Bypass In Liver Transplantation Research Articles

Venovenous bypass in liver transplantation: Exploring the benefits, efficacy, and safety.

Venovenous bypass (VVB) is a technique used in liver transplantation (LT) to maintain hemodynamic stability and abdominal organ perfusion and thereby improve patient outcomes. Despite its perceived benefits, VVB utilization has declined globally due to concerns related to heparinization, major bleeding and the need for expertise. Recent advancements, such as percutaneous cannulation techniques and improved extracorporeal technology have improved the safety of VVB in LT. This paper presents a modified VVB circuit with enhanced safety features. Cannulation plays a pivotal role in VVB establishment, with percutaneous methods increasingly favored. Studies demonstrate VVB's efficacy in improving patient outcomes with lower incidence of acute kidney injury and reduced operative time and blood loss, with no added morbidity or mortality. However, its routine use faces challenges, with alternative techniques gaining traction. Our experience highlights VVB's role in various clinical scenarios, including patients with high Model for End-Stage Liver Disease (MELD) scores, challenging surgical anatomy, portal vein thrombosis and pre-existing cardiovascular disease, emphasizing its safety and efficacy. Continued research is needed to optimize VVB techniques and ensure better outcomes for liver transplant recipients.

Reverse Takotsubo Stress Cardiomyopathy During Liver Transplantation

Reverse Takotsubo Stress Cardiomyopathy During Liver Transplantation

Veno-venous bypass in liver transplantation: a commonly used technique with elusive outcome benefits.

Veno-venous bypass in liver transplantation: a commonly used technique with elusive outcome benefits.

Physiological reno-portal bypass in liver transplantation with non-tumorous portal vein thrombosis.

Reno-portal anastomosis (RPA) in presence of spleno-renal shunts (SRS) is a physiological option to restore blood flow in liver transplantation with portal vein thrombosis (PVT). Diffuse splanchnic venous system thrombosis (complex PVT) is its main indication but RPA proved to be useful in selected cases of less extensive thrombosis (non-complex PVT). Up until now only two monocentric and one multicentric case series has been published on this topic in addition to few anecdotal reports. After 2014, we introduced RPA in our institution to manage some cases of complex PVT in presence of SRS. Here, we present the evolution of indication to RPA. From 2014 to 2020, we performed ten RPA: nine patients presented non-complex and one complex PVT. Overall early and late complication rates were 66.6% and 50%, respectively. Two patients developed RPA stenosis, treated by interventional radiology. Self-resolving acute kidney injury (AKI) was observed in three cases. No re-transplantation was necessary. RPA was patent in all patients, with a mean follow-up of 41.9months. The overall patient survival was 70% at 1year and 60% at 3 and 5years. Four patients died at 1, 2, 3 and 20months from LT. Causes of deaths were, respectively, stroke, cerebral infection, sepsis (MOF) and sudden variceal bleeding in sinusoidal obstruction syndrome. The relative simplicity and effectiveness of RPA in presence of SRS allowed us to rely more and more often on this technique in liver transplantation with challenging non-complex PVT.

Re-appropriation of a right anterior thoracotomy approach to portal-systemic bypass for liver transplantation in a patient with complete superior vena cava occlusion

The utilization of venovenous bypass in liver transplantation (LT) has become less frequent and more center dependent over time. Unfortunately, this has left many transplant surgeons, particularly younger trainees, unfamiliar with the techniques and indications for its utilization. We present a case of LT in a patient with complete superior vena cava (SVC) occlusion prohibiting direct vascular access. A multi-disciplinary approach involving interventional radiology, anesthesiology, cardiac surgery, and transplant surgery, was used to diagnose, evaluate, and develop an operative plan for successful LT. In doing so, a novel approach to portosystemic bypass was utilized involving a right mini-thoracotomy with direct cannulation of the right atrium to gain central venous access and optimize venous return during LT. As a center that does not routinely use venovenous bypass, this multidisciplinary approach was crucial identifying the need for a rarely used technique for vascular access and performance of a successful LT.

A systematic review and meta-analysis of rescue revascularization with arterial conduits in liver transplantation.

