MORPHOLOGICAL CHANGES IN THE LIVER AFTER 8 HOURS OF PRESERVATION BY MACHINE PERFUSION

Patients with refractory cardiac arrest, who have undergone Extracorporeal Life Support (ECLS) for resuscitation, but have not achieved cardiac recovery, can be considered as potential donors (Cardiac Death Donors). In such cases, it takes time to notify and obtain the principle consent of the relatives and finalize the clinical and legal documents. During this time, prior to obtaining consent for the removal of organs, ECLS can be extended. In this case, the extracorporeal circulation implies organ preservation "in situ" until the ethical, religious and organizational problems should be decided. Correspondingly, the identification of safe time terms during which the donor organs do not suffer by the changes not compatible with transplantation is extremely important. We aimed to study the morphological changes in the liver after 8 hours of extracorporeal circulation in experiments. The investigation was performed on 6 sheep with simulated cardiac arrest and undergone 8-hours extracorporeal circulation with own blood by using of new portable perfusion apparatus, made on the basis of a universal volumetric blood pump of our own design. The device was connected to the body through the femoral artery and vein with special cannulas. The biopsy of the liver was performed before the starting of perfusion, and on 4 and 8 hours of the experiment. The histological slices were stained by H&E and were assessed by standard criteria: level of steatosis (large-droplet macrovesicular steatosis [ld-MaS] and/or small-droplet macrovesicular steatosis [sd-MaS]); mononuclear portal inflammatory cell infiltrates; bile ductular proliferation; cholestasis; venous congestion; hepatocellular necrosis. Before the perfusion, no venous congestion, hepatocellular necrosis or ld-MaS were observed; Less than 3% of cells were suffered by sd-MaS; mononuclear portal inflammatory cell infiltrates were found only in several areas. Mild mixed ld-MaS and sd-MaS was found in less than 5 % and 10% of the cells accordingly on the 4 and 8 hours after in vivo Machine perfusion. Similarly the mild venous congestion was present in 1 out of 6 livers after 4-hours perfusion and in 2 out of 6 livers after 8-hours Perfusion. The number of necrotic hepatocytes and portal triads infiltrated with mononuclear cells did not exceed 10% and 15% accordingly. However, there were no differences in the degree of biliary damage - cholestasis or ductular proliferation - correlating with the terms of the experiment. Taking into the consideration all internationally accepted criteria of donor liver histological assessment, 8-hour in vivo perfusion of the liver in Cardiac Death Donors by using of the machine of own design providing the pulsatile blood flow guarantees the satisfactory preservation of liver making it useful for successful transplantation.