Cardiac Catheterization Health Article

Normal results

Normal findings from a cardiac catheterization will indicate no abnormalities in the size or configuration of the heart chamber, the motion or thickness of its walls, the direction of blood flow, or motion of the valves. Smooth and regular outlines indicate normal structure of the coronary arteries.

The measurement of intracardiac pressures, or the pressure in the heart's chambers and vessels, is an essential part of the catheterization procedure. Pressure readings that are higher than normal are significant for a patient's overall diagnosis. Pressure readings that are lower, other than those resulting from shock, are usually not significant.

The ejection fraction is also determined by performing a cardiac catheterization. The ejection fraction is a comparison of the quantity of blood ejected from the heart's left ventricle during its contraction phase with the quantity of blood remaining at the end of the left ventricle's relaxation phase. The cardiologist will look for a normal ejection fraction reading of 60–70%.

Abnormal results are obtained by viewing the still and live motion x rays during cardiac catheterization for evidence of coronary artery disease, poor heart function, disease of the heart valves, and septal defects.

The most prominent sign of coronary artery disease is narrowing or blockage (stenosis) in the coronary arteries, with narrowing greater than 50% considered significant. A clear indication for intervention by angioplasty or surgery is a finding of significant narrowing of the left main coronary artery and/or blockage or severe narrowing in the high left anterior descending coronary artery.

A finding of impaired wall motion is an additional indicator of coronary artery disease, an aneurysm, an enlarged heart, or a congenital heart problem. Using an ejection fraction test that measures wall motion, cardiologists regard an ejection fraction reading under 35% as increasing the risk of complications while also decreasing the possibility of a successful long- or short-term outcome from surgery.

Detecting the difference in pressure above and below the heart valve can verify the presence of valvular disease. The greater the narrowing, the higher the difference in pressure.

To confirm the presence of septal defects, measurements are taken of the oxygen content on both the left and right sides of the heart. The right heart pumps unoxygenated blood to the lungs, and the left heart pumps blood containing oxygen from the lungs to the rest of the body. Elevated oxygen levels on the right side indicate the presence of a left-to-right atrial or ventricular shunt. Low oxygen levels on the left side indicate the presence of a right-to-left shunt.

Alternatives

Other methods of visualization are available that limit radiation exposure, by using ultrasound imaging to observe the coronary arteries. Imaging of general cardiac architecture and valvular function can be visualized by noninvasive cardiac ultrasound. Cardiac ultrasound and Doppler ultrasound can be used together to observe valvular insufficiency and stenosis. Areas of poor myocardial function can also be evaluated by ultrasound.

Nuclear medicine scans of the heart can show the perfusion of blood to a region of the myocardium. If blockages of the coronary artery exist, blood flow will be reduced. By adding a radioactive marker to the blood, images are generated to show areas of poor perfusion. Combined with exercise, these tests can accurately demonstrate cardiovascular disease. However, the imaging process can take several hours, and the patient is still internally exposed to high levels of radiation.

BOOKS

Bennett, J. Claude, and Fred Plum, eds. "Cardiac Catheterization and Angiography." In Cecil Textbook of Medicine. 20th ed. Vol. 1. Philadelphia: W. B. Saunders Company, 1996.

"Diagnostic Cardiovascular Procedures: Invasive Procedures." In The Merck Manual of Diagnosis and Therapy, 17th ed, Ed. Mark H. Beers, and Robert Berkow. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Segen, Joseph C., and Joseph Stauffer. "Cardiac Catheterization." In The Patient's Guide To Medical Tests: Everything You Need To Know About The Tests Your Doctor Prescribes. New York: Facts On File, Inc., 1998.

PERIODICALS

Norris, Teresa G. "Principles of Cardiac Catheterization." Radiologic Technology 72, no. 2 (November-December 2000): 109–136.

Scanlon, Patrick J, et al. ACC/AHA Guidelines for Coronary Angiography 33, no. 6 (May 1999): 1756–1824.

Segal, A. Z., et al. "Stroke as a Complication of Cardiac Catheterization: Risk Factors and Clinical Features." Neurology 56 (April 2001): 975–977.

ORGANIZATIONS

American College of Cardiology. Heart House, 9111 Old Georgetown Road, Bethesda, MD 20814-1699. (800) 253-4636. <http://www.acc.org>.

American Heart Association National Center. 7272 Greenville Avenue, Dallas, TX 75231. (800) AHA-USA1. <http://www.americanheart.org>.

OTHER

Cardiology Channel. Cardiac Catheterization. <http://www.cardiologychannel.com/cardiaccath/>.

Jennifer E. Sisk, MA Allison J. Spiwak, MSBME