Cardiac Exercise Testing
Some forms of heart disease may not show up on an EKG test until the heart is asked to perform under an increased workload. An exercise (or "stress") test can reveal these conditions.
When a patient is at rest, some conditions such as partial restriction of blood flow to the heart may not be revealed by an electrocardiogram test. But when the heart is required to work harder during exercise, the same EKG can detect the presence and seriousness of several heart conditions.
How an Exercise Test is Performed
EKG electrodes are attached to the patient, as in a standard EKG test. But this time, instead of lying down, the patient is standing up. A blood pressure cuff is attached to one arm. After a baseline EKG is recorded, the patient begins a low level of exercise, usually walking on a treadmill. The level of exercise is slowly increased by increasing the speed of the treadmill at intervals, usually three minutes. As the patient exercises, the EKG recording is monitored and blood pressure is taken frequently.
The level of exercise may be increased until the patient becomes fatigued or until a certain heart rate is reached. After this, the patient continues to be monitored until pulse, heart rate and blood pressure return to the baseline level.
What the Test Shows and Detects
- Coronary Artery Disease. Partially blocked blood vessels around the heart may be providing enough blood to the heart muscle when the patient isn't active. But during exercise, the blocked blood vessels prevent the heart from getting the increased level of blood it now needs, and this causes recognizable changes on an EKG. The exercise stress exposes the abnormality that was not apparent at rest.
- Congestive Heart Failure. Periodic exercise tests can be used to detect worsening of the condition or if medication changes may be warranted.
- Arrhythmia (Irregular Heartbeat). Increased levels of adrenaline during exercise can reveal certain types of irregular heartbeat that occur during periods of increased adrenaline.