Cardiac catheterization (kath-uh-tur-ih-ZAY-shun) is a test or treatment for certain heart or blood vessel conditions, such as clogged arteries or irregular heartbeats. It uses a thin, flexible tube called a catheter. A doctor guides the tube through a blood vessel to the heart.

Results from cardiac catheterization give important details about the heart muscle, heart valves and blood vessels in the heart. During the procedure, a doctor can open a narrowed artery or test the pressures in the heart. Sometimes a piece of heart tissue is removed for examination.

Cardiac catheterization is a common heart procedure. It may be done to help find or fix many different heart conditions, such as:

• 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.

Your healthcare team may suggest cardiac catheterization if you have symptoms of heart disease, such as:

• Irregular heartbeats, called arrhythmias.
• Chest pain, called angina.
• Shortness of breath with physical activity.

During cardiac catheterization, a doctor can:

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

The risk of major complications is generally low.

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 dye, called contrast, or medicines used during the test.

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

Your healthcare team tells you how to prepare. Some things you may have to do before cardiac catheterization are:

• Do not eat or drink anything for several hours before your test. Follow the instructions your healthcare team gives you. Food or liquids in the stomach can increase the risk of complications from medicines used during the procedure. Usually, you can eat and drink soon after the procedure.
• Tell your healthcare team about all the medicines you take. You may need to temporarily stop taking some medicines before cardiac catheterization. Examples include warfarin (Jantoven), aspirin, apixaban (Eliquis), dabigatran (Pradaxa) and rivaroxaban (Xarelto).
• Tell your healthcare team if you have diabetes. Dye, called contrast, may be used during cardiac catheterization. Some types of contrast increase the risk of side effects of some diabetes medicines, including metformin. Your healthcare team gives you specific instructions to follow if you have diabetes and need cardiac catheterization.

Before the procedure

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

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

• You may be asked to use the toilet to empty your bladder.
• You change into a hospital gown.
• You remove all jewelry and dentures.

Your healthcare team checks your blood pressure and pulse. Sticky patches with sensors on them 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 healthcare 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. This is called sedation.

Usually, you are awake during cardiac catheterization. But 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 thin, flexible 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. Dye, called contrast, 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 faulty electrical signals. This treatment is done to fix irregular heartbeats.
• Right heart catheterization. A catheter is placed in a vein in the neck or groin. The catheter has special sensors in it. The sensors check the pressure and blood flow in the right side of the heart.
• 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 placed in the wrist or groin. A mesh tube called a stent is sometimes placed in the artery to keep it open.
• Balloon valvuloplasty. This treatment helps widen a narrowed heart valve. It uses a catheter and a tiny balloon. 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, also called TAVR.
• Repair a heart condition present at birth, called a congenital heart defect. Cardiac catheterization may be used to close holes in the heart. Examples are an atrial septal defect or patent foramen ovale.
• Heart biopsy. A doctor removes a sample of heart tissue using a catheter with a small, jawlike tip. The sample goes to a lab, where it is looked at under a microscope.

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 you lie on during the procedure may be tilted at times. But a safety strap keeps you on the table. Tell your healthcare team if you have any discomfort.

When the test or treatment is done, the catheter is removed. A healthcare 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 healthcare team if you have:

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

After cardiac catheterization, a member of your healthcare 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.