Cardiac catheterization involves passing a catheter (a thin flexible tube) into the right or left side of the heart. In general, this procedure is performed to obtain diagnostic information about the heart or its blood vessels or to provide treatment in certain types of heart conditions.

Cardiac catheterization can be used to determine pressure and blood flow in the heart's chambers, collect blood samples from the heart, and examine the arteries of the heart with an x-ray technique called fluoroscopy. Fluoroscopy provides immediate ("real-time") visualization of the x-ray images on a screen and provides a permanent record of the procedure.

You will be given a mild sedative prior to 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 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, contrast material is injected and pictures are taken.

Food and fluid are restricted 6 to 8 hours before the test. The procedure takes place in the hospital and you will be asked to wear a hospital gown. Sometimes, admission the night before the test is required. 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, if you have had a bad reaction to contrast material in the past, if you are taking Viagra, or if you might be pregnant.

The study is carried out in a laboratory by a trained cardiologist or radiologist and technicians or nurses.

You will be awake and able to follow instructions during the catheterization. A mild sedative is usually given 30 minutes before the procedure to help you relax. The procedure may last from 1 to several hours.

You may feel some discomfort at the site where the IV 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 at the insertion site, used to prevent bleeding. If the IV 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.

Cardiac catheterization is usually performed to evaluate heart valves, heart function and blood supply, or heart abnormalities in newborns. It may also be used to determine the need for heart surgery.

Therapeutic catheterization may be used to repair certain types of heart defects, open a stenotic heart valve, and open blocked arteries or grafts in the heart.

The procedure can identify heart defects or disease, such as coronary artery disease, valve problems, ventricular aneurysms, or heart enlargement.

The procedure also may be performed for the following:

• Primary pulmonary hypertension
• Pulmonary valve stenosis
• Pulmonary embolism
• Tetralogy of Fallot
• Transposition of the great vessels
• Tricuspid regurgitation
• Ventricular septal defect

Cardiac catheterization carries a slightly increased risk when compared with other heart tests. However, the test is very safe when performed by an experienced team.

Generally, the risk of serious complications ranges from 1 in 1,000 to 1 in 500. The risks include the following:

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

Considerations associated with any type of catheterization include the following:

• In general, there is a risk of bleeding, infection, and pain at the IV site.
• There is always a very small risk that the soft plastic catheters could actually 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.