Cardiac Catheterization

• What is the test?
• How do I prepare for the test?
• What happens when the test is performed?
• What risks are there from the test?
• Must I do anything special after the test is over?
• How long is it before the result of the test is known?

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What is the test?

Cardiac catheterization with coronary angiogram takes pictures of the blood vessels in your heart, to evaluate the health of your heart and detect any narrowing of the blood vessels or other problems. The catheterization is performed by a cardiologist (or sometimes a radiologist) who is a specialist in doing this type of test.

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How do I prepare for the test?

During this procedure, local anesthetics (numbing agents) are used to minimize pain. Tell the cardiologist if you have ever had an allergic reaction to a local anesthetic or to contrast dyes. Also let your doctor know if you could be pregnant, since the x-rays used during this procedure can damage a fetus.

You might be asked not to eat anything for six to eight hours before the test, to reduce the risk that you might become nauseated and vomit during the procedure. Tell the cardiologist if you're taking a nonsteroidal anti-inflammatory drug (NSAID) or other medicines that affect blood clotting and could increase the chance of bleeding from the procedure. You should also tell your doctor if you take insulin shots or blood sugar-lowering pills so that you can take steps to avoid dangerously low blood sugar, or hypoglycemia.

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What happens when the test is performed?

You lie on your back as a medical technician connects you to a heart monitor and places an intravenous (IV) line in your arm. You may be given a sedative through the IV so that you are relaxed during the test.

First, the doctor injects a local anesthetic into the skin. This might sting momentarily. After the skin is numb, the cardiologist inserts a catheter (a thin, hollow plastic tube) into a large artery-usually in your groin but possibly in your arm or wrist.

Using live x-rays displayed on a video monitor as a guide, your doctor moves the catheter along the artery until it reaches your aorta (the large blood vessel that carries blood from your heart to the rest of your body). The tip of the catheter is pushed up the aorta until it reaches the heart and then gently pushed into the coronary arteries that supply blood directly to your heart muscle.When the tip of the catheter reaches one of the coronary arteries, the doctor injects contrast dye through the catheter. The dye illuminates the artery, allowing the doctor to see if it is blocked or narrowed. The procedure is repeated to visualize the other coronary arteries.

X-ray pictures are taken while the dye travels down the arteries. The arteries look like thick lines on the x-ray; a narrowing or blockage in an artery appears as a thinner line (see Figure 1). Your doctor might also inject some contrast medium into the left ventricle of your heart to show how forcefully your heart is pumping. The entire procedure usually takes from one to several hours.

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What risks are there from the test?

There are several potential risks. First, the catheter can irritate the heart, in rare cases causing a disturbance in the heart rhythm. Should this happen, the doctor can immediately use devices and medicines to restore a normal heart rhythm. The catheter occasionally can cause the coronary artery to go into spasm, temporarily reducing the blood flow and causing chest pain. For this reason, alert the doctors and nurses if you develop any chest discomfort, trouble breathing, or any other problem during the test.

In addition, the contrast medium can sometimes impair kidney function. This effect is almost always temporary, but some people have permanent damage. Another possible complication is bleeding at the place where the catheter was inserted. If blood collects under the skin, it can form a large painful bruise called a hematoma. This usually resolves on its own, without requiring additional treatment. Occasionally, people are allergic to the contrast dye and develop a rash, hives, or difficulty breathing after the dye is injected. If this should occur, the medical staff in the catheterization laboratory have medicines available to treat the allergic reaction.

The amount of radiation from this test is too small to be likely to cause harm.

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Must I do anything special after the test is over?

You should lie flat for a few hours after this procedure. Often, a small plug or stitch is used to prevent bleeding from the artery that was entered to perform the catheterization. If you received a sedative, you might feel sleepy and shouldn't drive or drink alcohol for one day after the catheterization.

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How long is it before the result of the test is known?

Your doctor will have your results as soon as the test is completed. In particular, the doctor can tell you if you have any blockages in the coronary arteries, how many and how severe they are, and the best way to treat them. In some cases, your doctor is even able to remove any blockages immediately by performing an intervention known as a coronary angioplasty, a procedure that uses a tiny inflatable balloon to reopen the artery.

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