Systolic time intervals. 1st communication: normal values from children without heart diseases.

The concept of "systolic time intervals" was introduced into noninvasive cardiologic examination by Weissler et al.; in detail these are the following data: the total electromechanical systole = QS2, the left ventricular ejection time = LVET, the preejection period = PEP and the quotient PEP/LVET. These quantities are not in principle new parameters; in the German literature the QS2 is known as "Systolendauer", the LVET is identical to the "Austreibungszeit" and the PEP is identical to the "Anspannungszeit". The determination of PEP (= QS2-LVET) is preferable to the usual calculation of the "Anspannungszeit" nach Blumberger in so far as longer time intervals must be measured and therefore the statistical error decreases. From 96 children between 3 and 15 years polygraphic tracings were recorded and the STI were calculated and standard values were ascertained and were evaluated statistically. QS2 and LVET grow longer linearly with increasing age (p less than or equal to 0.001) and diminish linearly with increasing heart rate (p less than or equal to 0.001). For PEP only the inverse correlation with the heart rate was significant. PEP/LVET does not very significantly. Girls have longer PEP (+ 6 msec, p less than or equal to 0.01) and higher PEP/LVET (+ 0.04, p less than or equal to 0.001) than boys. The normal range of variation of the STI is relatively large (QS2: 278-386 msec, LVET: 200-285 MSEC, PEP: 65-114 msec, PEP/LVET: 0.27-0.47). For the examination of individual cases it is better to compare them with the standard values ascertained by the regression equations (table 3+4).