Cardiac catheterization (kath-uh-tur-ih-ZAY-shun) is a test or treatment for certain heart or blood vessel problems, such as clogged arteries or irregular heartbeats. It uses a thin, hollow tube called a catheter. The tube is guided through a blood vessel to the heart. Cardiac catheterization gives important details about the heart muscle, heart valves and blood vessels in the heart.

During the procedure, a doctor can test the pressures in the heart or do treatments such opening a narrowed artery. Sometimes a piece of heart tissue is removed for examination.

Usually, you are awake during cardiac catheterization but given medicines to help you relax. The risk of major complications is generally low.

Cardiac catheterization is a common method to diagnose or treat a variety of heart problems. For example, your doctor may suggest cardiac catheterization if you have:

• Irregular heartbeats, called arrhythmias.
• Chest pain, called angina.
• Heart valve problems.
• Other heart problems.

You might need cardiac catheterization if you have, or your doctor thinks you have:

• Coronary artery disease.
• Congenital heart disease.
• Heart failure.
• Heart valve disease.
• Damage to the walls and inner lining of tiny blood vessels in the heart, called small vessel disease or coronary microvascular disease.

During cardiac catheterization, a doctor can:

• Look for narrowed or blocked blood vessels that could cause chest pain.
• Measure pressure and oxygen levels in different parts of the heart.
• See how well the heart pumps blood.
• Take a sample of tissue from your heart for examination under a microscope.
• Check the blood vessels for blood clots.

Cardiac catherization may be done at the same time as other heart procedures or heart surgery.

Major complications of cardiac catheterization are rare.

But possible risks of cardiac catheterization may include:

• Bleeding.
• Blood clots.
• Bruising.
• Damage to the artery, heart or the area where the catheter was inserted.
• Heart attack.
• Infection.
• Irregular heart rhythms.
• Kidney damage.
• Stroke.
• Allergic reactions to the contrast dye or medicines.

If you are pregnant or planning to become pregnant, tell your health care team before having cardiac catheterization.

Your health care team tells you how to plan for your specific procedure. Some things you might have to do before cardiac catheterization are:

• Do not eat or drink anything for at least six hours before your test, or as told by your health care team. Food or liquids in the stomach can increase the risk of complications from medicines used to put you in a sleep-like state during the procedure. You usually can have something to eat and drink soon after the procedure.
• Tell your health care team about all the medicines you take. Some medicines may need to be temporarily stopped before cardiac catheterization. For example, your doctor may tell you to briefly stop taking any blood thinners, such as warfarin (Jantoven), aspirin, apixaban (Eliquis), dabigatran (Pradaxa) and rivaroxaban (Xarelto).
• Let your health care team know if you have diabetes. Sometimes dye, called contrast, is used during cardiac catheterization. Some types of contrast may increase the risk of side effects of some diabetes medicines, including metformin. Your health care team will give you instructions on what to do if you need this procedure.

Before the procedure

Cardiac catheterization is usually done in a hospital room with special X-ray and imaging machines. The room is often called a cath lab, which is short for cardiac catheterization lab.

Before you go into the room, your health care team helps you get ready.

You may be asked to use the toilet to empty your bladder.

You change into a hospital gown. Remove all jewelry and dentures.

Your health care team checks your blood pressure and pulse. Sticky patches go on your chest and sometimes your arms or legs. Wires connect the patches to a computer. The computer constantly checks your heartbeat.

A member of your health care team may shave any hair from the area where the catheter will go.

During the procedure

A health care professional places an IV into your forearm or hand. Medicine called a sedative goes through the IV. The medicine helps you feel relaxed, calm or sleepy.

The amount of sedation needed for cardiac catheterization depends on the reason for the procedure and your overall health. You may be fully awake or lightly sedated. Or you may be given a combination of medicines to put you in a sleep-like state. This is called general anesthesia.

To do cardiac catheterization, a doctor inserts one or more flexible, hollow tubes called catheters into a blood vessel, usually in the groin or wrist. The doctor guides the tube or tubes to the heart.

What happens next depends on why you're having the procedure. These are some common reasons:

• Coronary angiogram. This test checks for blockages in the arteries leading to the heart. The catheter is placed in a blood vessel, usually in the groin or wrist. Dye flows through the catheter. Then X-ray images of the heart arteries are taken. The dye helps blood vessels show up more clearly on the X-ray images.
• Cardiac ablation. Heat or cold energy is used to create tiny scars in the heart to block irregular electrical signals. This procedure is used to correct heart rhythm problems.
• Right heart catheterization. This is done to check the pressure and blood flow in the right side of the heart. A catheter is inserted in a vein in the neck or groin. The catheter has special sensors in it.
• Balloon angioplasty, with or without stenting. This treatment uses a catheter and a tiny balloon to open a narrowed artery in or near the heart. The catheter is inserted in either the wrist or groin. A mesh tube called a stent is sometimes placed in the artery to keep it open.
• Balloon valvuloplasty. This treatment uses a catheter and a tiny balloon to widen a narrowed heart valve. The placement of the catheter depends on the specific type of heart valve problem.
• Heart valve replacement. Doctors can use a catheter to remove a narrowed heart valve and replace it with an artificial valve. An example is transcatheter aortic valve replacement (TAVR).
• Repair a heart problem you're born with, also called a congenital heart defect. Cardiac catheterization methods may be used to close holes in the heart, such as an atrial septal defect or patent foramen ovale.
• Heart biopsy. Sometimes a sample of heart tissue needs to be taken to examine under a microscope. During a heart biopsy, the catheter is usually placed in the vein in the neck. Less often, it may be placed in the groin. A catheter with a small, jaw-like tip is used to obtain a small piece of tissue from the heart.

If you're awake during cardiac catheterization, your doctor may ask you to:

• Take deep breaths.
• Hold your breath.
• Cough.
• Put your arms in different positions.

The table may be tilted at times. But a safety strap keeps you on the table. Tell your health care team if you have any discomfort.

When the test or treatment is done, the catheter is removed. A health care professional puts pressure on the area to stop any bleeding. If the catheter was placed into a blood vessel in the groin area, you may need to lie flat for several hours. This helps prevent serious bleeding and lets the artery heal.

After the procedure

You usually spend a few hours in a recovery room after cardiac catheterization. How long you need to stay in the hospital depends on your health and why you had the procedure.

The skin where the catheter was placed may feel sore for a few days. Tell your health care team if you have:

• Bleeding.
• New or increased swelling.
• Pain.

After cardiac catheterization, a member of your health care team talks to you and explains any results.

If a blocked artery is found during cardiac catheterization, the doctor may treat the blockage right away. Sometimes a stent is placed to keep the artery open. Ask your doctor whether this is a possibility before your cardiac catheterization begins.