Cardiac catheterization involves passing a a thin flexible tube (catheter) into the right or left side of the heart, usually from the groin or the arm.

You will be given a mild sedative before the test to help you relax. An intravenous (IV) line is inserted into one of the blood vessels in your arm, neck, or groin after the site has been cleansed and numbed with a local numbing medicine (anesthetic).

A catheter is then inserted through the IV and into your blood vessel. The catheter is carefully threaded into the heart using an x-ray machine that produces real-time pictures (fluoroscopy). Once the catheter is in place, your doctor may:

• Collect blood samples from the heart
• Measure pressure and blood flow in the heart's chambers and in the large arteries around the heart
• Measure the oxygen in different parts of your heart
• Examine the arteries of the heart with an x-ray technique called fluoroscopy (which gives immediate, "real-time" pictures of the x-ray images on a screen and provides a permanent record of the procedure)
• Perform a biopsy on the heart muscle

If possible, you will be asked not to eat or drink for 6 - 8 hours before the test. The test takes place in a hospital and you will be asked to wear a hospital gown. Sometimes, you will need to spend the night before the test in the hospital. Otherwise, you will be admitted as an outpatient or an inpatient the morning of the procedure.

Your health care provider should explain the procedure and its risks. A witnessed, signed consent for the procedure is required.

Tell your doctor if you:

• Are allergic to seafood
• Have had a bad reaction to contrast material or iodine in the past
• Are taking Viagra
• Might be pregnant

The study is done by trained cardiologists with the assistance of trained technicians and nurses.

You will be awake and able to follow instructions during the test. You will usually get a mild sedative 30 minutes before the test to help you relax. The test may last 30 - 60 minutes.

You may feel some discomfort at the site where the catheter is placed. Local anesthesia will be used to numb the site, so the only sensation should be one of pressure at the site. You may experience some discomfort from having to remain still for a long time.

After the test, the catheter is removed. You might feel a firm pressure, used to prevent bleeding at the insertion site. If the catheter is placed in your groin, you will usually be asked to lie flat on your back for a few hours after the test to avoid bleeding. This may cause some mild back discomfort.

In general, this procedure is done to get information about the heart or its blood vessels or to provide treatment in certain types of heart conditions. It may also be used to determine the need for heart surgery.

Your doctor may perform cardiac catheterization to:

• Diagnose or evaluate coronary artery disease
• Diagnose or evaluate congenital heart defects
• Diagnose or evaluate problems with the heart valves
• Diagnose causes of heart failure or cardiomyopathy

The following may also be performed using cardiac catheterization:

• Repair of certain types of heart defects
• Repair of a stuck (stenotic) heart valve
• Opening of blocked arteries or grafts in the heart

The procedure can identify heart defects or disease, such as:

• Coronary artery disease
• Valve problems
• Ventricular aneurysms
• Heart enlargement

The procedure also may be performed for the following:

• Primary pulmonary hypertension
• Heart valve defects, such as pulmonary valve stenosis, mitral valve regurgitation, aortic stenosis, and others
• Pulmonary embolism
• Birth defects, such as Tetralogy of Fallot, transposition of the great vessels, ventricular septal defect, coarctation of the aorta, and others
• Cardiac amyloidosis

Cardiac catheterization carries a slightly higher risk than other heart tests, but is very safe when performed by an experienced team.

Generally, the risks include the following:

• Cardiac arrhythmias
• Cardiac tamponade
• Heart attack
• Bleeding
• Low blood pressure
• Reaction to the contrast medium
• Stroke
• Trauma to the artery caused by hematoma

Possible complications of any type of catheterization include the following:

• A risk of bleeding, infection, and pain at the IV site
• A very small risk that the soft plastic catheters could damage the blood vessels
• Blood clots could form on the catheters and later block blood vessels elsewhere in the body.
• The contrast material could damage the kidneys (particularly in patients with diabetes).

Cardiac catheterization may include coronary angiography.

Davidson CJ, Bonow RO. Cardiac Catheterization. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa; Saunders Elsevier; 2007: chap 19.