Take a Stress Test
It is important to understand that a stress test does not measure the amount of stress that a person is under. Stress is completely subjective and no two people will characterize stress the same way or have the same connotation of what stress is.
So what does it measure and what is it used for?
These tests measure the blood flow to and from the heart during stress (exercise) and at rest.
The heart depends on effective pumping of blood to function effectively. One analogy is to compare the vessels of the heart to the fuel line of a car. You may be able to rest without issues if your pipes are clear, but if the blood/fuel cannot get through because of blockage, you will have a difficult time kicking it into high gear. If your blood vessels are blocked you will have some difficulties when you increase the stress by increasing your activity.
Do you have symptoms that suggest coronary heart disease?
Are you in the high risk category for coronary heart disease?
Or do you have breathlessness and fatigue that you can't explain?
If so then a stress test may be useful for you.
They can also be used for patients with borderline hypertension who want to look at the blood pressure response following exercise.
In this article we discuss the different types of tests that are conducted. More specifically, we look at the:
For each of these tests we discuss what you can typically expect from each of the tests and the reliability of their results.
What is a cardiac stress test?
It is important to understand from the go that a cardiac test does not measure the amount of stress a person is under.
This test is a medical procedure that can be done in a hospital setting or a cardiologist's office.
The regular exercise or cardiac test involves walking on a treadmill or riding a stationary bike. The patient is hooked up to an ECG machine, with electrodes placed on the chest and abdomen. The patient also has a blood pressure cuff placed on the right arm.
Usually this type of test is ordered when there are signs that suggest coronary heart disease or a significant risk of coronary heart disease.
A cardiac test can also be ordered for those patients who can't explain their shortness of breath or fatigue, or for people with borderline hypertension who want to know how their blood pressure responds with exercise.
The reliability of the this heart test is compromised if there are significant EKG changes at rest. This may occur for patients with high blood pressure or on medications such as digitalis.
In this case the test administrator or doctor will conduct an Echo test or a Nuclear test that involves imaging the heart at rest and following activity.
What is a nuclear stress test?
The nuclear test is also known as a thallium or Cardiolite stress test.
Basically an isotope is injected and those areas that have adequate blood flow pick up the nuclear isotope (or perfusion tracer) more quickly compared to those areas of the heart with poor blood flow.
Because the heart needs to be put under stress, this type of test involves the patient doing the treadmill test and about 2 minutes before the treadmill test finishes the isotope is injected. This gives an image of the heart under increased loading.
Depending on the type of isotope injected the resting images are either done before the test or two hours following the test.
If the patient is unable to get their heart rate up to the target heart rate, or unable to walk on the treadmill or ride a stationary bike there is a medication that can be given that will impact the heart in the same manner as the actual exercise.
What is a chemical stress test?
Also known as an adenosine stress test this type of test combines the above nuclear or isotope test with intravenous medication.
The intravenous medication (usually adenosine) increases the load on the heart and serves to replace the exercise component of the regular cardiac or heart test.
This type of test is usually reserved for people who aren't able to do a treadmill test or peddle a stationary exercise bike. They may have back trouble, prior strokes, or poor and unstable gait, that limit movement or balance.
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