Although aortohepatic conduits (AHCs) provide an effective technique for arterialization in liver transplantation (LT) when the native recipient artery is unusable, various publications report higher occlusion rates and impaired outcome compared to conventional anastomoses. This systematic review and meta-analysis investigates the published evidence of outcome and risk of AHCs in LT using bibliographic databases and following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Primary and secondary outcome were artery occlusion as well as graft and patient survival. Twenty-three retrospective studies were identified with a total of 22113 patients with LT, of whom 1900 patients (9%) received an AHC. An AHC was used in 33% of retransplantations. Early artery occlusion occurred in 7% (3%-16%) of patients with AHCs, compared to 2% (1%-3%) without conduit (OR 3.70; 1.63-8.38; P=.001). The retransplantation rate after occlusion was not significantly different in both groups (OR 1.46; 0.67-3.18; P=.35). Graft (HR 1.38; 1.17-1.63; P<.001) and patient (HR 1.57; 1.12-2.20; P=.009) survival was significantly lower in the AHC compared to the nonconduit group. In contrast, graft survival in retransplantations was comparable (HR 1.00; 0.82-1.22; P=.986). Although AHCs provide an important rescue option, when regular revascularization is not feasible during LT, transplant surgeons should be alert of the potential risk of inferior outcome.

Liver Transplantation Without Venovenous Bypass: Does Surgical Approach Matter?

BackgroundThe use of venovenous bypass in liver transplantation has declined over time. Few studies have examined the impact of surgical approach in cases performed exclusively without venovenous bypass. We hypothesized that advances in liver transplant anesthesia and perioperative care have minimized the importance of surgical approach in the modern era.MethodsDeceased donor liver transplants at the University of Toronto from 2000 to 2015 were reviewed, all performed without venovenous bypass. First, an unadjusted analysis was performed comparing perioperative outcomes and graft/patient survival for 3 different liver transplant techniques (caval interposition, piggyback, side-to-side cavo-cavostomy). Second, a propensity-matched analysis was performed comparing caval interposition to caval-preserving techniques.ResultsOne thousand two hundred thirty-three liver transplants were included in the study. On unadjusted analysis, blood loss, transfusion requirement, postoperative complications, and graft/patient survival were equivalent for the 3 different techniques. To account for possible confounding patient variables, propensity matching was performed. Analysis of the propensity-matched cohorts also demonstrated similar outcomes for caval interposition versus caval-preserving approaches.ConclusionsIn the modern era at centers with a multidisciplinary team, the importance of specific liver transplant technique is minimized. Full or partial cross-clamping of the inferior vena cava is feasible without the use of venovenous bypass.

Weaning of Veno-venous Bypass in Liver Transplantation: A Single Center Experience

BackgroundVeno-venous bypass (VVB) has been used in liver transplantation (LT) to minimize hemodynamic instability during caval anastomosis of anhepatic phase. With the introduction of the piggyback (PB) technique, which is a caval-sparing technique, the use of VVB progressively decreased over the world. The aim of this study was to introduce our experience using VVB with the focus on its weaning process. MethodsA total of 300 consecutive LT cases from May 1996 to November 2003 were examined. Except for pediatric LT, 242 LT cases were investigated to evaluate the trends in VVB use, surgical technique, the amount of transfusion requirements, and durations of operation and anhepatic phase. ResultsFor the early 100 LT cases, VVB was used in 97.5% of recipients, especially in all the recipients of deceased donor LT (DDLT). Then, the frequency of VVB use was decreased, and VVB was not used after the 268th recipient. In DDLT, the PB technique was first introduced in the 58th recipient and became a routine procedure of the DDLT since the 191th recipient. Living donor LT was increased, and the amount of transfusion requirement, duration of operation, and duration of anhepatic phase was reduced over time. ConclusionsThe increasing experience and sophisticated surgical and anesthetic techniques were important factors responsible for the weaning of VVB. The advancement of the PB technique used in living donor LT might be a main factor of its weaning.

The veno-venous bypass in liver transplantation: an unfinished product.

Veno-venous bypass (VVB) using a patent para-umbilical vein during liver transplantation (LT) has not been reported previously. Here, we report the decompression of the porto-mesenteric compartment via a patent para-umbilical vein in a patient needing a VVB during LT. Pre-transplant CT-scan showed a large patent para-umbilical vein. A femoro-axillary percutaneous VVB was installed prior to abdominal opening to decompress massive collateral veins in the abdominal wall. The para-umbilical vein was stapled and its proximal end was cannulated and connected to the VVB. The severe atrophy of the native liver allowed to place the whole liver graft in the "liver fossa" while maintaining the native liver pulled toward the left side and connected to the VVB. This maneuver maintained splanchnic venous decompression during latero-lateral cavo-caval anastomosis. The "portal" cannula was clamped and removed. The native portal vein was clamped and divided. Standard portal, arterial, and biliary reconstructions were then performed. A patent para-umbilical vein, present in one third of patients with portal hypertension could be used whenever VVB is indicated during LT in this setting.

