Ventricular Interaction with the Vascular System in Terms of Pressure-Volume Relationships

Abstract

Guyton and his associates (Guyton 1963; Guyton, Jones, and Coleman 1973) analyzed the regulation of cardiac output in the closed circulatory loop by experimentally opening the loop at the junction of the vena cava and the right atrium. Reasoning that the cardiac output curve depicts the performance of the ventricle as a pump and the venous return curve represents vascular system properties and circulatory blood volume, they superimposed these two relationship curves and showed that cardiac output in the natural closed-loop condition is found at their intersection. Although this concept was useful in analyzing the global mechanisms that govern cardiac output in the closed circulatory system, it did not allow separation of the contributions of the individual cardiac chambers and the pulmonary vascular components of the circulatory system.