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.     

Competition between native liver and graft in auxiliary liver transplantation in a rat model

The competition between the native and the grafted liver in heterotopic auxiliary liver transplantation (HALT) with portal vein arterialization (PVA) was investigated in a rat model. The experimental groups were: HALT with flow-regulated PVA and 70% resection of a native liver and graft (n = 32; group I) versus 70% liver resection (n = 32; group II). After HALT, the weight of the native liver increased until the sixth postoperative week (431% +/- 55% of the intraoperative weight), whereas, the graft weight was only 76% +/- 31% of the intraoperative weight at this time. In group II, liver weight increased continuously to 529% +/- 30% of the intraoperative weight after 6 weeks. On postoperative day 2, there was significantly increased proliferative hepatocellular activity in all groups. This was highest in the resected livers of group II, followed by the native livers of group I, and the grafts of group I (301 +/- 126 vs 262 +/- 97 vs 216 +/- 31 Ki-67-positive hepatocytes/10 visual fields). However, the differences between the groups were not significant. With regard to hepatocellular apoptosis, the livers were similar among all groups and at all time points, M30-positive hepatocyte counts were 相似文献   

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.     

Temporary portal vein arterialization as an attractive option in canine orthotopic partial liver transplantation.

We performed 22 canine orthotopic partial liver transplantations (PLTs) with three different revascularization methods; portal vein arterialization (PVA group, n = 11), hepatic arterial shunt (HAS group, n = 5), and conventional portal vein reperfusion (control group, n = 6). Our purpose was to evaluate the feasibility of PVA as a revascularization technique in PLT assessing the changes in arterial ketone body ratio (KBR) as an index of hepatic energy status. After the first anastomosis (left hepatic vein), the ischemic partial liver graft was revascularized with arterial blood flow shunted from the external iliac artery to the hepatic side of the portal vein (PVA group) or the proper hepatic artery (HAS group). Both anhepatic period and ischemia time were significantly shortened in groups PVA and HAS as compared with those in control. In the PVA group, 10 out of 11 recipients survived for at least 5 days (14.2 +/- 3.8 days, mean +/- SEM), while 3 out of 5 (5.2 +/- 1.0) survived in the HAS group and 4 out of 6 (6.2 +/- 1.3) in the controls. Although portal blood flow during PVA was only about 25% of the total hepatic blood flow at preclamping, the KBR was rapidly restored after PVA and showed almost the same values at preclamping. The KBR values during the arterialization time and initial velocity of KBR recovery in the PVA group were significantly higher than those in the HAS and control groups. These results suggest that PVA presents an attractive option in PLT.     

Hemodynamic interaction between portal vein and hepatic artery flow in small-for-size split liver transplantation

In split-liver transplantation, the entire portal flow is redirected through relatively small-for-size grafts. It has been postulated that excessive portal blood flow leads to graft injury. In order to elucidate the mechanisms of this injury, we studied the hemodynamic interactions between portal vein- and hepatic artery flow in an experimental model in pigs. Six whole pig liver grafts were implanted in Group 1 ( n=6) and six whole liver grafts were split into right and left grafts and transplanted to Groups 2 ( n=6) and 3 ( n=6), respectively. The graft-to-recipient liver volume ratio was 1:1, 2:3 and 1:3 in Groups 1, 2 and 3, respectively. Portal vein- and hepatic artery flows were measured with an ultrasonic flow meter at 60,120 and 180 min after graft reperfusion. Portal vein pressure was also recorded at the same time intervals. Graft function was assessed at 3,6h and 12h, and morphological changes at 12h after reperfusion. Following reperfusion, portal vein flow showed an inverse relationship to graft size, while hepatic artery flow was reduced proportionately to graft size. The difference was significant among the three groups ( P<0.05). Portal vein pressure was significantly higher in group 3, compared to groups 1 and 2 ( P<0.05). Hepatic artery buffer response was significantly higher in Group 3, compared to Groups 1 and 2 in relation to pre-occlusion values ( P<0.05). Split-liver transplantation, when resulting in small-for-size grafts, is associated with portal hypertension, diminished arterial flow, and graft dysfunction. Arterial flow impairment appears to be related to increased portal vein flow.     

