Hepatic artery thrombosis after liver transplantation: more than just a surgical complication?

Impact of donor age on short-term outcomes after pediatric split liver transplantation

Background

Donor shortage is an important limitation of liver transplantation (LT). Split liver transplantation (SLT) may increase the sources of donors and reduce the problem of organ shortage. However, there are no standard criteria of the selection of SLT donor, especially regarding the donor age.

Methods

We retrospectively analyzed the clinical data of children who received initial SLT between January 2015 and December 2021. Based on the age of donors, the patients were divided into groups A (1-10 years old; n = 26), B (10-45 years old; n = 87), and C (45-55 years old; n = 27). The short-term (<1 year after SLT) outcomes of the recipients were analyzed.

Results

A total of 140 patients received SLT from 122 donors. The 1-, 3- and 12-month patient survival rates in group A were 100.0%, and the graft survival rates were 92.3%. The 1-, 3- and 12-month survival rates of patient and graft in group B were 97.7%, 96.6%, and 95.0%, respectively, and in group C were 85.2%, 85.2%, and 81.1%, respectively. The patient survival rate was significantly lower in group C than in groups A and B (p = 0.0082). There was no significant difference in graft survival between the three groups (p = 0.0545).

Conclusions

Similar results were obtained for pediatric SLT with donors <10 years old and 10-45 years old. Pediatric SLT can be performed with older donors (45-55 years) after strict donor selection and selection of appropriate recipients.

RISK FACTORS ASSOCIATED WITH HEPATIC ARTERY THROMBOSIS: ANALYSIS OF 1050 LIVER TRANSPLANTS

Background:

Hepatic artery thrombosis is an important cause of graft loss and ischemic biliary complications. The risk factors have been related to technical aspects of arterial anastomosis and non-surgical ones.

Aim:

To evaluate the risk factors for the development of hepatic artery thrombosis.

Methods:

The sample consisted of 1050 cases of liver transplant. A retrospective and cross-sectional study was carried out, and the variables studied in both donor and recipient.

Results:

Univariate analysis indicated that the variables related to hepatic artery thrombosis are: MELD (p=0.04) and warm time ischemia (p=0.005). In the multivariate analysis MELD=14.5 and warm ischemia time =35 min were independent risk factors for hepatic artery thrombosis. In the prevalence ratio test for analysis of the anastomosis as a variable, it was observed that patients with continuous suture had an increase in thrombosis when compared to interrupted suture.

Conclusions:

Prolonged warm ischemia time, calculated MELD and recipient age were independent risk factors for hepatic artery thrombosis after liver transplantation in adults. Transplanted patients with continuous suture had an increase in thrombosis when compared to interrupted suture. Re-transplantation due to hepatic artery thrombosis was associated with higher recipient mortality.

Risk factors of hepatic artery thrombosis in pediatric deceased donor liver transplantation

PURPOSE

Hepatic artery thrombosis (HAT) remains a life-threatening complication in liver transplantation. We aim to investigate the risk factors of HAT in deceased donor pediatric liver transplantation.

METHODS

104 recipients from 2014 to 2016 were enrolled; donor and recipient characteristics, surgical variables, graft and recipient survival rate were compared between recipients with or without HAT. Univariate and multivariate analysis were applied to identify the risk factors of HAT.

RESULTS

The recipient survival rate was 87.0% and 96.3% at 1 year, and 87.0% and 96.3% at 3 years in HAT and non-HAT groups without significant difference. The graft survival rate was 73.9% and 96.3% at 1 year, and 73.9% and 95.1% at 3 years in HAT and non-HAT groups; significant difference was observed between two groups at both 1 and 3 years. Donor age less than 8.5 months, graft weight less than 190 g and GRWR less than 2.2% were identified as independent risk factors for HAT. Recipients with HAT were associated with higher incidence of post-operative biliary complications.

CONCLUSIONS

Young donor age and small liver graft are risk factors for HAT in deceased donor pediatric liver transplantation.

Perioperative Thromboelastometry for Adult Living Donor Liver Transplant Recipients with a Tendency to Hypercoagulability: A Prospective Observational Cohort Study

Background

Hypercoagulability can lead to serious thromboembolic events. The aim of this study was to assess the perioperative coagulation status in liver transplant recipients with a tendency to hypercoagulability.

