Veno-venous bypass without heparin in orthotopic liver allotransplantation in the pig.

It is now widely accepted that a veno-venous bypass is required to minimize the problems of the anhepatic phase in orthotopic liver transplantation. A technique that does not require systemic anticoagulation is needed to prevent damage by heparinization in hepatic patients. The use of heparin-bonded cannulas offers low risks of thromboembolic complication. Fourteen orthotopic liver transplantation were performed in pigs, including 7 with a roller pump and 7 with a centrifugal pump, without systemic anticoagulation and with heparin-bonded circuits except for the portal cannula, connectors, centrifugal pump head and the tract of the circuit on which the roller moves. All the circuits were previously utilized in clinical liver transplantation and repeatedly washed in saline solution and sterilized for each experiment. The haemodynamic control of the anhepatic state was excellent without hypotension and venous engorgement. In only one case a thromboembolic complication was noted. Arterial pressure, heart rate, urine flow, creatinine, arterial pH and thromboelastographic data did not change significantly while on bypass. No difference was found in the use of either a roller or a centrifugal pump even when the blood flow fell to less than 1000 ml/min to 500 ml/min.