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.     

Innovative techniques for and results of portal vein reconstruction in living-related liver transplantation

BACKGROUND: Portal vein reconstruction is a crucial factor affecting the outcome of a successful living-related liver transplantation. We describe here our experience with portal vein reconstruction in 314 cases of living-related liver transplantation with use of novel surgical modalities to enable the transplant surgeons to deal with any size mismatch between the donor's and recipient's portal veins. METHODS: Portal vein reconstruction was classified into 2 major groups, anastomosis without and with a vein graft. When there was no stenosis of the recipient portal vein and the diameter was the same, the portal trunk was used for anastomosis. When the diameter mismatch was minimal, branch patch anastomosis was feasible. When the recipient portal vein was significantly stenotic and the portal vein of the graft was long enough, we removed the stenotic trunk and constructed an anastomosis between the graft portal vein and the confluence of the recipient portal vein. When the graft portal vein was short, a vein graft was interposed. The vein patch technique was preferable when the diameter of the graft vein was not large enough for the interposition technique. RESULTS: Anastomosis without vein graft included trunk anastomosis (n = 156), branch patch anastomosis (n = 39), and confluence anastomosis (n = 22). Anastomosis with vein graft used the interposition technique (n = 77) and vein patch technique (n = 27). The origin of the grafts was mostly from the maternal left ovarian vein (70%) or the paternal inferior mesenteric vein (27%). Complications related to portal vein reconstruction occurred in 16 (5%) patients: portal vein thrombosis in 8, stenosis in 7, and fatal rupture in 1 patient. The incidence of complications was similar for all techniques except for confluence anastomosis. CONCLUSION: Our innovative techniques should be helpful for overcoming diameter or length mismatches in portal vein reconstruction in pediatric liver transplantation.     

Monosegmental living donor liver transplantation

BACKGROUND: Living donor liver transplant (LDLT) program has been started from 1990 in Japan, and is still major form of liver transplantation because of the scarcity of cadaveric donor organs. In small infants, implantation of left lateral segment grafts can be a problem because of a large-for-size graft. Until November 2002, we performed 867 transplants for 828 patients (561 children and 306 adults), and 14 cases received monosegment grafts from living donors. METHODS: Fifteen patients, median age 211 days, median weights 5.95 kg, received monosegmental LDLT. The indication for using this technique was infants with an estimated graft-to-recipient weight ratio of over 4.0%. RESULTS: Graft and patient survival is 85.7%. There were no differences in donor operation time and blood loss between monosegmentectomy and left lateral segmentectomy. Segment III grafts were indicated in 13 cases. Two vascular complications were observed (one hepatic artery thrombosis and one portal vein thrombosis). CONCLUSIONS: Monosegental living donor liver transplantation is a feasible option with satisfactory graft survival in small babies with liver failure.     

A selective approach to preexisting portal vein thrombosis in patients undergoing liver transplantation.

Splanchnic venous inflow is considered mandatory to ensure graft survival after liver transplantation. Over a 68-month period, we performed 570 liver transplants in 495 patients. Portal vein thrombosis was present in 16 patients. At transplant, the extent of the occlusion included portal vein alone (n = 4), portal including confluence of the splenic and superior mesenteric veins (n = 8), portal, splenic, and distal superior mesenteric veins (n = 2), and the entire portal vein, splenic vein, and superior mesenteric vein (n = 2). The operative approach included thrombectomy alone (n = 5), anastomosis at the confluence of the splenic and superior mesenteric splenic veins (n = 8), and extra-anatomic venous reconstruction (n = 3). The mean operative blood loss was 22 +/- 22 units, and the mean operative time was 9.7 +/- 4.8 hours. The 1-year actuarial survival rate was 81%, with a mean follow-up of 12.5 months. In summary, with a selective approach and the use of innovative forms of splanchnic venous inflow, portal vein thrombosis is no longer a contraindication to liver transplantation.     