Methods

In a prospective observational study (South African Cochrane Registry 201405000814129), 151 potential liver transplant recipients were screened for thrombophilic factors from October 2014 to June 2017, and 57 potential recipients fulfilled the inclusion criterion of presenting two or more of the following thrombophilic factors: low protein C, low protein S, low anti-thrombin, increased homocystein, increased antiphospholipid IgG/IgM antibodies, increased lupus anticoagulant, and positive Factor V Leiden mutation. Seven patients were excluded from the study because they fulfilled the exclusion criteria of cancelling the liver transplantation, oral anticoagulation, or intraoperative treatment with rFVIIa. Accordingly, 50 patients were included in the final analysis. Thromboelastometry (ROTEM) (EXTEM, INTEM and FIBTEM) and conventional coagulation tests (CCT) were performed preoperatively, during the anhepatic phase, post reperfusion, and on postoperative days (POD) 1, 3 and 7. ROTEM was used to guide blood product transfusion. Heparin was infused (60-180 U/kg/day) postoperatively for 3 days and then was replaced by low-molecular-weight heparin (20 mg/12 h).

Results

FIBTEM MCF significantly increased postoperatively above reference range on POD 7 despite normal fibrinogen plasma concentrations (p < 0.05). Both EXTEM and INTEM demonstrated significant changes with the phases of transplantation (p < 0.05), but with no intra- or postoperative hypercoagulability observed. INTEM CT (reference range, 100-240 s) normalized on POD 3 and 7 (196.1 ± 69.0 and 182.7 ± 63.8 s, respectively), despite prolonged aPTT (59.7 ± 18.7 and 46.4 ± 15.7 s, respectively; reference range, 20-40 s). Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) were reported in 12.0% and 2.0%, respectively, mainly after critical care discharge and with high FIBTEM MCF values in 57% on POD 3 and 86% on POD 7. Receiver operating characteristics curve analyses of FIBTEM MCF were significant predictors for thromboembolic events with optimum cut-off, area under the curve and standard error on POD 3 (>23 mm, 0.779 and 0.097; p = 0.004) and POD 7 (>28 mm, 0.706 and 0.089; p = 0.020). Red blood cells (mean ± SD, 8.68 ± 5.81 units) were transfused in 76%, fresh frozen plasma (8.26 ± 4.14 units) in 62%, and cryoprecipitate (12.0 ± 3.68 units) in 28% of recipients. None of the recipients received intraoperative platelet transfusion or any postoperative transfusion. Main transplant indication was hepatitis C infection in 82%. 76% of recipients included in this highly selected patient population showed increased lupus anticoagulant, 2% increased antiphospholipid IgG/IgM antibodies, 20% increased homocysteine, 74% decreased anti-thrombin, 78% decreased protein C, 34% decreased protein S, and 24% a positive Factor V Leiden mutation. Overall 1-year survival was 62%.

Conclusion

A significant postoperative step-wise increase in FIBTEM MCF beyond the reference range was observed despite normal fibrinogen plasma concentrations, and FIBTEM MCF was a predictor for thromboembolic events in this study population, particularly after POD 3 and 7 on surgical wards when CCTs failed to detect this condition. However, the predictive value of FIBTEM MCF for postoperative HAT and PVT needs to be confirmed in a larger patient population. A ROTEM-guided anticoagulation regime needs to be developed and investigated in future studies.

Perioperative Thromboelastometry for Adult Living Donor Liver Transplant Recipients with a Tendency to Hypercoagulability: A Prospective Observational Cohort Study

Background

Hypercoagulability can lead to serious thromboembolic events. The aim of this study was to assess the perioperative coagulation status in liver transplant recipients with a tendency to hypercoagulability.

Methods

In a prospective observational study (South African Cochrane Registry 201405000814129), 151 potential liver transplant recipients were screened for thrombophilic factors from October 2014 to June 2017, and 57 potential recipients fulfilled the inclusion criterion of presenting two or more of the following thrombophilic factors: low protein C, low protein S, low anti-thrombin, increased homocystein, increased antiphospholipid IgG/IgM antibodies, increased lupus anticoagulant, and positive Factor V Leiden mutation. Seven patients were excluded from the study because they fulfilled the exclusion criteria of cancelling the liver transplantation, oral anticoagulation, or intraoperative treatment with rFVIIa. Accordingly, 50 patients were included in the final analysis. Thromboelastometry (ROTEM) (EXTEM, INTEM and FIBTEM) and conventional coagulation tests (CCT) were performed preoperatively, during the anhepatic phase, post reperfusion, and on postoperative days (POD) 1, 3 and 7. ROTEM was used to guide blood product transfusion. Heparin was infused (60-180 U/kg/day) postoperatively for 3 days and then was replaced by low-molecular-weight heparin (20 mg/12 h).

