Increased Risk of Hemorrhagic Complications in Renal Allograft Recipients Receiving Systemic Heparin Early Posttransplantation

Evidence-Based Complementary Benefit of the Vascular Surgeon Among the Team of Renal Transplantation; a Single Center Experience

BACKGROUND

In a kidney transplant tertiary referral center; we compared 3 operating team configurations of different surgical specialties to highlight the effect of the operating surgeon's specialty on various operative details and procedural outcome.

METHODS

A total of 50 cases of living donor transplantations were divided into 3 main groups according to the operating surgeons' specialty, the first group (A) includes 12 patients exclusively operated on by urologists with advanced training in transplantation, the second group (B) includes 35 patients operated by combined surgical specialties; a urologist and a vascular surgeon both with advanced transplantation training, and a third group (C) includes 3 cases where the transplant operation commenced with operating urologists as in group (A) but required intraoperative urgent notification of a vascular surgeon to manage unexpected intraoperative technical difficulties or major complications. Cases were studied according to operative details, anastomosis techniques, ischemia times, total procedure time, recovery of urinary output, intensive care unit (ICU) stay, postoperative surgical complications and serum creatinine level for up to 3 years of follow-up.

RESULTS

Study of operative details revealed that total duration of graft ischemia was significantly shorter in group (B) and significantly longer in group (C) (P value 0.001), Total procedural duration also varied significantly between the 3 groups, group (B) being the shortest while group (C) was the longest (P value less than 0.001). Technically; group (A) used only end to end arterial anastomosis as a standard technique, while group (B) used both end-to-end and end-to-side anastomoses as required per each case. End to side anastomosis in group (B) yielded better immediate graft response in the form of change in color, texture, earlier and more profuse postoperative urine volumes (P value 0.025). Furthermore, anastomosis to common and external iliac arteries (group B) yielded earlier and higher urine volumes than the internal iliac artery (P values 0.024 and 0.031 respectively). Group (B) recorded significantly less postoperative perigraft hematomas and lymphoceles compared to the other 2 groups. Equal rates of urine leaks, ICU stay, creatinine levels, patient and grafts survival rates among groups (A) and (B), while postoperative recovery and ICU stay duration were more lengthy in the complicated group (C).

CONCLUSIONS

A vascular surgeon operating in a transplantation team would deal comfortably and efficiently with various vascular related challenges and complications, thus avoiding unnecessary time waste, complications and costs.

Approach to Kidney Allograft Dysfunction: A Brief Review

It is important for providers caring for kidney transplant recipients to be familiar with the common causes of allograft dysfunction. Early detection of allograft dysfunction leads to timely management, with the goal of preventing or delaying progression to allograft failure. Although transplant rejection is always a concern, the differential diagnoses for allograft dysfunction are broad and include perioperative complications, infections, recurrent disease, and calcineurin nephrotoxicity. In this review, we will go over early and late causes of allograft dysfunction and discuss the basic workup and principles of management for each condition.

Incidence and risk factors of in-hospital venous thromboembolism in non-oncological urological inpatients: A single center experience

Objective

To determine incidence and risk factors for venous thromboembolism (VTE) development of in-hospital VTE in urological inpatients who underwent non-oncological surgery in a tertiary hospital in China.

Methods

Consecutive 1453 inpatients who were admitted to a non-oncological urological ward in the tertiary hospital from January 1, 2018 to December 31, 2018 were enrolled in the study, and the VTE events were diagnosed by ultrasound or computed tomographic pulmonary angiography. Patients' occurrence of VTE and characteristics which may contribute to the development of VTE were collected and analyzed as incidence and risk factors.

Results

The incidence of VTE in non-oncological urological inpatients is 2.3%. In our cohort, patients who experienced previous VTE (adjusted odds ratios [aOR] 14.272, 95% CI 3.620-56.275), taking anticoagulants or antiplatelet agents before admission (aOR 10.181, 95% CI 2.453-42.256), D-dimer (max) ≥1 μg/mL (aOR 22.456, 95% CI 6.468-77.967), lower extremity swelling (aOR 10.264, 95% CI 2.242-46.994), chest symptoms (aOR 79.182, 95% CI 7.132-879.076), operation time of more than or equal to 180 min (aOR 10.690, 95% CI 1.356-84.300), and Caprini score (max) of more than or equal to 5 (aOR 34.241, 95% CI 1.831-640.235) were considered as risk factors for VTE.

Conclusion

In this study, we found that the incidence of VTE in non-oncological surgery was about 2.3%, which was higher than some previous studies. Risk factors could be used for early detection and diagnosis of VTE.

