Thrombotic events after pediatric liver transplantation

Comparative analysis of whole vs. split liver transplantation in infants

BACKGROUND

Liver transplantation (LT) in infants can be challenging due to their small size and small vasculature. Although both whole LT (WLT) and split LT (SLT) have been described in infants, the head-to-head comparison of these techniques in this population is sparse.

METHODS

We retrospectively analyzed the records of all patients with age ≤1 year at Indiana University between 2016 and 2022. All SLT were left lateral segment grafts split in situ.

RESULTS

A total of 24 infants were transplanted, with 11 SLT and 13 WLT. The median follow-up time was 52.1 months. Donor and recipient characteristics were comparable except for donor age (19 years vs. 2 years; p < .01) and weight (64 kg vs. 14.2 kg; p < .01). Early allograft dysfunction, primary nonfunction, and hepatic artery thrombosis developed more frequently in the WLT group. There were no biliary complications. There were two early deaths (2 and 4 days) in the WLT group. One-year graft survival (100% vs. 77%; p = .10) and patient survival (100% vs. 85%; p = .18) were numerically higher in the SLT group.

CONCLUSIONS

SLT with LLS offers a safe and viable option for liver transplantation in infants and is associated with a trend toward superior outcomes. SLT should be considered as a strategy to reduce waitlist times for infants in the absence of small, deceased donors for WLT.

Antithrombin supplementation for prevention of vascular thrombosis after pediatric liver transplantation

AIMS

After liver transplantation (LT), synthesis of coagulation factors by the graft recovers faster for pro thrombotic than anti thrombotic factors, resulting in a potential pro thrombotic imbalance. We studied the thrombotic and hemorrhagic complications in our pediatric LT series, providing supplementation of fresh frozen plasma (FFP) and/or antithrombin (AT) in the prophylactic antithrombotic regimen.

METHODS

This was a retrospective observational single center study. All isolated pediatric LTs performed between 1/11/2009 and 31/12/2019 (n = 181) were included. Postoperatively, in addition to low molecular weight heparin, 22 patients (12%) received FFP (10 ml/kg twice daily for 10 days), 27 patients (15%) were given FFP (reduced duration) and AT (50-100 IU/kg/day if AT activity remained <70%), and 132 (73%) received AT only. Complications, outcome, and coagulation profiles in postoperative days 0-10 were analyzed.

RESULTS

In all three treatment groups, AT activity normalized by day 4 while prothrombin remained <70% of normal until day 9. Hepatic artery thrombosis (HAT), portal vein thrombosis (PVT), and hemorrhagic complications occurred in 2.8%, 3.3%, and 3.9% of LTs. One- and 5-year patient and graft survival were 88% (±2.4% Standard Error) and 84% (±2.5%), and 86% (±2.6%) and 84% (±2.7%), respectively, without difference between groups. HAT were associated with low AT on days 0 and 1, and PVT with low AT on day 0.

CONCLUSIONS

Low antithrombin activity after LT was associated with postoperative thromboses. FFP and/or AT supplementation allowed early normalization of AT activity, while thrombotic or hemorrhagic complications were rare, suggesting efficient and safe management of post-LT coagulopathy.

Early thrombotic and hemorrhagic complications associated with a risk-adjusted postoperative anticoagulation protocol after pediatric liver transplantation

BACKGROUND

Systemic anticoagulation after pediatric liver transplantation (pLT) is believed to reduce the incidence of vascular thrombosis, but it may also cause an increase in hemorrhagic complications.

PROCEDURE

A 5-year retrospective review of pLT done at our institution was performed (2014-2018). The occurrence of early hemorrhagic and thrombotic complications was compared when using low-dose or high-dose anticoagulation after transplant (p < .05 considered significant).

RESULTS

Sixty-nine patients received 73 transplants during the study period. Median age at transplant was 2.3 years (40 days to 18.5 years). Low-dose anticoagulation was utilized in 71% cases. Additionally, six patients were converted from low-dose to high-dose anticoagulation because of a thrombotic event or concerns for suboptimal vascular inflow. Postoperative anticoagulation was discontinued in 18 occurrences due to bleeding (low dose 19%, high dose 47% vs. low dose to high dose 17%, p = .085). Surgical take back for bleeding occurred in 17 occasions (low dose 13.5%, high dose 53% vs. low dose to high dose 33%, p = .005). The overall incidence of hepatic artery thrombosis (HAT) and portal vein thrombosis were each 5.5%, respectively. While patient survival was not statistically different between groups, graft survival was significantly lower in the high-dose group (low dose 93%, high dose 73% vs. low dose to high dose 100%, p = .046). However, graft losses from HAT were similar between groups (low dose 2%, high dose 7% vs. low dose to high dose 0%, p = .56).

