What Happens During a Cardiac Stress Test?
High blood pressure, undefined chest pain or suffering a heart attack – among others heart issues – may warrant the need for a stress test. But, is a cardiac stress test really as stressful as it sounds?
“They’re very simple,” says Thomas Willke MD, of Indian Springs Family Medicine. “The test can be as short as one half-hour or up to three hours depending on what type of stress test you have.”
What is a Stress Test?
A stress test is an assessment done in two parts. In a very controlled situation, the heart is stressed using either exercise on a treadmill or a chemical injection, depending on the status of the individual getting the test. Heart rate, rhythm, and blood pressure are continuously monitored throughout the entire exam.
During the second phase of the test, pictures are taken of the heart. These pictures are compared with pictures taken prior to the exercise portion.
How Long Does a Stress Test Take?
While the exercise stress test itself usually takes around 10 or 15 minutes, part one of the test takes about 30 or 45 minutes total. Dr. Willke suggests blocking off most of your morning, because you will need to go in for follow-up photos about two hours later, for the second part of the test.
How Does a Stress Test Work?
Before the Test:
Most doctors recommend fasting prior to a stress test. "Usually we do them in the morning so we suggest fasting since midnight. It is easier and safer to do a stress test without a full belly," Dr. Willke explains.
He also says you should not take any beta blockers, which are a type of drug used to treat high blood pressure, for 12 to 18 hours prior, because these impact the heart rate and may cause inaccurate results. You should also:
- Avoid caffeine prior to the test
- Wear shoes that are good for exercise
- Discuss any concerns you have with your technician before the test
During the Test:
The First Set of Pictures
First, your technician will start an IV line in your arm. You will then be injected with Myoview (or another medication). After the medication circulates, an initial set of pictures will be taken of your heart while you are lying under a nuclear imaging scanner. This medication highlights areas of the heart that are using up oxygen.
In a healthy heart, the highlighted section resembles the shape of a donut or horseshoe. “You want the rest images and stress images [which are taken during the second part of the test] to look similar, even if the images show there’s a defect,” Dr. Willke points out.
Your doctor is also looking for significant problems that may be showing up before you undergo the stress portion of the test. “You compare the patient’s story with the cardiogram, the images taken, and any old films you may have, to decide whether to go through with the stressed heart portion,” he explains. If the images indicate major issues, you may be referred to a cardiologist right away.
The Stress Test
From there, you undergo the stress portion of the test. During this half, you will walk on a treadmill, which will slowly increase in speed or resistance, until you reach your target heart rate or exhibit symptoms indicating that you need to stop (chest pain or a change in blood pressure that is concerning, for example).
Once you reach your target heart rate, you are injected with Myoview again. You will stay on the treadmill for another minute to allow the Myoview to circulate. A second type of stress test has your heart stressed by an injected chemical (there are a number of different types of chemical injections that may be used), allowing you to bypass the treadmill if your condition warrants it.
You will then be monitored until your heart rate returns to baseline.
The Second Set of Pictures
Once the exercise portion is complete, you will be instructed to eat a meal and then come back two hours later. Then, you will have a second set of photos taken of your heart.
“You can eat anything you want,” Dr. Willke says. “The second set of pictures looks better with food in the belly!”
After the Test: What Your Results Mean
From there, your doctor will read the images later that day. You are usually notified of the results within 24 hours.
If the test is normal, your family doctor will advise follow-up care to determine what else may be causing your discomforts. Depending on how serious these abnormalities are, you may need to see a cardiologist the same day.