Hypercoagulability in renal transplant recipients. Identifying patients at risk of renal allograft thrombosis and evaluating strategies for prevention

Non-Invasive Biomarkers for Early Diagnosis of Kidney Allograft Dysfunction: Current and Future Applications in the Era of Precision Medicine

Kidney transplantation stands as the preferred treatment for end-stage kidney disease, significantly improving both the quality and longevity of life compared to dialysis. In recent years, the survival rates for patients and grafts have markedly increased thanks to innovative strategies in desensitization protocols for incompatible transplants and advancements in immunosuppressive therapies. For kidney transplant recipients, preventing allograft rejection is of paramount importance, necessitating the use of immunosuppressive medications. Regular follow-up appointments are essential, as monitoring the function of the kidney allograft is critical. Currently, established biomarkers such as serum creatinine, estimated Glomerular Filtration Rate (eGFR), proteinuria, and albuminuria are commonly employed to assess allograft function. However, these biomarkers have limitations, as elevated levels often indicate significant allograft damage only after it has occurred, thereby constraining treatment options and the potential for restoring graft function. Additionally, kidney biopsies, while considered the gold standard for diagnosing rejection, are invasive and carry associated risks. Consequently, the identification and development of new, sensitive, and specific biomarkers like dd-cfDNA, microRNAs (e.g., miR-21, miR-155), and sCD30 for allograft rejection are crucial. To tackle this challenge, intensive ongoing research employing cutting-edge technologies, including "omics" approaches, like genomic techniques, proteomics, or metabolomics, is uncovering a variety of promising new biomarkers.

Prophylactic Anticoagulation Reduces the Risk of Kidney Graft Venous Thrombosis in Recipients From Uncontrolled Donation After Circulatory Death Donors With High Renal Resistive Index

Background

Uncontrolled donation after circulatory death (uDCD) increases organ availability for kidney transplantation (KT) at the expense of a higher risk of primary graft nonfunction (PNF). At least half of the cases of PNF are secondary to graft venous thrombosis. The potential benefit from prophylactic anticoagulation in this scenario remains unclear.

Methods

In this single-center retrospective study we compared 2 consecutive cohorts of KT from uDCD with increased (≥0.8) renal resistive index (RRI) in the Doppler ultrasound examination performed within the first 24-72 h after transplantation: 36 patients did not receive anticoagulation ("nonanticoagulation group") and 71 patients underwent prophylactic anticoagulation until normalization of RRI in follow-up Doppler examinations ("anticoagulation group").

Results

Anticoagulation was initiated at a median of 2 d (interquartile range, 2-3) after transplantation and maintained for a median of 12 d (interquartile range, 7-18). In 4 patients (5.6%), anticoagulation had to be prematurely stopped because of the development of a hemorrhagic complication. In comparison with the nonanticoagulation group, recipients in the anticoagulation group had a lower 2-wk cumulative incidence of graft venous thrombosis (19.4% versus 0.0%; P < 0.001) and PNF (19.4% versus 2.8%; P = 0.006). The competing risk analysis with nonthrombotic causes of PNF as the competitive event confirmed the higher risk of graft thrombosis in the nonanticoagulation group (P = 0.0001). The anticoagulation group had a higher incidence of macroscopic hematuria (21.1% versus 5.6%; P = 0.049) and blood transfusion requirements (39.4% versus 19.4%; P = 0.050) compared with the nonanticoagulation group. No graft losses or deaths were attributable to complications potentially associated with anticoagulation.

Conclusions

Early initiation of prophylactic anticoagulation in selected KT recipients from uDCD with an early Doppler ultrasound RRI of ≥0.8 within the first 24-72 h may reduce the incidence of graft venous thrombosis as a cause of PNF.

Risk and factors associated with venous thromboembolism following abdominal transplantation

Background

Venous thromboembolism (VTE) remains under-studied among patients undergoing kidney, liver and pancreas (abdominal) transplantation. We characterized the risk and predictors of VTE using a nationally-representative cohort.

Methods

The 2014-2019 Nationwide Readmissions Database was queried to identify all adults undergoing abdominal transplantation. Patients who developed pulmonary embolism or deep venous thrombosis were considered the VTE cohort (others: nonVTE). Multivariable models were developed to identify factors linked with VTE and assess the independent associations between VTE and key outcomes.

Results

Of ~141,977 transplant recipients, 1.9 % (2722) developed VTE. The VTE cohort was similarly female (39.2 vs 38.0, p = 0.51), but more often demonstrated a higher Elixhauser comorbidity index (4.19 ± 1.40 vs 3.93 ± 1.39, p < 0.001).After adjustment, congestive heart failure (AOR 1.54, 95%CI 1.25-1.91), cardiac arrhythmias (AOR 1.54, 95%CI 1.34-1.78), peripheral vascular disease (AOR 1.29, 95%CI 1.02-1.63), coagulopathies (AOR 1.63, 95%CI 1.38-1.92), previous history of VTE (AOR 1.14, 95%CI 1.06-1.22), and heparin-induced thrombocytopenia (AOR 2.61, 95%CI 2.07-3.28) were associated with VTE. The development of VTE was linked with significantly greater in-hospital mortality (AOR 4.56, 95%CI 2.07-10.10), as well as infectious (AOR 2.59, 95%CI 1.55-4.21), cardiac (AOR 2.59, 95%CI 1.39-4.82), and respiratory (AOR 1.78, 95%CI 1.21-2.63) complications. VTE was further associated with increased length of stay (+8.18 days, 95%CI +1.32-15.41), expenditures (+$42,000, 95%CI $24,800-59,210), and odds of VTE upon readmission (AOR 4.51, 95%CI 1.32-15.41).

