What is a stress test?

Your primary care doctor or a cardiologist may order a cardiac stress test that causes your heart rate to speed up through exercise or a special medication for several reasons:

  • You may be experiencing shortness of breath or an odd pressure in your chest
  • You may have had an abnormal result from another test
  • You may have had a heart attack, and your doctor wants to make sure you're strong enough to participate in a cardiac rehabilitation program
  • Your doctor may want to ensure that you're strong enough to engage in a sport or intense exercise or tolerate a major surgery
What is a stress test?

"If you have a blockage in your heart, shortness of breath or chest pain with any exertion may be present," said Christina Reuss, MD, FACC, a cardiologist and independent member of the HonorHealth medical staff. "A stress test lets us sort out if there is a high or low chance that your symptoms are being caused by a blocked artery."

A stress test:

  • Can detect a 70 percent or greater narrowing of an artery
  • Can determine if your fitness is higher or lower than average
  • Measures your blood pressure response to exercise
  • Measures your body's ability to slow down after exercise has stopped

Types of cardiac stress tests and how they work

Depending on your level of physical fitness and any limitations imposed by medical conditions, you may undergo one or more of the following cardiac stress tests:

  • Exercise stress test: You're asked to walk on a treadmill where the speed and incline are gradually increased, typically increasing your heart rate.
  • Exercise echo stress test: This test is recommended if you're able to exercise on a treadmill and have minor EKG abnormalities that will make it difficult to interpret. Ultrasound images are taken of the heart before exercise. You walk on the treadmill until the maximal heart rate is achieved, then lie down quickly on the same table to have ultrasound images taken of your heart right after exercise. This allows the doctor to find an area of heart muscle that's weaker after exercise. A weakness after exercise signifies a blockage or problem with blood flow in an artery.
  • Nuclear stress test: You may need a nuclear stress test if a routine exercise stress test could not identify the cause of symptoms. When a nuclear stress test is performed, a completely safe radiotracer medication will be injected into a vein. For up to 45 minutes, you'll wait for it to flow into your circulatory system while a special camera records how the radiotracer travels through your blood and into your heart.

    "After that, most people will walk on a treadmill until their heart rate speeds up and repeat the process of following the radiotracer through the heart," Dr. Reuss said.

  • Chemical stress test: Most often, this type of stress test is recommended for patients who are unable to exercise. Your doctor will administer a medication called Regadenoson or adenosine intravenously to dilate the heart arteries and mimic exercise for those who can't.

    Another option to mimic exercise is to give intravenous dobutamine, making your heart beat harder and faster. Either Regadenoson, adenosine or dobutamine are then administered, along with a radiotracer imaging material, to visualize blood flow through the heart.

There's no pain associated with a cardiac stress test. Some patients report discomfort as their heart rate accelerates.

What to wear for a stress test

Always choose closed-toe gym shoes and socks, Dr. Reuss advised. Choose a shirt and pants that can be easily removed because electrodes (attached with circular stickers) will be placed on your chest and legs to measure your heart rate. You'll wear a hospital gown while on the treadmill. Women are encouraged to wear a sports bra for extra support.

Understanding the results of your stress test

A normal stress test result "means we believe there is a low chance of having an artery blockage," Dr. Reuss said. In a cardiologist's office, about half of all stress test results are normal.

If the stress test results are abnormal, "then we have to look for why this occurred," she said. If someone does have a known blockage, a stress test can help determine if that blockage is progressing.

"If there are borderline changes, we may want to do the test again, this time looking at the heart with pictures before and after exercise to be sure you really do have a blockage," Dr. Reuss said.

Determining treatment options

After your doctor has reviewed your results with you, he or she will determine a treatment plan, if needed. Medical treatment might include:

  • A medication to help lower blood pressure, or to lower your heart rate during maximum exercise if that's presenting a problem
  • A cholesterol-lowering medication
  • A daily low-dose aspirin
  • Medication to reduce chest pain (angina) or the feeling of chest pressure

If medications are at maximum dosage, you may be advised to have a coronary angiogram to see if your blockage can be fixed.

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