Cardiac Catheterization


What Is It?

Cardiac catheterization is a procedure in which surgeons insert a small tube (catheter) through a large blood vessel in the arm or leg, then pass the tube into the heart. Once inside the heart, doctors use the catheter to evaluate how the heart is working by measuring pressure and oxygen levels within the heart’s chambers. Through the catheter, doctors also may inject a special dye that provides an X-ray image of the heart’s internal structure and blood flow patterns. In some patients, the X-ray dye also is injected into the coronary arteries to identify areas that have become narrow. This procedure is called coronary angiography.

What It’s Used For

Cardiac catheterization is used to evaluate patients who:

  • Will be undergoing heart surgery, especially coronary artery bypass surgery
  • May have suspected coronary artery disease
  • Have heart valve problems, including abnormal narrowing (stenosis), leakage (insufficiency) or significant backflow of blood through a valve (regurgitation)
  • May have cardiomyopathy (a specific form of heart-muscle damage)

Surgeons can use heart catheters to carry special surgical instruments into the heart. These instruments can open narrowed coronary arteries (a procedure called coronary angioplasty) or correct certain congenital (inborn) heart defects in children.


Before the procedure, the doctor will review your medical history, your current medications and your allergy history. If you know you are allergic to X-ray dye, tell your doctor. He or she may need to switch the X-ray dye that will be used for your procedure (some newer dyes are less likely to trigger allergies) or give you medication to reduce the likelihood of an allergic reaction. Also, if there is any chance that you might be pregnant, tell the doctor before your cardiac catheterization.

Leave bracelets, necklaces and watches at home. Someone will have to drive you home from the hospital, so make arrangements beforehand. Follow your doctor’s instructions for when to stop eating and drinking before your catheterization.

How It’s Done

A nurse or aide will clean and shave a specific area of your arm or leg to prepare for the insertion of the catheter. In the cath lab, a special room inside a hospital, you will lie on a flat table under a large X-ray machine. Several electrocardiogram (EKG) electrodes (small metal discs) will be applied to your arms and legs. Medication will help you to relax. An intravenous (IV) line will be inserted into a vein in your arm to deliver fluids and medications.

After the catheter site is cleaned with antiseptic solution, the doctor will numb your skin, and then make a small cut to reach a large blood vessel under the skin surface. The doctor inserts the catheter into the blood vessel and moves it through your circulatory system toward the heart. By using X-rays, the doctor can watch the catheter’s progress on a nearby monitor. Once the catheter is in your heart, it will measure pressures inside the heart, take blood samples, inject X-ray dye or perform other functions.

After all the tests are finished, the catheter will be removed, and the insertion site will be closed with stitches. A special pressure dressing may be applied. You will have to stay in bed for six to eight hours with your arm or leg extended while a nurse monitors your vital signs and checks for bleeding at the catheter site. The nurse will also monitor the pulse, color and temperature of the limb (your arm or leg) in which the catheter was inserted.

When you have recovered enough, you will be able to go home. Your doctor will tell you when you can start eating and drinking again.


After your heart catheterization, you will need to avoid strenuous activity for at least 24 to 48 hours. Within five to seven days, you will need to return to your doctor’s office for a checkup.


Although heart catheterization is generally a safe procedure, there is some risk of the following complications:

  • heart attack or stroke
  • Abnormal heartbeat (cardiac arrhythmia)
  • Puncture of a blood vessel or of the heart
  • Bleeding, blood clot or infection at the catheter insertion site
  • A blocked blood vessel in the arm or leg in which the catheter was inserted
  • An allergic reaction to the X-ray dye

Because some of these problems may be life threatening, heart catheterization should always be performed in a hospital that has the necessary equipment and personnel to deal with any complications immediately.

Certain patients have a higher than average risk of complications. These include infants younger than 1 month, people older than 80 years, people with severely decreased heart function and people with certain chronic illnesses, such as kidney failure, insulin-dependent diabetes and severe lung disease.

When To Call A Professional

Call your doctor immediately if the catheter insertion site becomes swollen, painful and red, or if it oozes blood. Also call your doctor immediately if the arm or leg in which the catheter was inserted becomes painful, cold and pale, with a weak or absent pulse.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.