RELATION BETWEEN LENGTH OF DIASTOLE AND STROKE INDEX IN INTACT DOG

Abstract

The relationship between stroke index and the length of previous diastole was plotted for intact dogs in a variety of physiological conditions. The derived curves are quite similar in form. Changes in venous inflow or in arterial pressure shift the curve to different stroke index values without serious distortion. Recalculation of the data of Y. Henderson indicates that his cardiometer values show a similar relation. When these relations are expressed in terms of cardiac index and heart rate, the optimal heart rate falls at about 130, and heart rates above about 180 are associated with a significant decline in output. Hence the rising venous pressure, small heart size and decreasing cardiac output seen in late hemorrhage are probably reflecting an inadequate diastolic interval for ventricular filling.