Cardiac catheterization is used to study the various functions of the heart.

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The purpose of cardiac catheterization is to determine whether you have disease in your coronary arteries, and if so, pinpoint the size and location of plaque that may have built up in your coronary arteries from atherosclerosis. This is generally done to determine whether you may need bypass surgery or angioplasty.  Additionally, the cardiologist can measure oxygen concentration across the valves and walls (septa) of the heart, along with measuring pressures within each chamber of the heart and across the valves.

How To Prepare

Tell your doctor if you:
Are allergic to the iodine dye used in the contrast material or any other substance that contains iodine. Also tell your health professional if you have asthma or have ever had a serious allergic reaction (anaphylaxis) from any substance, such as the venom from a bee sting.
Are allergic to any medications and whether you are taking any medications, including sildenafil (Viagra). This test may require the use of nitrate medication, such as nitroglycerin, that can cause a serious reaction if you have taken sildenafil (Viagra) within the previous 48 hours.
Have any bleeding problems or take blood-thinning medication.
Are or might be pregnant.
Have kidney disease or diabetes, especially if you take metformin (Glucophage) to control your diabetes. If you take metformin (Glucophage), your doctor will instruct you to stop the medication 48 hours before the test. The contrast material used during cardiac catheterization can cause kidney damage in people who have poor kidney function. If you have a history of kidney problems, blood tests (creatinine, blood urea nitrogen) may be done before the test to confirm that your kidneys are functioning properly. For more information, see the medical tests Creatinine and Creatinine Clearance and Blood Urea Nitrogen.

Consent
You will be asked to sign a consent form before the test. Consent for cardiac catheterization is a two-step process. The first step is to consent to the testing, or diagnostic, portion of cardiac catheterization, which includes a coronary angiogram to evaluate the blockages in your coronary arteries. The second step is to consent to the treatment portion, which may include a percutaneous coronary intervention (PCI) to open your blocked arteries, based on the results of the diagnostic portion. Talk to your health professional about any concerns you have regarding the need for the test, its risks, or how it will be done. Also, be sure you clearly understand what treatment will be recommended if a blockage is found during this test. To help you understand the importance of this test, fill out the medical test consent form.

Cardiac catheterization may be done on an outpatient basis without requiring an overnight stay in the hospital. In this case, you should know where you have to go and what time you need to arrive. You will need someone to pick you up after your test because you will not be allowed to drive home yourself. Wear comfortable clothes.

You will have a physical examination, some blood tests, an electrocardiogram (EKG), and possibly other heart tests or a chest X-ray. If you are taking any medications, ask your doctor whether you should take them on the day of the test.

Do not eat or drink (except for a small amount of water) for 6 to 12 hours before the test. You will not be put you to sleep, since it is important that you be awake to follow instructions during the test.

Before the test, remove any necklaces, bracelets, rings, or other jewelry. You should also remove nail polish from your fingernails and toenails to permit observation of the blood circulation in your fingers and toes. Areas on your arms or groin will be shaved to prepare these sites for possible insertion of the catheter. Be sure to empty your bladder completely just before the test. Before the procedure starts, you may want to ask for cushions or pillows to keep you as comfortable as possible.

How It Is Done

This test is performed in the cardiac catheterization laboratory ("cath lab") by a cardiologist.

You will be asked to lie on a flat table under a large X-ray machine. Several small metal leads (electrodes) will be attached to your legs and arms with a special paste or gel. These leads are connected to an electrocardiogram (EKG) machine that continuously records the electrical activity of your heart during the test. For more information, see the medical test Electrocardiography. A device called a pulse oximeter that measures oxygen levels in your blood and monitors your pulse may be clipped to your finger.

A small intravenous (IV) needle may be inserted into a vein in one of your arms to give you fluids or medications during the procedure. You may receive a sedative medication through the IV line. This medication reduces discomfort and will make you feel relaxed. You will remain awake during the procedure.

The location for the insertion of the cardiac catheter may be a blood vessel at the crease of your elbow (brachial artery), wrist (radial artery), or in your groin (femoral artery). If the catheter is to be inserted in your femoral artery, a health professional will shave your groin area and cleanse the area with antiseptic solution. You will then be draped with sterile towels except for the area over the insertion site.

Next, a small amount of local anesthetic is injected into the skin at the insertion site. A blood vessel is punctured by a special needle or exposed by making a small incision in the skin so that the catheter can be passed into the blood vessel. The catheter is slowly advanced through the blood vessel into your body. The catheter tip is moved into various positions in the heart's vessels and chambers while the doctor watches its progress on the imaging screen. Pressures within the heart chambers can be measured, and blood and heart tissue samples may also be removed through the catheter.

The lights are usually dimmed in the room to make it easier for the doctor to see the images of your heart on a video monitor.

You may be asked to hold your breath or move your head slightly to provide clear views of the heart and its blood vessels.

A small amount of contrast material will be injected through the catheter into your heart chamber or one of your coronary arteries. Pictures show the arteries as the dye moves through them. The table you are lying on during the procedure may be tilted in different directions to obtain different views of your heart. You may be asked to cough to help clear the contrast material out of your heart or breathe deeply and hold your breath.

It is important to lie as still as possible, since motion can distort the images. A health professional will help you stay comfortable and will help you resist the urge to move around. Be careful not to touch the sheets or reach for your groin area because you may contaminate the sterile areas and increase the risk of infection.

Your doctor may allow you to watch the video monitor so you can see the images of your heart and coronary arteries. If the images are recorded on photographic film, you will hear the recording machine's motor, which can be noisy.


After the test
After all the necessary pictures and measurements have been taken, the catheter will be removed. If the catheter insertion site was in your elbow, a few stitches will be used to close the wound. If the insertion site was in your wrist or groin, firm pressure will be applied to the area for about 10 minutes to stop the bleeding. Then a pressure dressing will be placed over the area.

The entire procedure usually takes 1 to 2 hours, but it may take longer if additional tests are required. The length of the test is not an indication of the seriousness of your condition. After the test, you will be taken to an observation room and a health professional will periodically monitor your heart rate, blood pressure, and temperature and check for signs of bleeding at the insertion site. The pulse, color, and temperature of the arm or leg in which the catheter was inserted will also be checked periodically.

If your procedure was performed using your leg, you will be asked to lie in bed with your leg extended for 4 to 12 hours, depending on the exact procedure used and your medical condition. After that, you can move about freely, but you should avoid strenuous activity for at least 1 to 2 day.

You should drink plenty of liquids for several hours after the test, because the contrast material may cause you to urinate frequently. Drinking liquids will prevent dehydration and help flush the contrast material out of your body.

Depending on the results of the test and whether any complications develop, you may be sent home either after a 3-6-hour observation period or on the next day. If any stitches were placed in your leg or arm, they may be removed in 5 to 7 days.