The methods of recording and analysis of the signal averaged ECG

Signal averaging is the most common computer method for improving the signal-to-noise ratio of the ECG in order to record low level cardiac signals which are not identifiable with standard ECG techniques. The process of signal averaging assumes that the interfering noise is random and that the signal of interest repeats with every beat included in the average. The process uses the computer to detect each beat and to time align each beat. The average is performed for each moment in time, for a specified number of beats, and over a selected period of the cardiac cycle. Typically the signal averaged ECG is performed while the patient is connected to the system and stored on computer disk for later processing. Quality assurance of the SAECG should be part of the data acquisition phase because of the statistical nature of signal averaging. There is a significant literature on ECG based signal averaging and several in-depth technical reviews have been published1,2.

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