Results

FIBTEM MCF significantly increased postoperatively above reference range on POD 7 despite normal fibrinogen plasma concentrations (p < 0.05). Both EXTEM and INTEM demonstrated significant changes with the phases of transplantation (p < 0.05), but with no intra- or postoperative hypercoagulability observed. INTEM CT (reference range, 100-240 s) normalized on POD 3 and 7 (196.1 ± 69.0 and 182.7 ± 63.8 s, respectively), despite prolonged aPTT (59.7 ± 18.7 and 46.4 ± 15.7 s, respectively; reference range, 20-40 s). Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) were reported in 12.0% and 2.0%, respectively, mainly after critical care discharge and with high FIBTEM MCF values in 57% on POD 3 and 86% on POD 7. Receiver operating characteristics curve analyses of FIBTEM MCF were significant predictors for thromboembolic events with optimum cut-off, area under the curve and standard error on POD 3 (>23 mm, 0.779 and 0.097; p = 0.004) and POD 7 (>28 mm, 0.706 and 0.089; p = 0.020). Red blood cells (mean ± SD, 8.68 ± 5.81 units) were transfused in 76%, fresh frozen plasma (8.26 ± 4.14 units) in 62%, and cryoprecipitate (12.0 ± 3.68 units) in 28% of recipients. None of the recipients received intraoperative platelet transfusion or any postoperative transfusion. Main transplant indication was hepatitis C infection in 82%. 76% of recipients included in this highly selected patient population showed increased lupus anticoagulant, 2% increased antiphospholipid IgG/IgM antibodies, 20% increased homocysteine, 74% decreased anti-thrombin, 78% decreased protein C, 34% decreased protein S, and 24% a positive Factor V Leiden mutation. Overall 1-year survival was 62%.

Conclusion

A significant postoperative step-wise increase in FIBTEM MCF beyond the reference range was observed despite normal fibrinogen plasma concentrations, and FIBTEM MCF was a predictor for thromboembolic events in this study population, particularly after POD 3 and 7 on surgical wards when CCTs failed to detect this condition. However, the predictive value of FIBTEM MCF for postoperative HAT and PVT needs to be confirmed in a larger patient population. A ROTEM-guided anticoagulation regime needs to be developed and investigated in future studies.

Impact of early reoperation on graft survival after liver transplantation: Univariate and multivariate analysis

BACKGROUND

Data on rate, risk factors, and consequences of early reoperation after liver transplantation are still limited.

STUDY DESIGN

Single-center retrospective analysis of data of 428 patients, who underwent liver transplantation in period between January 2009 and December 2014. Univariate and multivariate analysis were used to study the risk factors of early reoperation and its impact on graft survival.

RESULTS

Of 428 patients, 74 (17.3%) underwent early reoperation. Of them, 46 (62.2%) underwent reoperation within the first week and 28 (37.8%) underwent reoperation later than 1 week after transplantation. With multivariate analysis, significant risk factors of early reoperation included pretransplant ICU admission, previous abdominal surgery and diabetes. Early reoperation itself was not found to be an independent predictor of graft loss. However, early reoperation later than 7 days from transplant was found to be independent predictor of graft loss (odds ratio [OR] = 5.125; 95% CI, 1.358-19.552; P = .016). In our series, other independent predictors of graft loss were MELD score (P = .010) and operative time (P = .048).

CONCLUSIONS

This analysis demonstrates that early reoperations later than a week appear to negatively impact the graft survival. The timing of early reoperation should be a focus of additional studies.

