Auxiliary liver transplantation with arterialization of the portal vein for acute hepatic failure

A modified kidney-sparing portal vein arterialization model of heterotopic auxiliary liver transplantation increases liver IL-6, TNF-α, and HGF levels and enhances liver regeneration: an animal model

BACKGROUND AND AIM

The success of partial donor liver transplantation is affected by the implantation site of the donor liver and the vascular reconstruction approach. We investigated the effects of different donor liver implantation sites and vascular reconstruction approaches on liver regeneration using a rat kidney-sparing heterotopic auxiliary liver transplantation model, with portal vein arterialization (PVA).

METHODS

Sixty male Sprague-Dawley rats underwent end-to-end anastomosis of the donor liver portal vein and the right renal artery stent (control group), or end-to-side anastomosis of the donor liver portal vein and the left common iliac artery (experimental group).

RESULTS

The experimental group had significantly lower plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, and cholinesterase than the control group (all, P < 0.05). The levels of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and hepatocyte growth factor (HGF) in the liver were significantly higher in the experimental group than that in the control group (all, P < 0.05). Hematoxylin and eosin (HE) staining of the liver tissue specimens indicated that the experimental group had greater hepatocyte regeneration compared to the control group.

CONCLUSIONS

The modified kidney-sparing PVA model of heterotopic auxiliary liver transplantation is more conducive to liver regeneration with quicker return of liver function.

Portal vein arterialization following a radical left extended hepatectomy for Klatskin tumor: A case report

Portal vein arterialization (PVA) has been attracting attention for its role as a salvage inflow technique in various clinical applications. Initially performed in shunt surgery for portal hypertension, with the aim of preventing a decreased hepatic inflow, it is largely used in case of hepatic artery thrombosis in the transplantation domain or in the enlarged radical operations in case of hilar cancer invading the hepatic artery. A 62-year-old man underwent a left extended hepatectomy with hepatic bile duct resection and right Roux-en-Y hepaticojejunostomy for hilar cholangiocarcinoma. Computed tomography scan on postoperative day (POD) 5 revealed right hepatic artery pseudo-aneurysm, which was confirmed by an angiography. Stent placement was infeasible. Coiling of the pseudoaneurysm was associated with a risk of complete occlusion inducing critical liver failure. Since his general conditions were deteriorated, the patient underwent an emergency laparotomy. Hepatic artery reconstruction was impossible. Thus, a PVA was performed by anastomosing the ileocecal artery and vein. The intraoperative ultrasound showed satisfactory patency of the PVA with good portal flow in the absence of arterial flow. Doppler ultrasound on POD 15 showed that the cross-sectional area and blood flow of the portal vein were increased. The patient was discharged on POD 54 in good general condition. Hepatic artery disruption represents potentially lethal complications of hepatic, biliary, and pancreatic surgery. PVA may be a feasible therapeutic strategy to guarantee arterial inflow to the remnant liver. Although PVA is a salvage surgical procedure, increased portal flow should be controlled to avoid portal hypertension and liver fibrosis.

A hemodynamic, metabolic and histopathological study of a heterotopic auxiliary swine liver graft with portal vein arterialization

BACKGROUND

Auxiliary heterotopic liver transplantation with portal vein arterialization (AHLT-PVA) is a model that has been hardly studied, despite its therapeutic potential.

METHODS

Hemodynamic and biochemical characterization was carried out during graft implantation, in a pig-to-pig model (n=15 AHLT-PVA). Furthermore a histopathological study was performed to establish microscopic alterations due to PVA.

RESULTS

Reperfusion of the arterialized graft produced an increase in heart rate (HR) vs. baseline (P=.004) and vs. inferior vena cava clamping phase (P=.004); and a decrease in systemic vascular resistance vs. cava clamping phase (P=.021). At the end of implantation, cardiac output remained elevated (P=.001), likewise HR remained increased vs. baseline phase (P=.002). Mean arterial pressure decreased with cava clamping, but was not affected by the reperfusion of the graft, nor the skin closure. The histopathological study at 3, 10, and 21 days post-PVA revealed that functional liver structure was maintained although it is common to find foci of perilobular necrosis on day 3 (P=.049), and perilobular connective tissue proliferation at day 10 (P=.007), vs. native liver.

