Reduction of cardiac work during venous blood perfusion of lower body

¹ Department of Medicine, University of Southern California, School of Medicine, Los Angeles; and Department of Cardiology, Elsinore and George Machris Cardiac Hospital, City of Hope Medical Center, Duarte, California

A system of venoarterial perfusion was established in the adult dog, simulating that which normally exists in the mammalian fetus. Blood was passively drained from the inferior vena cava by way of both femoral veins, and continuously infused through a catheter inserted into the femoral artery in the abdominal aorta at its bifurcation. The system was adjusted so that approximately 50% of normal cardiac output was provided by the extracorporeal system. Indicator dilution and oxygen saturation measurements showed that the output of the heart was reduced by an amount approximately equal to the output of the pump. In the aorta, an abrupt change in oxygen saturation occurred 5 cm cephalad to the infusion catheter. A prominent continuous murmur was detected at this site. The pulse rate, peripheral resistance, and central blood volume were reduced. Cardiac output was decreased to 55% and stroke work to 50% of the control value. There was a slight fall of pH and pCO₂ of arterial blood. This system of assisted circulation effectively reduces the work load on the heart, and may be a promising technique for the treatment of heart failure accompanied by venous congestion. However, these experiments indicate that it appears less promising for the treatment of hypotension and shock due to peripheral circulatory failure when venous return is deficient.