The passage of a catheter (a thin flexible tube) into the right or left side of the heart to obtain diagnostic information about the heart or its vessels, or to provide therapeutic interventions in certain types of heart conditions.

Cardiac catheterization can determine pressure and blood flow in the heart's chambers, collect blood samples from the heart, and examine the arteries of the heart by X-ray (fluoroscopy). Fluoroscopy provides immediate ("real time") visualization of the X-ray images on a screen as well as a permanent record of the procedure.

Food and fluid is restricted for 6 to 8 hours before the test. Sometimes, admission the night before the test is required. Otherwise, admission will be as an outpatient the morning of the procedure. A health care provider is required to explain the procedure and its risks. A witnessed, signed consent for the procedure is required. A mild sedative is usually given 1/2 hour before the procedure. You will wear hospital clothing.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

The procedure takes place in a radiology department, special procedures room, or cardiac diagnostics laboratory within a hospital. Sedation is given to relax you prior to the procedure, but you are awake and able to follow instructions during the test.

You will remain on a stretcher for the duration of the test. An incision is made into your vein or artery for threading the catheter into your heart. Local anesthesia is given to insert the catheter, so the only sensation is one of pressure at the site. Discomfort may arise from having to remain still for prolonged periods of time. The procedure may last from less than 1 to several hours.

Cardiac defects or disease may be present, such as coronary artery disease, valvular heart disease, ventricular aneurysms or enlargement.

Additional conditions under which the test may be performed:

• primary pulmonary hypertension
• pulmonary valve stenosis
• pulmonary embolism
• tetralogy of Fallot
• transposition of the great vessels
• tricuspid regurgitation
• ventricular septal defect

Risks of the procedure are cardiac arrhythmias, cardiac tamponade, trauma to the vein or artery, low blood pressure, infection, embolism from blood clots at the tip of the catheter, reaction to contrast medium, hemorrhage or hematoma at the site of catheter access, stroke, and heart attack.