CONCLUSIONS

The described arterialized liver graft model minimizes the number of vascular anastomoses vs. previously described models. It is hemodynamically and metabolically well tolerated and the double arterial vascularization of the graft does not cause significant changes in liver histology.

A new rat model of auxiliary partial heterotopic liver transplantation with liver dual arterial blood supply

Auxiliary partial heterotopic liver transplantation (APHLT) with portal vein arterialization is a valuable procedure to be considered in the treatment of patients with acute liver failure and metabolic liver diseases. The aim of this study was to develop a new rat model of APHLT with liver dual arterial blood supply (LDABS). A total of 20 rats were used. The donor liver was resected, and the celiac trunk was reserved. Left and medial hepatic lobes accounting for 70% of the liver mass were removed en bloc and the suprahepatic caval vein was ligated simultaneously. Thus, 30% of the donor liver was obtained as the graft. Sleeve anastomosis of the graft portal vein and splenic artery were performed after narrowing the portal vein lumen through suturing. The right kidney of the recipient was removed, and sleeve anastomosis was performed between the celiac trunk of the graft and the right renal artery of the recipient. In addition, end-to-end anastomosis was performed between the infrahepatic caval vein of the graft and the right renal vein of the recipient. Following the reperfusion of the graft, the blood flow of the arterialized portal vein was controlled within the physiological range through suturing and narrowing under monitoring with an ultrasonic flowmeter. The bile duct of the graft was implanted into the duodenum of the recipient through an internal stent catheter. A 70% section of the native liver (left and medial hepatic lobes) was resected using bloodless hepatectomy. The mean operative duration was 154.5±16.4 min, and the warm and cold ischemia times of the graft were 8.1±1.1 min and 64.5±6.6 min, respectively. The blood flow of the arterialized portal vein to the graft was 1.8±0.3 ml/min/g liver weight. The success rate of model establishment (waking with post-surgical survival of >24 h) was 70% (7/10). Following successful model establishment, all rats survived 7 days post-surgery (100%; 7/7). The graft was found to be soft in texture and bright red in color following exploratory laparotomy. In conclusion, a new rat model of APHLT with LDABS without stent for vascular reconstruction was developed. This is a feasible and reliable rat model for liver transplantation study.

Portal vein arterialization: a salvage procedure for a totally de-arterialized liver. The Paul Brousse Hospital experience

BACKGROUND

Portal vein arterialization (PVA) has been used as a salvage inflow technique when hepatic artery (HA) reconstruction is deemed impossible in liver transplantation (LT) or hepatopancreatobiliary (HPB) surgery. Outcomes and the management of possible complications have not been well described.

METHODS

The present study analysed outcomes in 16 patients who underwent PVA during the period from February 2005 to January 2011 for HA thrombosis post-LT (n = 7) or after liver resection (n = 1), during curative resection for locally advanced HPB cancers (requiring HA interruption) (n = 7) and for HA resection without reconstruction (n = 1). In addition, a literature review was conducted.

RESULTS

Nine patients were women. The median age of the patients was 58 years (range: 30-72 years). Recovery of intrahepatic arterial signals and PVA shunt patency were documented using Doppler ultrasound until the last follow-up (or until shunt thrombosis in some cases). Of five postoperative deaths, two occurred as a result of haemorrhagic shock, one as a result of liver ischaemia and one as a result of sepsis. The fifth patient died at home of unknown cause. Three patients (19%) had major bleeding related to portal hypertension (PHT). Of these, two underwent re-exploration and one underwent successful shunt embolization to control the bleeding. Four patients (25%) had early shunt thrombosis, two of whom underwent a second PVA. After a median follow-up of 13 months (range: 1-60 months), 10 patients (63%) remained alive with normal liver function and one submitted to retransplantation.

