Stress tests are used to measure the performance of your heart and/or lungs while under physical stress. Stress tests provide information on how your heart responds to stress.
Metabolic Exercise Stress Test
The metabolic stress test is used to:
Determine the health of your heart and lungs
Diagnose symptoms of shortness of breath or chronic fatigue (medical problem or poor fitness)
Measure your heart’s functional capacity
Evaluate the effectiveness of your cardiac treatment program
How do I prepare?
To prepare for the test, do not eat or drink anything except water four hours prior to the test and do not drink or eat anything containing caffeine for 12 hours prior to the test. Caffeine can interfere with the results. Do not smoke on the day of the test. Consult your doctor on the medications that should be taken on the day of your test. If you use an inhaler, bring it with you, and if you’re diabetic, talk to your physician on how to adjust your medications the day of the test. Be sure to wear comfortable clothes and soft-soled shoes. Do not wear jewelry or bring valuables with you.
What can I expect?
Ten electrode patches will be attached to your chest and then to an electrocardiograph (ECG) monitor. This will chart your heart’s activity during the test. Men may have their chest partially shaved so the electrodes will stick. The technician will get a resting ECG, heart rate and blood pressure rate before you start exercising. You will be asked to breathe through a mouthpiece for a few minutes before you begin the test. You will then continue breathe only through your mouth throughout the test. A nose-clip will be placed on your nose.
You will begin walking on a treadmill or pedaling a stationary cycle. The degree of difficulty will gradually increase, and you will be asked to continue until you are exhausted. Your ECG, heart rate, blood pressure and breathing rate will be monitored throughout the test. An increase in these rates is normal during the test. The technician will ask how you are feeling at regular intervals. The questions will be phrased in a way that you will “nod” your answers, yes or no. Please tell them if you experience any chest, arm or jaw pain; dizziness; lightheadedness; or any other unusual symptoms.
After the test you will cool down by walking or pedaling slowly for a couple of minutes. The appointment usually lasts about one hour and 15 minutes and the actual exercise is usually between five and 12 minutes.
Thallium Stress Test
This is a type of nuclear scanning test or myocardial perfusion imaging test. It shows how well blood flows to the heart muscle and is usually performed along with an exercise stress test.
The thallium stress test is used to determine:
Extent of a coronary artery blockage
Prognosis of patients who've suffered a heart attack
Effectiveness of cardiac procedures done to improve circulation in coronary arteries
Cause(s) of chest pain
Level of exercise that a patient can safely perform
When you reach your maximum level of exercise, a small amount of a radioactive substance called thallium is injected into your bloodstream. Then you lie down on a special table under a camera that can see the thallium and makes pictures. The thallium mixes with the blood in the bloodstream and heart's arteries and enters your heart muscle cells. If a part of the heart muscle doesn't receive a normal blood supply, less than a normal amount of thallium will be in those heart muscle cells.
The first pictures are made shortly after the exercise test when the heart is “stressed” and show blood flow to the heart. The patient then lies quietly for two to three hours and another series of pictures is made. These show blood flow to the heart muscle during rest.
Chemical Stress Test
Sometimes you can't do an exercise test because you're too sick or have physical problems. In this case, a drug such as dipyridamole or adenosine is given. This drug increases blood flow to the heart and thus "mimics" an exercise test. Your ECG will be monitored throughout the test. Thallium will be injected into your bloodstream and two sets of images will be taken, one following administration of dipyridamole or adenosine and one following a period of rest. Each set of pictures takes between 15-30 minutes.
It is important to let the technician know if you experience any shortness of breath, headache, chest pains, palpitations or a flushed feeling during the test.