QUANTITATIVE INTERPRETATION OF THE EXERCISE ELECTROCARDIOGRAM. USE OF COMPUTER TECHNIQUES IN THE CARDIAC EVALUATION OF AVIATION PERSONNEL

In aviation medicine a missed diagnosis of coronary heart disease is associated with increased danger to the pilot in flight while a false-positive error results in the loss of a highly trained man from operational flying. Exercise stress tests improve the sensitivity of the ECG as a method of detecting coronary heart disease, but a high diagnostic error ratio has been found with currently accepted methods. This report describes a system of quantitating ECG changes after exercise which utilizes a special purpose analog computer (integrator) and calculation of mean VCG parameters by digital computer. Synchronizing circuitry automatically adjusts the period of integration for changes of heart rate. The vectorcardiographic response to stress of a group of patients with mild symptomatic coronary disease is compared to a normal control group. Highly significant changes in the direction of the T vector appear three minutes after exercise and allow separation of the normal subjects from the patients with coronary disease. The quantitative output of this system is being used in an epidemiological approach to the problem of coronary disease in the aviator. (Author) Rept. includes Appendix 'A Statistical Proof of the Unity Vector Analysis', by Robert J. Wherry, Jr.