CONCLUSION

The use of a standardized risk-adjusted anticoagulation protocol after pLT is associated with a low occurrence of thrombotic and hemorrhagic complications. High-dose anticoagulation leads to more bleeding, but those risks outweigh the risks of possible graft loss.

Practice variation in the immediate postoperative care of pediatric liver transplant patients: Framework for a national consensus

Advancements in critical care management have led to improvement in pediatric LT outcomes. However, there are no specific guidelines for many aspects of immediate post-LT care. This survey examines practice variations in the immediate postoperative care of pediatric LT patients at a large number of active US centers. This study is a cross-sectional survey of medical directors at PALISI-affiliated PICU in the United States. Centers performing pediatric LT were analyzed. Study measures included PICU practices regarding staffing, composition of the multidisciplinary team, early post-LT graft and patient monitoring, and anticoagulation. Of the thirty-five responding centers, twenty-five had a LT program which accounted for one-half of all US pediatric LTs. For analysis, centers were categorized by volume: high (7), medium (11), and low (7). The majority of PICU teams included an intensivist (80%) and hepatologist (84%). High-volume centers were less likely to have 24-hour in-house attending coverage (29%, compared to 64% (medium) and 100% (low)). High-volume centers were most likely to have pre-printed orders, but least likely to have written PICU management protocols. Most centers utilize routine daily liver ultrasound. Routine prophylactic anticoagulation, and the agent of choice, was variable. There is marked inconsistency in post-LT practice across PALISI centers in regards to team composition and immediate post-LT management. A national US consensus for post-LT PICU practices would facilitate outcomes research and would establish a platform for multicenter studies.

Perioperative fatal pulmonary embolism in a pediatric liver transplant recipient

Patients with cirrhotic liver disease are in a state of fluctuating hemostatic balance. Hepatic synthetic dysfunction is commonly complicated by coagulation disorders that constitute an important parameter of most prognostic scores. The dominant feature of this dysfunction is bleeding tendencies, but cirrhotic patients may also exhibit inappropriate clotting and pro-coagulation placing them at risk for thromboembolism. We present a case of perioperative fatal pulmonary embolism in an 8-year-old patient with biliary cirrhosis secondary to drug-induced vanishing bile duct syndrome undergoing a deceased donor liver transplant. The massive pulmonary embolism occurred intra-operatively after reperfusion of the donor liver. Despite the initiation of extracorporeal membrane oxygenation, the postoperative course was complicated by bleeding and the patient expired. This unique case highlights the need for venous thromboembolism prevention by screening and prophylaxis prior to liver transplant in at least a subpopulation of pediatric patients. While the risk of thrombosis postoperatively in pediatrics patients is well known, the preoperative risk is less frequently described and deserves attention and practice changing action.

Whole liver deceased donor liver transplantation for pediatric recipients: single-center experience for 20 years

Background

We investigated the incidence and outcomes of pediatric deceased donor liver transplantation (DDLT) using whole liver grafts in a high-volume liver transplantation (LT) center.

Methods

The study was a retrospective single-center analysis of whole LT in pediatric recipients. The study period was set as 20 years between January 2000 and December 2019. We defined pediatric recipients and donors to be aged ≤18 years.

Results

During the study period, there were 98 cases of pediatric DDLT, and 34 patients (34.7%) received whole liver grafts. The age range of the deceased donors was 3 months to 56 years and that of pediatric recipients was 7 months to 17 years. Common primary diseases for LT were biliary atresia in 13, acute liver failure in four, Wilson disease in four, congenital portal vein agenesis in three, and genetic metabolic diseases in three. Pediatric-to-pediatric and adult-to-pediatric whole LTs were 22 (64.7%) and 12 (35.3%), respectively. A good correlation was noted between the donor and the recipient’s body weight, and the recipient’s body weight and allograft’s weight. Graft and overall patient survival rates were 91.2% and 91.2% at 1 year, 88.0% and 88.0% at 3 years, and 88.0% and 88.0% at 5 years, respectively.

