The Relationship between the Pulmonary Blood Content, the Heart Tolume and the Filling Kate of the Left Ventricle

Abstract

Summary. Variations in the pulmonary blood content have been recorded as changes in the absorption of roentgen rays in small areas of the pulmonary fields. The systolic and diastolic deflections as well as the changes of the electrokymographic records obtained from the left and right ventricles due to varying size of the heart have been recorded with the electrokymograph. Measurements have also been made of the heart volume on roentgenograms. Changes in the distribution of the blood have been induced with two procedures. In the first, the blood circulation to the lower extremities was cut off with the subject in the upright position and released in the supine position. In the second, the circulation was stopped when the legs were elevated and released after raising the head end of the X‐ray table. The investigation shows that the pulmonary blood content varies inversely with the blood content of the lower extremities. The heart volume increases with an increase in the pulmonary blood content and decreases with a decrease in it. This is found to be due, at least in part, to variations in the filling rate of the left ventricle with variations in the pulmonary blood content. The volume of the right ventricle also appears – though inconstantly and to a lesser degree – to increase simultaneously with the left ventricle. The results illustrate the significance of the lungs as a blood reservoir and stabilization chamber in the regulation of the circulation. They also indicate that Starling's law is modified under normal conditions presumably by changes in the autonomic nervous control of the heart.