Reconstruction of hepatic or portal veins by use of newly customized great saphenous vein grafts

Background and aims Segmental resection of major hepatic veins or the portal vein is sometimes required if one is to secure adequate surgical margins from hepatic or pancreatic malignancies. An external iliac vein is widely sacrificed as a vein graft to replace the defect, but this is associated with postoperative edema of the lower leg. We developed a new method for constructing the great saphenous vein to interpose the hepatic or portal veins.Patients and methods The great saphenous vein was divided transversely into three sections, which were aligned side-to-side. The three pieces were anastomosed to make a sheet 3 × 2 cm, which was rolled up into a cylindrical form of approximately 1 cm in diameter and 2 cm in length. We applied the finished vein grafts to interpose the major hepatic veins in three patients with metastatic liver tumors and the portal vein in two patients with pancreatic malignancies in cylindrical form and to reconstruct the portal vein in one patient with a pancreas cancer, using a three-row sheet as a patch graft.Results No patient developed venous thrombosis of the graft or edema of the lower leg.Conclusions The newly customized vein graft was safe and useful for the reconstruction of the major hepatic or portal veins.     

Superior mesenteric vein inflow for liver transplantation when the portal vein is occluded

An alternative solution to the problem of liver transplantation in the patient with an occluded portal vein is described. It uses a bridge graft of donor iliac vein from the superior mesenteric vein at the base of the colonic mesentery. The graft is tunnelled over the pancreas and under the stomach to the region of the liver hilum to provide portal inflow. This procedure was employed successfully in four patients, with patency for more than 2 years in the patient with the longest follow-up. By this approach it is routinely possible to perform a transplant procedure in a recipient with an occluded portal vein.     

Liver transplantation in patients with portal vein thrombosis and central portacaval shunts.

The authors have analyzed the impact of pre-existing portal vein pathology on the outcome of orthotopic liver transplantation. The incidence was high in patients suffering from chronic active hepatitis, hypercoagulable states, trauma or previous dissection of the porta hepatis, and splenectomy. The existence of portal vein thrombosis (23 patients) or surgical central portosystemic shunt (10 patients) was documented by preoperative Doppler sonogram or angiography (26/33), or operative findings of occluded vein (7/33). Successful thrombectomy and dismantling of portacaval shunts were achieved in most cases (24/33). Only nine patients required the placement of an interposition vein graft to the superior mesenteric vein. The intraoperative course was characterized by increased blood loss and coagulopathy, significantly higher than in patients with a patent portal vein. When compared with all liver transplants, the immediate postoperative complication rate was higher for primary nonfunction (33% versus 8%), re-exploration for intraperitoneal bleeding and hematomas, and morbid infections. Rethrombosis rate of thrombectomized veins or vein graft was low (2/33). The mortality rate was 35% in the presence of portal vein thrombosis (PVT) and 30% for portacaval shuct (PCS), both significantly higher than the 12% for other orthotopic liver transplant (OLT) patients. These results are expected to improve with better patient selection, surgical experience, and anticipation of the complex postoperative course. The authors conclude that PVT or the presence of PCS are not contraindications to orthotopic liver transplantation.     

Interpostion vein graft in living donor liver transplantation

In adult-to-adult living donor liver transplantation (LDLT), right lobe grafts without a middle hepatic vein can cause hepatic congestion and disturbance of venous drainage. To solve this problem, various types of interposition vein graft have been used. OBJECTIVES: We used various types of interposition vein grafts for drainage of the paramedian portion of the right lobe in living donor liver transplantation. METHODS: From June 1996 to June 2003, 37 of 176 patients (128 adults, 48 pediatric) who underwent LDLT received vein grafts for drainage of segments V, VIII, or the inferior portion of the right lobe. RESULTS: In 36 adult cases the reconstruction included the inferior mesenteric vein of the donor (n = 14); cadaveric iliac vein stored at cold (4 degrees C) temperature (n = 5); cryopreserved (-180 degrees C) cadaveric iliac vein (n = 10); cryopreserved cadaveric iliac artery (n = 1 case); donor ovarian vein (n = 1); recipient umbilical vein (n = 3); recipient saphenous vein (n = 1); recipient left portal vein (n = 1); recipient left hepatic vein (n = 1). In a pediatric case with malignant hemangioendothelioma that encased and compressed the inferior vena cava, we used an interposition vein graft to replace the inferior vena cava. CONCLUSION: Various types of interposition vein grafts can be used in living donor liver transplantation. Cryopreserved cadaveric iliac vein and artery are useful to solve these drainage problems.     

