Treadmill Stress Test

My doctor says I need a stress test. What is it? What's it for?

Doctor monitoring heart rate of female patient on treadmill

It can be daunting. You go in for your annual physical and, based on a routine check-up, and in addition to the normal blood workup, your doctor tells you he would like you to come back for a stress test. If you have never had one before, you may be wondering exactly what it is and why you would need one. If you have a family history of heart disease, or if you have mentioned or he has observed certain symptoms which could point to a heart condition, he may want to do tests to observe how your heart functions when under stress. By making the heart work a little harder, symptoms which may not be present most of the time may surface. Depending on your physical condition, there are a number of ways to induce a stressed state.  

The most common is the Exercise Stress Test. This test is most often conducted on a stationary bike or a treadmill, with the difficulty gradually increasing while your heart rate, blood pressure and heart rhythm are monitored. The information generated can be used to determine:

  • If there is adequate blood flow to your heart during increasing levels of activity
  • If any medications you are currently taking for angina or ischemia are working effectively
  • If further evaluation is needed to diagnose heart conditions
  • If heart procedures you have had done previously have been effective in improving blood flow within the heart vessels
  • If you have an abnormal heart rhythm
  • If your heart valves are functioning properly

Adam was in his thirties and thought he was in pretty good condition until he started having chest pains and it felt as though his heart was skipping beats now and then. “One day they got bad enough that we went to the hospital to make sure it was nothing; however they recommended he go through the stress test to rule out any complications,” Sara, Adams wife, relates. “He was not nervous at first but after seeing how many people were in the room, he got a little freaked out. They had an ER doctor, the heart specialist and two nurses there to help perform the test. The test itself was easy although he was out of breath by the end of it. He really liked the heart doc and he passed the test with flying colors. Adam is fine and does not have a heart condition to date.”

In patients where physical exercise is impractical (such as in cases of limited mobility or in someone where exercising is not recommended), a pharmacological stress test may be conducted instead using drugs such as dobutamine, dipyridamole or adenosine. These drugs make the heart respond as if the person was exercising. The doctor can still determine how the heart responds to stress, but no physical exercise is required.

Occasionally your stress test will be conducted in conjunction with imaging such as isotope imaging (also known as a nuclear stress test) or echocardiography to increase the detail and accuracy of a diagnosis.Doctor monitoring a patient during a health check

In both tests, you are monitored before, during and after the ‘stress’ to get a complete picture of the heart’s functionality. Throughout the test, the lab technician will ask you how you are feeling and will determine if the test needs to be stopped at any time based on your answers or on the readings generated by the ECG (monitoring your heart rhythm), blood pressure monitor or your heart rate.  

Cindy had both an exercise stress test and a nuclear stress test after she went into V-Tach upon administration of Morphine at the end of a surgical procedure. “The Exercise Stress Test ended up being very simple and a lot less difficult than I feared,” she explains. “The Nuclear Stress Test was very different.”

“During [the nuclear stress] test I had to lie on the table at rest, while they injected me with a radioactive dye to highlight appropriately on the images the progress of my blood throughout my heart. The radioactive dye made me feel nauseated, lightheaded, with a metallic taste in my mouth. The images were captured by the table I was lying on sliding into a scanner (like a CT scan). They are first looking for images while you are at rest, so I had to lie there about a half hour or so. (I was also connected to an ECG and a blood pressure cuff so that all responses could be measured). After the first session, I was then intravenously given a dose of Thallium to manually force my heart into an accelerated rate. This, of course, caused very disturbing side-effects including immediate intense heat, sweating, feeling faint and confused and very, very agitated. They then injected more of the dye and back into the scanner I went for another ½ hour or so.” Like Adam, neither test showed any signs of a problem or damage to Cindy’s heart. When asked if it was worth it, Cindy replied “It was. Because of the V-tach, there was real concern about something really being wrong or damaged. Knowing there were no long term issues was good.”

It is important to note not everyone has the same experience during these tests. Reactions to medications used are as varied as the people who receive them. Talk to your doctor about possible side effects before the tests if you have concerns.  
Based on the results of your test, your doctor may order further tests (such as a coronary angiogram). If you are being tested for the efficacy of a current heart treatment plan, your plan may be modified based on the findings of the exercise stress test. It may also help your doctor determine the safest level of exercise for you.

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