Conclusions

The results of this study revealed that Korean Network for Organ Sharing (KONOS) regulations with donor-recipient body weight matching exhibited good performance. Considering the reciprocal trades of liver organs among pediatric and adult donors and recipients, it is necessary to establish a policy for pediatric donor liver grafts to pediatric recipients on a priority basis.

Korea-nationwide incidence of pediatric deceased donors and single-institutional status of liver transplantation using pediatric donor liver grafts

Background

The present study intended to investigate the allocation status of pediatric deceased donor liver allografts. We analyzed the incidence of pediatric deceased donors in the Korean Network for Organ Sharing (KONOS) database and single-institutional status of liver transplantation (LT) using pediatric donors.

Methods

We assessed the nationwide incidence of pediatric donors aged ≤15 years and conducted single-center analysis of LT using pediatric donors.

Results

Between 2010 and 2019, pediatric donors aged ≤15 years accounted for 171 out of 4,395 donors (3.9%) in the KONOS database and 31 out of 640 liver donors (4.8%) in Asan Medical Center (AMC) database. In AMC, 11 (35.5%) and 20 (64.5%) grafts were allocated to pediatric recipients aged ≤15 years and adult recipients aged ≥19 years, respectively. All nine livers from donors aged ≤5 years were implanted in pediatric recipients aged ≤5 years. From 21 donors aged ≥9 years, 16 whole liver grafts and four split extended right liver grafts were implanted in 20 adult recipients and two split left lateral section grafts were implanted in two pediatric recipients. Four split liver grafts were implanted in other institutions. The overall patient survival rates at 1, 3, and 5 years were 90.9%, 80.8%, and 80.8%, respectively in pediatric-to-pediatric LT group and 69.6%, 58.4%, and 58.4%, respectively in pediatric-to-adult LT group (P=0.21).

Conclusions

More than half of the pediatric donor livers were allocated to adult patients. Recipient criteria for allocation of liver allografts from pediatric donors need revision for children on pediatric LT waitlist.

Hepatic Artery Thrombosis in Liver Transplantation in Adult Recipients Using Pediatric Deceased Donors

INTRODUCTION

Routinely, pediatric donor (PD) grafts are allocated to pediatric liver transplantation (LT) recipients; however, occasionally they can be allocated for adult recipients (ARs). Some authors reported decreased patient/graft survival and higher vascular complications, such as hepatic artery thrombosis (HAT), in LT in ARs using PDs.

METHODS

It is a retrospective study enrolling 1202 ARs undergoing LT using whole liver grafts during the period of January 2002 to April 2019. The patients were categorized according to donor age in 2 groups: PDs and adult donors (ADs). The variables were collected from the database including the graft to recipient weight ratio (GWRW) and the incidence of HAT and graft primary nonfunction (PNF).

RESULTS

The AD group had 1152 patients, and the PD group had 50 patients. PNF occurred in 68 (5.66%) patients, and the distribution between the 2 groups were similar: 65 (5.64%) in the AD group, and 3 (6%) in the PD group (P = .915). HAT was diagnosed in 30 (2.6%) patients in the AD group and in 6 (12%) patients in the PD group. HAT was significantly higher in the PD group (P = .001). In the PD group, the GWRWs among patients diagnosed with HAT were similar (P = .152).

CONCLUSION

HAT is higher in PDs, although it is a viable alternative with satisfactory results. Serial Doppler in the first week and early introduction of platelet antiaggregants and/or anticoagulants may be beneficial, albeit it is not clear if it could reduce the incidence of HAT.

Antithrombotic management and thrombosis rates in children post-liver transplantation: A case series and literature review

Thrombosis is a major postoperative complication in pediatric liver transplantation. There is marked heterogeneity in prophylactic antithrombotic therapies used, without established guidelines. This review summarizes current worldwide incidence of thrombotic events and compares antithrombotic therapies in children post-liver transplant, with comparison to our institution's experience. Of the twenty-three articles with sufficient detail to compare antithrombotic regimens, the overall incidence of thrombosis ranged from 2.4% to 17.3%. Incidence of HAT ranged from 0% to 28.1%, of HVT from 0% to 4.7%, of PVT from 1.5% to 11.2%, and of IVC thrombosis from 0% to 2.8%. Re-transplantation due to thrombosis ranged from 0% to 4.8%. Prophylactic antithrombotic therapies varied between studies, and bleeding complications were infrequently reported. Since 2010, 96 children underwent 100 liver transplants at our institution with thrombosis incidence comparable to international literature (HAT 6%, PVT 5%, IVC 1%, and HVT 0%). Re-transplantation due to thrombosis occurred in 2% and major bleeding occurred in 10%. The prophylactic antithrombotic therapies used post-liver transplantation in children remain varied. Low rates of thrombosis have been reported with antiplatelet use both with and without anticoagulation. Standard definitions and consistent reporting of bleeding complications are required, in addition to thrombosis rates, so that true risk-benefit assessment of reported regimes can be understood.