Liver transplantation in transthyretin amyloidosis: issues and challenges

Hereditary transthyretin amyloidosis (ATTR) is a rare worldwide autosomal dominant disease caused by the systemic deposition of an amyloidogenic variant of transthyretin (TTR), which is usually derived from a single amino acid substitution in the TTR gene. More than 100 mutations have been described, with V30M being the most prevalent. Each variant has a different involvement, although peripheral neuropathy and cardiomyopathy are the most common. Orthotopic liver transplantation (OLT) was implemented as the inaugural disease-modifying therapy because the liver produces the circulating unstable TTR. In this review, we focus on the results and long-term outcomes of OLT for ATTR after more than 2063 procedures and 23 years of experience. After successful OLT, neuropathy and organ impairment are not usually reversed, and in some cases, the disease progresses. The overall 5-year survival rate is approximately 100% for V30M patients and 59% for non-ATTR V30M patients. Cardiac-related death and septicemia are the main causes of mortality. Lower survival is related to malnutrition, a longer duration of disease, cardiomyopathy, and a later onset (particularly for males). Deposits, which are composed of a mixture of truncated and full-length TTR (type A) fibrils, have been associated with posttransplant myocardial dysfunction. A higher incidence of early hepatic artery thrombosis of the graft has also been documented for these patients. Liver-kidney/heart transplantation is an alternative for patients with advanced renal disease or heart failure. The sequential procedure, in which ATTR livers are reused in patients with liver disease, reveals that neuropathy in the recipient may appear as soon as 6 years after OLT, and ATTR deposits may appear even earlier. Long-term results of trials with amyloid protein stabilizers or disrupters, silencing RNA, and antisense oligonucleotides will highlight the value and limitations of liver transplantation.

Impact of early reoperation following living-donor liver transplantation on graft survival

BACKGROUND

The reoperation rate remains high after liver transplantation and the impact of reoperation on graft and recipient outcome is unclear. The aim of our study is to evaluate the impact of early reoperation following living-donor liver transplantation (LDLT) on graft and recipient survival.

METHODS

Recipients that underwent LDLT (n = 111) at the University of Tokyo Hospital between January 2007 and December 2012 were divided into two groups, a reoperation group (n = 27) and a non-reoperation group (n = 84), and case-control study was conducted.

RESULTS

Early reoperation was performed in 27 recipients (24.3%). Mean time [standard deviation] from LDLT to reoperation was 10 [9.4] days. Female sex, Child-Pugh class C, Non-HCV etiology, fulminant hepatitis, and the amount of intraoperative fresh frozen plasma administered were identified as possibly predictive variables, among which females and the amount of FFP were identified as independent risk factors for early reoperation by multivariable analysis. The 3-, and 6- month graft survival rates were 88.9% (95%confidential intervals [CI], 70.7-96.4), and 85.2% (95%CI, 66.5-94.3), respectively, in the reoperation group (n = 27), and 95.2% (95%CI, 88.0-98.2), and 92.9% (95%CI, 85.0-96.8), respectively, in the non-reoperation group (n = 84) (the log-rank test, p = 0.31). The 12- and 36- month overall survival rates were 96.3% (95%CI, 77.9-99.5), and 88.3% (95%CI, 69.3-96.2), respectively, in the reoperation group, and 89.3% (95%CI, 80.7-94.3) and 88.0% (95%CI, 79.2-93.4), respectively, in the non-reoperation group (the log-rank test, p = 0.59).

CONCLUSIONS

Observed graft survival for the recipients who underwent reoperation was lower compared to those who did not undergo reoperation, though the result was not significantly different. Recipient overall survival with reoperation was comparable to that without reoperation. The present findings enhance the importance of vigilant surveillance for postoperative complication and surgical rescue at an early postoperative stage in the LDLT setting.

Splenic Artery Syndrome after orthotopic liver transplantation: a review

Splenic Artery Syndrome (SAS) has emerged as a controversial cause for graft ischemia in orthotopic liver transplant (OLTx) recipients. A complex combination of factors including hepatic artery hypoperfusion and portal hyperperfusion can result in SAS. Clinical and laboratory findings suggest graft ischemia but are generally non-specific. Conventional angiography findings of hepatic artery hypoperfusion with early and rapid filling of the splenic artery are suggestive of the diagnosis in the appropriate clinical setting. Treatment involves proximal splenic artery embolization, surgical splenic artery ligation, or in extreme cases, splenectomy. Most patients with SAS improve clinically following treatment. However, no randomized control trials are available to compare treatment options. Identification of at risk patients with pre-operative CT scans and intra-operative ultrasound has been proposed by some and may allow for prophylactic treatment of SAS.

