What is a ‘stress test’ and why is this called a stress test?
The resting heart muscle’s blood supply needs are usually well met even in the presence of blocked arteries. When the heart is stressed either by exercise or chemicals, the demand for blood increases. The blood flow through the blocked arteries- while adequate at rest- may not be able to keep up with the demands of a stressed heart. This can show up on the pictures of the heart taken after stress. This is the principle behind all the stress tests. The word stress test is used for any means used to increase heart muscle’s demand for blood. This can be done by exercise or by chemical means.
What is exercise stress echo?
This is a test used to look for evidence of blockage of heart arteries. As a part of this test, an echocardiogram is done before and after exercise. Exercise portion is the same as described under ‘stress test’. Echo images before and after stress are compared to look for any evidence of blockage of heart arteries. As compared to nuclear stress test, this test can also unearth any gross valve abnormalities or any other structural heart abnormalities.
How do you prepare for this test?
The preparation is same as for an exercise treadmill test.
What are the shortcomings of this test?
The quality of echo images depends on the ease with which the sound waves can travel through the chest wall to the heart. This can be adversely affected by thickness of the chest wall, lung abnormalities etc. Moreover, the echo technologist has to be able to acquire pictures within a few minutes after you come off the treadmill. Different parts of the heart are divided into segments. According to some studies, up to 37% of segments may not be seen well on stress echo.
Which is better- stress echo or nuclear stress test?
This depends on several patient related issues as well as the expertise of the person performing these tests.