Conclusions

VTE after abdominal transplantation is linked with significantly greater in-hospital mortality, complications, resource utilization, and risk of VTE at readmission. Novel risk assessments and prophylaxis protocols are needed to reduce VTE incidence and sequelae.

Pathophysiological Changes in the Hemostatic System and Antithrombotic Management in Kidney Transplant Recipients

Nowadays, the main cause for early graft loss is renal graft thrombosis because kidney transplant outcomes have improved drastically owing to advances in immunological techniques and immunosuppression. However, data regarding the efficacy of antithrombotic therapy in the prevention of renal graft thrombosis are scarce. Adequate antithrombotic management requires a good understanding of the pathophysiological changes in the hemostatic system in patients with end-stage kidney disease (ESKD). Specifically, ESKD and dialysis disrupt the fine balance between pro- and anticoagulation in the body, and further changes in the hemostatic system occur during kidney transplantation. Consequently, kidney transplant recipients paradoxically are at risk for both thrombosis and bleeding. This overview focuses on the pathophysiological changes in hemostasis in ESKD and kidney transplantation and provides a comprehensive summary of the current evidence for antithrombotic management in (adult) kidney transplant recipients.

How to Deal With Kidney Retransplantation-Second, Third, Fourth, and Beyond

Kidney transplantation is the best health option for patients with end-stage kidney disease. Ideally, a kidney transplant would last for the lifetime of each recipient. However, depending on the age of the recipient and details of the kidney transplant, there may be a need for a second, third, fourth, or even more kidney transplants. In this overview, the outcome of multiple kidney transplants for an individual is presented. Key issues include surgical approach and immunologic concerns. Included in the surgical approach is an analysis of transplant nephrectomy, with indications, timing, and immunologic impact. Allograft thrombosis, whether related to donor or recipient factors merits investigation to prevent it from happening again. Other posttransplant events such as rejection, viral illness (polyomavirus hominis type I), recurrent disease (focal segmental glomerulosclerosis), and posttransplant lymphoproliferative disease may lead to the need for retransplantation. The pediatric recipient is especially likely to need a subsequent kidney transplant. Finally, noncompliance/nonadherence can affect both adults and children. Innovative approaches may reduce the need for retransplantation in the future.

Evanescing renal allograft cortical necrosis from living donor renal transplantation: A lesson learned over two decades

BACKGROUND

Renal graft cortical necrosis (GCN) is a catastrophic cause of graft failure. We evaluated the incidence, causes, management, and outcome of GCN across two decades from our center.

METHODS

This is a retrospective analysis of transplant patients who had biopsy-proven GCN transplanted between 2000 and 2020. The clinical details, immunological workup, induction, maintenance regimen, causes of cortical necrosis, and the outcomes were compared between the first period 2000-2012, and the second period 2013-2020, when Flow cytometric and Luminex based crossmatch were included in the workup plan.

RESULTS

Among 2333 live ABO-compatible renal transplants, 37 (0.015%) patients (36 patients between 2000 and 2012 and 1 between 2013 and 2020) developed GCN (60% had diffuse and 40% patchy GCN) at a median of 8 days after transplantation.Twenty-six (60%) received ATG, 4 received plasmapheresis, and ATG (10.8%) as antirejection therapy. The cyclosporine-based regimen was associated with a higher risk of GCN (RR 2.54; 95% CI 1.26 to 5.12, p = 0.009), whereas tacrolimus-based therapy had a lower risk (RR 0.39; 95% CI 0.19 to 0.79, p = 0.009). The introduction of flow cytometry and DSA assay has significantly decreased the incidence of acute rejection and GCN. Only one patient had GCN during the 2013-2020 period because of graft's mucormycosis. Twenty-five (67.56%) patients had no recovery, and 12 (32.43%) had partial recovery of graft function.

CONCLUSION

GCN is mainly associated with rejection, and cyclosporin-based maintenance regimen had a higher incidence. The remarkable decrease in GCN after 2013 onwards could be attributed to the use of Flowcytometry, Luminex-based DSA assays, and tacrolimus-based regimens.

Thrombosis Associated With Cytomegalovirus (CMV) in a Kidney Transplant Recipient

Cytomegalovirus (CMV) infection is a common infectious complication after kidney transplantation. Indirect effects of CMV infection include an increased risk of secondary infections, increased risk of acute rejection, and chronic allograft dysfunction. However, it is not well known that CMV may also increase the risk of venous and arterial thrombosis. Here, we present a case of acute deep venous thromboembolism associated with acute CMV disease in a kidney transplant recipient. We also performed a literature review of cytomegalovirus-associated thrombosis in immunocompromised individuals.

Is there a procoagulant state long-term after lung transplantation? A prospective study

BACKGROUND

Venous thromboembolism (VTE) is a major complication after lung transplantation (LT). However, its pathophysiology remains unknown, and coagulation profiles have yet to be described.

OBJECTIVE

The aim of this study was to longitudinally assess coagulation status after LT.

