Differences in Systolic Time Intervals Attributable to the Type of Mechanocardiographs

Differences in systolic time intervals(STI's) attributable to the types of mechanocardiographs used for their determinations were studied in a total of 341 healthy adult males. The STI's were measured from mechanocardiograms consisting of simultaneously rocorded electrocardiograms, phonocardiograms and carotid arterial pulse tracings obtained by each of three different types of mechanocardiographs in 125, 56 and 160 subjects, respectively. The study revealed that there were slight to considerabe differences among the three groups in the correlation coefficients between the individual STI's and heart rate. Thus, regression equations using heart rate as variables, for those STI's which were significantly correlated with heart rate, differed slightly to considerably among these groups. In addition, the mean values of those STI's and their derivatives, which showed no significant correlation with heart rate, were also silghtly or significantly different among the three groups. These findings suggest that if STI's obtained from patients are to be adequately evaluated at all, each laboratory must define its own normal standards worked out by using its own methods of recording and analysis of the mechanocardiogram, and cannot rely on those proposed by others.

Systolic Time Intervals in Valvular Heart Disease

Systolic time intervals were studied in a total of 83 patients with pure or predominant isolated valvular heart disease. They consisted of three groups of patients : namely, 38 cases of mitral stenosis, 25 cases of mitral regurgitation and 20 cases of aortic regurgitation. The mean of the electromechanical systole was within normal ranges in all three groups, and threre was no significant difference between the groups. The mean of the left ventriclar ejection time was also within normal limits in all groups, as was that of the electromechanical systole, but it was significantly shorter in patients with mitral regurgitation than in the others, and was significantly longer in patients with aortic regurgitation. The mean of the pre-ejection period and the ratio of the pre-ejection period to the left ventricular ejection time were within normal ranges in patients with aortic regurgitation, whereas both parameters were significantly increased in patients with mitral stenosis or mitral regurgitation, particularly in the latter.