A stress ECG is an test done to monitor the heart's response to an increased need for oxygen. It measures the heart's electrical activity as the person's heart is "stressed" by having them exercise using a treadmill or exercise bicycle (exercise stress test) or by injecting medications (pharmacological stress test).
A stress ECG may be ordered when the healthcare provider suspects coronary heart disease. Sometimes it is used to rule out exercise-induced cardiac stress or other heart disease. It may be used to evaluate a patient with atrial fibrillation to see if there heart rate is under adequate control when they exercise.
The ECG technician will clean and shave 12 to 15 sites on the person's chest and arms. Electrodes are attached at these sites with an adhesive.
During the stress (exercise or pharmacologic), the ECG machine records the electrical activity of the heart.
In the case of an exercise stress test, the person may either pedal on a stationary exercise bike or walk on a treadmill. Exercise continues until the target heart rate is reached.
With either form of stress test, at the point the target heart rate is reached, the healthcare provider takes readings for 10 to 15 minutes as the heart returns to its normal baseline rate.
Sometimes this test in used in conjunction with an imaging agent or echocardiogram. This may add greater accuracy to the test.
Generally, no preparation is required for a stress ECG.
Normally, the heart rate goes up as workload goes up. The ECG will show a pattern that is normal for the individual's age, sex, and level of physical conditioning. Abnormal results may indicate coronary heart disease. The test may also show exercise-induced cardiac stress. It also may show an arrhythmia, which is an abnormal heartbeat.