A comparative study of the classic and piggyback techniques for orthotopic liver transplantation.

Background:The classic technique of hepatectomy with venovenous bypass may cause a longer anhepatic phase and increase the rate of some complications, such as post-operative renal failure and thromboembolic events. But, in some cases, such as tumors and anatomic difficulties, the surgeon is obligated to use the classic technique even though there is some controversy about the safety of this technique without venovenous bypass in liver transplantation. The aim of this study was to compare the results of using the classic technique without venovenous bypass and the piggyback technique for liver transplantation.Methods:A retrospective case-series study was conducted on 227 consecutive successful liver transplants, including 55 cases in which the classic technique was used and 172 cases in which the piggyback technique was used. The transplants were performed from March 2010 through June 2011 in the Visceral Transplantation Ward at Namazi Hospital in Shiraz, Iran. The piggyback method was the preferred approach for hepatectomy, but the classic technique without venovenous bypass was performed in cirrhotic cases with anatomic difficulties, when there was a tumor, or when the surgeon preferred it.Results:There were no significant differences in post-operative rise in creatinine, decreases in intraoperative blood pressure, transfused packed red blood cells (RBC), or survival rates between the groups. Warm ischemic time (duration that donor liver is out of ice until it’s blood reperfusion in the recipient) was approximately seven minutes longer in the classic group (P = 0), but it was less than 52 minutes, which is an acceptable time for this phase. Hospital stays were shorter in the classic group than in the piggyback group (P = 0.024).Conclusion:Although the piggyback technique is the preferred technique for hepatectomy in liver transplantation, the classic technique without venovenous bypass can be used safely in cirrhotic livers when necessary or if the physician prefers it.

Aorto-hepatic bypass in liver transplantation in the MELD-era: outcomes after supraceliac and infrarenal bypasses

Poor arterial inflow during orthotopic liver transplantation (OLT) may necessitate arterial revascularisation using aorto-hepatic bypasses with supraceliac (SC) or infrarenal (IR) allografts. This study compared both techniques focusing on the patients' preoperative conditions, postoperative graft/organ function, complications and survival. Fifteen out of 114 OLT patients underwent revascularisation (7 IR/8 SC) between 2005 and 2008 and were included in the study. The patients' records were reviewed retrospectively. IR patients presented with a higher BMI, received more male donor organs and their reperfusion sequence was predominately portal venous (SC: primary arterial). SC patients presented a significantly worse preoperative creatinine clearance and a trend towards a higher MELD score. The postoperative graft/organ function, morbidity and mortality did not differ between the groups despite a trend towards a worse survival in the SC group. A deteriorated preoperative creatinine clearance and higher MELD score negatively impacted the survival. Postoperative bleeding episodes and major re-interventions also affected the outcome. We found no evidence for superiority of either bypass technique in our OLT patients. The trend toward a worse survival in SC patients was most likely caused by the worse preoperative conditions of these patients and highlights the importance of the impact of the MELD score on the outcome after OLT.

Transplante de fígado clínico sem desvio venovenoso

INTRODUÇÃO: O problema da utilização do desvio venovenoso no transplante de fígado é um ponto de discussão e controvérsia entre anestesistas e cirurgiões transplantadores. Apesar de proporcionar ambiente hemometabólico estável durante a fase anepática o seu uso poderá levar a algumas complicações, inclusive fatais. OBJETIVO: Revisar a prática atual do uso do desvio venovenoso no transplante de fígado clínico, com suas vantagens e desvantagens. MÉTODO: Foi realizada ampla pesquisa na literatura, com especial atenção aos artigos publicados nos últimos 10 anos e indexados ao PubMed e Medline. Foram utilizados os seguintes descritores de forma cruzada: liver transplantation, venovenous bypass, conventional technique, classic technique. Entre os artigos encontrados foram considerados para análise os mais relevantes além dos considerados "clássicos" sobre o assunto. CONCLUSÃO: Transplante de fígado sem desvio venovenoso é técnica segura e rápida. Pode ser utilizada, com poucas exceções, sem acarretar complicações maiores nos pacientes com doença hepática.

