Vergleich zweier Techniken der auxiliären, heterotopen Rattenlebertransplantation mittels „OPS imaging“

Abstract

We developed a technique of auxiliary, heterotopic rat liver transplantation with arterialization of the portal vein (1). Using a stent with an inner diameter of 0,3 mm for the portal vein reconstruction it was possible to achieve a physiologic average blood-flow in the arterialized portal vein of the graft. We compared our technique with the auxiliary, heterotopic rat liver transplantation with porto-portal anastomosis concerning the microcirculation and the early function of the graft (2). Lewis rats were operated under ether inhalation anesthesia. After a right nephrectomy the grafts, which were reduced to about 30% of original size, were implanted into the right upper quadrant of the abdomen. The infrahepatic caval vein was anastomosed end-to-side. The portal vein was completely arterialized by the right renal artery in splint-technique (group I, n = 8) or anastomosed end-to-end to the recipient portal vein (group II, n = 8). By means of OPS (Orthogonal Polarization Spectral) -imaging, video-sequences of the microcirculation on the caudal surface of the right liver lobe were recorded after reperfusion of the portal vein and after reperfusion of the hepatic artery. Using OPS imaging, the contrast is obtained by absorption of orthogonal polarized light from hemoglobin in the erythrocytes. During these acute experiments, the blood flow in the portal vein, the oxygen saturation on the liver-surface, the quantitative bile production and the transaminases were determined 90 minutes after portal reperfusion. In both groups the grafts were reperfused homogeneously. The average blood flow in the portal vein was significantly higher in group I than in group II (group I: 1,7 ± 0,4 ml/min/g liver weight, group II: 1,2 ± 0,2 ml/min/g liver weight, p = 0,03). In group II, OPS imaging showed inhomogeneous perfusion-patterns with focal sinusoidal stasis and microthrombi; this was less prominent in group I. In accordance with these results the functional sinusoidal density in group I was significantly higher than in group II (group I: 335 ± 48/μfm, group II: 232 ± 58/μm, P = 0,003), whereas the diameter of the sinusoids and the postsinusoidal venules yielded no significant differences between both groups (Sinusoids: Group I: 6,4 ± 0,6 μm, group II 6,7 ± 0,7 μm; postsinusoidal venules: group I: 31,1 ± 3,3 μm, group II: 28,8 ± 3,4 μm). The oxygen saturation on the liver-surface was significantly higher in group I than in group II (Group I: 62 ± 2%, group II: 48 ± 7%, P = 0,0007). There were no significant differences with respect to the height of the transaminases (GOT: Group I: 698 ± 386 U/l, group II: 866 ± 290 U/l; GPT: Group I:643 ± 296 U/l, group II: 839 ± 420 U/l) and bile production (group I: 27 ± 8 μl/h/g liver weight, group II: 29 ± 11 μl/h/g liver weight) 90 minutes after reperfusion of the portal vein. In our rat model the auxiliary, heterotopic liver transplantation with flow-regulated portal vein arterialization achieved better results regarding the microcirculation than the technique with porto-portal anastomosis. The liver-function was comparable. Whether the portal vein arterialization leads to morphological changes and functional impairment in the long term, will be addressed by further experiments.