How does a treadmill stress test work?
You may have coronary artery blockages and not even know it because you have minimal symptoms and/or an unremarkable or unchanged EKG while at rest. However, when the heart is exposed to stress (like that of exercise) your symptoms will likely come to the surface. During exercise, healthy coronary arteries dilate or open up to supply more blood to the heart muscle. When the arteries are narrowed due to a blockage, they supply a reduced flow of blood. This reduced flow causes the involved muscle to "starve" during exercise, producing symptoms such as chest pain or shortness of breath, which should produce abnormalities on an EKG.
During a treadmill stress test, a motorized treadmill is typically used for exercise.
Why is the test performed?
Your doctor will likely order a treadmill stress test for several reasons:
You have symptoms or signs of coronary artery disease
You have significant risk factors for coronary artery disease
You have unexplained fatigue and shortness of breath
To evaluate blood pressure response to exercise if you have borderline hypertension
To look for exercise-induced serious irregular heartbeats.
How is a treadmill stress test performed?
Your heart rate and blood pressure will be recorded prior to starting. The technician then attaches electrodes to your chest, shoulders and hips and then to the EKG portion of the stress test machine.
You’ll start with a relatively slow "warm-up" on the treadmill, increasing speed and incline during every three minute stage. Your blood pressure will be recorded during the second minute of each stage, and it may be recorded more frequently if the readings are too high or too low.
When you have achieved your target heart rate (85% of the maximal heart rate predicted for your age) the test can be stopped, or if you’re doing extremely well at peak exercise, the test may be continued further. Your doctor will stop the test prior to achievement of the target heart rate if you develop significant chest discomfort, shortness of breath, dizziness, or if the EKG shows alarming changes or serious irregular heartbeats.
How to Prepare
Ask your doctor if you should take any of your routine medicines the day of the test (especially if you are taking heart medication) as some medicines may interfere with test results. Do not eat or drink for at least three hours before the test and be sure to wear loose, comfortable clothing.
What do the results mean?
A normal result means that blood flow through the coronary arteries is normal. Abnormal results may call for further tests such as Stress Echocardiography
or a Nuclear Stress Test
to confirm coronary artery disease. Treatment may include angioplasty or stent placement, changes to your heart medication, or even bypass surgery depending on the severity of your condition.