The experimental study on the temporary portal vein arterialization in the canine liver transplantation: preliminary report

To evaluate the feasibility of temporary portal vein arterialization (PVA) in orthotopic partial liver transplantation (PLT), we performed 5 canine PLTs with PVA assessing the changes in arterial ketone body ratio (AKBR) as an index of hepatic energy status, and measuring portal pressure and flow. After anastomosis of hepatic vein, the graft liver was revascularized with arterial blood shunted from the external iliac artery to the hepatic side of the portal vein. By using this technique, both anhepatic period of the recipient and ischemic time, especially warm ischemic time, of the allograft were markedly shortened (31.0 +/- 4.5 min: Mean +/- SEM). Four out of 5 recipients survived for at least 5 days (13 days in average). The AKBR was restored immediately after PVA and showed almost the same values as those at preclamping and after completion of anastomoses of both portal vein and hepatic artery. No significant difference in portal venous pressure was observed between during PVA and after vascular reconstruction. Portal blood flow during PVA was about one fourth of the total hepatic blood flow at preclamping. These results suggest that PVA can be used as an alternative procedure in PLT.     

Sinusoidal microcirculatory changes after small‐for‐size liver transplantation in rats

Small‐for‐size graft injury is characterized by portal venous hypertension and loss of intracellular homeostasis early after transplant. The long‐term alteration of sinusoidal microcirculatory hemodynamic state remains unknown. A syngeneic rat orthotopic liver transplantation model was developed using small‐for‐size grafts (35% of recipient liver weight) or whole grafts (100% of recipient liver weight). Graft survival, portal pressure, liver function, hepatocellular apoptosis as well as morphological changes (by light microscopy and electron microscopy) were assessed. Sinusoidal microcirculatory hemodynamics was examined by intravital fluorescence microscopy. Although portal hypertension lasted only for 1 h after performance of small‐for‐size liver transplantation, a sustained microcirculatory disturbance was accompanied by dramatic reduction of sinusoidal perfusion rate, elevation of sinusoidal diameter as well as increase in the number of apoptotic hepatocytes during the first 7 days. These resulted in lower survival rate (50% vs. 100%, P = 0.012), higher level of liver function, and more severe morphological changes, which could induce small‐for‐size syndrome. In conclusion, persistent microcirculatory hemodynamic derangement during the first 7 days after reperfusion as well as transient portal hypertension is significant manifestation after small‐for‐size liver transplantation. Long‐term microcirculation disturbance displayed as decrease of sinusoidal reperfusion area and increase of spread in functional liver mass seems to be the key factor for graft injuries.     

Arterialization of the portal vein in pediatric liver transplantation

Portal vein arterialization (PVA) is an acquired concept in shunt surgery for portal hypertension. This technique, recently described as both a temporary and permanent procedure in adult liver transplantation, is reported by the authors in two cases of pediatric transplantation. The indication was low portal blood flow after reperfusion with poor graft function due to persistence of spontaneous retroperitoneal venous shunts. In both cases described, PVA allowed for satisfactory macroscopic liver reperfusion. The increase in portal blood flow from 150 to 500 ml/min in the second patient enabled the liver to be reperfused correctly and led to successful transplantation. The graft function in both cases improved in the 1st postoperative week, but thrombosis of the PVA occurred in the 1st patient 2 months after transplantation. Signs of hepatic hyperarterialization occurred in the second patient and this necessitated a dearterialization of the portal vein 2 weeks later. Although the benefit of this procedure appears to be beyond doubt in the immediate postoperative period, we have no data on long-term arterialization. We do think that PVA can be performed in pediatric liver transplantation, but it may need to be done only in special, individual situations when no valid alternative can be proposed, such as in the absence of a mesenteric vein and/or the presence of spontaneous retroperitoneal venous shunts. Received: 24 June 1997 Received after revision: 27 November 1997 Accepted: 28 November 1997     

Long-term venous complications after full-size and segmental pediatric liver transplantation

