Performance characteristics of the right heart bypass preparation

Abstract

In eight dogs under morphine-barbital anesthesia, the right ventricle was replaced by a sigmamotor pump in order to study steady-state responses of circuit pressures to arbitrary variations in ‘right heart’ output. In the systemic circuit, it was found that arterial pressure (P_AS, mm Hg) was a positive and venous pressure (P_VS, mm Hg) a negative function of pump output (Q, cc/min). In the pulmonary circuit, both arterial (P_AP) and left atrial (P_LA) pressures were positive functions of pump output. Despite considerable variations in detail between animals, individual animal pressure-flow curves could all be represented to a reasonable degree of approximation by linear functions within the range of the data. Average regression equations for the eight animals were: P_AS = 18.3 + 0.0639Q, P_VS = 20.2 – 0.0124Q, (P_AS – P_VS) = 0.0756Q – 1.59 P_AP = 11.2 + 0.0151Q, P_LA = 7.0 + 0.00208Q, and (P_AP – P_LA) - 3.9 + 0.0154Q. These results were interpreted in terms of a quantitative theory of mechanical self-regulation in the cardiovascular system.