International survey on anticoagulation and antiplatelet strategies after pediatric liver transplantation

In pediatric LT, anticoagulants and antiplatelet agents are regularly used to reduce the risk of vascular thrombosis. As evidence for optimal strategy is lacking, local practices vary greatly. The present survey aimed to compile an international overview of anticoagulation and antiplatelet strategies in pediatric LT. An online survey was sent to 98 pediatric LT centers in North and South America, Europe, Asia, and Australia. Twenty-four centers answered the survey. 20/24 (83%) use some sort of anticoagulation and antiplatelet therapy, yielding 20 different strategies. Perioperative vascular problems, size of the hepatic artery, and patient weight were the most frequent determinants of changes in anticoagulant and antiplatelet strategy. Early HAT rates were reported to be 5% or less in 79% of responding centers. Anticoagulation and antiplatelet strategies were not significantly associated with early HAT rates (P = 0.63), or with the number of pediatric LTs performed per year and center (P = 0.92). Internationally, there is a wide variety in anticoagulation and antiplatelet strategies after pediatric LT. Efforts must be made to design a prospective multicentric trial to identify the optimal antithrombotic strategy.

Thrombosis prophylaxis in pediatric liver transplantation: A systematic review

AIM

To review current literature of thrombosis prophylaxis in pediatric liver transplantation (PLT) as thrombosis remains a critical complication.

METHODS

Studies were identified by electronic search of MEDLINE, EMBASE and Cochrane Library (CENTRAL) databases until March 2018. The search was supplemented by manually reviewing the references of included studies and the references of the main published systematic reviews on thrombosis and PLT. We excluded from this review case report, small case series, commentaries, conference abstracts, papers which describing less than 10 pediatric liver transplants/year and articles published before 1990. Two reviewers performed study selection independently, with disagreements solved through discussion and by the opinion of a third reviewer when necessary.

RESULTS

Nine retrospective studies were included in this review. The overall quality of studies was poor. A pooled analysis of results from studies was not possible due to the retrospective design and heterogeneity of included studies. We found an incidence of portal vein thrombosis (PVT) ranging from 2% to 10% in pediatric living donor liver transplantation (LDLT) and from 4% to 33% in pediatric deceased donor liver transplantation (DDLT). Hepatic artery thrombosis (HAT) was observed mostly in mixed LDLT and DDLT pediatric population with an incidence ranging from 0% to 29%. In most of the studies Doppler ultrasonography was used as a first line diagnostic screening for thrombosis. Four different surgical techniques for portal vein anastomosis were reported with similar efficacy in terms of PVT reduction. Reduced size liver transplant was associated with a low risk of both PVT (incidence 4%) and HAT (incidence 0%, P < 0.05). Similarly, aortic arterial anastomosis without graft interposition and microsurgical hepatic arterial reconstruction were associated with a significant reduced HAT incidence (6% and 0%, respectively). According to our inclusion and exclusion criteria, we did not find eligible studies that evaluated pharmacological prevention of thrombosis.

CONCLUSION

Poor quality retrospective studies show the use of tailored surgical strategies might be useful to reduce HAT and PVT after PLT; prospective studies are urgently needed.

Perioperative anticoagulation practices for pediatric liver transplantation

Despite continued advancements in perioperative care for pediatric liver transplant (LT), graft-threatening vascular occlusion events including hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) remain a source of significant morbidity and mortality. Perioperative anticoagulation is commonly used for the prevention of HAT and PVT, but evidence-based guidelines are lacking. The goals of this survey were to determine the frequency of use of an anticoagulation protocol and to describe variation in anticoagulation practices among pediatric LT centers. The study consisted of an online survey distributed to members of SPLIT. The survey focused on institutional anticoagulation practices employed to reduce the incidence of graft and life-threatening vascular occlusion events. Responses were received from 31 of 39 SPLIT centers. All respondents report using anticoagulation after pediatric LT, and approximately 90% have institutional anticoagulation protocols. Subgroup analysis of high volume pediatric LT centers revealed similar variability in anticoagulation patterns. All participating SPLIT centers reported the use of post-transplant anticoagulation and nearly all use a protocol. However, there is marked variability in the type and dose of anticoagulation as well as the timing of initiation and duration of therapy across centers.

