It is well known that the mechanocardiogram, a noninvasive polygraphic recording of mechanical events associated with cardiac cycles, provides extremely valuable information for the evaluation of the cardiovascular status alone or in combination with various data obtained by other diagnostic methods, including cardiac catheterization. A certain extent of distortion, however, accompanies polygraphic records obtained from the body surface in which recording instruments and technic play a role, at least in part. Furthermore, the points of the beginning and the ends of the recorded curves or waves are frequently not clearly distinguishable. These factors probably account for the-fact that several different regression formulas are currently available for the prediction of normal values´ of systolic time intervals. Realizing these facts, it is highly desirable for each,. laboratory to have its own normal values. Nevertheless, only a few reports are available on normal data based upon an extensive study of sufficient numbers of males and females of various age groups. The purpose of the present study is to obtain the normal values in our laboratory, hoping that the results will provide information for the establishment of the normal values of Koreans. In this study, two parameters´ out of an apexcardiogram, a phonocardiogram, a carotid pulse wave and a finger-tip plethysmogram in various combinations, were simultaneously recorded with an electrocardiogram. The subjects studied consisted of 70 healthy males and 62 females. The age range was from 19 to 61 years old in the former and from 15 to 72 in the latter; the mean age being 33.99 years and 35.0, respectively.
All the time intervals of mechanical events of cardiac cycles were corrected for _heart rate and were compared to those which previously appeared in medical literatures. It was apparent that a. large number of diverse figures had been reported by many authorities. In addition, not many authors had given separate values for each sex or made a clear-cut statements whether or not they were corrected for heart rate. Our study revealed that among various systolic time intervals, electromec hanical systole, mechanical systole, left ventricular ejection time, and isovolumic contraction time were significantly longer in females than in males, whereas the delay time and the ratio of left ventricular ejection time to the isovolumic contraction time were significantly larger in males. Among the time intervals of mechanical events in systole, obtained from the. mechanocardiogram including the apexcardiogram, isovolumic contraction time, derived by two different methods, ventricular pressure elevation time, mechanical systole, ejection period and intervals from the onset of the upstroke in the apexcardiogram caused by the left ventricular contraction to the aortic sound (C-A2) and from the mitral sound to the beginning of the abrupt downstroke in the apexcardiogram in late systole(M1-D) were significantly longer in females than in males. Among those in diastole, the protodiastole, the rapid ventricular filling and the F-C interval were significantly longer in males, but isovolumic relaxation time was longer in females. Pulse -transmission times, which include measurements of four different intervals, three in systole and one in diastole, in the mechanocardiogram including a finger-tip plet4ysmogram, showed no difference between the sexes except A2-C interval, an interval measured in diastole from the onset of the aortic sound to the dicrotic notch in the finger-tip plethysmogram, which was significantly longer in males. Comparisons of our observed systolic time intervals to the predicted values, calculated by Weissler´s regression formulas, revealed that the formulas significantly over-estimated electromechanical systole,, left ventricular ejection time, Q-M1 interval, indices of left ventricular ejection time and electromechanical systole, whereas the formulas under-estimated c isovolumic contraction time, in both males and females. However, the formulas were appropriate for the prediction of the preejection period and its index in both sexes. These facts suggest that each laboratory should have its own normal values and/or regression formulas for each sex.
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