METHODS

We performed a prospective study and described the coagulation profiles of 48 patients at 5 different time-points: before LT and at 24-72 h, 2 weeks, 4 months, and 1 year after LT.

RESULTS

At baseline, almost all analyzed coagulation factors were within the normal range, except for FVIII, which was above the normal range. Von Willebrand factor (vWF) and FVIII were increased after LT and remained high at 1 year after transplantation. The cumulative incidence of VTE was 22.9%. Patients who developed VTE had higher FVIII activity 2 weeks after LT.

CONCLUSIONS

This is the first study to describe coagulation profiles up to 1 year after LT. We show that most markers of a procoagulant state normalize at 2 weeks after LT, but that values of FVIII and vWF remain abnormal at 1 year. This problem has received little attention in the literature. Larger studies are necessary to confirm the results and to design appropriate prophylactic strategies.

Interventions for preventing thrombosis in solid organ transplant recipients

BACKGROUND

Graft thrombosis is a well-recognised complication of solid organ transplantation and is one of the leading causes of graft failure. Currently there are no standardised protocols for thromboprophylaxis. Many transplant units use unfractionated heparin (UFH) and fractionated heparins (low molecular weight heparin; LMWH) as prophylaxis for thrombosis. Antiplatelet agents such as aspirin are routinely used as prophylaxis of other thrombotic conditions and may have a role in preventing graft thrombosis. However, any pharmacological thromboprophylaxis comes with the theoretical risk of increasing the risk of major blood loss following transplant. This review looks at benefits and harms of thromboprophylaxis in patients undergoing solid organ transplantation.

OBJECTIVES

To assess the benefits and harms of instituting thromboprophylaxis to patients undergoing solid organ transplantation.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 10 November 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) and quasi-RCTs designed to examine interventions to prevent thrombosis in solid organ transplant recipients. All donor types were included (donor after circulatory (DCD) and brainstem death (DBD) and live transplantation). There was no upper age limit for recipients in our search.

DATA COLLECTION AND ANALYSIS

The results of the literature search were screened and data collected by two independent authors. Dichotomous outcome results were expressed as risk ratio (RR) with 95% confidence intervals (CI). Random effects models were used for data analysis. Risk of bias was independently assessed by two authors using the risk of bias assessment tool. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We identified nine studies (712 participants). Seven studies (544 participants) included kidney transplant recipients, and studies included liver transplant recipients. We did not identify any study enrolling heart, lung, pancreas, bowel, or any other solid organ transplant recipient. Selection bias was high or unclear in eight of the nine studies; five studies were at high risk of bias for performance and/or detection bias; while attrition and reporting biases were in general low or unclear. Three studies (180 participants) primarily investigated heparinisation in kidney transplantation. Only two studies reported on graft vessel thrombosis in kidney transplantation (144 participants). These small studies were at high risk of bias in several domains and reported only two graft thromboses between them; it therefore remains unclear whether heparin decreases the risk of early graft thrombosis or non-graft thrombosis (very low certainty). UFH may make little or no difference versus placebo to the rate of major bleeding events in kidney transplantation (3 studies, 155 participants: RR 2.92, 95% CI 0.89 to 9.56; I² = 0%; low certainty evidence). Sensitivity analysis using a fixed-effect model suggested that UFH may increase the risk of haemorrhagic events compared to placebo (RR 3.33, 95% CI 1.04 to 10.67, P = 0.04). Compared to control, any heparin (including LMWH) may make little or no difference to the number of major bleeding events (3 studies, 180 participants: RR 2.70, 95% CI 0.89 to 8.19; I² = 0%; low certainty evidence) and had an unclear effect on risk of readmission to intensive care (3 studies, 180 participants: RR 0.68, 95% CI 0.12 to 3.90, I² = 45%; very low certainty evidence). The effect of heparin on our other outcomes (including death, patient and graft survival, transfusion requirements) remains unclear (very low certainty evidence). Three studies (144 participants) investigated antiplatelet interventions in kidney transplantation: aspirin versus dipyridamole (1), and Lipo-PGE₁ plus low-dose heparin to "control" in patients who had a diagnosis of acute rejection (2). None of these reported on early graft thromboses. The effect of aspirin, dipyridamole and Lipo PGE₁ plus low-dose heparin on any outcomes is unclear (very low certainty evidence). Two studies (168 participants) assessed interventions in liver transplants. One compared warfarin versus aspirin in patients with pre-existing portal vein thrombosis and the other investigated plasmapheresis plus anticoagulation. Both studies were abstract-only publications, had high risk of bias in several domains, and no outcomes could be meta-analysed. Overall, the effect of any of these interventions on any of our outcomes remains unclear with no evidence to guide anti-thrombotic therapy in standard liver transplant recipients (very low certainty evidence).

AUTHORS' CONCLUSIONS

Overall, there is a paucity of research in the field of graft thrombosis prevention. Due to a lack of high quality evidence, it remains unclear whether any therapy is able to reduce the rate of early graft thrombosis in any type of solid organ transplant. UFH may increase the risk of major bleeding in kidney transplant recipients, however this is based on low certainty evidence. There is no evidence from RCTs to guide anti-thrombotic strategies in liver, heart, lung, or other solid organ transplants. Further studies are required in comparing anticoagulants, antiplatelets to placebo in solid organ transplantation. These should focus on outcomes such as early graft thrombosis, major haemorrhagic complications, return to theatre, and patient/graft survival.

