A treadmill test, also called a stress test, is a tool doctors use to diagnose heart disease. Although your doctor may order a treadmill test because you exhibit symptoms such as chest pain or angina, this is not always the case. If your lifestyle puts you at risk and you want to begin an exercise program,or if you already had a heart attack or heart bypass surgery, your doctor may order the test for evaluation purposes. Blood pressure readings taken before and during the test are essential to helping your doctor determine the state of your heart.
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Blood pressure is a measurement of the force in which your blood hits artery walls as it pumps through your body. A normal blood pressure reading is less than 120/80, with the 120 referring to systolic or beat pressure, and the 80 referring to diastolic, or the pressure between heartbeats.
Your doctor uses blood pressure readings obtained from a treadmill test to find evidence of coronary artery blockage. Under normal circumstances, you can expect systolic blood pressure to increase to about 200 at the peak of the test and diastolic blood pressure to remain steady or fall only slightly. Heart disease is a likely if your systolic pressure does not rise above 120, if it falls, or if your diastolic pressure rises above 90 to 100.
Before starting the test, your doctor will take your resting blood pressure and heart rate to set a baseline. He then attaches 12 electrocardiogram, or EKG, leads to different areas around your heart. The test starts out slowly and moves through three stages, each lasting for three minutes and gradually building momentum. Your doctor will take blood pressure readings during the second minute of each stage, but can include additional readings if he suspects a problem.
During the test, says HeartSite.com, an unblocked coronary artery will dilate, or become larger to provide increased blood flow to your heart. Blood pressure will rise as your heart begins pumping faster to accommodate the muscles need for additional blood. If, however, your arteries cannot dilate enough to accommodate this increased need for blood due to coronary artery blockage, blood pressure will not increase sufficiently and your heart, as well as your muscles will not get the extra blood they require. If the test continues, reduced blood flow to muscles can cause symptoms such as chest pain or extreme shortness of breath.
The level of activity performed during a treadmill test is about as strenuous as jogging or running up a flight of stairs, says HeartSite.com. In addition, you complete this test in the presence of medical professionals who monitor your heart and blood pressure from beginning to end. If you already have heart disease or high blood pressure, your doctor may order an alternate form of stress test. Other ways of conduction a stress test include cardiac catheterization, an echo stress test or a nuclear stress test.