A long, thin, flexible tube called a catheter is inserted into an artery in your groin or arm and is carefully threaded into your heart under the guidance of continuous x-ray imaging, or fluoroscopy. Pressures within your heart and coronary arteries are recorded through the catheter. Next, a contrast dye is injected through the catheter to help delineate your coronary arteries and other cardiac structures on x-rays films; this portion of the test is termed coronary angiography or arteriography.
In some cases, this procedure is immediately followed by treatment, such as percutaneous transluminal coronary angioplasty, which uses a catheter equipped with a small balloon to unblock coronary arteries.
Purpose of the Cardiac Catheterization
- To examine the coronary arteries, identify any blockages due to atherosclerosis, and determine the need for treatment
- To assess the function of heart valves, coronary artery bypass grafts, and other cardiac structures
- To evaluate pressures in the heart’s chambers and the pumping function of the heart
- To study congenital heart defects
- To monitor blood flow through the heart following surgery
Who Performs Cardiac Catheterization
Special Concerns about Cardiac Catheterization
- This procedure is performed in a hospital catheterization laboratory.
- The risks associated with this test are increased in people with bleeding disorders or poor kidney function; the test may not be possible in those with severe atherosclerosis in the arms or legs.
- People who have an allergy to shellfish or iodine may experience an allergic reaction to the contrast dye.
- Pregnant women should not undergo this test because exposure to ionizing radiation may harm the fetus.
Before the Cardiac Catheterization
- Tell your doctor if you regularly take anticoagulants or nonsteroidal anti-inflammatory drugs (such as aspirin, ibuprofen, or naproxen). You will be instructed to discontinue them for some time before the test.
- Be sure to tell your doctor if you have a known shellfish or iodine allergy or have ever had an adverse reaction to x-ray contrast dyes. You may be given a combined antihistamine-steroid preparation for several days before the test to reduce the risk of an allergic reaction.
- Do not ingest food and fluids for 6 to 8 hours before the test.
- Empty your bladder before the procedure.
- Immediately before the test, an intravenous (IV) line is inserted into a vein in your arm. You may also be given a mild sedative, but you will remain conscious throughout the procedure.
- A mild sedative will be administered before the test to help you relax.
- Tell your doctor if you had a previous bad reaction to contrast material or iodine
- Tell your doctor if you are pregnant or may be pregnant.
- Tell your doctor if you have diabetes, especially if you take metformin (Glucophage) to treat diabetes. Your doctor may instruct you to stop taking metformin 48 hours before the procedure.
What You Experience during Cardiac Catheterization
- You lie on your back on a padded table, and ECG leads are applied to monitor your heart rate and rhythm.
- The area of catheter insertion (your groin or arm) is shaved, cleansed with an antiseptic to help prevent infection, and numbed with a local anesthetic. The doctor then makes a small incision and inserts a catheter into the artery; you will feel pressure during insertion, but no other discomfort.
- The doctor guides the catheter to your heart, using fluoroscopy to watch its progress on a viewing monitor.
- The contrast dye is administered through the catheter. You may feel a hot, flushing sensation for about 15 to 20 seconds after the injection; rarely, some people experience nausea and possibly vomiting.
- The doctor takes several moving and still x-ray pictures (angiograms) of your heart for later analysis.
- If you develop chest pain during the procedure, nitroglycerin may be administered.
- The test itself usually takes 30-60 minutes.
Risks and Complications of Cardiac Catheterization
- Possible risks include blood clot formation, bleeding, blood vessel damage, injury to the artery caused by hematoma or infection at the site of catheter insertion.
- Kidney damage caused by contrast material (particularly in patients with diabetes).
- Some people may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, sneezing, vomiting, hives, and occasionally a life-threatening response called anaphylactic shock. Emergency medications and equipment are kept readily available.
- Rarely, the procedure may provoke a heart attack, stroke, or cardiac arrest; emergency equipment is available at the catheterization lab. Among stable patients, the risk of heart attack or death is very low (about 1 in 1,000).
After the Cardiac Catheterization
- The catheter is removed, and pressure is applied to the incision site until the bleeding stops (up to 30 minutes). A pressure bandage is then applied, and a small sandbag is typically placed over the incision site for several hours to prevent bleeding.
- You will rest in a recovery room for about 6 to 8 hours. During this time, you should not move the limb where the catheter was inserted. Nurses will check you periodically to ensure there is no bleeding at the incision site, to look for signs of delayed reaction to the contrast dye, and to monitor your blood pressure and other vital signs.
- You are encouraged to drink clear fluids during this period to avoid dehydration and help flush the contrast dye out of your system.
- Most people are able to return home after about 5 to 6 hours, though some may require overnight hospitalization.
- Before you leave, a doctor or nurse will demonstrate how to apply pressure to stop any bleeding at the incision site.
- Avoid heavy lifting and do only light activities for a few days after the test. You may develop a small lump at the insertion site, but it should disappear in a few weeks.
Cardiac Catheterization Results
- The doctor will examine the x-ray films and other test data for signs of significantly narrowed or blocked coronary arteries and other cardiac abnormalities.
- This test is usually definitive. Based on the findings, your doctor will then decide on a course of medical or surgical treatment.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media