Clinical Observations on the Dynamics of Ventricular Systole

The phases of ventricular systole have been fully studied in the experimental animal under various dynamic conditions. Wiggers, 1 in a recent critical report, not only analyzed the effect of general arterial constriction, but also studied the results of aortic compression at different points. The isometric period under increased arterial resistance was, in most cases, unaltered, although occasionally it was shortened; and when the aorta was compressed near the semilunar valves, the isometric period was lengthened. The ejection phase was shortened by increasing the arterial resistance except when it was associated with considerable systolic retention in the ventricle. Under the latter conditions, the ejection phase was lengthened. On this basis of experimental data we might anticipate certain clinical findings in hypertension. With an efficient heart, elevation of blood pressure should cause no change or slight lengthening of the isometric period and a shortening of the ejection phase. In a failing heart,