THE PROCEDURE for extracorporeal circulation to be described is a relatively simple operation in which one animal (donor) provides the functions of the heart and lungs for himself and for a second animal (recipient) as well. By means of cross circulation an adequate supply of oxygenated blood is delivered to the recipient in order that the heart may be bypassed either in whole or in part, thus making experimental intracardiac surgery possible in laboratories where a mechanical heart or heart-lung is not at hand. It is the purpose of this paper to present the details of a workable cross circulation together with the results in an initial 20 pairs of dogs in which the left heart was bypassed.
Healthy mongrel dogs at least 15 kg. in weight are chosen, a larger dog serving as donor for a smaller one when possible. Sodium pentobarbital is used for anesthesia; the donor