CONCLUSIONS

Portal vein arterialization results in acceptable rates of survival in relation to spontaneous outcomes in patients with completely de-arterialized livers. The management of complications (especially PHT) after the procedure is challenging. Portal vein arterialization may represent a salvage option or a bridge to liver retransplantation and thus may make curative resection in locally advanced HPB cancers with vascular involvement feasible.

Portal vein arterialization for hepatic artery thrombosis in liver transplantation: a case report, Doppler-ultrasound aspects, and review of the literature

Portal vein arterialization (PVA) is a salvage procedure for insufficient hepatic arterial or portal vascularization. It plays a role in auxiliary and orthotopic liver transplantation (OLT). In OLT, current indications for PVA include hepatic artery thrombosis (HAT), pre-OLT or post-OLT extended splanchnic vein thrombosis, intraoperative low portal flow, and anatomic variations like the absence of portal and mesenteric veins. Out of the transplantation domain, PVA is used both in extensive surgery for malignancies of the liver, biliary tract, and pancreas and in the treatment of fulminant hepatic failure (FHF) due to intoxications. We describe a case of acute post-OLT HAT successfully treated with PVA as a short bridge to retransplantation. By Doppler ultrasound of clinical PVA we detected an increased intrahepatic portal flow velocity, with disappearance of the arterial spikes, a finding that needs further investigation. PVA represents a rare surgical procedure. In fact, it has been used most of all in urgent conditions or in case of abrupt vascular complications during surgery. According to the literature, PVA emerges as a salvage procedure for poor arterial or portal hepatic flow, both in OLT and in general abdominal surgery. The outcome of this procedure is unpredictable. The aim of the shunt is to gain time, awaiting the onset of collateral arterial vessels or the performance of definitive surgery. Its early thrombosis may be a catastrophic event, due to acute liver ischemia. In contrast, a late occlusion is often well tolerated. Strict surveillance is always useful because sometimes it is mandatory to embolize the arterioportal fistula to treat or to prevent the onset of portal hypertension.

Portal vein arterialization increases hepatocellular apoptosis and inhibits liver regeneration

BACKGROUND

Portal vein arterialization is performed in particular situations to guarantee sufficient blood flow in the portal vein. In addition, some authors have postulated a proliferation-promoting influence of portal vein arterialization on the liver tissue. However, portal vein arterialization is an unphysiological procedure: It increases portal blood flow and blood pressure as well as oxygenation of the liver tissue. On the other hand, it reduces the influx of hepatotrophic factors from the portal venous blood. The aim of these experiments was to investigate apoptosis and proliferation of hepatocytes during various conditions of the portal perfusion.

MATERIALS AND METHODS

After 70% liver resection in Lewis rats, the following four experimental groups were formed differing in portal perfusion: (I) hyperperfused, nonarterialized; (II) flow-regulated, nonarterialized; (III) hyperperfused, arterialized; (IV) flow-regulated, arterialized. A warm ischemia of 30 min was kept in all groups.

RESULTS

Portal vein arterialization of 70% reduced rat livers significantly reduced liver regeneration as shown by a significant reduction in liver weight, body weight, and liver function after 6 wk, in contrast to the group with 70% liver mass reduction and portal venous inflow of the portal vein. Furthermore, we found a significantly elevated number of apoptotic hepatocytes after portal vein arterialization. These results were independent from blood flow regulation of the arterialized portal vein, which caused no improvement of the results.

CONCLUSIONS

Portal vein arterialization should be performed only temporarily and is clinically not recommended as a permanent option, because of the increased hepatocellular apoptosis and the very distinctive, negative long-term effects on liver weight.

