Exercise myocardial perfusion imaging, often referred to as a stress test or stress myocardial nuclear imaging study, shows whether the heart muscle is receiving an adequate supply of blood. The purpose of this study is to:
- Determine the location and extent of areas of the heart that are not receiving enough blood
- Provide information about the heart's pumping ability
- Show areas of scarring after a heart attack
- Evaluate the results of treatments to restore sufficient blood flow to the heart, such as coronary artery bypass surgery or angioplasty
How an Exercise Myocardial Perfusion Imaging Test Is Performed
Two series of heart images are taken: one during exercise and one at rest. To begin, an intravenous line is placed in the arm. Next, EKG electrodes and a blood pressure cuff are applied so that blood pressure and heart rate can be monitored before, during and after exercise. The patient exercises on a treadmill, similar to a conventional exercise treadmill, at a gradually increasing pace.
At peak exercise, a small dose of radioactive material is injected through the intravenous line. This substance is carried throughout the bloodstream. It highlights areas of the heart that are not receiving enough blood. This material does not usually cause side effects and is eliminated quickly by the body.
After the exercise portion of the study, cardiac images are obtained using a special camera that is able to trace the injected material in the heart. Patients are encouraged to breathe normally while these images are taken, but to remain still. After about one to two hours, another series of "resting" images is obtained. The entire test takes between three and five hours.
Some patients are unable to exercise due to orthopedic difficulties or other health problems. If so, the effect of exercise on the heart can be simulated with medication. For these patients, IV administration of this drug replaces the treadmill portion of the study.
Exercise Myocardial Perfusion Imaging Preparation
Patients must not eat or drink anything except water for three hours before the test. Avoid caffeine, including coffee, tea, chocolate and cola for 24 hours before the study. Please consult your doctor for advice on whether to take your medications or hold them until after the study. If you are diabetic, consult your physician regarding dietary restrictions and insulin use, if applicable.
Exercise Myocardial Perfusion Imaging Precautions
If you are pregnant, or suspect that you might be, please notify your physician or the technologist performing the study. Pregnant women should not undergo this test.