THE SYSTOLIC TIME INTERVALS IN NORMAL SUBJECTS WITH SPECIAL REFERENCE TO THE INFLUENCE OF THE SEX, AGE, AND HEART RATE

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Noninvasive measurements of systolic time intervals were performed in 195 normal subjects, 98 males and 97 females, between the age of 5 and 79 years. Sex difference was not obvious for almost all measured parameters. The only exception was preejection period (PEP) /left ventricular ejection time (LVET) in the third decade, in which the values in males were slightly greater than in females. Although Q-II time, LVET, PEP and PEP/LVET were all prolonged with advancing age, the differences were not statistically significant between the age of 20 and 79 years. On the other hand, all measured systolic time intervals were significantly smaller in children and young subjects under the age of 19 years. Decreased sympathetic tone and myocardial contractility as well as the increased aortic impedance are thought to be the significant contributing factors for the decrease in systolic time intervals with advancing age. Although no significant correlation was observed between PEP/LVET and the heart rate, Q-II time, LVET and PEP were inversely correlated with the heart rate. The regression equations are as follows : in adults (msec) Q-II =-1.66 HR + 493 LVET =-1.18 HR + 367 PEP =-0.46 HR + 125 in young subjects (msec) Q-II =-1.53 HR + 480 LVET =-1.19 HE + 372 PEP =-0.34 HR + 108
北関東医学会の論文