It may take many tests to confirm a diagnosis of cardiovascular disease. Tests can also help determine the severity of the disease. Some procedures carry a small risk of stroke, heart attack, or death. The benefits of having a correct diagnosis far outweigh the risks. The risk is greater with more complicated procedures or for those with more advanced heart disease.
Laboratory and Nonimaging Tests
Blood tests can be used to detect changes in the blood that may indicate a heart attack, stroke, or other disorder. Certain proteins, electrolytes, or other substances (like glucose) may be elevated or altered. With a heart attack for example, a series of blood tests will check for specific markers that indicate heart muscle damage.
An electrocardiogram (EKG) measures the initiation and conduction of electrical currents in the heart. All those who are suspected of having a heart attack have an EKG. A healthy heart creates a specific rhythm pattern that can be printed to a strip of paper. A heart attack and heart damage will cause disruptions in this pattern. EKGs can also be used to identify abnormal heart rhythms (arrhythmias), thickening of heart muscle (cardiomyopathy), and inadequate blood flow to the heart (myocardial ischemia).
An exercise stress test evaluates 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 EKG for changes, checks the blood pressure, and observes for symptoms.
This test is used to assess serious electrical conduction abnormalities that increase the risk of 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.
Imaging tests use different types of energy waves to produce pictures. Some tests use contrast dyes to improve the visibility of internal structures.
Angiography 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 lets doctors see the outlines of the arteries’ interior, and identify irregularities or narrowing due to atherosclerotic plaques, or abnormal widening due to aneurysms.
Cardiac catheterization examines and assesses the major blood vessels and chambers of the heart. The most common use of cardiac catheterization is for coronary angiography. 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 artery disease.
Echocardiography is a 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 chambers, valves, major blood vessels and its surrounding pericardial sac. It is used to diagnose conditions involving the structure or function of the heart, such as heart murmurs and heart failure.
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.
This is a noninvasive vascular study that uses ultrasound technology to visualize the flow of blood in the veins. It is primarily used to diagnose deep vein thrombosis (DVT), 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 DVT, though duplex venous ultrasound is usually a better option because it is not invasive.
In a CT scan, a computer creates cross-sectional images from a series of 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 atherosclerosis.
MRI scan 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
Myocardial perfusion 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 SPECT and PET scans.
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.
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. It can also be combined with other tests, such as a CT scan (PET/CT scan).
- Reviewer: Michael J. Fucci, DO
- Review Date: 11/2016 -
- Update Date: 09/22/2015 -