OBJECTIVE: To assess the long-term incidence of venous complications, including portal vein and hepatic vein stenoses, in both whole cadaveric and reduced-size cadaveric and living related liver transplants in a pediatric population, and to assess the therapeutic modalities in the treatment of these lesions. SUMMARY BACKGROUND DATA: A shortage in appropriate-sized liver grafts for pediatric patients led to the use of segmental liver grafts, which became the predominant graft used in 325 of 600 (54%) transplants at the authors' institution. To assess the long-term impact of this strategy, the authors examined the incidence of late (>90 days) venous complications and the efficacy of all therapeutic interventions. METHODS: Six hundred pediatric liver transplants were performed in 325 patients, with reduced-size or split (RSS; n = 207), living related (LRD; n = 118), or full-size cadaveric grafts (FS; n = 275) from 1988 to 2000. All transplants identified with late portal vein or vena caval stenoses or thromboses from a cohort of 524 grafts with survival greater than 90 days were reviewed for demographics, symptoms, therapeutic intervention, recurrence, morbidity, and mortality. RESULTS: Fifty lesions were identified in 49 patients (38 portal vein and 12 hepatic vein-cava stenoses). Sex distribution was similar between portal vein and hepatic vein to cava, as was the mean patient age. Portal vein stenoses occurred in 32 LRD, 3 RSS, and 3 FS, while hepatic vein-cava stenoses occurred in 2 LRD, 8 RSS, and 2 FS. In the 38 portal vein stenoses, 9 had prior perioperative portal vein and/or 5 hepatic artery thrombectomies. Portal vein stenoses were identified after bleeding (17/38), ascites (6/38), increased liver function tests (6/38), splenomegaly (5/38), or screening ultrasound (4/38). Portal vein stenosis was associated most often with cryopreserved vein for portal conduits. Excluding conduits, the incidence of late portal vein complications was reduced to 1%. Lesions became symptomatic at a mean of 50.8 +/- 184.2 months posttransplant. All patients underwent venous angioplasty with a 66% (25/38) success rate, while 7 of 25 required further angioplasty and stenting. In the 13 unsuccessful angioplasties, 8 required surgical shunts for complete portal vein thrombosis. Recurrence occurred in 9 patients: all were amenable to stenting. Nine patients (24%) eventually died of sepsis (4) and surgical deaths at shunt or retransplant (5). Hepatic vein-cava stenoses occurred after a mean of 37.2 +/- 35.2 months, presenting with ascites (n = 10), increased liver function tests (n = 2), and splenomegaly (n = 2). All patients were diagnosed by venogram and managed by balloon dilatation alone (n = 6) or stented (n = 4), with an 80% (10/12) success, with two late recurrences amenable to repeat angioplasty or stenting. Long-term survival was 80% at 1 year. CONCLUSIONS: The use of segmental grafts without venous conduits is not associated with a significant rate of long-term venous complication. When late venous complications do occur, venous angioplasty and stenting are both a safe and effective management modality. If necessary, venous angioplasty may be repeated with the placement of a stent. When this is required, care must be taken to place the stent in a position where the metallic object will not interfere with future surgical manipulations should retransplantation be necessary.     

Portal vein pressure is the key for successful liver transplantation of an extremely small graft in the pig model

In partial-liver transplantation, the use of small grafts sometimes results in graft failure, usually caused by portal hypertension after transplantation (Tx). Portal hypertension after Tx can be decreased with a porto-caval shunt (PCS). The purpose of this study is to clarify the effect of the PCS on extremely reduced-size liver Tx. In a pig model, the posterior segment of 25% of a whole liver was transplanted orthotopically. The pigs were divided two groups: group A, graft with PCS ( n=7), and group B, graft without PCS ( n=7). The PCS was made by means of side-to-side anastomosis of the portal vein and the inferior vena cava. We examined the portal vein pressure, survival rate, regeneration rate of the graft, Ki-67 as an index of cell proliferation, and histological findings, and carried out liver-function tests. In group A, five pigs survived for more than 4 days and the remaining two died of a perforated gastric ulcer on post-operative day (POD) 2. In group B, all pigs except one died of graft failure within 24 h. Portal vein pressure after reperfusion in group A and group B was of statistically significant difference ( P<0.05), 14.2+/-3.2 and 18.9+/-4.7 cmH(2)O, respectively. In group A, the regeneration rate of the graft was 94%, 4 days after Tx, and Ki-67 stained remarkably in the parenchymal hepatocytes. In TEM finding, structure of the sinusoid was also well maintained after Tx. From these results we can conclude that the key to success in liver Tx with extremely small grafts lies in the control of the portal vein pressure.     