Portal hyperperfusion causes disturbance of microcirculation and increased rate of hepatocellular apoptosis: investigations in heterotopic rat liver transplantation with portal vein arterialization

Clinical results of portal vein arterialization (PVA) in liver transplantation are controversial. One reason for this is the lack of a standardized flow regulation. Our experiments in rats compared PVA with blood-flow regulation to PVA with hyperperfusion in heterotopic auxiliary liver transplantation (HALT). In group I (n = 19), the graft's portal vein was completely arterialized via the right renal artery in-stent technique, using a 0.3-mm stent, leading to a physiological average portal blood flow. In group II (n = 19), a 0.5-mm stent was used. In group II, the average portal blood flow after reperfusion was significantly elevated (group II: 6.4 +/- 1.5; group I: 1.7 +/- 0.4 mL/min/g of liver weight; P < .001). The sinusoidal diameter after reperfusion was significantly greater in group II (9.8 +/- 0.5 microm) than in group I (5.5 +/- 0.2 microm; P < .001). Red blood cell velocity in the dilated sinusoids was significantly lower in group II (171 +/- 18 microm/s) than in group I (252 +/- 13 microm/s). Stasis of erythrocytes occurred; consequently, the functional sinusoidal density was significantly reduced in group II (38 +/- 7%) compared with group I (50 +/- 3%; P < .01). Two hours after reperfusion of the portal vein, the number of apoptotic hepatocytes was significantly higher in group II than in group I (I: 0 +/- 0 vs II: 7 +/- 9 M30-positive hepatocytes/10 high-power fields). The 6-week survival rate was 9 of 11 in both groups. In group II, 6 of 9 grafts showed massive hepatocellular necroses after 6 weeks, whereas in group I, only 1 of 9 presented a slight hepatocellular necrosis. Finally, our results demonstrate negative effects of portal hyperperfusion in transplanted livers, which are correctable by adequate flow regulation.

Improved technique of heterotopic auxiliary rat liver transplantation with portal vein arterialization

BACKGROUND AND AIMS

In acute, potentially reversible hepatic failure, auxiliary liver transplantation is a promising alternative approach. Using the auxiliary partial orthotopic liver transplantation (APOLT) method--the orthotopic implantation of auxiliary segments--most of the technical problems (lack of space for the additional liver mass, the portal vein reconstruction, and the venous outflow) are avoided, but extensive resections of the native liver and the graft are necessary. Erhard described the heterotopic auxiliary liver transplantation (HALT) with portal vein arterialization (PVA). Initial clinical results demonstrated that an adequate liver function can be achieved using this technique. We developed and improved a technique of HALT with flow-regulated PVA in the rat to perform further investigations. The aim of this paper is to explain in detail this improved experimental surgical technique.

MATERIALS AND METHODS

Liver transplantations were performed in 122 male Lewis rats: After a right nephrectomy, the liver graft, which was reduced to about 30% of the original size, was implanted into the right upper quadrant of the recipient's abdomen. The infrahepatic caval vein was anastomosed end-to-side. The donor's portal vein was completely arterialized to the recipient's right renal artery in stent technique. Using a stent with an internal diameter of 0.3 mm, the flow in the arterialized portal vein was regulated to achieve physiologic parameters. The celiac trunk of the graft was anastomosed to the recipient's aorta, end-to-side. The bile duct was implanted into the duodenum.

RESULTS

After improvements of the surgical technique, we achieved a perioperative survival of 90% and a 6-week survival of 80% in the last 112 transplantations.

CONCLUSION

We developed a standardized and improved technique, which can be used for experiments of regeneration and inter-liver competition in auxiliary liver transplantation. Furthermore, this technique is suitable for the investigation of the influence of portal vein arterialization and portal hyperperfusion on liver microcirculation, function, and morphology.

Arterialisation of the portal vein as a model for the induction of hepatic fibrosis: description of microsurgical models in the rat

