The relation of age to the duration of contraction, ejection, and relaxation of the normal human heart

Abstract

The chief findings in healthy persons with advancing age were as follows: (1) Progressive prolongation of the period of dicates that the pulse transmission time is the same at the end as at the beginning of ejection. Thus, the carotid upstroke-carotid incisura interval appears to be a reliable guide to the duration of ejection. (3) No significant change in the duration of ejection when corrected for heart rate. (4) Slight reduction in the excitation-carotid upstroke interval. However, the excitation-ejection time (i.e., the excitation-carotid upstroke interval corrected for pulse transmission time) tended to lengthen slightly with advancing age.

The findings have led to the following tentative conclusions: (a) The prolongation of relaxation may be a factor of some importance in regard to the relative inability of old normal hearts to tolerate tachycardia. Rough calculations suggest that, as an average, a sustained rate of 120, or more, cannot be tolerated beyond the age of 70. (b) The basic mechanisms responsible for initiating pressure, for sustaining pressure, and for relaxation appear to vary independently.

These findings and conclusions are based on data secured by indirect methods. Pending confirmation (or refutation) by more precise techniques, they should be considered as points of departure for further studies rather than as established concepts.