Bedeutung der Flußregulierung in der arterialisierten Pfortader bei der heterotopen, auxiliären Lebertransplantation — Untersuchungen mittels OPS imaging

The clinical results of portal vein arterialization in the context of heterotopic and orthotopic liver transplantation are contrary without a consequent blood flow regulation in the arterialized portal vein. Aim of these experiments was to compare portal vein arterialization (PVA) with blood flow regulation to PVA with hyperperfusion in the context of heterotopic auxiliary liver transplantation (HALT). 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 via the right renal artery in splint-technique. In group I, HALT was performed with blood flow regulation in the arterialized portal vein, using a stent with an inner diameter of 0,3 mm; in group II HALT was performed with hyperperfusion of the arterialized portal vein (0,5 mm stent). 8 acute experiments including examination of the microcirculation by means of OPS imaging (contrast is obtained by absorption of orthogonal polarized light from the hemoglobin in the erythrocytes) and 11 survival experiments (sacrification of the animals after 6 weeks) were performed in each experimental group. In both groups, the grafts were reperfused macroscopically homogeneously. In group II, the average portal blood flow after reperfusion was significantly higher than in group I (group I: 1,7 ± 0,4 ml/min/g of liver weight vs. group II: 6,4 ± 1,5 ml/min/g of liver weight, p < 0,001). The diameter of the sinusoids after reperfusion was significantly greater in group II than in group I and than the normal values (group I: 5,5 ± 0,2 µm vs. group II: 9,8 ± 0,5 µm, p < 0,001, normal values: 6,5 ± 0,4 µm). The volumetric blood flow in the sinusoids was also significantly higher in group II (group I: 5174 ± 1112 µm3/s vs. group II: 12977 ± 2154 µm3/s, p < 0,001, normal values: 6289 ± 701 µm3/s), whereas the functional sinusoidal density was significantly reduced in group II (group I: 50 ± 3% vs. group II: 38 =b 7%, p < 0,01, normal values: 53 ±2%). In group II, OPS imaging showed inhomogeneous perfusion-patterns with focal sinusoidal stasis and microthrombi. The diameter of the postsinusoidal venules remained uninfluenced by hyperperfusion (group I: 32 ± 5 µm vs. group II: 31 ± 3 µm, normal values: 31 ±4 µm). The 6 week survival was 9/11 in both groups. After a loss of body weight from 389 ± 16 g to 361 ± 25 g in group I and from 384 ± 33 g to 355 ± 32 g in group II, it rose faster in group I than in group II, and after 6 weeks it was significantly higher in group I than in group II (group I: 440 ±9 g vs. group II: 410 zb 31 g, p = 0.03). In group II 6 of 9 animals showed massive necrosis of the hepatocytes of the graft, whereas in group I only one animal showed a slight necrosis of hepatocytes.