The Information Content of Successive RR-Interval Times in the ECG. Preliminary Results Using Factor Analysis and Frequency Analysis

Factor analysis and frequency analysis were applied to series of interval times between successive heart beats in a preliminary effort to get a maximal amount of information from this kind of data. From a sample, with a mean heart rate ranging from 56·2 to 156·4 per minute, 25 values (partly by using thresholds) were derived and intercorrelated. Scores based on the summation of successive differences and standard-deviation scores showed a mean correlation of 0·96 and were called together a D-complex. Factor analysis revealed 4 interpretable factors, explaining 85% of the total variance. Frequency analysis results were intercorrelated with all other values and showed a high correlation with the D—complex.‘scoring ’versus ‘measuring’ is discussed.