Clinical utility of viscoelastic tests of coagulation in patients with liver disease

The prothrombin time (PT) and international normalised ratio (INR) are used in scoring systems (Child-Pugh, MELD, UKELD) in chronic liver disease and as a prognostic tool and for dynamic monitoring of hepatic function in acute liver disease. These tests are known to be poor predictors of bleeding risk in liver disease; however, they continue to influence clinical management decisions. Recent work on coagulation in liver disease, in particular thrombin generation studies, has led to a paradigm shift in our understanding and it is now recognised that haemostasis is relatively well preserved. Whole blood global viscoelastic tests (TEG(®) /ROTEM(®) ) produce a composite dynamic picture of the entire coagulation process and have the potential to provide more clinically relevant information in patients with liver disease. We performed a systematic review of all relevant studies that have used viscoelastic tests (VET) of coagulation in patients with liver disease. Although many studies are observational and small in size, it is clear that VET provide additional information that is in keeping with the new concepts of how coagulation is altered in these patients. This review provides the basis for large scale, prospective outcome studies to establish the clinical value of these tests.

Hepatic artery kinking during liver transplantation: survey and prospective intraoperative flow measurement

BACKGROUND

Hepatic artery thrombosis (HAT) represents the most common vascular complication occurring after liver transplantation (LT). Herein, we report the results of a prospective study of hepatic artery flow (HAF) measurement during abdominal wall closure after LT along with the results of an international survey of procedures adopted, in order to avoid the arterial kinking (AK) in case of long artery.

METHODS

Sixty-four surgeons were asked regarding the different procedures used to avoid AK in the presence of long artery. We prospectively assessed the HAF during three phases of LT in 26 consecutive LT performed in patients with a long HA: after completion of the biliary anastomosis (M0), and partial abdominal wall closure with (M1w) or without (M1w/o) hepatic artery anti-kinking method (HAAK).

RESULTS

Sixty (93.7 %) surgeons replied to the survey: 44 (73.3 %) surgeons cut the artery as short as possible, of whom 38 (86.3 %) interposed an oxidized polymer or the omentum, and six (13.7 %) used other systems. Fourteen (23.3 %) surgeons did not use any interposition methods. The remaining two (3.3 %) surgeons left a long artery without HAAK. In our cohort we obtained the following HAF measures: M0 152 mL/min (89-205), M1 without HAAK 114 (66-168) and M1 with HAAK procedure 158 (91-219) (p = 0.002).

CONCLUSIONS

Our survey confirms that no consensus is currently available regarding the most effective method for avoiding AK. Kinking occurs most probably when the liver is released in its final position. The utilization of an interposition method could ensure the maintenance of a correct HAF.

The impact of perioperative transfusion of blood products on survival after pediatric liver transplantation

Intraoperative transfusion of red blood cells (RBC) is associated with adverse outcome after LT in adult patients. This relationship in pediatric patients has not been studied in depth, and its analysis is the scope of this study. Forty-one variables associated with outcome, including blood product transfusions, were studied in a cohort of 243 pediatric patients undergoing a cadaveric LT between 2002 and 2009 at the General Hospital of Bergamo. Multivariate stepwise Cox proportional hazards models were adopted with adjustment by propensity scores to minimize factors associated with the use of blood products. Median age at transplant was 1.37 yr. In uni- and multivariate analyses, perioperative transfusion of FFP and RBC was an independent risk factor for predicting one-yr patient and graft survival. The effect on one-yr survival was dose-related with a hazard ratio of 3.15 for three or more units of RBC (p = 0.033) and 3.35 for three or more units of FFP (p = 0.021) when compared with 1 or no units transfused. The negative impact of RBC and FFP transfusion was confirmed by propensity score-adjusted analysis. These findings may have important implications for transfusion practice in the LT pediatric recipients.

Prediction of early hepatic artery thrombosis by intraoperative color Doppler ultrasound in pediatric segmental liver transplantation

Early hepatic artery thrombosis (eHAT) after transplantation is associated with a high incidence of graft failure and mortality in pediatric segmental liver transplantation (LT). The evaluation of intraoperative color Doppler ultrasound (CD-US) parameters and their sensitivity and specificity for the prediction of eHAT were important. Pediatric segmental LTs were performed in 49 consecutive patients from October 2006 to December 2010 in our hospital. A total of seven patients (14.3%) experienced eHAT (within one month) after LT. The intraoperative hepatic artery (HA) diameter (p = 0.026), hepatic arterial peak systolic velocity (HAPSV) (p = 0.006), and hepatic artery resistance index (HARI) (p = 0.000) had significant difference between eHAT group and non-eHAT group. Taking a HA diameter <2 mm, a HAPSV of <40 cm/s and a HARI of <0.6 as threshold to predict eHAT, the sensitivity and specificity were 85.7%, 85.7%, 85.7%, and 61.9%, 76.2%, 88.1%, respectively. A HARI of <0.6 was shown to be the most sensitive and specific single parameter for predicting eHAT.

