Cesar A. Caceres

COMPUTER AIDS IN ELECTROCARDIOGRAPHY

The technique of electrocardiography had its origin a half century ago when an analog computing system was used to record the hearts electrical signal. That system has become the basis of one of the most useful tools in medicine. Today, the great advancements in electronics and digital computing systems a r e being incorporated into the practice of electrocardiography to make it more practical and more valuable for the diagnosis and treatment of heart disease. This paper reviews the progress of analog and digital modes of electrocardiographic processing.

Duration of the normal P wave

Abstract Accurate use of the P wave in electrocardiographic measurernent and in electrocardiographic timing of physiologic events requires prior study in each individual to determine the lead with the maximal P wave duration. Magnification of electrocardiographic waves is useful to determine their duration. The duration of the P wave in the electrocardiograms of 50 normal males was found to exceed the accepted normal. Criteria for normal P wave duration based on average values of the duration in all leads or average values of the duration in specific leads are not representative of maximal P wave duration in the electrocardiogram. Maximal P wave duration must be considered most representative of atrial electrical activity. P waves of less than 0.12 sec in duration should not generally be considered representative of atrial electrical activity in normal subjects.

Formation of the P-R segment.

Variance of opinion among authors regarding the cause and duration of each succeeding portion of the P-R interval points out that knowledge regarding the physiologic basis for these waves is incomplete. Data regarding the P-R segment are scant in electrocardiographic literature. The necessity for precision in measurement and the need for better visualization of electrocardiographic waves to enhance their diagnostic value are illustrated by study of the generally ignored region between the P and QRS.

Telephone transmission of cardiac and pulmonary data.

The role of telecommunication equipment in medicine is reviewed. A system for telephone transmission of cardiac and pulmonary data is described. The system was tested by transmission of electrocardiograms and spirograms, using a digital computer for analysis. Analysis of the original medical signal was compared to the telephone transmitted and received signal. The differences were recorded and tabulated. In general, the system described was satisfactory for its intended use.

Techniques for the use of the digital computer as an aid in the diagnosis of heart disease

The rapid computational capabilities and large storage capacity of the digital computer can provide the physician with a powerful tool for diagnostic procedures. Numerous techniques are available that can be used in attempts to use the digital computer as an aid in diagnosis [1]. For this reason, a study in the use of a general-purpose digital computer in analyzing physiological waveforms of the heart and their relationship to cardiovascular pathology has been undertaken, and a pattern recognition program for automatically recognizing clinically useful parameters in the electrocardiogram (ECG) has been developed. The techniques presented are components of a system that can be used as an automated aid for the physician in his diagnostic process [2].

The Intracavitary Electrocardiogram of Atrial Fibrillation

a From the Department of Medicine, George Washington University Hospital, Washington 37, D. C. and the Instrumentation Field Station, Heart Disease Control Program, Division of Chronic Diseases, Public Health Service, United States Department of Health, Education and Welfare, Washington 25, D. C. b Chief, Instrumentation Field Station, Heart Disease Control Program, Division of Chronic Diseases, Public Health Service, United States Department of Health, Education and Welfare and Assistant Professor of Medicine, George Washington University Hospital, Washington, D. C. c Dr. J. B. Calatayud is Assistant Professor of Medicine, Dr. Nutter is Cardiology Fellow, and Dr. Kelser is Associate Professor of Medicine at George Washington University, School of Medicine, Washington 37, D. C. d 2,6-Bis(1-piperitylmethyl)-4-(α-trimethylbenzyl)phenol dihydrobromide. (HoffmanLaRoche, Inc., Nutley, New Jersey). * Electronics for Medicine, White Plains, New York. A number of reviewsl-3 of human intracavitary electrocardiography have appeared following the initial use of this technique in 1945. The majority of reports have been concerned with a description of normal intracavitary potentials, atrio-ventricular (AV) conduction, ventricular activation in bundle branch block and hypertrophy, and the value of this technique in cardiac catheterization studies. The reported arrhythmias of the human heart studied