Within the framework of liver transplantation, arterialisation of the portal vein in the case of non-recanalisable thrombosis has been reactivated. However, one of the consequences of this vascular reconstruction is the development of hepatic fibrosis. Clinical experience has shown that the development of fibrosis can be avoided by reducing portal inflow. We present, as a model for the induction of hepatic fibrosis, techniques of PVA, including transplantation. For PVA, several different techniques were used: the first with reduction of the portal inflow over a stent inserted in the right renal artery (PVA-B), the second with unrestricted flow using an aortic-portal segment (PVA-APS). The third technique was orthotopic liver transplantation with unrestricted portal arterialisation (OLTx-APS). Portal blood flow was measured with an ultrasonic flow probe. To determine the degree of hepatic fibrosis the amount of hydroxyproline was measured. Quantification of relative transcript levels of procollagen I was effected with real-time PCR using the TaqMan technology on a lightcycler instrument. The extracellular matrix was visualised with picro-sirius staining. Measurements with the ultrasonic probe showed a significant increase in flow rates, both with reduced (PVA-B) and unrestricted inflow (PVA-APS; OLTx-APS). The lowest survival rate (58%) was found in the group with unrestricted portal inflow. The reason for this was a high rate of thrombosis in the in the portal vascular tree (4 out of 12). In the OLTx-APS group four animals died within the first 3 postoperative days (69%), as a result of protracted postoperative shock. The overall survival rate was the highest (85%) in the group undergoing PVA with reduction of the portal inflow. PVA with unrestricted inflow was followed by a significant increase in extracellular collagen, which showed a clear correlation with the increase in the amount of hydroxyproline, the level of the mRNA for procollagen I and picro-sirius staining. With the operative PVA techniques presented herein, different arterial flow rates in the portal vein can be investigated. In our opinion these techniques represent an excellent animal model for studying the genesis of fibrosis and antifibrotic substances. By regulating the blood flow in the arterialised portal vein hepatic fibrosis can be reduced or even avoided. After a brief period of learning the microsurgical techniques, the surgeon can limit clamping times and achieve good results with these techniques.

Effects of Portal Vein Arterialization on Regeneration and Morphology in Liver Transplantation: Investigations Using the Rat Model

BACKGROUND

Portal vein arterialization (PVA) has been proposed as a technical variant in liver transplantation in the case of non-recanalizable thrombosis. The present study investigates the effects of the arterialized portal vein on the function, morphology, and regenerative behavior of the liver.

METHODS

Different PVA techniques, including orthotopic liver transplantation, were used in a rat model. Portal blood flow was measured using a ultrasonic flowmeter. The regeneration capacity was determined on the basis of the increase of liver weight and the proliferating cell nuclear antigen index. The amount of hydroxyproline and the transcript levels of procollagen I were measured to determine the degree of fibrosis. The extracellular matrix was visualized with Picro-Sirius staining.

RESULTS

The measurements obtained with an ultrasonic probe revealed a significant increase in portal blood flow after PVA. The regeneration capacity in the groups after PVA with no flow reduction was comparable to that of the control. Liver transplantation and PVA with no flow reduction was followed by a significant increase (four- to sixfold) in the amount of hydroxyproline and the level of the mRNA for procollagen I. In the Picro-Sirius staining, periportal and perivascular fibrosis with incipient formation of septa was seen. After reduction of the portal blood flow, these effects were significantly less pronounced.

CONCLUSIONS

These operative techniques represent an excellent small animal model for studying the mechanism of liver regeneration and the genesis of fibrosis in liver and vessel tissue. The presenting findings indicate that the negative effects of "overarterialization" may be largely avoided by reducing portal blood flow. This implies that permanent PVA in clinical liver transplantation should be performed only in conjunction with a down-regulation of portal flow.

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.

Description of a new auxiliary heterotopic partial liver transplantation technique with portal vein arteriolization of applicability in heterotopic liver xenotransplantation

OBJECTIVE

The aim of this study was to describe a new model of auxiliary heterotopic partial liver transplantation with portal vein arterialization.

MATERIALS AND METHODS

Three standard hepatectomies were performed in pigs. The left lateral lobe was surgically resected and portal vein arteriolization constructed by an end-to-side "Y" anastomoses between the distal to the celiac axis aorta and the portal vein.