Drug interactions between direct-acting oral anticoagulants and calcineurin inhibitors during solid organ transplantation: considerations for therapy

Introduction: There is a high incidence of venous thromboembolism (VTE) in solid organ transplant recipients. The safety and efficacy of direct-acting oral anticoagulants (DOAC) have been well established in clinical practice for the prevention and treatment of VTE in broad populations. However, the management of VTE in the setting of solid organ transplantation remains a challenge to clinicians due to limited evidence of DOAC usage with calcineurin inhibitors. Areas covered: The current literature available on the pharmacokinetic-pharmacodynamic interaction between DOACs and calcineurin inhibitors is presented. A comprehensive review was undertaken using PubMed, Embase, drug product labeling, and drug product review conducted by the US Food and Drug Administration using Drugs@FDA. The potential for mitigation strategies and clinical management using extant knowledge is explored. Expert opinion: Immunosuppression therapy is necessary to prevent graft rejection by the host. The sparsity of data together with the lack of well-designed prospective studies of DOAC use in solid organ transplant recipients presents a unique challenge to clinicians in determining the clinical relevance of possible drug interactions. Existing evidence suggests that with attention to concomitant drug use and renal function, the co-administration of DOACs and calcineurin inhibitors is safe and effective.

Successful Living-Related Renal Allograft in a Recipient With Factor V Leiden Deficiency: A Case Report

Thrombophilia due to activated protein C resistance (Leiden mutation) is the most common inherited thrombophilic disorder with 5% incidence in whites. Renal transplant of these patients entails a risk of vascular thrombosis soon after the transplant; and acute rejection episodes and graft loss within the first year. We present a case of a successful living-related renal transplant in man with a recent history of repeat episodes of vascular access thrombosis attributed to inherited thrombophilia (heterozygosity for factor V mutation Q506 and homozygosity for mutation T677 for methylene-tetrahydrofolate reductase). Transplant recipient was administered anticoagulation therapy with low molecular weight heparin pre- and postoperatively. No thrombotic or hemorrhagic events occurred posttransplant. A high suspicion of thrombophilic disorders in patients with end-stage renal disease with vascular access thrombotic events should be screened further to prevent failure of a subsequent renal transplant. Inherited thrombophilic disorders may not exclude living-related kidney transplant provided that anticoagulation therapy is admin-istered perioperatively.

Immediate Vascular Complications After Kidney Transplant: Experience from 2100 Recipients

OBJECTIVES

Vascular complications, especially immediate events during kidney transplant, are the major cause of graft loss, and prompt surgical intervention is important for salvage of the graft and recipient. In this study, our aim was to show our experiences with vascular interventions and their effects on graft outcomes in transplant patients with suspected immediate vascular events.

MATERIALS AND METHODS

Over 24 years (from 1990 to 2014), 2100 renal transplant procedures (1562 living and 538 deceased donors) were performed by one fixed team. We reviewed the recipients to find cases with immediate vascular complications, including artery or vein kinking or torsion, renal artery thrombosis, and renal vein thrombosis. Diagnosis of a vascular event was suspected when urinary output suddenly stopped and was confirmed by color Doppler ultrasonography or immediate exploration. Characteristics of the patients and events, surgical interventions for saving grafts, and graft outcomes were assessed.

RESULTS

Our study included 28 vascular accidents (1.3% of total renal transplants). Arterial kinking or torsion, venous kinking or torsion, renal artery thrombosis, and renal vein thrombosis occurred in 11 (0.52%), 2 (0.09%), 12 (0.57%), and 3 patients (0.14%). Nine of the 11 cases of arterial kinking occurred with use of internal iliac artery. Eleven of 13 grafts with vascular kinking or torsion were saved by immediate surgical intervention, but only 4 grafts in patients with renal artery thrombosis and only 1 graft in patients with renal vein thrombosis were saved by surgical intervention. Delayed graft function occurred in all cases of saved renal artery and renal vein thrombosis but only in 5 cases (4 arterial and 1 venous) of vascular kinking or torsion.

CONCLUSIONS

The incidence of immediate vascular complications was 1.3% in our study. Sudden cessation of urine after renal transplant is a warning sign, and immediate diagnosis of vascular events will help salvage the graft with proper intervention.

Organ Pretreatment With Cytotopic Endothelial Localizing Peptides to Ameliorate Microvascular Thrombosis and Perfusion Deficits in Ex Vivo Renal Hemoreperfusion Models

BACKGROUND

Hypothermic machine organ perfusion (HMP) offers opportunity to manipulate grafts with pharmacological agents prior to transplantation. Pretreating organs with novel cytotopic anticoagulant peptides that localize to endothelial cell membranes could ameliorate microvascular thrombotic sequelae posttransplantation. We describe experiments testing thrombalexin (TLN), a novel cell binding thrombin inhibitor, using porcine and unused human kidneys in a series of ex vivo normothermic hemoreperfusion models.

METHODS

Thirty-eight porcine kidneys were used. Control kidneys underwent pretreatment via HMP with either unmodified perfusion solution (n = 15) or solution with inactive-TLN (absent anticoagulant effect, n = 4). Test kidneys were perfused with TLN-treated solution (n = 19). All kidneys then underwent hemoreperfusion. Two unused human kidneys underwent a similar protocol.