Effects of plasma transfusions on antithrombin levels after paediatric liver transplantation

BACKGROUND AND OBJECTIVES

Thrombotic complications affect 3-10% of patients after liver transplantation (LT), leading to potentially life-threatening complications. In the days following LT, antithrombin (AT) is decreased longer than pro-coagulant factors, thus favouring a pro-thrombotic profile. Plasma transfusions are given empirically in some centres to correct AT levels following LT. We assessed the effect of plasma transfusion on AT levels after paediatric LT.

MATERIALS AND METHODS

Prospective single-centre observational study in 20 consecutive paediatric LT recipients over a 24-month period. Plasma was administered twice daily (10 ml/kg/dose) according to an existing protocol. AT levels were measured once daily, immediately prior to and one hour after the morning plasma transfusion. Sample size was calculated based on a non-inferiority hypothesis.

RESULTS

The median age and weight were 11.6 years (IQR 2.8; 14.7) and 40 kg (IQR 12.75; 44.8), respectively. We collected 85-paired blood samples. The median AT level prior to plasma transfusion was 58%. The median difference in AT levels before and after plasma transfusion was 4.2% (P = 0.001). Changes in AT levels after plasma transfusion were not correlated with baseline AT levels (R = 0.19) or patient weight (R = 0.18).

CONCLUSION

Plasma transfusions only marginally increase AT levels in children after LT. Therefore, prophylactic plasma transfusions probably do not seem to confer an advantage in the routine management of paediatric LT patients. Randomized controlled trials are needed to identify the optimal anticoagulation strategy in this specific population.

Bleeding and thrombotic complications of pediatric liver transplant

BACKGROUND

Pediatric patients undergoing liver transplant are at significant risk for bleeding and thrombotic complications due to the complex nature of rebalanced hemostasis in patients with liver disease.

METHODS/OBJECTIVES

We reviewed records of 92 pediatric liver and multivisceral transplant cases at Duke University Medical Center between January 2009 and December 2015. The goal was to define the nature and incidence of bleeding and thrombotic complications in this cohort and define potential risk factors.

RESULTS

There were 24 major bleeding events in 19 transplants (incidence 20.7%) and 30 thrombotic events in 23 transplants (incidence 25%). Five of the 10 retransplantations were for vascular thrombotic complications. Thirty-day mortality was 4.9%, and three of these four deaths were due to vascular thrombosis. No bleeding events led to retransplantation or mortality. Prophylactic aspirin was associated with decreased risk of thrombosis without increased bleeding. Prophylactic heparin did not increase bleeding risk. Laboratory assays predicted events poorly, apparently failing to capture the nuanced and dynamic interplay between pro- and anticoagulant factors in the posttransplant patient.

CONCLUSIONS

Both bleeding and thrombosis are frequent in this population, but only thrombotic complications contributed to retransplantation and mortality. A standardized approach to coagulation testing and antithrombotic therapy may be useful in predicting and reducing adverse outcomes. Alternative approaches to monitoring hemostasis need to be prospectively investigated in this complex patient population.

Outcomes of Liver Transplantation Using Pediatric Deceased Donor Livers: A Single-Center Analysis of 102 Donors

BACKGROUND

The outcome of pediatric deceased donor liver transplantation (LT) has not been well studied, especially pediatric deceased donor livers used in adult transplantation. This study aimed to evaluate the efficacy of LT using pediatric deceased donor livers and compare the outcomes between pediatric-to-pediatric LT and pediatric-to-adult LT.

METHODS

A retrospective review of LT using pediatric deceased donor livers from June 2013 to August 2016 was performed. The patients were divided into the pediatric-to-pediatric LT group and pediatric-to-adult LT group based on the ages of the recipients. The survival and incidence of early vascular complications (VCs) were observed between the two groups. We also analyzed the risk factors of early VCs in pediatric LT and the effect of donor hypernatremia on the prognosis of recipients.

