Cardiac catheterization (kath-uh-tur-ih-ZAY-shun) is a procedure in which a thin, flexible tube (catheter) is guided through a blood vessel to the heart to diagnose or treat certain heart conditions, such as clogged arteries or irregular heartbeats. Cardiac catheterization gives doctors important information about the heart muscle, heart valves and blood vessels in the heart.

During cardiac catheterization, doctors can do different heart tests, deliver treatments, or remove a piece of heart tissue for examination. Some heart disease treatments — such as coronary angioplasty and coronary stenting — are done using cardiac catheterization.

Usually, you'll be awake during cardiac catheterization but be given medications to help you relax. Recovery time for a cardiac catheterization is quick, and there's a low risk of complications.

Cardiac catheterization is a common procedure done to diagnose or treat a variety of heart problems. For example, your doctor may recommend this procedure if you have irregular heartbeats (arrhythmias), chest pain (angina) or heart valve problems, among other things.

Cardiac catheterization may be done during the diagnosis or treatment of:

• Coronary artery disease
• Congenital heart disease
• Heart failure
• Heart valve disease
• Microvascular heart disease

During a cardiac catheterization, a doctor can:

• Locate narrowing or blockages in the blood vessels that could cause chest pain (angiogram)
• Measure pressure and oxygen levels in different parts of the heart (hemodynamic assessment)
• See how well the heart pumps blood (right or left ventriculogram)
• Take a sample of tissue from your heart (biopsy)
• Diagnose heart problems present from birth (congenital heart defects)
• Diagnose heart valve disease
• Examine the blood vessels for blood clots

Cardiac catherization may be done at the same time as other heart procedures, such as:

• Widening a narrowed artery (angioplasty) with or without stent placement
• Treating irregular heart rhythms with cold or heat energy (cardiac ablation)
• Closing holes in the heart and repairing other congenital heart defects
• Opening narrowed heart valves (balloon valvuloplasty)
• Repairing or replacing heart valves (heart valve surgery)

As with most procedures done on the heart and blood vessels, cardiac catheterization has some risks. Major complications are rare, though.

Possible risks of cardiac catheterization are:

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

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

If your doctor recommended a cardiac catheterization, you'll need to follow some steps to prepare for the procedure.

• Don't eat or drink anything for at least six hours before your test, or as directed by your doctor. Having food or liquids in your stomach can increase the risk of complications from anesthesia. Ask the doctor or nurse if you should take your medications with a small amount of water. If you have diabetes, ask for instructions about diabetes medications and insulin. You'll usually be able to have something to eat and drink soon after the procedure.
• Tell your doctor if you take blood thinners. Your doctor may recommend that you stop medications that may thin your blood, such as warfarin (Jantoven), aspirin, apixaban (Eliquis), dabigatran (Pradaxa) and rivaroxaban (Xarelto).
• Tell your doctor if you take diabetes medications. Certain dyes used during some cardiac catheterization procedures can increase the risk of side effects of some diabetes medications, including metformin.
• Take all your medications and supplements with you to the test. It's best if you take the original bottles so that your doctor will know the exact dose you take.

Before the procedure

Before a cardiac catheterization, you will likely have your blood pressure and pulse checked. You may be asked to use the toilet to empty your bladder.

You may be asked to remove dentures and any jewelry, especially necklaces that could interfere with pictures of the heart.

Sticky patches (electrodes) will be placed on your chest to monitor your heartbeat before, during and after the procedure.

A nurse or technician may shave the hair from the site where the catheter will be inserted.

During the procedure

Cardiac catheterization is usually done in the hospital in a room with special X-ray and imaging machines. Like an operating room, the cardiac catheterization lab is a sterile area.

A specialist will insert an IV into your forearm or hand and give you a medication called a sedative to help you relax. The amount of sedation needed for the procedure depends on your health conditions and why you're having the procedure. You may be fully awake or lightly sedated, or you may be given general anesthesia (fully asleep).

During cardiac catheterization, one or more catheters are passed through a blood vessel in the groin, wrist or neck, depending on the reason for the procedure, and guided to the heart.

The area where the catheter will be inserted is numbed, and then a small cut is made to access the blood vessel. A plastic sheath is passed into this opening to allow your doctor to insert the catheter.

What happens next depends on why you're having a cardiac catheterization. These are some of the common uses for cardiac catheterization:

• Coronary angiogram. During this test to check for blockages in the arteries leading to the heart, a dye is injected through the catheter, and X-ray images of the heart arteries are taken. The dye helps blood vessels show up more clearly on the X-ray images. In a coronary angiogram, the catheter is usually first placed in the artery in the groin or wrist.
• Cardiac ablation. In this procedure, a doctor uses heat or cold energy to create tiny scars in your heart to block abnormal electrical signals and restore a normal heartbeat.
• Right heart catheterization. This procedure checks the pressure and blood flow in the right side of the heart. A catheter is inserted in the vein in the neck or groin. The catheter has special sensors in it to measure the pressure and blood flow in your heart.

• Balloon angioplasty, with or without stenting. This procedure is used to open a narrowed artery in or near the heart. The catheter can be inserted in either the wrist or groin for this procedure.

  The catheter is guided to the narrowed artery. Then, a smaller balloon catheter is inserted through the flexible catheter and inflated at the narrowed area to open it. Often, the doctor will also place a mesh coil called a stent at the narrowed part to help keep the artery open.

• Heart biopsy. If the doctor is taking a sample of heart tissue (biopsy), the catheter will usually be 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.
• Repair of congenital heart defects. If the doctor is closing a hole in the heart, such as an atrial septal defect or patent foramen ovale, catheters may be inserted in both the arteries and veins of the groin and neck. A device is then inserted into the heart to close the hole.
• Balloon valvuloplasty. This procedure is done to widen a narrowed heart valve. The placement of the catheters depends on the specific type of heart valve problem. A catheter is threaded across the valve. A balloon is then inflated to make the valve open more easily.
• Heart valve replacement. A catheter is used to implant an artificial valve in the heart to replace a narrowed heart valve. For example, a procedure called transcatheter aortic valve replacement (TAVR) uses a catheter to replace a faulty aortic heart valve.

If you're awake during a cardiac catherization procedure, you may be asked to take deep breaths, hold your breath, cough or place your arms in various positions throughout the procedure. The table may be tilted at times, but you'll have a safety strap on to keep you on the table.

Threading the catheter shouldn't be painful, and you shouldn't feel it moving through your body. Tell your doctor or nurse if you have any discomfort.

After the procedure

You'll likely spend several hours in a recovery room after the procedure while the sedation wears off.

After you leave the recovery room, you'll usually be moved to a regular hospital or outpatient room. After your catheter is removed, a technician or nurse will apply pressure to the insertion sites. If the catheter was placed in the groin area, you may need to lie flat for several hours after the procedure to avoid serious bleeding and to allow the artery to heal.

How long you need to stay in the hospital depends on your overall health and the reason for the catheterization.

The area where the catheter was inserted may feel sore for a few days. Tell your doctor if you have any bleeding or new or increased swelling or pain at or near the access site.

If cardiac catheterization was done to diagnose a heart condition, your doctor should explain the results to you.

If your doctor finds a blockage during cardiac catheterization, he or she may treat the blockage with or without a stent placement right away so that you won't need to have another catheterization procedure. Your doctor should discuss whether this is a possibility before the procedure begins.