Cardiac stress test
Some forms of heart disease are easily missed when the patient is at rest. A stress test can be an important diagnostic tool because some heart problems only become apparent when the heart is working a little harder. The stress test is used to evaluate the heart and vascular system during exercise.
How to prepare for your stress test
- Refrain from eating or drinking for 3 hours before the exam.
- Wear comfortable shoes and clothing appropriate for exercise.
- Your doctor may ask you to stop taking certain medications prior to your exam.
What to expect
Your test will take place in an exercise lab. Your heart rate and blood pressure will be recorded at rest, then a total of 12 electrodes will be attached to your chest, shoulders, and hips. The electrodes are painless and will essentially feel like sticky patches with lightweight wires attached. Each of the 12 electrodes transmits information about a different portion of the heart so your doctor can observe how these different areas respond under stress.
Once the electrodes are attached, you will step onto a treadmill and the exam will begin. The treadmill will start at a minimal incline, at a relatively low speed. The speed and incline will increase every three minutes; each increase is called a stage. Your blood pressure will be recorded using an arm compression device during the second minute of each stage, sometimes more often if the readings are particularly high or low.
Generally, the exam will end once you have reached your target heart rate, as determined by the doctor supervising the exam. If you are performing exceptionally well at your target heart rate, the test may continue. Conversely, the test may be stopped early if you begin to experience significant chest discomfort, shortness of breath, dizziness, unsteady gait, serious irregular heartbeats, or if your blood pressure rises or falls outside of acceptable limits.
The performing cardiologist will give you a general overview of the results before you leave, and your regular doctor will follow up with official results after reviewing your exam.
Nuclear perfusion stress test
A nuclear perfusion stress test, also known as an isotope stress test, is sometimes ordered when your doctor wants a clearer picture of how your heart works under stress. In this exam, a special type of radioactive contrast material is injected to help create more detailed images of your heart.
What to expect
Before your test begins, a small amount of liquid contrast material (called an isotope) is injected into the bloodstream. Then you will be asked to lie down on an exam table under a scanning camera. The scanning process will take about 10 to 20 minutes, and you will need to lie very still.
After the resting scans are taken, you will proceed with the stress test described above.
Concern about radiation
This test utilizes low doses of radiation to highlight blood-flow patterns to the heart walls. This type of testing has been done for many years, and there are no known long-term adverse effects from such low-dose exposure.
After the procedure, a small amount of radioactive material will remain in your body. Through the natural process of radioactive decay, it will lose its radioactivity over time. More than likely, it will pass out of your body through your urine or stool during the first few hours or days following the test. You may be instructed to take special precautions after urinating including flushing the toilet twice and washing your hands especially thoroughly. You should also drink plenty of water to help flush the radioactive material out of your body. A nuclear medicine clinician will go over this information with you in detail.
Women who are pregnant or nursing should notify their doctor before undergoing this test.