RESULTS

Hypothermic machine perfusion pretreatment facilitated delivery and tethering of TLN in the organ microvasculature. Hemoreperfusion challenge demonstrated improved perfusion in TLN-treated kidneys compared with controls: 26.4% superior flow (30.6 vs. 23.1 mL/min per 100 g, P = 0.019) and 28.9% higher perfusion flow indices (0.43 vs. 0.32 mL/min per 100 g mm Hg, P = 0.049). Orthogonal polarization spectral imaging demonstrated superior microvascular capillary perfusion in TLN-treated organs versus controls (9.1 vs 2.8 pl/s per mm, P = 0.021). Rapid-sampling microdialysis for cortical [lactate] as a marker of tissue ischemia/metabolism detected lower levels in TLN-treated kidneys. Perfusate analysis demonstrated reduced fibrin generation in TLN-treated kidneys correlating with perfusion data.

CONCLUSIONS

Our data suggest that HMP graft pretreatment with cytotopic anticoagulants is feasible and ameliorates perfusion deficits seen in ex vivo hemoreperfusion models. There is potential for further development and application of this translational strategy to deliver locally active anticoagulants directly within grafts and decrease microvascular thrombotic sequelae, while avoiding systemic anticoagulation and its associated risks.

Living donor renal transplantation in patients with antiphospholipid syndrome: A case report

INTRODUCTION

Antiphospholipid syndrome (APS), autoantibodies directed against phospholipid-binding proteins are associated with cause vascular thrombosis. Patients with APS requiring renal transplantation are at risk of early graft loss due to arterial or venous thrombosis, or thrombotic microangiopathy (TMA). Here, we report 3 cases of successful renal transplantation in patients with APS.

CLINICAL FINDINGS

A 53-year-old man with end-stage renal disease (ESRD) had experienced bilateral deep venous thrombosis (DVT) in the lower extremities 16 years ago and was administered warfarin. However, he frequently experienced recurrent DVT despite of anticoagulation therapy. Before the surgery, APS was confirmed based on positive results lupus anticoagulant in serological tests. A 40-year-old man with polycystic kidney disease and a history recurrent DVT tested positive for lupus anticoagulant and anticardiolipin antibodies. Lastly, a 42-year-old woman with ESRD was diagnosed with APS 7 years ago. She also developed DVT and tested positive for lupus anticoagulant and anti-B2-glycoprotein 1.

THE ANTICOAGULATION PROTOCOL WAS AS FOLLOWS IN ALL CASES

Warfarin was stopped 5 days before living donor renal transplantation and intravenous heparin therapy was started. During surgery, bolus heparin injections (3000 U) were administered to prevent arterial or venous thrombosis. Heparin was substituted with warfarin on postoperative day 4. The third patient (42/F) developed clinical rejection indicated by increased serum creatinine levels and donor-specific antibodies (DSA) and received steroid pulse therapy, plasmapheresis, and rituximab. This treatment restored graft function to within the normal range. The latest graft function in all patients was maintained at normal levels in the outpatient clinic.

CONCLUSIONS

Living donor renal transplantation may be successful in patients with APS following perioperative anticoagulation therapy. However, because of the high risk of TMA or vascular thrombosis in the early postoperative period, close monitoring for hypercoagulability and continuous anticoagulation is essential for maintaining graft function.

Successful living donor kidney transplantation in a patient with prothrombin gene mutation: Case report and literature review

We present a patient with known prothrombin gene mutation and a history of prior vascular events, who underwent living donor kidney transplantation. Given the presumed elevated risk of complication from known prothrombin mutation, clinical management was directed towards optimizing living donor allograft function.

Splanchnic vein thrombosis following renal transplantation: a case report

Background

Recurrent episodes of venous thrombosis have been closely correlated with JAK2 V617F mutation. Upto date, JAK2 gene mutation has not been defined as a prothrombic risk factor in renal transplant recipients. Herein; we present a case of portosplenic vein thrombosis in a primary renal transplant recipient with JAK2 V617F mutation who had no history of prior venous thromboembolism or thrombophilia.

Case presentation

A 59 year old female caucasian patient with primary kidney transplant admitted with vague abdominal pain at left upper quadrant. Abdominal doppler ultrasound and magnetic resonance imaging angiography demonstrated splanchnic vein thrombosis (SVT). The final diagnosis was SVT due to MPD (essential thrombocytosis, ET) with JAK2 V617F mutation. After 3 months of treatment with warfarin (≥5 mg/day, to keep target INR values of 1.9-2.5), control MRI angiography and doppler USG demonstrated partial (>%50) resolution of thrombosis with recanalization of hepatopedal venous flow. The patient is still on the same treatment protocol without any complication.

Conclusion

JAK2 V617F mutation analysis should be a routine procedure in the diagnosis and treatment of kidney transplant patients with thrombosis in uncommon sites.

Vascular complication in live related renal transplant: An experience of 1945 cases

Introduction and Objective:

Among the surgical complications in renal transplantation, the vascular complications are probably most dreaded, dramatic, and likely to cause sudden loss of renal allograft. We present our experience and analysis of the outcome of such complications in a series of 1945 live related renal transplants.

