Cardiac Catheterization

Definition

Cardiac catheterization is the procedure of inserting a thin, hollow tube into a blood vessel in the leg, (or, rarely the arm), then passing it into or around the heart in order to obtain information about cardiovascular anatomy and function. The test can measure blood pressure within the heart, how much oxygen is in the blood, and the pumping ability of the heart.

Description

First attempted experimentally on humans in 1929, cardiac catheterization evolved into widespread clinical use in the 1940's. It is most commonly employed for evaluating disease of the coronary arteries, as well as valvular, congenital and primary myocardial (heart tissue) diseases.

More than 900,000 cardiac catheterization procedures are performed in hospitals each year, making it one of the most widely used advanced diagnostic tests. Catheterization of the coronary arteries, called coronary arteriography, is considered "the gold standard" against which all other methods of diagnosing coronary artery disease are compared.

The findings from coronary artery catheterization are almost always compared with the findings from nuclear studies and exercise stress tests. In this manner, the important correlation is made between the anatomic site of the problem and its clinical and physiologic consequences.

Major Uses

Cardiac catheterization has three main uses, the first two being routine with all catheter procedures. The measurement of heart function is done by taking pressure readings around valves and within the ventricles, arteries and veins, using special catheters.

The visualization of the ventricles, coronary arteries and other vessels after injection of radio-opaque contrast dye, which is used to produce X-ray movies is called cineoangiograms or simply, angiograms. The procedure itself is called angiography.

Biopsy of the heart muscle via the insertion of biopsy instruments into the catheter can also be performed. Microscopic examination of the biopsied tissue helps assess the possibilities of transplant rejection and diagnose heart muscle diseases and inflammatory heart diseases such as myocarditis.

Biopsy is performed only if there are specific indications of disease. Angiography is especially useful for diagnosing congenital (at birth) abnormalities, for examining overall patterns of contraction of the ventricles, and for identifying blood vessels anywhere in the body - but especially the coronary arteries - that are narrowed or obstructed, often by atherosclerosis.

Procedure

Cardiac catheterization may be performed as an inpatient procedure requiring a one-night hospital stay or it may be performed on an outpatient basis, in which the patient has the test in the morning and goes home in the early evening. In either case, the patient will be asked not to eat for at least six hours prior to the procedure and will be given a sedative for relaxation.

The area where the catheter will be inserted, usually the groin, may be shaved. The procedure itself takes place in a catheterization laboratory, commonly referred to as a cath lab, where the patient will lie on a padded table under a fluoroscope (moving X-ray camera.) The patient receives an injection of local anesthesia at the site of the incision, and an intravenous infusion (IV line) may be started.

To perform cardiac catheterization, the doctor inserts the catheter through a large-diameter needle and hollow sheath into an artery (to examine the left side of the heart) or a vein (to examine the right side of the heart.) Using the fluoroscope for guidance, the doctor threads the catheter through the vein or artery into the heart, during which time the patient may feel some pressure, but usually no pain.

Once the catheter is in place, pressure readings may be taken in several locations and dye may be injected through the catheter. During the release of the dye, the patient may feel some nausea, hot flashes and the need to urinate. These sensations generally pass quickly. At various times during the procedure, the patient may be asked to cough, pant or breathe deeply. The procedure usually lasts about an hour.

Afterward, the patient is usually wheeled back to his or her room. The leg through which the procedure was performed is immobilized to ensure that there is no bleeding. The patient may often eat solid food immediately. He or she will be offered pain medication once the anesthesia wears off and will generally be discharged from the hospital the following morning.

Risks

In general, cardiac catheterization is considered to be a very safe procedure with little risk of complications. Nevertheless, an invasive procedure such as this has more potential for complications than non-invasive procedures. For this reason, most catheterization procedures are performed in a hospital or an outpatient center attached to a hospital so that rapid access to emergency services will be available should a serious complication such as a ruptured artery or embolism (dislodged clot) occur.

The primary factors that influence the risk are the level of expertise of the team performing the procedure and the patient's general health and severity of heart disease.