The electrocardiomultigraphimeter in the variability analysis.

The electrocardiomultigraphimeter (ECXGM) is a software package for clinical research in many branches of electrocardiography. The ECXGM makes available a set of conversions and representations of the ECG signal that are usually implemented in clinical practice on different instruments such as electrocardiographs, vectorcardiographs and spectrum analysers. This paper analyses the tools offered by the ECXGM for macro and microscopic variability analysis: graphic processing (contourograms, superimposed VCG loops), wave recognition programs, measuring and measurement synthesis: histograms and statistical diagrams.

A computer-based system for the study of ECG/VCG variability.

A description is given of a computer-based system for electrocardiogram and vectorcardiogram analysis. Its main purpose is to provide a basic research and study tool of the variability occurring in electrocardiographic activity when the observation time is of the order of 30 min. System/operator interaction is designed to allow the user to validate or correct the identifications executed by the program. Special attention is given to graphic representation techniques suitable for synthesizing a great many numerical results. Data acquisition and analysis are performed by two different PDP 11 systems. The acquisition programs are written in ASSEMBLER, the analysis programs are in FORTRAN. Intermediate files are structured by a data compression technique. At present the program is oriented to study normal subjects. A new version to study bundle-branch blocks is now available.

Time-domain remarks on the cycle-to-cycle variability in some quantities measured on the vectorcardiogram magnitude.

Traces from five patients with different pathophysiological conditions were considered. For each of them more than ten successive cardiac cycles were observed. In each cycle, fourteen temporal intervals were measured. Diagrams were prepared with all values from many measurements made on the electrocardiogram of a patient. Means, variances and coefficients of variation were also computed. A consistent variability was detected in all measurements on every patient. The causes of such a situation have to be studied in detail. However, the coefficient of variation appears make it possible by itself, to distinguish some pathological cases (infarcts and conduction defects) from all others considered here.