Materials and Methods:

One thousand nine hundred and forty five consecutive live related renal transplants were evaluated retrospectively for vascular complications. Complications were recorded and analyzed for frequency, time of presentation, clinical presentation, and their management.

Results:

The age of patients ranged from 6 to 56 years (mean = 42). Vascular complications were found in 25 patients (1.29%). Most common among these was transplant renal artery stenosis found in 11 (0.58%), followed by transplant reznal artery thrombosis in 9 (0.46%), renal vein thrombosis in 3 (0.15%), and aneurysm formation at arterial anastmosis in 2 (0.10%) patient. The time of presentation also varied amongst complications. All cases of arterial thrombosis had sudden onset anuria with minimal or no abdominal discomfort, while venous thrombosis presented as severe oliguria associated with intense graft site pain and tenderness. Management of cases with vascular thrombosis was done by immediate surgical exploration. Two patients of renal artery stenosis were managed with angioplasty and stent placement.

Conclusions:

Major vascular complications are relatively uncommon after renal transplantation but still constitute an important cause of graft loss in early postoperative period. Aneurysm and vessel thrombosis usually require graft nephrectomy. Transplant renal artery stenosis is amenable to correction by endovascular techniques.

Genetic Predisposition and Renal Allograft Failure

Renal allograft rejection or dysfunction often results in graft failure, and remains the major obstacle in the success of renal transplantation. Various immunological and nonimmunological factors are involved in allograft rejection. In addition to human leukocyte antigen loci, several genetically controlled molecules have been identified in recent years as playing important roles in the process of rejection. Genetic variants in genes encoding different T-helper (Th) type 1 and Th2 cytokines, chemokines and their receptors, growth factors, molecules of the renin-angiotensin system, enzymes of the homocysteine pathway, and proteins acting as substrates of immunosuppressive drugs impact on the success of engraftment and highlight the concept of genetic predisposition to allograft rejection. This review evaluates specific genetic variants and their functional roles in graft failure, with an emphasis on the latest methodologies available for genotyping, and appropriate strategies to enable them to become a tool of predictive and individualized medicine to ensure better transplant outcome.

KDIGO clinical practice guideline for the care of kidney transplant recipients

The 2009 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline on the monitoring, management, and treatment of kidney transplant recipients is intended to assist the practitioner caring for adults and children after kidney transplantation. The guideline development process followed an evidence-based approach, and management recommendations are based on systematic reviews of relevant treatment trials. Critical appraisal of the quality of the evidence and the strength of recommendations followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. The guideline makes recommendations for immunosuppression, graft monitoring, as well as prevention and treatment of infection, cardiovascular disease, malignancy, and other complications that are common in kidney transplant recipients, including hematological and bone disorders. Limitations of the evidence, especially on the lack of definitive clinical outcome trials, are discussed and suggestions are provided for future research.

Coagulation monitoring: current techniques and clinical use of viscoelastic point-of-care coagulation devices

Perioperative monitoring of blood coagulation is critical to better understand causes of hemorrhage, to guide hemostatic therapies, and to predict the risk of bleeding during the consecutive anesthetic or surgical procedures. Point-of-care (POC) coagulation monitoring devices assessing the viscoelastic properties of whole blood, i.e., thrombelastography, rotation thrombelastometry, and Sonoclot analysis, may overcome several limitations of routine coagulation tests in the perioperative setting. The advantage of these techniques is that they have the potential to measure the clotting process, starting with fibrin formation and continue through to clot retraction and fibrinolysis at the bedside, with minimal delays. Furthermore, the coagulation status of patients is assessed in whole blood, allowing the plasmatic coagulation system to interact with platelets and red cells, and thereby providing useful additional information on platelet function. Viscoelastic POC coagulation devices are increasingly being used in clinical practice, especially in the management of patients undergoing cardiac and liver surgery. Furthermore, they provide useful information in a large variety of clinical scenarios, e.g., massive hemorrhage, assessment of hypo- and hypercoagulable states, guiding pro- and anticoagulant therapies, and in diagnosing of a surgical bleeding. A surgical etiology of bleeding has to be considered when viscoelastic test results are normal. In summary, viscoelastic POC coagulation devices may help identify the cause of bleeding and guide pro- and anticoagulant therapies. To ensure optimal accuracy and performance, standardized procedures for blood sampling and handling, strict quality controls and trained personnel are required.

Necessity of routine postoperative heparinization in non-risky live-donor renal transplantation: results of a prospective randomized trial

OBJECTIVES

To determine the exact value of postoperative heparinization in preventing thrombotic sequelae in non-risky renal transplants and to assess the possible hazards of this therapy through a prospective randomized trial.

METHODS

Of 120 consecutive live-donor renal transplants, 45 patients were excluded because of young age, multiple or atheromatous graft arteries, a history of thromboembolic disease, or intraoperative technical difficulties. The remaining patients were prospectively randomized into three groups, with 25 patients each. Group 1 did not undergo heparinization. Groups 2 and 3 received a prophylactic dose of low-molecular-weight heparin and conventional heparin, respectively, for 1 week.