Auxiliary rat liver transplantation with portal vein arterialization in acute hepatic failure

BACKGROUND: The aim of our work was to study the effect of the portal vein arterialization of an auxiliary liver graft on survival, liver function, and regeneration of the native liver suffering from surgically induced acute liver failure (ALF). METHODS: In Lewis rats (control group: n=10), ALF was induced by resection of about 85% of liver tissue. The auxiliary liver graft (reduced size of 30%) was transplanted into the right upper quadrant of the abdomen (trial group: n=12). The portal vein was arterialized via the renal artery. The infrahepatic vena cava was anastomosed end-to-side, and the bile duct was implanted into the duodenum. RESULTS: Survival rate over a 3-month period was 10/12 in the trial group vs. 2/10 in the controls. In the trial group, the prothrombin time rose up to 38+/-2 sec on day 1 after surgery (control group: 66+/-6 sec); on day 5 after surgery, it returned to values of 30+/-1 sec. On day 1 after surgery, serum albumin fell to 25+/-1 g/L (preoperative value: 32+/-1 g/L). Within 3 weeks, it returned to normal. The hepatobiliary scan on day 7 after surgery showed normal uptake in the liver graft, whereas the uptake of the native liver was distinctly reduced. After 3 months, the transplanted liver had atrophied (0.6% of body weight), the native liver hypertrophied (2.5% of body weight), with a normal total weight for both livers of 3.1% of body weight. CONCLUSIONS: Thus, auxiliary liver transplantation with arterialized portal vein allows maintenance of liver function at the time of ALF and regeneration of the native liver.     

可量化的受体门静脉干预调节猪辅助性部分肝移植两肝门静脉血流竞争

目的 观察不同程度的受体肝门静脉缩窄对猪辅助性部分肝移植(APLT)受体肝和移植肝门静脉血流竞争的防治作用,探讨一种可量化的受体肝门静脉干预标准.方法 32头健康幼猪按体重相近原则配对,取右半肝作为供肝,切除受体肝左叶,共行16次APLT.根据移植后受体门静脉缩窄程度,将其分为4组:对照组(n=5,门静脉未行处理),缩窄1/4组(n=4,受体门静脉宽度缩窄1/4),缩窄1/3组(n=4,缩窄1/3)和结扎组(n=3,门静脉结扎).定期观察各组受体肝和移植肝的体积大小、血流状况及组织结构的变化.结果 术中电解质变化各组基本相似,血流动力学变化以对照组和缩窄1/4组较为平稳;各组存活率和最长存活时间均以缩窄1/4组最优;门静脉造影示缩窄1/4组两肝之门静脉均得到较好显影,未见明显造影剂淤积和血管扩张;多普勒超声示各组移植肝门静脉依次增宽,流速分别为0.220、0.293、0.336和0.400 m/s,受体门静脉流速分别为0.275、0.294、0.328和0 m/s;两肝体积、充盈度和包膜紧张度以缩窄1/4组最为适中,坏死程度亦以缩窄1/4组最轻.结论 在供受体体重相近且无明显肝硬化时,为防治APLT门静脉血流竞争,以受体门静脉宽度缩窄1/4较为适宜.     

Application of cryopreserved vein grafts as a conduit between the coronary vein and liver graft to reconstruct portal flow in adult living liver transplantation

Abstract:  Adult-to-adult living donor liver transplantation is an alternative to donation from a deceased individual, and can help relieve the shortage of liver donations available for adult patients in Asian countries. When transplant candidates have thrombosis and deterioration of the portal vein, living donor liver transplantation is relatively contraindicated because portal veins in the grafts are short and vein grafts may not be available to reconstruct the portal vein. From June 2003 to May 2007, 82 adult living donor liver transplantations were performed at Chang-Gung Memorial Hospital. Three patients had portal vein thrombosis and marked fibrosis of the portal vein and cryopreserved vein grafts were used to reconstruct portal flow from the engorged coronary vein to the graft portal vein. All vein grafts are patent and all patients have normal liver function at 21–36 months after transplantation. When cryopreserved vein grafts are available, adult living donor liver transplantation can be successfully performed in patients with marked deterioration of the portal vein. The short distance from the engorged coronary vein to the graft portal vein may decrease the incidence of re-thrombosis of the venous conduit.     

