Assessing How Your Heart Works During Physical Activity
Exercise makes your heart work harder and can reveal problems that might not be noticeable otherwise. Stress tests are used to determine how much physical activity your heart can safely handle before developing an irregular heartbeat or loss of blood flow.
Types of stress tests
Exercise stress test
In this test, you’ll walk on a treadmill or ride a stationary bike while we monitor your heart rhythm, blood pressure and breathing. Wear comfortable clothing and walking shoes.
You’ll wear sticky patches called electrodes on your chest, arms and legs to records your heart’s electrical signals and a cuff on your arm to monitor your blood pressure. You also may need to breathe into a tube to evaluate your oxygen levels.
As you walk on the treadmill, the speed and incline of the treadmill will increase. Similarly, if you’re pedaling a stationary bike, the resistance will increase. You’ll continue until you reach a target heart rate or you experience:
- Abnormal heartbeat
- Changes in your heart rhythm
- Chest pain
- High or low blood pressure
- Shortness of breath
When the test is over, you will be asked to rest until your heart rate and breathing return to normal. You can then return to your normal activities for the day. The appointment will take about an hour, but you’ll only be exercising for 10 to 15 minutes. Depending on the results of the test, additional testing or a more advanced stress test, such as a nuclear stress test or stress echocardiogram, may be needed.
Myocardial flow reserve
Myocardial flow reserve (MFR) is a measurement of how much blood flow can increase through the coronary microvascular arteries when the heart is under stress and the need for oxygen increases. This test is a tool for the diagnosis, risk stratification and management of patients with coronary artery disease.
A Rubidium-82 radioactive tracer, which produces a type of energy called gamma rays, is injected into your blood vessel. These gamma rays are detected by positron emission tomography-computed tomography (PET-CT) and are used to create three-dimensional images of the heart. The is a safe test for most people as the patient is only radioactive for about 10 minutes during the scan before it decays.
Nuclear stress test
A nuclear stress test, also known as a thallium stress test, may be recommended in addition to an exercise stress test. It will take two to five hours and include taking images of your heart before and after exercise.
A very small amount of a radioactive dye will be injected through an IV in your arm. Then we’ll take detailed pictures of the heart tissue with a special camera that detects the dye. These images can identify areas of the heart that have decreased blood flow. After we take these images, you’ll proceed with the treadmill or bike stress test. Once that is over, another set of images will be taken.
When the nuclear stress test is over, you should be able to return to your daily activities. You can help flush the dye out of your system by drinking extra water. The results of this test will help determine whether you need additional testing or treatment.
This type of stress test helps us better assess the structures of the heart by doing an echocardiogram before, during and after a treadmill or bike stress test.
For the echocardiogram, or echo, a technician will stick patches called electrodes to your body so we can monitor your heartbeat. They will then rub gel on the area to be tested and will press a device called a transducer against your chest. The transducer creates sound waves and picks them up as they bounce back from your heart. These sound waves will create detailed images of your heart.
After these images are taken, you’ll begin the treadmill or bike stress test. You may be stopped at one or more points to take additional echo images. One last image will be taken when you’ve finished exercising.
The appointment will take about an hour, but you’ll only be exercising for 10 to 15 minutes. When the stress echocardiogram is over, you should be able to return to your daily activities. The results of this test will help determine whether you need additional testing or treatment.
Chemically induced stress test
If you’re unable to endure the level of physical activity needed to get the test results, you may be given medication that triggers a similar effect on the heart as that of exercise. This allows the doctor to assess the heart’s response to stress without physical activity.
This test can be performed as a nuclear stress test or stress echocardiogram. You’ll feel your heart rate increasing during the test, but it should not be uncomfortable otherwise. The length of the appointment depends on whether images will be taken. You should be able to return to your daily activities when it is over.
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Why Do I Need A Stress Test?
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