Stress tests show how well your heart works when it’s pumping hard. Some heart diseases are easier to find when your heart is working its hardest to pump blood through your body. So stress tests check your heart while you exercise on a treadmill or stationary bicycle. If you’re not able to exercise, medicine can be used to make your heart work harder , as if you were exercising.
There are different types of stress tests. They all check:
- Blood flow in your heart
- Your blood pressure
- The rate and rhythm of your heartbeat
- The strength of the electrical signals that control your heartbeat
Some stress tests also take pictures of your heart at rest and when it’s working hard. The pictures provide more detail about how your heart is working.
Other names: exercise stress test, treadmill test, stress EKG, stress ECG, exercise tolerance test, exercise EKG, stress echocardiogram, nuclear stress test, thallium stress test, sestamibi stress test, cardiac MRI stress test, myocardial perfusion imaging test, cardiac single photon emission computed tomography (SPECT), stress perfusion test
What are they used for?
Stress tests are most often used to find the cause of symptoms that may be from a heart problem.
The tests can help diagnose certain heart conditions, including:
- Coronary artery disease (CAD)
- Heart failure
- Heart valve diseases
Stress testing is also used:
- To find out how serious a known heart condition is, including the chance that you’ll have a heart attack in the future.
- To help make treatment decisions for a heart condition.
Why do I need a stress test?
You may need a stress test if you have symptoms that could be from a heart condition. Symptoms may include:
- Chest pain or discomfort without a known cause
- Shortness of breath
- Irregular or rapid heartbeat that may feel like a fluttering in your chest
- Feeling dizzy or lightheaded
You may also need a stress test to check your heart health if you:
- Have a heart condition with new or worsening symptoms.
- Are going to have surgery. Your health care provider may want to see if your heart is strong enough for the operation.
- Are being treated for heart disease. The test can show how much treatment is helping, including heart surgery.
- Have a high risk for heart disease. Your risk may be higher than normal if you have a family history of heart disease and/or certain conditions, such as diabetes, that are linked to heart disease.
- Plan to start an exercise program. If you have a heart condition or a high risk for a heart condition, a stress test can show what level of exercise is safe for you. (Always talk with your provider before starting any strenuous, new exercise.)
What happens during a stress test?
Stress tests may be done with or without imaging (pictures of your heart). The most common type of test is an exercise stress test. It doesn’t include pictures. But the main steps of an exercise stress test are part of all stress tests:
- You’ll have a blood pressure cuff on your arm to check your blood pressure.
- Electrodes will be placed on your body for an electrocardiogram test (also called EKG or ECG). Electrodes are small sensors that stick to your skin. Wires connect the electrodes to a computer or an EKG machine that records the electrical activity in your heart during the stress test.
- If you’re unable to exercise: An intravenous (IV) line will be inserted into a vein in your arm. You’ll get medicine through the IV. The medicine will make your heart work harder for 10 to 20 minutes while an EKG records your heart’s electrical activity. Medicine can be used instead of exercise for all types of stress tests.
- If you can exercise: You’ll walk on a treadmill or ride a stationary bicycle. On a treadmill, the speed will slowly increase. The treadmill may also tilt so you feel like you’re walking uphill. On a bicycle, the resistance will slowly increase, so it’s harder to pedal. You’ll exercise for about 10 to 15 minutes until you reach a target heart rate based on your age and fitness level. But you may stop the test sooner if:
- You develop chest pain, shortness of breath, dizziness, fatigue or other symptoms
- The EKG shows a problem with your heart
Stress tests with pictures include stress echocardiograms, nuclear stress tests, and cardiac (heart) MRI stress tests. These tests have extra steps:
A stress echocardiogram or “echo” takes moving pictures of your heart using doppler ultrasound. The pictures show the size and shape of your heart and blood flow through your heart. Pictures will be taken before and after your heart has worked its hardest. You’ll lie on your left side on a table as a provider moves an ultrasound device on your chest. If you exercise on a bicycle, the second set of pictures may be taken while you’re pedaling.
A nuclear stress test takes pictures of your heart using a small amount of a radioactive substance called a “tracer” and a special camera that scans your heart. A provider injects the tracer into your bloodstream through an IV line that’s placed in a vein. Your heart and blood vessels absorb the tracer, which makes them show up more clearly in the pictures.
Pictures are taken while you lie on a table before and after your heart has worked its hardest. After the test, the tracer naturally leaves your body in your urine (pee). Drinking lots of water will help remove it faster.
A cardiac MRI stress test takes the most detailed pictures of your heart using radio waves, magnets, and a computer. It is a newer test that’s mostly used for very serious heart problems. For an MRI stress test:
- A provider may inject dye into your bloodstream through an IV line placed in your arm. Some cardiac MRIs, but not all, use dye to help show very small details on the pictures.
- Pictures of your heart may be taken before and after your heart has worked hard. To take the pictures, you’ll lie on a table that slides into a large, tunnel-like MRI machine. You’ll hear loud sounds as the machine takes pictures. If you’re exercising for the test, you may use a treadmill near the MRI, or you may exercise while lying in the MRI machine using special devices to move your arms or legs.
Will I need to do anything to prepare for the test?
Wear comfortable shoes and clothing for exercise. Your provider will tell you what else to do before a stress test. You’ll usually need to fast (not eat or drink) and stop smoking for at least a few hours before the test. You may need to avoid drinks with caffeine, such as coffee, tea, and colas, for a longer period of time.
If you take medicines or supplements, ask your provider if you should take them as usual. Don’t stop taking any medicine unless your provider tells you to. If your test uses MRI, tell your provider about any metal you have in your body. An MRI can heat certain metal and cause burns.
Are there any risks to the test?
Stress tests are usually safe. You will be closely watched during the test. If a problem develops, you’ll be treated quickly. Medicines that make your heart work harder sometimes cause symptoms such as chest pain, dizziness, or nausea. An IV may bruise your arm.
The tracers and dyes used in nuclear and MRI stress tests may cause an allergic reaction, but this is rare. If you are or could become pregnant or are breastfeeding, talk with your provider before you have these tests.
What do the results mean?
A normal test result means no blood flow problems were found. Your heart is working well.
If your test result was not normal, it may mean you have heart disease. Ask your provider to explain what condition you may have. You may need more tests to find out how serious your condition is.
Courtesy of MedlinePlus from the National Library of Medicine.