Veno-venous bypass versus none for liver transplantation

Veno-venous bypass is used to overcome the effects of clamping of the inferior vena cava and portal vein during liver transplanation. The routine use of veno-venous bypass is, however, controversial. To compare the benefits and harms of veno-venous bypass (irrespective of open or percutaneous technique; heparin-coated or no heparin-coating) versus no veno-venous bypass during liver transplantation. To compare the benefits and harms of the different techniques of veno-venous bypass during liver transplantation. We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until December 2010. We included randomised clinical trials comparing veno-venous bypass during liver transplantation (irrespective of language or publication status). Two authors independently assessed trials for inclusion and independently extracted data. We analysed the data with both the fixed-effect and the random-effects models using RevMan Analysis. For continuous outcomes, we calculated the mean difference (MD) with 95% confidence intervals (CI) based on intention-to-treat or available case analysis. For binary outcomes, we used the Fisher's exact test since none of the comparisons of binary outcomes included more than one trial. We identified three trials with high risk of bias which compared veno-venous bypass (n = 65) versus no veno-venous bypass (n = 66). None of the trials reported patient or graft survival. There were no significant differences regarding renal failure or blood transfusion requirements between the two groups. None of the trials reported on the morbidity related to veno-venous bypass or the requirement of veno-venous bypass in the control group.We identified one trial with high risk of bias which compared percutaneous (n = 20) versus open technique (n =19) of veno-venous bypass. The patient or graft survival was not reported. There was no difference in veno-venous bypass related morbidity between the two groups. The operating time was significantly shorter in the percutaneous technique group (MD -59 minutes; 95% CI -102 to -16). There is no evidence to support or refute the use of veno-venous bypass in liver transplantation. There is no evidence to prefer any particular technique of veno-venous bypass in liver transplantation.

Percutaneous bypass cannulae can interfere with rapid infusion during liver transplantation

VENOVENOUS BYPASS (VVB) may be used during orthotopic liver transplantation (OLT) to maintain adequate preload when blood return to the heart is interrupted by cross-clamping of the inferior vena cava. Traditionally, when VVB is used, 1 drainage cannula is inserted via surgical cutdown into a femoral vein, and another is used to cannulate the portal vein directly. A centrifugal pump is used to aspirate venous blood from these sites and return it through a cannula inserted via surgical cutdown into an axillary vein. To avoid the complications of surgical cutdowns, percutaneous VVB has been used. 1 Tisone G Mercadante E Dauri M et al. Surgical versus percutaneous technique for veno-venous bypass during orthotopic liver transplantation: A prospective randomized study. Transplant Proc. 1999; 31: 3162-3163 Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar , 2 Frenette L Cox J Singer D et al. Five years of experience with percutaneous cannula for establishing venous bypass access in orthotopic liver transplantation. Transplant Proc. 1996; 28: 2974-2977 PubMed Google Scholar , 3 Manas DM Gibbs P Talbot D et al. Use of percutaneously placed catheters for venovenous bypass in orthotopic liver transplantation. Transplantation. 1996; 62: 144-145 Crossref PubMed Scopus (3) Google Scholar , 4 Spiekermann BF Bogdonoff DL Hershey JE McLaughlin JD A method for percutaneous cannulation for veno-veno bypass during orthotopic liver transplantation. Anesth Analg. 1995; 80: 432-433 PubMed Google Scholar , 5 Scherer R Erhard J Giebler R et al. Percutaneous portofemoro-subclavian venovenous bypass during orthotopic liver transplantation. Transplantation. 1994; 57: 472-473 Crossref PubMed Google Scholar , 6 Scherer R Giebler R Schmutzler M et al. Effect of high shunt flows during portofemoro-subclavian venovenous bypass in human orthotopic liver transplantation. Transplant Proc. 1993; 25: 2591 PubMed Google Scholar , 7 Washburn WK Lewis WD Jenkins RL Percutaneous venovenous bypass in orthotopic liver transplantation. Liver Transpl Surg. 1995; 1: 377-382 Crossref PubMed Scopus (9) Google Scholar , 8 Ozaki CR Langnas AN Bynon JS et al. A percutaneous method for venovenous bypass in liver transplantation. Transplantation. 1994; 57: 472-473 Crossref PubMed Google Scholar , 9 Scherer R Giebler R Erhard J et al. A new method of veno-venous bypass during human orthotopic liver transplantation. Anaesthesia. 1994; 49: 398-402 Crossref PubMed Scopus (15) Google Scholar , 10 Johnson SR Marterre WF Alonso MH Hanto DW A percutaneous technique for venovenous bypass in orthotopic cadaver liver transplantation and comparison with the open technique. Liver Transpl Surg. 1996; 2: 354-361 Crossref PubMed Scopus (16) Google Scholar Although these reports all use at least 1 percutaneous cannula in the VVB circuit, they vary in their choice of cannulation sites, types and sizes of percutaneous cannulae, and VVB circuit configuration. The authors' VVB technique also varies from what has been reported. The authors routinely insert percutaneously a left femoral venous drainage cannula and a right internal jugular (RIJ) venous return cannula. The RIJ cannula serves a dual role as the major conduit for intravenous infusions from the rapid infusion system (RIS) (Haemonetics Corporation, Braintree, MA); this eliminates the need for additional large-bore intravenous access. In the following case, an unusually high VVB flow rate limited the maximal intravenous infusion rate of the RIS.