Accuracy of magnetic resonance imaging for preoperative detection of portal vein thrombosis in liver transplant candidates.

The detection of main portal vein thrombosis (PVT) on preoperative imaging of liver transplant candidates has important technical implications for the transplantation procedure. Data are scarce regarding the accuracy of magnetic resonance imaging (MRI) at detecting PVT. The aim of our study was to compare preoperative findings of the portal vein on MRI to operative findings at liver transplantation. Abdominal MRI and clinical records of 172 consecutive patients who received liver transplants between January 1999 and September 2004 were reviewed. Two radiologists independently evaluated the last abdominal magnetic resonance examinations obtained before liver transplantation, blinded to the original reading, operative findings, and clinical data. Findings on MRI were compared with intraoperative findings at transplantation. Main PVT was detected in 12 patients, in whom 8 were found to have thrombus at surgery, with 6 requiring a jump graft or thrombectomy. Sensitivity and specificity of MRI for detecting main PVT were 100% and 98%, respectively. The cause of discordance between findings on MRI and at transplantation in 2 cases was a diminutive caliber of the main portal vein that was interpreted as recanalized chronic thrombosis on MRI. In conclusion, in our study group MRI detected PVT in all liver transplant recipients requiring jump grafts at transplantation. The major reason for a false-positive MRI was a diminutive but patent portal vein.     

Prevalence, presentation, and endovascular management of hemodynamically or clinically significant arterio-portal fistulae in living and cadaveric donor liver transplant recipients

Saad W, Lippert A, Davies M, Arslan B, Kumer S, Waldman D, Turba U, Schmitt T, Matsumoto A, Angle J. Prevalence, presentation, and endovascular management of hemodynamically or clinically significant arterio‐portal fistulae in living and cadaveric donor liver transplant recipients. Abstract: Purpose: To compare the prevalence (cadaveric vs. living donor transplants), clinical features, and the effectiveness of endovascular management of significant arterio‐portal fistulae (APF) in liver transplant recipients. Methods: A retrospective audit of liver transplant recipients in two institutions was performed (1996–2009). Significant APF were included and were defined as symptomatic and/or hemodynamically significant (causing graft dysfunction and/or having abnormal Doppler findings in the portal vein). Patients with significant APF were evaluated for presenting symptoms, imaging features, size/branch order portal vein involvement, and effectiveness of the endovascular management (coil embolization). Results: Four significant APF were found in 1992 (0.2%) liver transplants. Two were symptomatic and two were asymptomatic but were hemodynamically significant with liver function test abnormalities. All four APF were found in cadaveric donor graft recipients (0.23%, N = 4/1753) and none in 239 living donor graft recipients. However, there was no statistical difference between cadaveric and living donor graft recipients (p = 1.0, odds ratio = 1.23). Coil embolization was technically and clinically successful in all 4 without complications and causing normalization of the abnormal Doppler findings. Conclusion: Significant APF are a rare diagnosis (0.2% of transplants). Coil embolization is a safe and effective treatment option for APF in transplants.     

Explanted portal vein grafts for middle hepatic vein tributaries in living-donor liver transplantation

BACKGROUND: The availability of a venous graft is limited in the setting of living donor liver transplantation (LDLT), and the management of the middle hepatic vein middle hepatic vein tributaries in right lobe LDLT still remains controversial. METHODS: Twenty-three right lobe LDLT grafts, with the reconstruction of middle hepatic vein tributaries using the explanted portal veins from the explanted livers, were evaluated for the patency, postLDLT liver function tests, and graft survival. RESULTS: The methods of outflow reconstruction were classified into three types: the interposition of the graft to the middle/left hepatic vein (n=12), to the vena cava (n=9), and to the vena cava as a co-orifice with the graft right hepatic vein (n=2). The 1- and 3-year patency rates were 76.7% and 76.7% respectively, with the graft occlusion in five cases. The occluded cases (n=5) had significantly higher aspartate aminotransferase and alanine transaminase levels as compared with those of patent cases (n=18) at 4 weeks after transplantation (P<0.01). However, there was no significant difference in the total bilirubin and prothrombin time in either group during the observation periods. The 1- and 3-year graft survival rates were 91.1% and 91.1%, respectively. In addition, there was no graft loss due to occlusion. CONCLUSION: The use of the recipient's explanted full-length hilar portal vein for the reconstruction of the middle hepatic vein tributaries is thus considered to be a feasible and valuable strategy in the setting of a right lobe LDLT, where appropriate vascular grafts are not always available.     

