A cardiac stress test monitors your heart's and body's response during increased physical activity. To do this, a cardiologist monitors your electrocardiogram, blood pressure, and heart rate while you use a treadmill. Patients unable to endure the physical requirement of using a treadmill may undergo a non-exercise (pharmacologic) stress test performed using medications to obtain similar results.
During stress testing, you exercise (walk or run on a treadmill or pedal a stationary bike) to make your heart work hard and beat fast. Tests are done on your heart while you exercise.
You might have arthritis or another medical problem that prevents you from exercising during a stress test. If so, your doctor may request to give you medicine to make your heart work hard, as it would during exercise. This is called a pharmacological (FAR-ma-ko-LOJ-ih-kal) stress test.
Doctors usually use stress testing to help diagnose coronary heart disease (CHD). They also use stress testing to find out the severity of CHD.
CHD is a disease in which a waxy substance called plaque (plak) builds up in the coronary arteries. These arteries supply oxygen-rich blood to your heart.
Plaque narrows the arteries and reduces blood flow to your heart muscle. The buildup of plaque also makes it more likely that blood clots will form in your arteries. Blood clots can mostly or completely block blood flow through an artery. This can lead to chest pain called angina (an-JI-nuh or AN-juh-nuh) or a heart attack.
You may not have any signs or symptoms of CHD when your heart is at rest. But when your heart has to work harder during exercise, it needs more blood and oxygen. Narrow arteries can't supply enough blood for your heart to work well. As a result, signs and symptoms of CHD may occur only during exercise.
A stress test can detect the following problems, which may suggest that your heart isn't getting enough blood during exercise:
- Abnormal changes in your heart rate or blood pressure
- Symptoms such as shortness of breath or chest pain, especially if they occur at low levels of exercise
- Abnormal changes in your heart's rhythm or electrical activity
- During a stress test, if you can't exercise for as long as what is considered normal for someone your age, it may be a sign that not enough blood is flowing to your heart. However, other factors besides CHD can prevent you from exercising long enough (for example, lung disease, anemia, or poor general fitness).
Doctors also may use stress testing to assess other problems, such as heart valve disease or heart failure.