The best person to speak to about this question is the doctor
who ordered your father's test. The basic principle of a cardiac stress test is to use the heart's response to exertion in order to infer how well blood is flowing to different areas of the heart. There are many different ways that a stress test can be performed and interpreted, but the basic goal is the same: determining if any arteries in the heart are likely to be blocked.
The first way different types of stress test vary is in the way the "stress" is induced. In this case, "stress" does not refer to the type of emotional stress one might feel if they or someone they love were, say, scheduled for a stress test, but rather an induced state of exertion where the heart increases the rate and strength of its contractions. This can be induced either by exercise (e.g. running on a treadmill) or by drugs (e.g. dobutamine). The choice of which method to use is based on the way the heart will being monitored during the test and the ability of the patient to tolerate exercise.
The most significant way types of stress test differ from each other is in the way the heart's performance is measured during the test. The oldest way of doing this was to hook up electrodes to the patients chest and perform a continuous EKG
, where changes in the heart's electrical properties are detected and used to infer information about blood flow. Now there are a wide variety of ways to image the heart and these have been adapted to produce more accurate stress tests. One notable method is to use ultrasound
(echocardiography) to detect abnormalities in the the heart's structure and movement to infer information about blood flow. Another common method is to administer a radiologic tracer that is delivered by the bloodstream to the exercising heart and then use a scanner to detect how well this tracer is being delivered, thus providing direct information about blood flow.
Because there are so many different ways stress tests can be performed, there are a wide variety of risks and benefits specific to each test that are important understanding why the test was chosen, what information it will give, how accurate it will be, and what potential risks exist. For this reason I would highly recommend consulting with the doctor who ordered your father's test, because only a physician familiar with your father's case will be able to answer all those important questions about his stress test.