Compact digital storage of ECG's.

The technique of predictive coding is applied to the problem of reversible compression of digitized electrocardiograms. Integer-based predictors and MMSE predictors are studied as regards performance at varying sampling rates and digital resolutions for both long-term ECGs and ECGs recorded at rest. It is concluded that MMSE predictors are to be preferred only in the case when the ECG is oversampled (i.e., the sampling rate is much higher than twice the cut-off frequency of the presampling filter). In other cases the integer predictor which yields the so-called 2nd differences is superior. The problem of encoding the resulting residuals with a variable-length code is studied for long-term ECGs digitized at 100 Hz and using 8 bits digital resolution. The code has a simple struture leading to speed of execution while the efficiency loss is small.