Caval inflow to the graft: a successful way to overcome diffuse portal system thrombosis in liver transplantation

Portal vein thrombosis was considered to be a major contraindication to liver transplantation before the introduction of vessel grafts from the recipient's area of confluence of the splenic and superior mesenteric veins, behind the neck of the pancreas, to the graft's portal vein. Refinement in surgical technique has given rise to a large number of possibilities to overcome portal vein thrombosis in OLT recipients, ranging from portal vein thrombectomy to several different venous graft jump reconstructions. All these reconstructions require the presence of a patent vein of the portal system. When neither splanchnic veins nor sufficiently large venous collaterals are available, liver transplantation has been considered impossible. Salvage solutions include arterialization of the portal vein with the associated risk of liver damage in the longterm, a combined liver and bowel transplantation has been proposed but not yet reported (and in any case the results of combined liver and bowel transplants are not as good as those of liver transplantation alone) and finally the use of blood inflow from the inferior vena cava as first reported by Tzakis and coworkers. Portal flow from the inferior vena cava may be performed as a last resort. Although the consequences of severe pretransplantation portal hypertension remain and should be treated before, during, and after transplantation, liver function is normal in the short and midterm. With this new procedure, diffuse portal vein thrombosis is no longer an absolute contraindication to liver transplantation. But this needs to be confirmed in light of further experience and longterm followup.     

Reconstruction of portal vein using a hepatic vein patch graft after combined hepatectomy and portal vein resection

BACKGROUND: Surgical resection is the only treatment modality that ensures complete tumor removal in patients with liver tumors involving a major portal vein branch or its bifurcation. Restoration of good portal blood flow is essential for recovery in the early postoperative period and for long-term survival. However, such extended resections often result in large defects at the bifurcation of the portal vein that are not amenable to suturing or end-to-end anastomosis. METHODS: A patch graft technique is very useful for reconstruction of long and elongated defects when other methods are not technically appropriate. We describe a simple technique for reconstructing the portal vein using a patch graft obtained from the hepatic vein stump of the resected specimen. CONCLUSIONS: This technique permits surgeons to reconstruct the portal vein without any need for harvesting another vein and with no need for an additional incision.     

Rex shunt for acute portal vein thrombosis after pediatric liver transplantation in children with biliary atresia

Background/Purpose

Posttransplantation portal vein thrombosis (PVT) can have severe health consequences, and portal hypertension and other consequences of the long-term privation of portal inflow to the graft may be hazardous, especially in young children. The Rex shunt has been used successfully to treat PVT patients since 1998. In 2007, we started to perform this surgery in patients with idiopathic PVT and late posttransplantation PVT. Herein we have reported our experience with this technique in acute posttransplantation PVT.

Methods

Three patients of ages 12, 15, and 18 months underwent cadaveric (n = 1) or living donor (n = 2) orthotopic liver transplantation (OLT). All patients had biliary atresia with portal vein hypoplasia; they developed acute PVT on the first postoperative day. They underwent a mesenteric-portal surgical shunt (Rex shunt) using a left internal jugular vein autograft (n = 2) or cadaveric iliac vein graft (n = 1) on the first postoperative day.

Results

The 8-month follow-up has confirmed shunt patency by postoperative Doppler ultrasound. There have been no biliary complications to date.

Conclusions

The mesenteric-portal shunt (Rex shunt) using an autograft of the left internal jugular or a cadaveric vein graft should be considered for children with acute PVT after OLT. These children usually have small portal veins; reanastomosis is often unsuccessful. In addition, this technique has the advantage to avoid manipulation of the hepatic hilum and biliary anastomosis. Although this study was based on a limited experience, we concluded that this technique is feasible, with great benefits to and low risks for these patients.     

