Invasive Cardiac Testing

According to the National Institutes of Health, coronary artery disease is the most common type of heart disease and is the leading cause of death in the United States in men and women. A variety of tests are available to assist physicians in diagnosing heart diseases, including coronary artery disease. Some of these medical procedures pose little risk and are noninvasive, while others are invasive and, therefore, more risky.

Invasive vs. Noninvasive

• Noninvasive cardiac tests are those which do not disturb the body’s integrity in any way. Tests are performed without inserting needles, fluids or instruments into the body. Such diagnostic procedures include chest x-rays, electrocardiograms, computer imaging and exercise stress tests. Invasive procedures involve the insertion of something foreign into the body. The foreign object may be as simple as a needle used to draw blood or as complex as a special scope used to observe the inner workings of the heart. Invasive cardiac testing procedures include cardiac catheterization, myocardial biopsy, intravascular ultrasound and thallium stress test.

Cardiac Catheterization

• Cardiac catheterization is an invasive procedure in which a long, narrow tube, called a catheter, is inserted into a blood vessel in the groin. The catheter is guided through the vessel until it reaches the heart. Once the catheter is in place, a contrast dye is administered through it. The dye spreads through the heart's chambers, valves and blood vessels, allowing the physician to visualize blocked arteries, evaluate heart muscle function, assess valve or aorta problems, and determine the need for further interventional procedures.

Myocardial Biopsy

• A myocardial biopsy is one in which a piece of heart muscle is removed and examined for abnormalities. The small piece of tissue (the size of the head of a pin) is obtained using a bioptome, a small catheter with a grasping apparatus on the end. Unlike cardiac catheterization, where the catheter is inserted into a blood vessel in the groin, the catheter used for obtaining a myocardial biopsy is inserted through a blood vessel in the neck. The procedure is used to determine the presence of heart inflammation or to assess possible organ rejection following a heart transplant.

Intravascular Ultrasound

• Intravascular ultrasound, or IVUS, is performed in conjunction with cardiac catheterization and utilizes a sound probe that is attached to the end of the catheter. The probe emits high frequency sound waves that are used to provide detailed images of the interior walls of the coronary arteries. IVUS is helpful in determining whether artery blockages, called plaques, are stable or vulnerable. Vulnerable plaques, also called soft plaques, are more likely to cause heart attacks than stable plaques.

Thallium Stress Test

• An exercise stress test monitors heart function while the patient walks on a treadmill. A thallium stress test is an exercise stress test with pictures. When the patient on the treadmill reaches his maximum exercise level, he is given an injection of thallium dye. The dye allows observation of blood flow through the heart. Consequently, the doctor is able to determine the severity of artery blockages, the amount of blood flow to the heart during periods of rest and stress, and the intensity of exercise tolerated by the patient’s heart.