Risk factors for intraoperative portal vein thrombosis in pediatric living donor liver transplantation

Pathologic changes of the recipient native portal venous system may cause thrombosis of the portal vein, especially in pediatric living donor liver transplantation (LDLT). This study assessed the utility of Doppler ultrasound (US) for the detection of intraoperative portal vein occlusion and identification of predisposing risk factors in the recipients. Seventy-three pediatric recipients who underwent LDLT at Chang Gung Memorial Hospital, Taiwan, from 1994 to 2002 were included. Preoperative and intraoperative Doppler US evaluation of the portal vein was performed. Age, body weight, native liver disease, type of graft, graft recipient weight ratio (GRWR), type of portal anastomosis, portal velocity, portal venous size and presence of portosystemic shunt were analyzed for statistical significance of predisposing risk factors. Eight episodes of intraoperative portal vein thrombosis, with typical findings of absent Doppler flow in portal vein and prominent hepatic artery with a resistant index lower than 0.5 (p < 0.001), were detected during transplantation, which was then corrected by thrombectomy and re-anastomosis. Children age < or =1 yr (p = 0.025), weight < or =10 kg (p = 0.024), low portal flow < or =7 cm/s (p = 0.021), portal venous size < or =4 mm (p = 0.001), and GRWR >3 (p < 0.017) were all risk factors for intraoperative portal vein thrombosis. Doppler US is essential in the preoperative evaluation, early detection and monitoring of outcome of the portal vein in liver transplant.     

Hepatic microcirculatory disturbances due to portal vein clamping in the orthotopic rat liver transplantation model

Most modifications and applications of the orthotopic rat liver transplantation (ORLT) model require clamping of the portal vein, thus leading to ischemia of the gut. The purpose of this study was to evaluate the effect of portal vein clamping during ORLT on hepatic microcirculation and leukocyte--endothelial interaction by intravital fluorescence microscopy. ORLT were performed following 1 hr of cold storage in EuroCollins solution without (standard group) and with insertion of a portojugular shunt (shunt group) to minimize intestinal ischemia. ORLT induced reduction of perfused sinusoids (83%) and velocity of leukocytes (311 +/- 4.5 microns/sec; mean +/- SEM) compared with nontransplanted controls (99% and 417 +/- 4.9 microns/sec). Portojugular shunt during ORLT improved hepatic microvascular perfusion (89% and 355 +/- 3.4 microns/sec; P less than 0.05). Furthermore, percentage of permanent and temporary adherent leukocytes decreased significantly when a portosystemic shunt was applied (from 33.5 +/- 1% to 22.1 +/- 1% and 19.7 +/- 1.2% to 14.0 +/- 0.9%; P less than 0.05). The results of the study reveal that intestinal congestion and reperfusion results in a rise in leukocyte adhesion to the sinusoidal wall and in disturbances of the hepatic microcirculation. It seems likely that increased endotoxin concentrations in the portal vein induce an activation of hepatic macrophages that subsequently cause release of chemoattractant mediators. In conclusion, side effects of intestinal ischemia during experimental liver transplantation surgery on liver function due to release of chemoattractant mediators should be considered when experimental data are transferred to clinical settings.     

Effects of exogenous endothelin-1 application on liver perfusion in native and transplanted porcine livers

PURPOSE: This study was designed to assess and differentiate the impact of progressivly increasing portal venous endothelin-1 (ET) plasma concentrations on hepatic micro- and macroperfusion of native porcine livers (Group A) and liver grafts after experimental transplantation (Group B). METHODS: A standardized gradual increment in systemic ET plasma concentration (0-58 pg/ml) was induced by continuous ET-1 infusion into the portal vein in both groups (A: n = 10, B: n = 10). Control animals received only saline (n = 5, each group). Hepatic microcirculation (HMC) was quantified by thermodiffusion electrodes, hepatic artery flow (HAF), and portal venous flow (PVF) by Doppler flowmetry. RESULTS: No changes in ET or perfusion parameters were observed in controls. The mean ET level after orthotopic liver transplantation (OLT) in Group B was elevated (baseline: 3.8 +/- 2.4 pg/ml) compared with Group A (2.8 +/- 1.9 pg/ml). With rising ET levels HAF decreased progressively in Group A from 205 +/- 97 (baseline) to 160 +/- 72 ml/min, and in Group B from 161 +/- 87 to 146 +/- 68 ml/min. PVF decreased in Group A from 722 +/- 253 to 370 +/- 198 ml/min, and in Group B from 846 +/- 263 to 417 +/- 203 ml/min. Baseline HMC in Group A was 86 +/- 15 and decreased significantly to 29 +/- 9 ml/100 g/min, and baseline MC in Group B was 90 +/- 22 and decreased to 44 +/- 32 ml/100 g/min. No significant alteration in systemic circulation was noted at the ET concentrations investigated. CONCLUSIONS: Significant impairment of hepatic micro- and macrocirculation was detected after induction of systemic ET levels above 9.4 pg/ml both in native and in transplanted livers. Disturbance of HMC was caused predominantly by reduction of portal venous flow, while the effect of ET on HAF was less pronounced. Characteristics of flow impairment in transplanted and native livers were analogous after short cold ischemic graft storage (6 h).     