RESULTS

The graft was placed in the left iliaca fossa using anastomoses of the donor infrahepatic inferior cava vein end-to-side to the host infrarenal inferior vein and the donor aortic stump with portal vein arteriolization end-to-side to the left iliac artery. After graft reperfusion, the 3 recipients showed intraoperative hypotension, which was treated with fluid administration and vasoactive drugs. At the end of the operation, the graft displayed normal arterial blood flow and good venous drainage. The donor liver graft appeared more red than the host liver, which was due to the increased arterial blood flow. One pig of 3 died at 24 hours after surgery, probably due to hypothermia. However, the other 2 pigs survived the procedure and remained stable. Echographic monitoring showed intrahepatic arterial expansion, which may be the result of high blood pressure due to the arteriolization procedure.

CONCLUSIONS

We have developed a novel and easy to perform technique that diminishes the number of anastomoses and does not involve vessels from other organs.

Outcome and hepatic hemodynamics in liver transplant patients with portal vein arterialization

Few cases of successful portal vein arterialization in orthotopic and auxiliary liver transplantation have been reported.

AIM

To evaluate the effect of portal vein arterialization on hepatic hemodynamics and long-term clinical outcome in three patients undergoing liver transplantation.

METHODS

Two patients with extensive splanchnic venous thrombosis received an orthotopic liver transplant and one with fulminant hepatic failure received an auxiliary heterotopic graft. Portal vein arterialization was performed in all cases.

RESULTS

One patient died 4 months after transplant and two are still alive. Auxiliary liver graft was removed 3 months post-transplant when complete native liver regeneration was achieved. Immediate post-transplant liver function was excellent in all cases. Only one patient developed encephalopathy and variceal bleeding owing to prehepatic portal hypertension secondary to arterioportal fistula 14 months after transplant. He was successfully treated by embolization of the hepatic artery. Hepatic hemodynamic measurements demonstrated a normal pressure gradient between wedged and free hepatic venous pressures in all cases. Liver biopsy showed acceptable graft architecture in two cases and microsteatosis in one.

CONCLUSIONS

Liver transplantation with portal vein arterialization is an acceptable salvage alternative when insufficient portal venous flow to the graft is present. The double arterial supply does not imply changes in hepatic hemodynamics, at least in the early months post-transplant.

Auxiliary liver transplantation with portal arterialization in the rat: description of a new model

In recent years, portal arterialization has been used in liver transplantation to increase the portal flow, as a solution for singular technical problems. We have developed a new auxiliary liver transplantation model in the rat with portal arterialization, so the native hepatic hilium remains untouched, consisting on a graft with a previous 70% hepatectomy. It is sited on the right renal bed, joining the infrahepatic inferior vena cava (IVC) of the graft with the recipient IVC. With an abdominal aortic graft, we connect the recipient aorta with the portal vein from the auxiliary liver. All the animals survived at the seventh day. No thrombosis was seen in any graft and an important rejection was observed in all the fields. We have developed a new experimental model of an auxiliary liver with portal arterialization, avoiding the utilisation of the native hepatic hilium, necessary for the possible recovering of the proper liver in the case of a reversible fulminant hepatitis.

Effects of portal vein arterialization on liver regeneration after partial hepatectomy in the rat

Although portal venous supply is considered essential to preserve hepatic integrity, in this study, effects of portal arterialization on liver regeneration were evaluated in a rat model of partial hepatectomy (PH). Ninety-six Lewis rats were randomly assigned to four groups of 24 rats each: PH only (group 1), PH with either venous or arterialized portal supply (groups 2 and 3, respectively), and PH without portal supply (group 4). Liver regeneration rate (LRR), 5-bromo-2-deoxyuridine (BrdU) labeling index, and liver biological characteristics were assessed on days 1, 2, 3, and 7. Compared with group 1, all tested rats had a marked body weight loss after surgery, and only rats in group 4 showed no signs of recovery on day 7. With maintained portal inflow (groups 1, 2, and 3), LRRs increased steadily to day-7 values of 89.2% +/- 11.8%, 81.4% +/- 8%, and 77.4% +/- 9.4%, respectively (P = not significant), and 24-hour peak values of BrdU labeling index were 159 +/- 26, 157 +/- 42, and 149 +/- 48, respectively (P = not significant). Conversely, rats deprived of portal supply (group 4) showed profound inhibition of these two parameters (14 +/- 13; P <.01;32.1% +/- 7.7%; P <.001, respectively). These results indicate that proper portal blood supply is essential to initiate and maintain liver regeneration after PH. With an equivalent portal inflow rate of either venous or arterial source, the hepatic regeneration response can be sustained.

