Chemical / Pharmalogical
Stress tests:
How does it work?
A chemical stress test combines an intravenous medication with an imaging
technique
Isotope imaging
echocardiogram
In these cases the medication will increase the heart load instead of exercise. When the patient has a blocked artery, the blood flow to a specific area of the heart muscle will be reduced, causing decreased movement in the affected heart muscle segment (as seen in the stress echo), or reduced isotope uptake (as seen in the nuclear scan).
When is a chemical stress
test performed?
The test of choice is treadmill stress test, because of the physiological
effect on the blood pressure and heart rate. However, exercise may not be
possible for physical limitation, shortness of breath, etc. in such cases,
chemical stress testing may be done.
Types of chemical stress testing:
Dipyridamole (Persantine) stress test
Adenosine stress test
Dobutamine stress test
Since caffeine products can alter the efficacy of any stress test, it is essential that no caffeine or decaffeinated products including coffee, tea, pop, and chocolate, be consumed for 24 hours prior to the test.