Recipient and donor thrombophilia and the risk of portal venous thrombosis and hepatic artery thrombosis in liver recipients

Background

Vascular complications, such as HAT, are an important cause of graft loss and recipient mortality. We aimed to characterize post-transplant thrombotic events in a cohort of liver transplant recipients, and identify independent risk factors for these complications.

Methods

We conducted a thrombophilic study of 293 orthotopic liver transplants performed in the Digestive Surgery Department of the 12 de Octubre Hospital (Madrid, Spain) between January 2001 and December 2006.

Results

The most frequent post-transplant thrombotic events were HAT (9%) and PVT (1.7%). The one variable associated with post-transplant thrombotic event was a high fibrinogen level in the global cohort of liver transplantation. But toxicity as event post-OLT has been associated with post-transplant thrombotic event in the retrospective group and high fibrinogen level and low protein C levels were associated post-transplant thrombotic event in the prospective group. Liver disease relapse (HR 6.609, p < 0.001), high levels of FVIII (HR 1.008, p = 0.019)) and low levels of antithrombin (HR 0.946, p < 0.001) were associated with poor overall survival (OS).

In conclusion, high fibrinogen and decreased protein C levels were associated with allograft thrombosis. Further studies are required in order to assess the clinical relevance of these parameters in prospective studies and to study the effect of anticoagulation prophylaxis in this group of risk.

Long-term management of the liver transplant recipient: pearls for the practicing gastroenterologist

Liver transplantation is becoming more common and patients are surviving longer after transplantation. Special care must be paid to the long-term management of these patients because they are at increased risk for medical problems, malignancies, and adverse effects from immunosuppression. A stable and continuing relationship must be developed between the physician and the patient to optimize the long-term outcomes for these individuals.

Liver transplantation and spontaneous neovascularization after arterial thrombosis: "the neovascularized liver"

The only arterial pathway available after liver transplantation is the hepatic artery. Therefore, hepatic artery thrombosis can result in graft loss necessitating re-transplantation. Herein, we present evidence of neovascularization at long-term follow-up in a series of transplant patients with hepatic artery thrombosis. We termed this phenomenon "neovascularized liver". Hepatic artery thrombosis was noted in 30/407 cases (7.37%), and occurred early in 13 patients (43.3%) and late (>30 days) in 17 (56.7%) patients. At the time of this study, 11 (36.7%) patients had a neovascularized liver. Those patients with neovascularized liver and normal liver function were closely followed. Of these patients, 10 (91%) showed evidence of neovascularized liver by imaging, and an echo-Doppler arterial signal was recorded in all patients. The mean interval between the diagnosis of hepatic artery thrombosis and neovascularized liver was 4.1 months (range of 3-5.5 months). Liver histology showed an arterial structure in 4 (36.4%) patients. Four factors were associated with development of neovascularized liver: late hepatic artery thrombosis, early hepatic artery stenosis, site of thrombosis, and Roux-en-Y anastomosis. The overall survival rate at 54 months was 90.9%. In conclusion, a late hepatic artery thrombosis may be quite uneventful and should not automatically lead to re-transplantation.

Risk factors associated with early hepatic artery thrombosis after orthotopic liver transplantation - univariable and multivariable analysis

Hepatic artery thrombosis (HAT) is a serious complication in patients undergoing orthotopic liver transplantation (OLT). It is associated with a high graft loss and mortality rate. In this study, possible risk factors associated with early HAT (occurring within the first postoperative month) were evaluated using univariable and multivariable analyses. Nine-hundred-and-fourteen consecutive OLTs in our institution were examined by univariable and multivariable analyses. Early HAT occurred in 43 patients (4.7%). Graft number, abnormal donor arterial anatomy, bench arterial reconstruction, aortic conduit use, multiple anastomoses, reperfusion time (interval between portal vein reperfusion and restoration of arterial flow) and the number of units of blood received intraoperatively were significantly associated with early HAT in the univariable analysis(P<0.1). These variables were included in a multivariable regression model which showed that bench arterial reconstruction was associated with a fourfold risk of early HAT(P<0.0001), whereas each additional 10min delay in reperfusion was associated with a 27% increase in the risk of early HAT (P<0.04). The main risk factors associated with early HAT are abnormal arterial anatomy in the graft requiring bench reconstruction and a delay in arterial reperfusion. Early recognition of these factors, strict surveillance protocols with arterial Doppler and selective anticoagulation for patients at risk need to be evaluated prospectively.