Venous complications after orthotopic liver transplantation

Complications involving the portal vein or the vena cava, are rare after orthotopic liver transplantation. We report on the incidence and treatment of venous complications following 1000 orthotopic liver transplantations in 911 patients. Twenty-six of the adult patients (2.7%) suffered from portal complications after transplantation, whereas complications of the vena cava were observed in only 17 patients (1.8%). Technical problems or recurrence of the underlying disease (e.g. Budd-Chiari syndrome) accounted for the majority of complications of the vena cava, whereas alteration of the vessel wall or splenectomy during transplantation could be identified as important risk factors for portal vein complications. In patients undergoing modification of the standard end-to-end veno-venous anastomosis of the portal vein due to pathological changes of the vessel wall, complications occurred in 8.3%, whereas only 2.4% of patients who received a standard anastomosis of the portal vein experienced complications of the portal vein. Furthermore, splenectomy during transplantation was also associated with an increased incidence of portal vein complications (10.5 vs. 2.2% in patients without splenectomy). Treatment was dependent on the signs and symptoms of the patients, and varied considerably between patients with portal vein complications and patients suffering from complications of the vena cava. Complications of the vena cava led to retransplantation in about one-third of the patients, whereas in patients with occlusion of the portal vein, retransplantation was necessary in only 15%, and more than half of the patients suffering from portal vein complications did not require any treatment at all. Usually, treatment of patients with portal vein complications only became necessary when additional complications such as arterial occlusion or bile duct injuries occurred.     

Portal vein complications after adult‐to‐adult living donor liver transplantation

Successful management of portal vein (PV) complications after liver transplantation is crucial to long‐term success. Little information is available, however, regarding the incidence and treatment of PV complications after adult‐to‐adult living donor liver transplantation (LDLT). Between January 1996 and October 2006, 310 adult LDLTs were performed at our institution. PV thrombus was present in 54 patients at the time of LDLT. The incidence of PV complications, choice of therapeutic intervention, and outcomes were retrospectively analyzed. Among the 310 recipients, PV complications were identified in 28 (9%). Risk factors included smaller graft size, presence of PV thrombus at the time of LDLT, and use of jump or interposition cryo‐preserved vein grafts for PV reconstruction. When divided into early (within 3 months, n = 11) and late (after 3 months, n = 17) complications, the use of vein grafts for PV reconstruction predisposed to the occurrence of late, but not early, PV complications. Portal vein thrombosis occurred more frequently in the early period (eight out of 11, 73%), whereas stenosis occurred more frequently in the later period (14 out of 17, 82%). Surgical interventions were favored in the earlier period, whereas interventional radiologic approaches were selected for later events. Overall 3‐ and 5‐year survival rates were 81% and 77%, respectively, in patients with PV complications and 88% and 84%, respectively, in those without PV complications (P = 0.21, log‐rank test). PV complications are a significant problem following LDLT with both early and late manifestations. Acceptable long‐term results, however, are achievable with periodic ultrasonographic surveillance and timely conventional therapeutic interventions. The use of cryo‐preserved vein grafts for reconstructing portal flow should be discouraged.     

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

Six adult patients suffering from acute hepatic failure and with a high urgent status underwent heterotopic auxiliary liver transplantation. In four of these patients, the portal vein of the liver graft was arterialized in order to leave the native liver and the liver hilum untouched and to be able to place the liver graft wherever space was available in the abdomen. The arterial blood flow via the portal vein was tapered by the width of the anastomosis. Two patients died, one of sepsis on postoperative day 17 (POD), the other after 3 months due to a severe CMV pneumonia. There were no technically related deaths. The native liver showed early regeneration in all cases. In one patient, the auxiliary graft was removed 6 weeks after transplantation. Four weeks later, he had to undergo orthotopic retransplantation due to a recurrent fulminant failure of the recovered native liver. This patient is alive more than 1 year after the operation. We conclude that heterotopic auxiliary liver transplantation with portal vein arterialization is a suitable approach to bridging the recovery of the acute failing native liver. Received: 15 September 1997 Received after revision: 4 February 1998 Accepted: 2 March 1998