T1 relaxation times for viability evaluation of the engrafted and the native liver in a rat model of heterotopic auxiliary liver transplantation: a pilot study

Following a heterotopic auxiliary liver transplantation, commonly used measurements are either invasive or non-indicative of individual viability of the coexisting engrafted and native livers. Magnetic resonance imaging (MRI) was therefore tested for its potential to monitor the post-transplant hepatic viability in a rat model. Thirteen Wistar rats were systematically evaluated with MRI and serum biochemical liver parameters. Post-transplant complications and the causes of animal death were identified by autopsy and histo-pathological examinations. The data of the healthy survivors were compared with those of the rats that developed complications. On MRI, the hepatic complications could be depicted in the individual livers. A specific pattern of signal evolution was found in the livers of the healthy survivors: the mean T1 relaxation times of the engrafted livers increased immediately after transplantation (476 +/- 64 ms, mean +/- standard deviation, pre-operative; 730 +/- 48 ms, week 1) and then declined steadily to a 3 month value of 489 +/- 246 ms, while, following a transient first rise (476 +/- 64 ms, pre-operative; 589 +/- 28 ms, week 1), the mean T1 value of the native livers increased again 4 weeks after surgery and reached a 3 month value of 859 +/- 43 ms. However, in the rats with various complications, the mean T1 relaxation times of the engrafted livers continued to increase throughout the first post-operative month (760 +/- 48 ms, week 1; 922 +/- 76 ms, week 4), while that of the native liver only varied mildly (546 +/- 25 ms, week 1; 473 +/- 25 ms, week 4). After the first post-transplant week, the healthy engrafted livers could already be distinguished from those with complications by a significant decrease in T1 relaxation times. These data suggest that, besides demonstrating major complications, MRI may allow one to monitor the viability of each liver by analysing the relative signal intensity and T1 relaxation times after a heterotopic auxiliary liver transplantation.

Arterialization of the portal vein in liver transplantation: a new microsurgical model in the rat

BACKGROUND

A preexisting thrombosis of the portal vein and the deep splanchnic bed can make it extremely difficult to reestablish the portal blood flow in orthotopic liver transplantation in man. Complete arterialization of the liver transplant, including the donor portal vein, might be a viable therapeutic option. A new rat transplantation model is described, in which the liver is completely arterialized.

METHODS

The outflow of the portal blood in the recipient was secured via a portocaval shunt. Hepatectomy was then performed and the liver transplant placed in orthotopic position. An interposed aortic segment was used for direct arterialization of the donor portal vein.

RESULTS

The laboratory parameters determined in the serum at the end of the observation period of 28 days revealed normal functioning of the transplant. The histological examinations showed largely normal cellular architecture, with no signs of necrosis, but incipient fibrosis.

CONCLUSIONS

Using this new surgical technique in the rat liver transplantation model, long-term morphological and functional changes in a completely arterialized liver graft, and the regenerative capability of liver tissue perfused in this way, can be investigated.

Auxiliary heterotopic liver transplantation with portal vein arterialization for fulminant hepatic failure

Auxiliary liver transplantation for patients with fulminant hepatic failure supports the patient's failing liver for a period of time until the native liver (NL) has recovered and immunosuppression can be withdrawn. Auxiliary heterotopic liver transplantation (AHLT) with portal vein arterialization (PVA) has several advantages over auxiliary orthotopic liver transplantation: NL resection is not required, and the hepatic hilum is left untouched; thus, the chances of liver regeneration are optimal. The successful application of emergency AHLT with PVA in a young patient who developed toxic fulminant hepatic failure caused by tuberculostatic drugs is described. Two and one-half months after the procedure, the NL had completely regenerated; the graft was removed, and immunosuppression was suspended.