RESULTS

There were 102 cases of LT using pediatric deceased donor livers in our hospital from June 2013 to August 2016, 83 pediatric-to-pediatric LT (recipients' age ≤13 years) and 19 pediatric-to-adult LT (recipients' age ≥19 years). The ratio of early VC was similar in the two groups (19.3% vs. 10.6%, P = 0.514). Low body weight of recipient was an independent risk factor of early VC in pediatric LT (odds ratio: 0.856, 95% confidence interval: 0.752-0.975, P = 0.019). The 1-year cumulative survival rates of grafts and patients were 89.16% and 91.57% in pediatric-to-pediatric LT and 89.47% and 94.74% in pediatric-to-adult LT, respectively (all P > 0.05). In all cases, patients using donors with hypernatremia (serum sodium levels ≥150 mmol/L) had worse graft survival (χ2=4.330, P = 0.037).

CONCLUSIONS

Pediatric-to-pediatric LT group has similar graft and patient survival rates with those of pediatric-to-adult LT group. Low body weight of recipients is an independent risk factor of early VC in pediatric LT. Patients using donors with hypernatremia have worse graft survival.

Predicting early outcomes of liver transplantation in young children: The EARLY study

AIM

To determine potentially modifiable predictors of early outcomes after liver transplantation in children of age < 3 years.

METHODS

This study was a retrospective chart review including all consecutive children of age less than 3-years-old having had a liver transplant done at the Western Canadian referral center from June 2005 to June 2015. Pre-specified potential predictor variables and primary and secondary outcomes were recorded using standard definitions and a case report form. Associations between potential predictor variables and outcomes were determined using univariate and multiple logistic [odds ratio (OR); 95%CI] or linear (effect size, ES; 95%CI) regressions.

RESULTS

There were 65 children, of mean age 11.9 (SD 7.1) mo and weight 8.5 (2.1) kg, with biliary-atresia in 40 (62%), who had a living related donor [LRD; 29 (45%)], split/reduced [21 (32%)] or whole liver graft [15 (23%)]. Outcomes after liver transplant included: ventilator-days of 12.5 (14.1); pediatric intensive care unit mortality of 5 (8%); re-operation in 33 (51%), hepatic artery thrombosis (HAT) in 12 (19%), portal vein thrombosis (PVT) in 11 (17%), and any severe complication (HAT, PVT, bile leak, bowel perforation, intraabdominal infection, retransplant, or death) in 32 (49%) patients. Predictors of the prespecified primary outcomes on multiple regression were: (1) HAT: split/reduced (OR 0.06; 0.01, 0.76; P = 0.030) or LRD (OR 0.16; 0.03, 0.95; P = 0.044) vs whole liver graft; and (2) ventilator-days: surgeon (P < 0.05), lowest antithrombin (AT) postoperative day 2-5 (ES -0.24; -0.47, -0.02; P = 0.034), and split/reduced (ES -12.5; -21.8, -3.2; P = 0.009) vs whole-liver graft. Predictors of the pre-specified secondary outcomes on multiple regression were: (1) any thrombosis: LRD (OR 0.10; 0.01, 0.71; P = 0.021) or split/reduced (OR 0.10; 0.01, 0.85; P = 0.034) vs whole liver graft, and lowest AT postoperative day 2-5 (OR 0.93; 0.87, 0.99; P = 0.038); and (2) any severe complication: surgeon (P < 0.05), lowest AT postoperative day 2-5 (OR 0.92; 0.86-0.98; P = 0.016), and split/reduced (OR 0.06; 0.01, 0.78; P = 0.032) vs whole-liver graft.

CONCLUSION

In young children, whole liver graft and surgeon was associated with more complications, and higher AT postoperative day 2-5 was associated with fewer complications early after liver transplantation.

Axillobifemoral Bypass for Aortitis Syndrome in a Living-Donor Liver Transplant Patient

A 64-year-old female patient with aortitis syndrome presented with progressive intermittent claudication for 6 months. Her medical history was notable for living-donor liver transplantation for primary biliary cirrhosis 4-years prior and chronic immunosuppressive therapy. Evaluation included normal laboratory examination, and contrast-enhanced computed tomography angiography which demonstrated severely calcified descending aorta with high-grade stenosis below the diaphragm. The patient was treated by axillobifemoral bypass using an 8-mm ringed expanded polytetrafluoroethylene graft under general anesthesia. Medical management included decreased preoperative doses of immunosuppressants and predonisolone, which were resumed after the operation, and chronic anticoagulation. There were no postoperative complications.