Vascular complications after deceased and living donor liver transplantation: a single-center experience

INTRODUCTION

Vascular complications (VC) after liver transplantation (OLT) are one of the most feared problems that frequently result in graft and patient loss. Herein we have reported our experience with VC after either deceased donor liver transplantation (DDLT) or living donor liver transplantation (LDLT).

PATIENTS AND METHODS

Between April 2001 and September 2009, we performed 224 OLT: 155 DDLT and 69 LDLT. The overall male/female ratio was 136/88 and the adult/pediatric ratio was 208/16. We retrospectively identified and analyzed vascular complications in both groups.

RESULTS

In the DDLT group, 11/155 recipients (7%) suffered vascular complications; hepatic artery thrombosis (HAT; n=5; 3.2%), portal vein thrombosis occurred (n=4; 2.6%); hepatic vein stenosis (n=1; 0.6%), and severe postoperative bleeding due to a slipped splenic artery ligature (n=1, 0.6%). In the DDLT group, 4/11 (36.4%) patients died as a direct result of the vascular complications. In the LDLT group, 9/69 recipients (13%) suffered vascular complications: HAT (n=3; 4.3%), portal vein problems (n=5; 7.2%), and hepatic vein stenosis (n=1; 1.5%). Among LDLT, 3/9 (33.3%) patients died as a direct result of the vascular complications. In both groups vascular complications were associated with poorer patient and graft survival.

CONCLUSIONS

In our experience, the incidence of vascular complications was significantly higher among the LDLT group compared with the DDLT group. Vascular complications were associated with poorer graft and patient survival rates in both groups.

Hemostasis and thrombosis in patients with liver disease: the ups and downs

Patients with chronic or acute liver failure frequently show profound abnormalities in their hemostatic system. Whereas routine laboratory tests of hemostasis suggest these hemostatic alterations result in a bleeding diathesis, accumulating evidence from both clinical and laboratory studies suggest that the situation is more complex. The average patient with liver failure may be in hemostatic balance despite prolonged routine coagulation tests, since both pro- and antihemostatic factors are affected, the latter of which are not well reflected in routine coagulation testing. However, this balance may easily tip towards a hypo- or hypercoagulable situation. Indeed, patients with liver disease may encounter both hemostasis-related bleeding episodes as well as thrombotic events. During the 3rd International Symposium on Coagulopathy and Liver disease, held in Groningen, The Netherlands (18-19 September 2009), a multidisciplinary panel of experts critically reviewed the current data concerning pathophysiology and clinical consequences of hemostatic disorders in patients with liver disease. Highlights of this symposium are summarized in this review.

Rebalanced hemostasis in patients with liver disease: evidence and clinical consequences

Patients with liver disease frequently acquire a complex disorder of hemostasis secondary to their disease. Routine laboratory tests such as the prothrombin time and the platelet count are frequently abnormal and point to a hypocoagulable state. With more sophisticated laboratory tests it has been shown that patients with liver disease may be in hemostatic balance as a result of concomitant changes in both pro- and antihemostatic pathways. Clinically, this rebalanced hemostatic system is reflected by the large proportion of patients with liver disease who can undergo major surgery without any requirement for blood product transfusion. However, the hemostatic balance in the patient with liver disease is relatively unstable as evidenced by the occurrence of both bleeding and thrombotic complications in a significant proportion of patients. Although it is still common practice to prophylactically correct hemostatic abnormalities in patients with liver disease before invasive procedures by administration of blood products guided by the prothrombin time and platelet count, we believe that this policy is not evidence-based. In this article, we will provide arguments against the traditional concept that patients with liver failure have a hemostasis-related bleeding tendency. Consequences of these new insights for hemostatic management will be discussed.

Normal to increased thrombin generation in patients undergoing liver transplantation despite prolonged conventional coagulation tests

BACKGROUND & AIMS

Patients with liver disease often show substantial changes in their hemostatic system, which may aggravate further during liver transplantation. Recently, thrombin generation in patients with stable disease was shown to be indistinguishable from controls provided thrombomodulin, the natural activator of the anticoagulant protein C system, was added to the plasma. These results indicated that the hemostatic balance is preserved in patients with liver disease, despite conventional coagulation tests suggest otherwise.