RESULTS

None of our patients in any group developed graft vascular thrombosis, deep venous thrombosis, or pulmonary embolism, and the rate of spontaneous closure of arteriovenous fistulas was comparable among the three groups (P = 0.79). No statistically significant difference was found among the three groups in terms of the development of significant perirenal hematomas, rate of blood transfusions, or mean number of transfused units (P = 0.37, P = 0.56, and P = 0.69, respectively). In contrast, a significant decrease in the hemoglobin level occurred in group 3 compared with group 1 among nontransfused patients (1.6 +/- 0.8 g% and 0.7 +/- 0.9 g%, respectively; P = 0.01). Moreover, a significant shortening of lymph drainage time and a reduction of the total amount of lymphorrhea were found in group 1 compared with groups 2 and 3 (P = 0.01, P = 0.03, respectively).

CONCLUSIONS

Postoperative heparinization should not be routinely indicated in non-risky live-donor renal transplantation.

Outcome after kidney transplantation in children with thrombotic risk factors

BACKGROUND

According to the data from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS), vascular thrombosis accounts for 11.6% of graft losses in pediatric renal transplantation. In adults, inherited and acquired thrombophilic risk factors, e.g. factor V Leiden mutation, have been associated with early graft loss and increased rejection episodes. Data on the impact of these factors on the outcome of children after renal transplantation are rare.

METHODS/PATIENTS

Sixty-six pediatric patients awaiting renal transplantation (mean age 10.1 yr) were screened for inherited and acquired risk factors for hypercoagulable disorders (protein C, S, and antithrombin III deficiency, antiphospholipid antibodies, factor V Leiden, prothrombin, and MTHFR mutation) in order to intensify anticoagulation in those with an increased risk for thrombophilia: intravenous heparin was administered with a partial prothrombin time (PTT) prolongation of 50 s for 14 days and switched to low-molecular-weight heparin for another 8 wk before aspirin was introduced for the first year. Patients without hypercoagulable risk factors were treated with heparin without PTT prolongation for 14 days and switched to aspirin immediately afterwards. The results on graft survival, incidence of acute rejection episodes, and long-term renal graft function were analyzed between recipients with and without hypercoagulable risk factors.

RESULTS

Thrombophilic risk factors were identified in 27.3% of our patients. No thrombosis occurred. One serious bleeding complication led to a second surgical intervention. The rate of acute rejection episodes was not increased in patients with and without thrombotic risk factors after 90 days (16.7 vs. 25%), 1 yr (22.2 vs. 33.3%), and 3 yr (38.9 vs. 41.7%) of follow-up, respectively (p = n.s.). After a mean follow-up of 3 yr the kidney function was comparable in both groups, with 63.1 in recipients with and 69.8 mL/min/1.73 m(2) in recipients without hypercoagulable risk (p = n.s.). At latest follow-up, three graft losses were found not to be attributed to thrombotic risk factors.

INTERPRETATION

Children with thrombophilic risk factors were identified and treated with an intensified anticoagulation regimen after renal transplantation. An increased risk for graft failure, acute rejection episodes, or impaired renal function for pediatric renal transplant recipients with hypercoagulable status was not found.

The Preoperative Evaluation of the Transplanted Patient for Nontransplant Surgery

With the improved success of solid-organ transplantation, there has been an increased willingness to transplant individuals previously felt to be unsuitable for such procedures. Factors such as age and various medical comorbidities are no longer considered contraindications to transplantation, and hence, an increasing number of recipients may require medical care not specifically related to the transplant. After transplantation, many of these patients may require elective or emergent surgery, making it important for all surgeons to be familiar with the factors that may influence surgical outcomes in this population, asa well asa factors that affect postoperative care. Most transplant centres use a team approach to manage these complex patients, relying on medical professionals experienced in their care and management. Close interaction with the transplant team is likely the single most important step in preparing the transplanted patient for surgery and managing their postoperative care.

Late caliceal fistula after kidney transplantation

Caliceal fistula is a rare urological complication that can occur usually shortly after kidney transplantation (KTx). The occlusion of the renal accessory artery with subsequent necrosis of the kidney pole is the most common cause of the fistula development. We report a case of a 57-year-old man with reconstruction of two accessory renal arteries by anastomosis to the side of the main artery during graft placement complicated by late caliceal fistula, managed surgically. Directly after KTx good kidney graft function (serum creatinine concentration 151 micromol/L) was observed. The patient noticed protuberance and pain in the kidney graft area 5 months later. Diagnostic imaging revealed moderate urostasis and liquid collection in the region of the lower graft pole. Administration of a contrast medium through the inserted drain visualized a fistula of a lower renal calyx and ureteric stenosis. Percutaneous drainage was applied with subsequent stop of diuresis through the urethral catheter. During the surgery, the resection of a lower kidney graft pole necrosis was performed, with the closure of caliceal fistula. Simultaneously double pigtail ureteric stent was inserted. After the next two months the pigtail catheter was removed, and neither urostasis in the kidney graft nor liquid collection in the perigraft area were observed. The exceptionality of the case is the late caliceal fistula occurrence. We may only speculate, why it happened 5 months after KTx. The thrombosis of stenosed accessory artery is the most probable cause.

Results of clinical renal transplantation in 15 dogs using triple drug immunosuppressive therapy

OBJECTIVE

To evaluate outcome of renal transplantation in dogs administered cyclosporine, azathioprine, and prednisolone immunosuppression.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Fifteen dogs with chronic renal failure.

