Physiologic microcirculation of the heterotopically transplanted rat liver with portal vein arterialization depending on optimal stent diameter.

BACKGROUND: Clinical experience with portal vein arterialization (PVA) in liver transplantation is controversial. One reason for this is the lack of standardized flow regulation. The present experiments aimed to establish flow regulation in the arterialized portal vein for heterotopic auxiliary liver transplantation (HALT), to obtain physiological portal blood flow, and to compare this technique with orthotopic liver transplantation. MATERIAL/METHODS: Lewis rats were divided into 7 groups (n = 8 transplantations/group). Group: A I-IV: In HALT, the portal vein was anastomosed to the right renal artery using stents with different diameters (0.2, 0.3, 0.4, 0.5 mm). Afterwards, HALT with PVA using the stent diameter that had achieved the most physiological portal blood flow (group B II) was compared with orthotopic liver transplantation with porto-portal anastomosis (group B III) and to the sham group (B I). RESULTS: After reperfusion, only the 0.3 mm stent resulted in an average blood flow in the arterialized portal vein in HALT which was within the normal range (1.7+/-0.4 ml/min/g liver weight). The parameters of microcirculation and early graft function were significantly better in group B II than in group B III (functional sinusoidal density: 335+/-48 vs. 224+/-31/cm, diameter of sinusoids: 6.4+/-0.6 vs. 5.2+/-0.6 microm, diameter of postsinusoidal venules: 31.1+/-3.3 vs. 25.5+/-2.0 microm, bile-production: 27+/-8 vs. 19+/-5 microl/h/g liver weight). CONCLUSIONS: Using an optimal stent diameter in HALT with portal vein arterialization, an adequate flow-regulation can be achieved. Avoiding portal hyper- and hypoperfusion, good results for microcirculation and early graft function can be obtained.

Auxiliary liver transplantation with flow-regulated portal vein arterialization offers a successful therapeutic option in acute hepatic failure--investigations in heterotopic auxiliary rat liver transplantation.

Heterotopic auxiliary liver transplantation (HALT) with portal vein arterialization (PVA) was proposed in acute hepatic failure (AHF). However, clinical results of PVA are controversial because of lacking standardized flow-regulation. In rats, we examined HALT with flow-regulated PVA in AHF. Group A: HALT with flow-regulated PVA and 85% resection of the native liver to induce AHF [acute experiments (n = 8), killing after 7 days (n = 8) and after 6 weeks (n = 11)]. Group B: 85% liver-resection (n = 10). The average blood-flow in the arterialized portal vein in HALT achieved normal values (1.7 +/- 0.4 ml/min/g liver-weight). After reperfusion, the diameters of the sinusoids (6.4 +/- 0.6 microm), the postsinusoidal venules (31.1 +/- 3.3 microm) and the intersinusoidal distance (17.9+/-0.7 microm) also achieved normal values. The functional sinusoidal density amounted to 335 +/- 48/cm. The 6-week survival was nine of 11 with excellent liver function (Quick's value: 110% +/- 7.8%). The hepatobiliary radioisotope scanning with (99mTc) ethyl hepatic iminodiacetic acid (EHIDA) showed no significant differences between the native livers and grafts. The hepatocellular morphology was regular, apart from low-grade necroses in two grafts. The grafts' sinusoidal endothelial cells did not show any morphological changes. In group B, however, all rats died from AHF within 6 days. HALT with flow-regulated PVA achieved good results regarding microcirculation, morphology and function and can reliably bridge AHF.

Improved microcirculation of a liver graft by controlled portal vein arterialization.

BACKGROUND: The clinical results of portal vein arterialization (PVA) in liver transplantation are controversial without a standardized portal flow regulation. The aim of these experiments was to perform a flow-regulated PVA in liver transplantation, to examine the microcirculation and early graft function after heterotopic auxiliary liver transplantation (HALT) with flow-regulated PVA, and to compare this technique with HALT with porto-portal anastomosis. Using the recently developed orthogonal polarization spectral (OPS) imaging, for the first time the microcirculation of liver grafts with PVA was visualized. MATERIALS AND METHODS: HALT was performed in Lewis rats. The portal vein was either completely arterialized via the right renal artery in a standardized splint-technique (Group I, n = 8) or anastomosed end-to-end to the recipient's portal vein (Group II, n = 8). RESULTS: After reperfusion, the average blood flow in the portal vein was within the normal range in Group I (1.7 +/- 0.4 ml/min/g liver weight) and significantly higher than in Group II (1.2 +/- 0.2 ml/min/g liver weight). The functional sinusoidal density in Group I (335 +/- 48/microm) was significantly higher than in Group II (232 +/- 58/microm), whereas the diameter of the sinusoids and the postsinusoidal venules yielded no significant differences between both groups. The bile production was comparable (27 +/- 8 versus 29 +/- 11 microl/h/g liver weight). CONCLUSIONS: In our experiments it was possible to achieve an adequate flow regulation in the arterialized portal vein with good results concerning microcirculation and early graft function. We recommend that further investigations on liver transplantation with PVA should be performed with portal flow regulation, before PVA is employed in clinical transplantation.