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An electrocardiogram (ECG) is a test that checks the electrical impulses of the heart. An ECG machine is not one instrument but several pieces of equipment working together to detect and record the heart's activity. The machine reads the heart impulses and translates them to a graph-style diagram on specially designed paper strips.
ECG equipment includes a set of lead wires. The majority of machines use 10 or 12 leads. The leads look like plastic-coated wires with small metal discs at the end of each one. The discs are designed to pick up the heart's electrical impulses. Each disc has a lead attached to one side, and the other side is flat and ready to accept sticky paste that will adhere the disc to the body when applied.
Most ECG equipment includes a typing keyboard that allows healthcare providers to type in the patient's name and other data that will then be printed out on the test strip. The ECG equipment is usually portable and mounted to a stand on wheels so that it is easily moved to different examination rooms as needed. The main machine also has an alarm installed to alert the test provider to test issues, such as a lead not properly attached to the patient's body.
Test strip paper is another tool used in ECG equipment. The test strip paper is designed in width to fit neatly into the main machine. As the ECG test occurs, the machine transmits the heart rate data to the paper with squiggle ink lines. The test paper strip background is usually colored pink, blue, or green to more easily illustrate the peaks and valleys of the electrical impulse diagrams. As the impulses are recorded, the strip paper is pushed through the machine and produces a long, narrow, diagram of the heart's activity.
Additional ECG equipment is not part of the actual ECG machine, but is necessary for a test. An examination table or chair is used to have the patient remain still during the testing process, which typically lasts less than a minute. In some cases, an ECG machine is constantly hooked up to a patient to continually monitor the heart rate, in which case, most patients lie in a bed. Stick adhesive is typically used to attach the electrode discs to the patient's skin. Rubbing alcohol is often used to remove the gluey substance from the skin once the test is complete and the electrodes have been removed.