RESULTS

Nine dogs died within 1 month of surgery; 5 died from complications associated with generalized thromboembolism. Three dogs survived for 6-25 months. Three dogs alive at the time of this report have survived 22-48 months; however, all 3 dogs have had bacterial infections that responded to antibiotic therapy. There was no biochemical evidence of acute allograft rejection in any dog. Perioperative use of enoxaparin may have prevented thromboembolism in 5 dogs.

CONCLUSIONS

Triple drug immunosuppressive therapy used in this study prevented acute renal allograft rejection in 6 dogs that survived >4 weeks; however, immunosuppression was excessive, resulting in an unacceptable frequency of infection and other drug-related complications. Perioperative anticoagulation therapy seem to be warranted.

CLINICAL RELEVANCE

Survival time and quality of life for this group of dogs was poor; however, there was no evidence of acute rejection in the dogs surviving >4 weeks. This protocol should only be used if the degree of immunosuppression is reduced, and early evidence of allograft rejection is monitored by renal biopsy or markers of lymphocyte activation.

Increased Thromboembolic Events After Lung Transplantation

BACKGROUND

Lung transplantation is a good therapeutic option for end-stage lung disease. Data on thromboembolic complications following lung transplantation are scarce.

STUDY OBJECTIVES

To evaluate the incidence of thromboembolic events following lung transplantation, and to determine their possible association with hypercoagulable state.

DESIGN

Retrospective study in a single, tertiary-care, university-affiliated referral center.

SUBJECTS AND METHOD

The records of 70 patients who underwent lung transplantation in our institution between September 1997 and September 2003 were reviewed for thromboembolic complications. Parameters pertaining to risk of thrombophilia were measured in the patients with thromboembolic complications.

RESULTS

Thromboembolic complications developed in 6 of the 70 patients (8.6%) at 4 to 24 months after transplantation: deep vein thrombosis (DVT) in 2 patients, pulmonary embolism (PE) in 1 patient, both DVT and PE in 1 patient, and retinal vein thrombosis in 2 patients. The fibrinogen level was elevated in all six patients, and factor VIII, IX, and/or XI levels were elevated in five patients. Heterozygosity for 5 10-methylene tetrahydrofolate reductase was documented in two patients, and mutation for factor II or factor V-Leiden mutation was found in one patient. Levels of protein C and protein S and activated protein C resistance were within normal range in all patients. Four patients had mildly elevated levels of at least one antiphospholipid antibody; none had a positive lupus anticoagulant test result. Overall, all patients demonstrated abnormalities on hypercoagulability tests.

CONCLUSIONS

Thromboembolic complications occur at a high rate (8.6%) in lung transplant recipients and are associated with abnormalities in hypercoagulability. The cause remains unclear. Our results should prompt a high index of suspicion for these potentially fatal complications, which would lead to early diagnosis and successful treatment.

Morphological and functional differences in haemostatic axis between kidney transplanted and end-stage renal disease patients

End-stage renal disease (ESRD) is characterized by several atherothrombotic abnormalities, and kidney transplant seems to improve most of them. However, because it is not clear which mechanism is responsible for such improvement, our purpose was to clarify that point.We conducted a cross sectional study involving 30 ESRD patients, 30 ESRD kidney-transplanted patients (Ktx) and 30 healthy controls (C) to evaluate platelet morphology and function, atherothrombotic profile, endothelial abnormalities and cytokine levels involved in the insulin resistance/endothelial dysfunction. (i) Platelet morphology: The ESRD group showed platelet size similar to the other two groups (ESRD=3518x10(3)+/-549x10(3) nm2, C=3075x10(3)+/-197x10(3) nm2, Ktx=2862x10(3)+/-205x10(3) nm2) with similar platelet granules and number. (ii) Platelet surface glycoprotein: The CD41 and P-Selectin were similar between groups. (iii) Platelet intracellular calcium: Resting intracellular calcium was statistically higher in ESRD compared to the C group (ESRD=182.1+/-34.5, Ktx=126.7+/-14.1, C=72.0+/-11.0 nM, P<0.01). (iv) Hypercoagulability markers and natural anticoagulants: The Ktx and ESRD groups showed higher levels of hypercoagulability markers compared to the C group. A reduction in antithrombin activity was evident in ESRD compared to the Ktx group (P=0.03). (v) Endothelial morphology: The ESRD group showed a thickened vessel basal membrane compared to the Ktx and C groups with more endothelial sufference. (vi) Insulin resistance and pro-inflammatory cytokine profile: The ESRD showed a higher homeostasis model assessment provided equations for estimating insulin resistance (HOMA-IR) compared to the Ktx and C groups (ESRD=2.6+/-0.3, Ktx=1.8+/-0.2, C=1.1+/-0.1, P=0.005) and increased soluble tumor neurosis factor alpha (sTNFalpha) (P<0.05) and soluble vascular cell adhesion molecule (sVCAM) levels (P<0.01). Positive correlations were evident among HOMA-IR and sTNFalpha (P<0.001) and sVCAM (P=0.01), respectively. In a small subgroup of ESRD who underwent Ktx (five pts), our findings were confirmed at 1 year of follow-up, suggesting an improvement of almost haemostatic abnormalities. Kidney transplant is associated with a better atherothrombotic profile in ESRD, platelet intracellular calcium and cytokines seem to be most influenced by the transplant, while most morphological abnormalities are retained.