STUDIES ON STARLING'S LAW OF THE HEART. V. LEFT VENTRICULAR FUNCTION IN MAN

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Abstract
This investigation was designed to determine whether Starling''s law of the heart is applicable to man. Changes in effective left ventricular end-diastolic pressure were determined by measuring left ventricular pressure with a catheter introduced through the atrial septum, and intraesophageal pressure with a balloon. The activity of the autonomic nervous system was reduced with an infusion of Arfonad (trimethaphan), which was continued at a constant rate throughout the study. The reduction in circulatory reactivity produced by this drug was indicated by the absence of an arterial pressure elevation during the cold pressor test. Measurements of cardiac output, stroke volume, left ventricular work, power, tension-time index, and of the duration and mean rate of left ventricular ejection were carried out before, during the course of, and upon completion of a transfusion of 1500 ml of the subject''s own blood. This transfusion resulted in a significant elevation of left ventricular end-diastolic pressure in each subject, the average level rising from 4.8 to 22.2 cm H2O. In each subject, as the left ventricular end-diastolic pressure rose, left ventricular performance, as reflected in the parameters listed above, also became augmented. These data are consistent with the hypothesis that under the conditions of these experiments the end-diastolic pressure is an important determinant of the characteristics of ventricular contraction and that Starling''s law of the heart is applicable to man.