METHODS

Here we examined thrombin generation profiles in serial plasma samples taken from ten consecutive patients undergoing liver transplantation.

RESULTS

At all time points, the endogenous thrombin potential (ETP) was slightly lower compared to healthy volunteers, despite substantially prolonged PT and APTT values. However, when thrombin generation was tested in the presence of thrombomodulin, the ETP was equal to or even higher than that in healthy subjects. In fact, thrombin generation was hardly affected by thrombomodulin, while thrombin generation in healthy subjects decreased profoundly upon the addition of thrombomodulin. In patients undergoing liver transplantation, efficient thrombin generation in the presence of thrombomodulin may be explained by decreased levels of protein C, S, and antithrombin, and by elevated levels of FVIII.

CONCLUSIONS

Thrombin generation in patients undergoing liver transplantation is equal or even superior to thrombin generation in healthy volunteers when tested in the presence of exogenous thrombomodulin. These results support the recently advocated restrictive use of plasma during liver transplantation and warrants further study of the prophylactic use of anticoagulants to reduce thromboembolic complications after transplantation.

Vascular complications of orthotopic liver transplantation: experience in more than 4,200 patients

BACKGROUND

Thromboses of the hepatic artery (HAT) and portal vein (PVT) may complicate orthotopic liver transplantation (OLT) and result in graft loss and mortality. Revision and retransplantation are treatment options, but their longterm outcomes remain undefined. This study was undertaken to evaluate the incidence of major vascular complications after OLT, determine efficacy of therapies, and identify factors influencing longterm outcomes.

STUDY DESIGN

All patients undergoing OLT from 1984 to 2007 were evaluated. Kaplan-Meier analysis was performed to define the effects of vascular complications on posttransplant survival. Anastomotic revision and arterial thrombolysis were compared with retransplantation as treatment for HAT. After 2002, porta hepatis dissection was initiated with early occlusion of common hepatic artery (CHA) inflow; its impact on HAT incidence was determined.

RESULTS

From 1984 to 2007, 4,234 OLTs were performed. HAT occurred in 203 patients (5%) and PVT in 84 (2%). Graft survival was significantly reduced by HAT or PVT; patient survival was reduced only by PVT. Retransplantation for HAT improved patient survival over revision or thrombolysis in the first year but did not provide longterm survival advantage (56% versus 56% at 5 years; p=0.53). Patients with HAT had only 10% graft salvage with anastomotic revision or thrombolysis. HAT was significantly reduced with early CHA inflow occlusion (1.1% versus 3.7%; p=0.002). Factors increasing risk of HAT included pediatric recipients, liver cancer, and aberrant arterial anatomy requiring complex reconstruction.

CONCLUSIONS

Both HAT and PVT significantly reduce graft survival after OLT; PVT more adversely affects patient survival. Revision and thrombolysis rarely salvage grafts after HAT; retransplantation provides superior short-term, but not longterm, survival. Avoidance of vascular complications in OLT is critical, especially with today's scarcity of donor livers. Early atraumatic CHA occlusion significantly reduces the incidence of HAT.

Development of a severe von Willebrand factor/ADAMTS13 dysbalance during orthotopic liver transplantation

Patients with liver disease show profound changes in their hemostatic system, which may further change during liver transplantation. We previously demonstrated that highly elevated levels of the platelet adhesive protein von Willebrand factor (VWF) in patients with cirrhosis lead to an increased VWF-dependent platelet deposition under flow as compared to healthy controls. In this study we examined VWF parameters during the course of liver transplantation. We collected serial plasma samples from 20 patients undergoing liver transplantation in which we determined plasma levels of VWF and the VWF-cleaving protease ADAMTS13. Furthermore, we performed functional tests of VWF-dependent platelet adhesion. We found persistently elevated levels of VWF during and after liver transplantation. The capacity of VWF to interact with platelets normalized during the course of transplantation, and flow-mediated VWF-dependent platelet adhesion remained at levels far exceeding those observed in healthy individuals during and after transplantation. Plasma levels of ADAMTS13 dropped during transplantation, and in four patients levels below 10% of normal were observed after reperfusion. We observed the development of a hyperreactive primary hemostatic system, as evidenced by high levels of fully functional VWF and a temporary ADAMTS13 deficiency, during liver transplantation, and speculate that these changes contribute to postoperative thrombotic complications.