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- Three types of leads are used to produce the ECG; standard, augmented, and chest leads.
- Standard leads are bipolar, meaning they measure electricity in two directions.
- Augmented leads are unipolar because they measure toward one electrode on the body. Chest leads record activity between six points on the chest and within the heart.
- A single channel ECG records 12 leads individually, and a multichannel ECG monitors all 12 leads and usually records three at a time.
- The ECG machine has three basic functions; input, signal processing, and output display.
- The controls for the ECG machine include the speed, gain, artifact filter, LCD display, heart rate limits, standardization, and the lead selector.
- Most common ECG machines include a keyboard and lead wires for input, a small machine that processes the ECG signal, and an LCD display and paper for output.
- Various types of disposable electrodes are used depending upon the equipment and type of ECG being recorded.
- ECG graph paper has boxes that are 5 mm by 5 mm and indicate 0.04 second in time horizontally and 0.1 mV in voltage vertically.
- There are three common ways to calculate the heart rate including the R-R (300) method, the 6-second method, and the 1500 method.