Nuclear Stress Testing: Cardiac Stress Test Procedure and Preparation
- Detection and evaluation of coronary artery disease
- Determination of myocardial viability vs. scar
- Detection of myocardial perfusion abnormalities secondary to causes other that coronary artery disease
Cardiac Stress Test Preparation
The patient may not eat for four hours prior to examination. No smoking for 24 hours prior to the scan. Caffeine may also be restricted.
Be sure to wear comfortable clothes and shoes, such as sneakers or running shoes if the patient is going to walk on the treadmill.
Cardiac Stress Test Procedure
For the resting portion of a cardiac stress test procedure, you receive an injection of thallium, a radioactive tracer. The tracer will circulate for 5-10 minutes and then pictures will be taken of your heart. This imaging session takes 15 to 30 minutes to complete. This first session shows the resting blood flow to your heart muscle.
For the exercise test, small pads called electrodes are placed on your chest so that an electrocardiogram (EKG) can monitor your heart rhythm while you exercise. An intravenous tube is placed in your arm for tracer administration, which occurs about one minute before the end of the exercise session. The exercise consists of walking on a treadmill. As the exercise continues, it becomes more difficult (similar to walking up a hill). As the exercise progresses, the heart rate and blood pressure rise. You will be asked to exercise as long as you can.
If a previous medical problem prevents you from exercising, your doctor may request using a special medication to replace exercise. Dobutamine, persantine or adenosine may be used. These drugs will mimic exercise and the second radiotracer will be injected during the infusion of the drug.
About 15-45 minutes after the second tracer is injected pictures of your heart are taken. The imaging session takes 15-30 minutes. This session shows the stress distribution of blood flow to your heart muscle during peak exercise as well as the wall motion of your heart and the ejection fraction of your heart (the percent of blood the heart pumps out as it beats).