Pediatric transplantation: preventing thrombosis

Due to progressive advances in surgical techniques, immunosuppressive therapies, and supportive care, outcomes from both solid organ transplantation and hematopoietic stem cell transplantation continue to improve. Thrombosis remains a challenging management issue in this context, with implications for both graft survival and long-term quality of life. Unfortunately, there remains a general paucity of pediatric-specific data regarding thrombosis incidence, risk stratification, and the safety or efficacy of preventative strategies with which to guide treatment algorithms. This review summarizes the available evidence and rationale underlying the spectrum of current practices aimed at preventing thrombosis in the transplant recipient, with a particular focus on risk factors, pathophysiology, and described antithrombotic regimens.

Do postliver transplant patients need thromboprophylactic anticoagulation?

Postoperative thromboprophylactic anticoagulation against Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) is standard of care with current evidence-based guidelines. However, majority of liver transplant (LT) patients have thrombocytopenia and/or prolonged INR before surgery. Studies or guidelines regarding role of prophylactic anticoagulation after LT are lacking. There is a need to balance the risk of thrombosis with significant hemorrhage, implying those needing transfusion or return to OR due to bleeding. We conclude that after LT, anticoagulation is not required routinely for DVT/PE prophylaxis. Rather, it is indicated in specific circumstances, chiefly for prophylaxis of hepatic artery thrombosis or portal vein thrombosis in cases with use of grafts, pediatric cases, small size vessels, Budd Chiari syndrome, amongst others.

Portal vein thrombosis and liver transplantation: implications for waiting list period, surgical approach, early and late follow-up

Portal vein thrombosis (PVT) is a well-known and relatively common complication of liver cirrhosis. In the past, PVT was considered as a contraindication for liver transplantation (LT). To characterize prevalence, risk factors, perioperative management and outcome of PVT in the setting of LT, the English literature published between 1991 and 2011 was reviewed. Of 6807 articles, 280 were selected, and 39 experiences were analyzed in detail (methodology, type and duration of treatments, peri-operative management, strategy to avoid recurrence, strengths and weaknesses, Oxford evidence level, citations). 3/39 studies were prospective; 9/39 were based on prospectively recorded databases; no studies of 1, 2a, 3a level of evidence were present; 5/39 were recognized as level 2b, 23/39 as level 3b, and 8/39 as level 4. High complication rate has been reported with consequent effect on graft and patient survival. Overall, PVT presents today good results similar to those obtained in patients without PVT undergoing LT even if they require a higher transfusion number and a longer ICU/hospital stay. Reported cases were retrospectively stratified according to Yerdel classification. Grade 1-2 patients (76%) do well with eversion thromboendovenectomy, resection of damaged vein and porto-portal anastomosis. Results of patients with grade 3-4 (24%) are inferior, however data on outcome in this subsets are fragmented and do not allow a reliable analysis. Moreover, results obtained in grade 3-4 cases are better in transplant centers with large specific experience. The small number of reports suggests caution. The role of anticoagulant treatment is still debated. Although in cirrhotics with PVT LT remains a demanding procedure, PVT should not be considered a contraindication anymore.

Factors predicting persistent thrombocytopenia after living donor liver transplantation in pediatric patients

Thrombocytopenia is common after LT for pediatric end-stage liver diseases. Seventy-six pediatric patients (≤15 yr old) who underwent LDLT were evaluated for the incidence and predictive factors of post-transplant thrombocytopenia (PLT <100, 000/mm(3) ). The prevalence of thrombocytopenia at two wk and at 12 months post-transplant was 22/76 (28.9%) and 11/62 (17.7%), respectively. Thrombocytopenia at two wk after LDLT was significantly associated with age at transplant, preoperative PLT, GRWR, acute rejection, and CMV infection in univariate analysis. Moreover, preoperative PLT, GRWR, and acute rejection had a strong correlation in multivariate analysis. Thrombocytopenia at 12 months after LDLT was associated only with preoperative PLT. We also demonstrated that vascular complications caused thrombocytopenia and that successful treatment recovered the PLT. These results showed that, in addition to considering the preoperative PLT, post-operative monitoring of platelets is very helpful for the early detection of adverse events related to the graft liver in pediatric liver transplant patients.