Veno-venous bypass in liver transplantation: heparin-coated perfusion circuits reduce the activation of humoral defense systems in an in vitro model.

We studied the effects of bypass circuit surface heparinization on kallikrein-kinin, coagulation, fibrinolytic and complement activation in a closed model system for simulating veno-venous bypass (WBP) in orthotopic liver transplantation (OLT). The circuits were identical to those in routine use during clinical OLT in our institution. Fresh whole human blood diluted 1:2 with Ringer's acetate was circulated at a non-pulsatile flow (2 l/min) and at a constant temperature (37.5 degrees C) for 12 h. In 10 experiments, the entire inner surface of the circuits was coated with end-point attached heparin (HC). In the remaining 10, non-treated PVC tubing was used (NC). Components of the plasma kallikrein-kinin, coagulation, fibrinolytic and complement systems were analyzed using functional techniques (chromogenic peptide substrate assays) and enzyme immunoassays at baseline, 3 and 12 h. Significant activation of the initial (C3bc) and terminal (TCC) components of the complement system were found in both the NC and HC groups after 3 and 12 h: C3bc: NC: baseline = 4 (3.5-7.7), 3 h = 17.3* (12.5-27), 12h = 31* (17.7-63.6), HC: baseline = 4.9 (3.2-6.8), 3h = 9* (6-14.4), 12h = 13.7* (7.4-18.1). TCC: NC: baseline = 0.4 (0.2-0.6), 3h = 5*(0.8-11.9), 12 h: 13.1* (4.2-25.7). HC: baseline = 0.5 (0.1-0.6), 3 h = 0.6* (0.1-0.8), 12 h = 1.2* (0.3-2) AU/ml; median and range (*: p < 0.05). The C3bc and TCC concentrations were significantly higher in the NC group at 3 and 12 h, compared to the HC group: C3bc (NC vs. HC group): 3 h, p < 0.001; 12 h, p < 0.001. TCC (NC vs. HC group): 3h, p < 0.001; 12 h, p < 0.001. Significant increases in the values of thrombin-antithrombin complexes (p = 0.003), prothrombin fragment 1 + 2 (p = 0.006) and plasmin-alpha2-antiplasmin complexes (p = 0.016) were found in the non-coated group, but not in the heparin-coated group during the observation period, showing that the coagulation and fibrinolytic systems were activated in the non-coated circuits. We conclude that heparin-coating of the internal surface of the extracorporeal perfusion circuit used for WBP reduces activation of the plasma cascade systems in a closed venous system in vitro.

Coagulability and fibrinolytic changes during veno-venous bypass in liver transplantation.

In clinical liver transplantation, a venous bypass that rechannels the blood flow from the inferior vena cava and portal vein to the superior vena cava has been used to maintain the venous return. However, the usage of mechanical shunt has given rise to derangements of blood coagulability and fibrinolysis. Therefore, changes of coagulability and fibrinolysis during the venous bypass were examined in dogs using a centrifugal pump (Bio-Pump), and the effect of gabexate mesilate for coagulation were studied. Venous bypass from the inferior vena cava and the portal vein to the external jugular vein was performed in mongrel dogs (group A: bypass without pump, group B: bypass with the Bio-Pump, group C: bypass with the Bio-Pump and the addition of gabexate mesilate). In group A, blood pressure gradually decreased, but in groups B and C it maintained the pre-bypass level. All results of coagulation parameters and fibrinolytic measurements of group B were not significantly different from those of group A; only partial thromboplastin time was prolonged in group B. However, this prolongation was effectively prevented by the addition of gabexate mesilate in group C.