Exercise Stress Test
What is an exercise stress test?
An
exercise stress test is a technique in which an EKG is obtained
while an individual walks or runs on a treadmill or pedals
a bicycle. The oxygen demand of the heart goes up with exercise,
because the heart rate and blood pressure increases. EKG changes
may show up when the heart rate increases and the heart is
not getting the oxygen supply it needs. This test is used
as a screening measure (for someone with no heart disease),
to help diagnose an individual experiencing chest pain or
syncope (fainting), or to follow the progress of someone who
has had a heart
attack or heart
rhythm disturbance in the past.
Preparing for the procedure
Eat nothing or only a light meal and avoid caffeine (since caffeine naturally speeds up the heart rate) for 2 to 4 hours before the test. Wear rubber-soled shoes and comfortable clothing. Your physician may ask you to decrease or stop the dose of a specific medication prior to the test. Allow about one hour for the test.
During the procedure
In this test, electrodes are placed on the chest wall and an EKG is recorded at rest, during exercise and after exercise. Blood pressure is also monitored. The individual typically walks on a treadmill and, according to the protocol that the Inova physician is using, the speed and hill (or grade) on the treadmill is increased every 3 minutes. The test is stopped when you become too tired to continue, when your Inova cardiologist has acquired enough information, or when an abnormality is detected. Be sure to alert the cardiologist if you feel any chest pain, dizziness, or other unusual symptoms. If no abnormalities are detected, the test is called a "negative stress test".
If an abnormality is detected, it is called a "positive stress test" and one or more of the following are noted:
- ST-changes. This is a change in the EKG rhythm that reflects a lack of blood flow in a part of the heart muscle, often caused by a blockage from coronary artery disease. The cardiologist can define the area of the heart (front, back, bottom) that shows the lack of blood flow based on the changes in the EKG.
- Chest pain. A test is considered positive if an individual experiences chest pain during or immediately following the exercise portion of the test.
- Irregular heart rhythms. The increased workload on the heart may trigger irregular heart rhythms. These are noted both during and immediately following the exercise portion of the exam.
- Hypertensive exercise response. A normal blood pressure response to exercise is when the diastolic blood pressure (the bottom number, or pressure of your arteries when the heart is not contracting) goes up no more than 10 mm/hg. The systolic blood pressure (the top number, or pressure of your arteries when the heart is contracting) should not exceed 200 mm/hg.
Of course, the most noteworthy positive stress tests are those with "ST depression" and/or chest pain. Unfortunately, exercise stress tests are not foolproof: There are false positives and false negatives. The exercise stress test holds only a small risk. The danger of suffering a heart attack or serious rhythm disturbance during the test is extremely remote, especially because cardiologists recommend these tests for people whom they believe can exercise safely. However, the staff at the Inova Heart Center are specially trained to handle any situation that may come up. In addition, all the needed equipment for an emergency, including cardiopulmonary resuscitation equipment, is located in the same room in which the test is being done.
After the procedure
You can resume normal activities. Your Inova physician will give you important feedback about the results of the test. If the test was positive, he or she may recommend other tests that more accurately determine whether there are blockages in the coronary arteries and where they are located.
