Kardiovaskulêre veranderinge gëinduseer deur middel van 'n binêre keusestelsel

Abstract

The purpose of this study was to trace cardiovascular reaction to concentration stress. Concentration stress was induced by means of a binary choice system which proved to be eminently suitable. for this purpose. Fisiological reaction takes place as a result of mental labour, that is, the integration of data and the answers thereto. A clear improvement in cardiac performance is observed where concentration stress is induced as reflected by the decrease in time interval measurings. Pre-ejection time, isovolumic contraction time and electromechanical systole as well as the reduction in the ratio of pre-ejection time on left ventricular ejection time and increase in left ventricular ejection time index. Stress on the vascular system increases as reflected by the increase in pressures, inclination time and crest time. When a moderate quantity of alcohol is administered and concentration stress is induced, reaction is practically the same as in the case of concentration stress only. The only clear decrease is in the peripheral resistance as reflected by a slight increase in inclination time and crest time. A slight decrease in diastolic pressure and a slight increase in pulse pressure therefore indicate an improved flow of blood - perfusion of organs also improves . A moderate quantity of alcohol during stress situations therefore slightly relieves the strain on the cardiovascular system. When caffeine is administered, in conjunction with induction of concentration stress, reaction is practically the same as in the case of concentration stress only. Heart rate clearly decreases and as a result some parameters do improve but isovolumic contraction time increases considerably. It would therefore indicate an

increase in heart strain, possibly as a result of the direct influence of caffeine on the myocardium. Peripheral resistance decreases slightly as a result of the dilatory influence of caffeine. Consumption of caffeine, therefore, strains the heart even more heavily when combined with concentration stress. One might well conclude that the influence of alcohol or caffeine : is very slight in comparison to the loud and clear responses given by concentration stress. The consequences of concentration stress on the cardiovascular system therefore undoubtedly dominate those of caffeine and alcohol.