Because of its serious nature, doctors often order multiple tests to confirm the diagnosis of a cardiovascular condition and determine its severity. Some diagnostic procedures carry a small risk of
, or death. However, the benefits of correctly diagnosing the problem usually outweigh any risks associated with the diagnosis. The risk is greater for more complex procedures, and for people with more advanced heart disease.
- Cardiac Isoenzymes
—Any suspicion of a heart attack will prompt your doctor to order serial blood tests to check for evidence that the heart muscle as been damaged. This usually requires an overnight stay in the hospital until all of the results are available.
—This study produces images of large and medium sized arteries throughout the body. A dye that is visible on x-rays is injected into the arteries through a catheter (plastic tube). This permits doctors to see the outlines of the arteries’ interior, and identify irregularities or narrowing due to atherosclerotic plaques, or abnormal widening due to aneurysms.
- Cardiac Catheterization
This procedure examines the major blood vessels and chambers of the heart.
The most common use of cardiac catheterization is for coronary angiography (see above), which uses x-ray absorbing dyes to illuminate blood flow through the arteries that feed the heart muscle. The same technique can also be used to study the anatomy and pumping action of the heart’s chambers. In addition, various instruments passed through the catheter can measure blood pressure in the major vessels and heart chambers; draw blood samples to be analyzed for oxygen and carbon dioxide content or for metabolic studies; and obtain heart muscle tissue samples for biopsy. Finally, cardiac catheterization is commonly used in the treatment of coronary heart disease.
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- Electrocardiography (ECG or EKG)
—ECGs measure the initiation and conduction of electrical currents in the heart. To take an ECG, doctors place small metal electrodes on a patient’s arms, legs, and chest. The electrodes measure the direction and flow of electrical impulses in the heart and record them on a monitor or moving strip of paper. All patients suspected of having a heart attack have an ECG taken. ECGs can also be used to identify abnormal heart rhythms (arrhythmias), thickening of heart muscle (hypertrophy), and inadequate blood flow to the heart (myocardial ischemia).
- Cardiac Stress Test / Exercise Tolerance Test
This test evaluates for the presence and severity of cardiovascular disorders by measuring the heart’s electrical activity as it responds to additional demand for oxygen during physical activity. Patients pedal on an exercise bike or walk on a treadmill at an increasing pace while the doctor monitors the ECG for changes, checks the blood pressure, and observes for symptoms.
Echocardiography a popular noninvasive test that does not use x-rays and can provide moving pictures of the heart’s activity in real time. The procedure uses high-frequency ultrasound waves to visualize the size, shape, and motion of the heart’s four chambers, valves, major blood vessels and it’s surrounding pericardial sac. It is used to diagnose conditions involving the structure or function of the heart, such as heart murmurs and congestive heart failure.
- Doppler Ultrasound
—Doppler ultrasound is a special echocardiographic technique that uses color coding to illustrate the direction and velocity of blood flow through the heart chambers and vessels. Doctors often use it to assess whether the heart valves are functioning properly.
- Duplex Venous Ultrasound
—This is a noninvasive vascular study that uses ultrasound technology to visualize the flow of blood in veins. It is primarily used to diagnose
deep vein thrombosis
, or blood clots in the major veins of the legs, which can break off and obstruct blood vessels in the lungs.
—Like angiography, venography uses injected dyes and x-rays to examine the interior of blood vessels, in this case veins. This procedure can also be used to diagnose
deep venous thrombosis,
though duplex venous ultrasound is usually more desirable because it is not invasive.
- Electrophysiology Study
—This test is used to assess serious electrical conduction abnormalities that predispose to life threatening arrhythmias. Small electrodes are inserted through the veins or, less often, the arteries, and directly into the chambers of the heart. The electrodes are used to stimulate the conduction pathways and record the direction and flow of their electrical activity. It is often used in preparation for the implantation of an artificial pacemaker.
- Computed Tomography (CT) Scan
With computed tomography, a computer creates cross-sectional images from serial x-ray scans. These images allow doctors to detect abnormalities in the brain, such as a stroke.
Newer CT scanners, called multidetector scanners, allow doctors to evaluate the heart, particularly the coronary arteries, for the presence of calcium deposits and
- Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging uses a powerful magnet and radio waves and to create detailed computerized images of inside the body. Like a CT scan it is often used to diagnosis abnormalities in the brain, such as a stroke, but it is also used examine structures in the chest, such as the heart and surrounding blood vessels. A specialized technique called magnetic resonance angiography (MRA) can create images of blood flow within arteries.
- Myocardial Perfusion Imaging
—These imaging procedures use radioactive isotopes (unstable substances that continuously emit small amounts of radiation) to assess how well blood is reaching the heart muscle. Two commonly used techniques for myocardial perfusion imaging are single photon emission computed tomography (SPECT), and positron emission tomography (PET).
- Single Photon Emission Computed Tomography (SPECT)
—SPECT studies use a radioactive isotope which emits photons, to map the blood flow to the heart muscle. It is commonly combined with an exercise tolerance test (see above), or a chemical stress test, to help determine whether there is sufficient blood flow to meet the demands of the heart during stress. It is also used to detect areas of the heart that have died due to a previous heart attack.
- Positron Emission Tomography (PET)
PET scans are highly specialized studies that use a radioactive isotope which emits particles called positrons to assess how well blood is reaching the heart muscle. It is commonly combined with a chemical stress test. In addition, PET scans can be performed to illustrate the levels of metabolic activity in different parts of the heart. PET scanning is now being more widely used in clinical settings.
American Heart Association
Heart Rhythm Society
Heart and Stroke Foundation
Diagnosis of Heart Disease. In: Berkow R and Beers MH, eds.
The Merck Manual of Medical Information—Home Edition
. [Internet Edition]. Merck & Co., Inc; 2000. Available at:
. Accessed December 16, 2002.