by Robert Neufeld, M.D.
Head of the Division of Cardiology, Niagara Falls Memorial Medical Center
Cardiac testing can help a doctor detect or rule out the presence of heart disease. If a heart attack has occurred, it can help your doctor understand how much heart damage was done.
But patients and their loved ones sometimes find themselves confused by the number of cardiac tests that are available, or are left wondering why their doctor ordered a particular test. A brief explanation of the different tests available may be helpful.
Cardiac tests can be divided into two broad categories: non-invasive and invasive. For the most part, non-invasive tests do not involve inserting needles, instruments or fluids into a patient's body. Invasive tests and procedures can range from a simple needle stick for a blood test to the insertion of a tube, device or scope to major surgeries such as open-heart surgery.
Perhaps the most commonly used tests are chest X-rays, which produce still pictures of the heart, and EKGs or electrocardiograms, which measure the heart's electrical activity. An EKG can indicate if a heart attack has occurred, help predict if a heart attack is developing and monitor changes in heart rhythm.
Patients are sometimes connected to a Holter monitor for a kind of ambulatory EKG that measures the heart's electrical activity during daily activities. Patients often wear such a monitor for 24 hours or longer.
Another very common test is a cardiac stress test. There are several types but all share common objectives: to diagnose coronary artery disease, determine the possible cause of symptoms such as chest pain (also called angina), help determine a patient's safe level of exercise and help predict dangerous heart-related conditions such as heart attack.
In an exercise stress test, patients walk on a treadmill while a monitor with electrodes attached to the skin around the heart records heart function. Exercise stress tests are sometimes supplemented by a nuclear imaging scan to get a visual record of blood flow through the coronary arteries.
In some cases, an exercise stress test is combined with an echocardiogram, a test that uses sound waves to create a motion picture of the heart. An echocardiogram is much more detailed than a chest X-ray and involves no radiation exposure. It is utilized to evaluate heart wall motion, blood flow, the size and thickness of the heart and its chambers, and heart valve function and to detect abnormalities in the structure of the heart as well as tumors, congenital defects and congestive heart failure.
Patients who cannot walk on a treadmill are sometimes given a nuclear stress test. This non-walking procedure involves the intravenous administration of a drug that simulates heart stress followed by a nuclear imaging scan. As is the case with treadmill stress tests, this type of test is sometimes combined with an echocardiogram,
The Heart Center of Niagara also utilizes two advanced imaging tests to detect and diagnose heart disease - PET scanning and CT angiography. A PET scan - PET stands for positron emission tomography -- uses nuclear medicine imaging to produce three-dimensional, color images of the heart's blood flow. CT angiography uses computed tomography to produce images of the coronary arteries and detect any kind of narrowing or blockage.
Invasive cardiac tests include cardiac catheterization. This procedure uses a long, thin, flexible tube called a catheter that is inserted into a blood vessel in your arm, groin or neck and then threaded into your coronary arteries. Dye is then injected into the bloodstream and X-rays of the coronary arteries are taken as the dye is flowing through them.
Which test is the right test for you? That depends on a number of indicators, including your age, general health, personal and family medical history, and lifestyle choices such as whether you smoke. Your doctor will evaluate your overall profile and order the most appropriate test or tests.
To learn more about cardiac testing, visit the American Heart Association website at www.heart.org or www.webmd.com/heart-disease.