A cardiac stress test
A cardiac stress test is a medical test that indirectly reflects arterial blood flow to the heart during physical exercise. When compared to blood flow during rest, the test reflects imbalances of blood flow to the heart’s left ventricular muscle tissue – the part of the heart that performs the greatest amount of work pumping blood.
The results may also be interpreted as a reflection on a person’s overall physical fitness.
The first standardized cardiac stress test was developed in 1929 by Arthur Master, a doctor at Mount Sinai Hospital in New York City.
How is a stress test performed?
First, you will have leads (wires) to an ECG machine attached to your chest, and a blood pressure cuff is placed on your arm. A clothespin-like sensor may be placed on your finger to measure the amount of oxygen in your blood. After a baseline ECG is obtained, you will be asked to begin performing a low level of exercise, either by walking on a treadmill, or pedaling a stationary bicycle. The exercise is “graded” – that is, every three minutes, the level of exercise is increased. At each “stage” of exercise, your pulse, blood pressure and ECG are recorded, along with any symptoms you may be experiencing.
With a “maximal” stress test, the level of exercise is gradually increased until you cannot keep up any longer because of fatigue, or until your symptoms (chest pain, shortness of breath, or lightheadedness) prevent further exercise, or until changes on your ECG indicate a cardiac problem. Maximal stress tests should be performed when the goal is to diagnose the presence or absence of CAD.
With a “submaximal” stress test, you will exercise only until a pre-determined level of exercise is attained. Submaximal tests are used in patients with known CAD, in order to measure whether a specific level of exercise can be performed safely.
After the test, you will be monitored until any symptoms disappear, and until your pulse, blood pressure and ECG return to baseline.
