Anatomical study on the surgical technique used for xenotransplantation: porcine hearts into humans.

The pig heart is an ideal graft for orthotopic cardiac xenotransplantation regarding its physiological attributes and ready availability. Although single clinical attempts have been performed since the 1960s, details concerning the surgical technique of pig-to-human transplantation have never been reported. The present investigation should verify which anatomical differences between humans and pigs require special care in cardiac xenotransplantation.We transplanted four pig hearts into human thoraces after autopsy. Implantation was performed using both the biatrial (modified Shumway) and bicaval techniques. The implanted hearts were not perfused.The four-legged walk of the pig implies a more transverse heart position and therefore a different outflow-angle of the great vessels. Accordingly, the thin-walled pulmonary artery and the superior vena cava (in bicaval technique) tend to kink and narrow. A special feature of porcine anatomy is the left azygous vein that empties into the coronary sinus. It must be ligated before the implantation.Keeping the porcine anatomical particularities in mind, technical problems in pig-to-human heart transplantation can be avoided. The anastomosis of the pulmonary artery requires special care. By using the biatrial technique surgeons can prevent imminent stenoses of the caval vein anastomoses.