Accuracy of the Stress Test

Submitted by Medical Health Test Team on October 16, 2012

A stress test is a method of analyzing a person’s physical vital signs when the body is under load. Many conditions, particularly to do with respiration and heart function may appear normal under normal conditions when the patient is resting or is performing normal physical tasks. These conditions tend to show themselves when there is stress applied to the organs concerned. This is why some patients report normal health with moments where they feel ill or uncomfortable and these moments are usually after some form of stress or strain has occurred.

Stress testing is typically conducted on the heart although the lungs may also be involved. Cardiac stress testing involves testing the various cardiac signs such as heart beat and blood pressure when the person is resting. This is followed by the use of some form of physical exercise, usually a treadmill.  A treadmill can simulate walking as well as walking on a slope. It can also simulate running or jogging which are both activities that will increase the heart rate, blood pressure and the speed of breathing. This is because exercise causes metabolism to speed up. The increased metabolism is required to produce energy from food. To make this metabolism process successful, one requires more oxygen and therefore the blood is pumped faster and air is breathed in more rapidly.

When the heart is stressed, any weakness or abnormality in its structure will cause its rhythm to be affected. This is diagnostically relevant and it could be used to diagnose an early heart condition which has not yet fully developed. Stress test accuracy is rather debatable as the test is often known to have its own shortcomings; thus affecting the results. It is possible that a person might be unable to continue the stress test simply based on poor stamina or on a lack of enough nutrition in the most recent meal. False negatives also can occur when there is a blockage that is not yet fully formed and is affecting blood flow negligibly. This is a slightly precarious situation because it can lead to a person feeling that there is no chance of a heart condition occurring soon. Another problem with stress test accuracy is the duration of tests. Often people are able to pull through short tests without any problems and the problems occur due to extended periods of physical activity. Therefore, stress tests are often used along with other diagnostic procedures to complete a full evaluation of the patient’s health.

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