Clinical application of arterialization of portal vein in living related donor partial liver transplantation

Arterialization of the portal vein was employed during hepatic arterial reconstruction in our first few clinical experiences of partial liver transplantation using liver grafts obtained from living related donors. This procedure reduced the time required for revascularization of the grafts to about 25 min, and could in fact reduce the ischemic phase of the grafts. Repeated practice of the clinical transplantation technique has shortened the time needed to complete vascular reconstruction, eliminating the need for this procedure in most of our subsequent cases. In many clinical cases, however, there may be emergency situations which require vascular reconstruction, resulting in a prolongation of ischemic phase and the deterioration of the cellular viability of the graft. In such situations, arterialization of the portal vein can be a useful way to prevent the prolongation of the ischemic phase and to rescue the graft.     

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.     

Long-term fate of heterotopic liver transplants in rats with portal vein inflow only

Previous studies have suggested that hepatic arterial flow in heterotopic partial liver transplants is necessary to ensure graft survival and regenerative capacity. This report presents findings in a syngeneic rat strain (Lewis) that partial liver transplants can be successfully heterotopically transplanted in the long term with the only inflow coming from the portal vein. When the host liver undergoes a nearly complete resection at 3-4 weeks, the transplanted liver regenerates to maintain the health of the host. Moderate to massive hepatocellular necrosis occurs in the first 3 months postoperatively, with recovery by 4-5 months. Liver transplants 8-10 months postoperatively appear architecturally normal. No host liver tissues were found to be regenerating after subtotal host liver resection. We conclude that portal vein reconstruction without hepatic arterial inflow can sustain a partial liver transplant in the long term, replacing the function of the host liver.     

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.     

Hepatic venous outflow reconstruction in adult living donor liver transplants without portal hypertension

Graft congestion is one of the causes of poor graft function in segmental liver transplantation. Three factors are implicated in segmental graft congestion: graft size, hepatic venous outflow and portal inflow. The graft size must be matched to the body weight, which is conventionally done by using graft to body weight ratio. Hepatic blood outflow must be optimized by hepatic vein reconstruction, which can be complicated. High portal blood flow has been shown to be detrimental to small-for-size grafts. These factors are strictly connected to each other. They can all contribute to graft congestion and poor function, while one factor can compensate for the others and decrease congestion. Ideally, all the accessory veins should be reconstructed, if possible, to maximize the outflow. In the absence of portal hypertension and with an adequate sized graft, complex venous reconstruction may not be necessary. We present a case report of an adult living donor liver transplant with the favorable conditions of normal portal pressure and a large sized graft, but complicated by the presence of several accessory hepatic veins. A simple hepatic vein anastomosis was sufficient for adequate outflow and prompt graft function.     

Liver transplantation complicated by misplaced TIPS in the portal vein.

OBJECTIVE: The purpose of this study was to determine the incidence and complications related to transjugular intrahepatic portosystemic shunt (TIPS) stents found in the portal vein at the time of an orthotopic liver transplantation. BACKGROUND: Transjugular intrahepatic portosystemic shunts are frequently used in patients with end-stage liver disease as a bridge to liver transplantation. The incidence of finding the metal stent outside of the liver parenchyma at the time of transplantation is reported as high as 30%. Most cases that have been detailed involve stents misplaced in the vena cava with various outcomes. Almost no data are available regarding stents misplaced into the portal vein. METHODS AND RESULTS: We report our experience with four patients with whom a TIPS stent was found misplaced in the portal vein at the time of liver transplantation, including one patient with a stent extending into the superior mesenteric vein. This patient required extensive venous reconstruction using a retropancreatic "pant" donor-iliac vein graft. The three other patients were transplanted without the need for extensive venous reconstruction. There was no significant difference in operative times for this group of patients, but there was a significant increase in the requirement for blood transfusion. In a follow-up period ranging from 6 months to 2 years, all patients remained alive and had normal portal venous flow and functioning allografts. Most misplaced stents were placed in patients with small cirrhotic livers and by radiologists with minimal experience with the procedure. CONCLUSIONS: Misplaced TIPS in the portal vein before liver transplantation is a more frequent complication than previously reported; however, it does not represent major technical difficulty if a clamp can be placed proximally on the portal vein. In the case of a stent extending below the spleno-mesenteric confluence, interposition grafts such as a donor-iliac vein graft are necessary for venous reconstruction. The experience of the radiologist is critical to prevent this complication.