A physician who has specialized training in nuclear medicine will interpret the images. It usually takes one to three days to interpret, report, and deliver the information to your referring physician. Your referring physician will then inform you of the results.
What are the benefits vs. risks?
Benefits
- The functional information regarding blood flow to the heart and the pumping function of the heart is well demonstrated. This information may be used to determine what treatment or additional testing, if any, is needed.
- Computers are involved in the generation of the images, so measurements or quantification of function, as well as the determination of abnormalities, are possible.
- Because the procedure is generally performed according to standardized protocols, the type of examination done at one hospital is likely to be similar to that performed at other hospitals, making the information easy to understand or to transfer to all doctors who may be involved in your care.
Risks
- If you have coronary artery disease, it is possible that you could experience chest pain, or angina, when stress due to exercise or a drug is applied to your heart. However, your test will be carried out under the supervision of a specialist trained to monitor you and your heart by using information being provided by the electrocardiogram, by your heart rhythm, and by your blood pressure. If necessary, medication can be given for your chest pain. You will be monitored long enough to ensure that you are at your baseline; that is, the condition you were in when you came for the test.
- The use of a radioactive substance will result in exposure to a small amount of radiation to the heart and to the body. However, the amount of radioactivity administered is the smallest amount necessary to provide adequate images. Cardiac nuclear medicine procedures have been done for more than three decades, and no long-term adverse effects have been reported from such low-dose studies.
- Allergic reactions to radiopharmaceuticals can occur but are extremely rare.
- As with all radiologic procedures, it is important that you inform your physician and the technologist if you are pregnant. In general, exposure to radiation during pregnancy should be kept to a minimum. Depending on the nature of your medical problem, the cardiac nuclear medicine procedure may be postponed until after your pregnancy.
What are the limitations of Cardiac Nuclear Medicine?
Compared with most radiology studies, cardiac nuclear medicine procedures are time-consuming. They involve either exercise or the administration of a drug to increase blood flow to the heart, obtaining gamma-camera images (usually two sets of images separated by a few hours), and then computer manipulation of the information. Depending on the exact procedure performed, the myocardial perfusion scan takes between two and five hours. Occasionally, a patient may be asked to return to the nuclear medicine department the next day. An outpatient may be allowed to leave the hospital between the two sets of images. An inpatient will usually return to his or her hospital room between the imaging sessions.
“To Rule Out Coronary Artery Disease” The ability of cardiac CT to rule out coronary artery disease exceeds a predictive value of 99%. This means that when the study is reported to be normal, it will be normal. This makes it a more accurate test than stress-testing, stress-echocardiography, stress-thallium and stress-perfusion MRI. More importantly, the heart does not have to be stressed to get this information.
“To Rule Out Coronary Artery Disease”
|
|
|
|
Other Indications:
|