Predictive Value of HAS-BLED Score Regarding Bleeding Events and Graft Survival following Renal Transplantation

Objective: Due to the high prevalence and incidence of cardio- and cerebrovascular diseases among dialysis-dependent patients with end-stage renal disease (ERSD) scheduled for kidney transplantation (KT), the use of antiplatelet therapy (APT) and/or anticoagulant drugs in this patient population is common. However, these patients share a high risk of complications, either due to thromboembolic or bleeding events, which makes adequate peri- and post-transplant anticoagulation management challenging. Predictive clinical models, such as the HAS-BLED score developed for predicting major bleeding events in patients under anticoagulation therapy, could be helpful tools for the optimization of antithrombotic management and could reduce peri- and postoperative morbidity and mortality. Methods: Data from 204 patients undergoing kidney transplantation (KT) between 2011 and 2018 at the University Hospital Leipzig were retrospectively analyzed. Patients were stratified and categorized postoperatively into the prophylaxis group (group A)—patients without pretransplant anticoagulation/antiplatelet therapy and receiving postoperative heparin in prophylactic doses—and into the (sub)therapeutic group (group B)—patients with postoperative continued use of pretransplant antithrombotic medication used (sub)therapeutically. The primary outcome was the incidence of postoperative bleeding events, which was evaluated for a possible association with the use of antithrombotic therapy. Secondary analyses were conducted for the associations of other potential risk factors, specifically the HAS-BLED score, with allograft outcome. Univariate and multivariate logistic regression as well as a Cox proportional hazard model were used to identify risk factors for long-term allograft function, outcome and survival. The calibration and prognostic accuracy of the risk models were evaluated using the Hosmer−Lemshow test (HLT) and the area under the receiver operating characteristic curve (AUC) model. Results: In total, 94 of 204 (47%) patients received (sub)therapeutic antithrombotic therapy after transplantation and 108 (53%) patients received prophylactic antithrombotic therapy. A total of 61 (29%) patients showed signs of postoperative bleeding. The incidence (p < 0.01) and timepoint of bleeding (p < 0.01) varied significantly between the different antithrombotic treatment groups. After applying multivariate analyses, pre-existing cardiovascular disease (CVD) (OR 2.89 (95% CI: 1.02−8.21); p = 0.04), procedure-specific complications (blood loss (OR 1.03 (95% CI: 1.0−1.05); p = 0.014), Clavien−Dindo classification > grade II (OR 1.03 (95% CI: 1.0−1.05); p = 0.018)), HAS-BLED score (OR 1.49 (95% CI: 1.08−2.07); p = 0.018), vit K antagonists (VKA) (OR 5.89 (95% CI: 1.10−31.28); p = 0.037), the combination of APT and therapeutic heparin (OR 5.44 (95% CI: 1.33−22.31); p = 0.018) as well as postoperative therapeutic heparin (OR 3.37 (95% CI: 1.37−8.26); p < 0.01) were independently associated with an increased risk for bleeding. The intraoperative use of heparin, prior antiplatelet therapy and APT in combination with prophylactic heparin was not associated with increased bleeding risk. Higher recipient body mass index (BMI) (OR 0.32 per 10 kg/m2 increase in BMI (95% CI: 0.12−0.91); p = 0.023) as well as living donor KT (OR 0.43 (95% CI: 0.18−0.94); p = 0.036) were associated with a decreased risk for bleeding. Regarding bleeding events and graft failure, the HAS-BLED risk model demonstrated good calibration (bleeding and graft failure: HLT: chi-square: 4.572, p = 0.802, versus chi-square: 6.52, p = 0.18, respectively) and moderate predictive performance (bleeding AUC: 0.72 (0.63−0.79); graft failure: AUC: 0.7 (0.6−0.78)). Conclusions: In our current study, we could demonstrate the HAS-BLED risk score as a helpful tool with acceptable predictive accuracy regarding bleeding events and graft failure following KT. The intensified monitoring and precise stratification/assessment of bleeding risk factors may be helpful in identifying patients at higher risks of bleeding, improved individualized anticoagulation decisions and choices of antithrombotic therapy in order to optimize outcome after kidney transplantation.

Prevention of Triglyceridemia by (Non-)Anticoagulant Heparin(oids) Does Not Preclude Transplant Vasculopathy and Glomerulosclerosis

Background: In renal transplantation, chronic transplant dysfunction (CTD) is associated with increased PCSK9 and dyslipidemia. PCSK9 is an enzyme that increases plasma cholesterol levels by downregulating LDLR expression. We recently showed increased PCSK9-syndecan-1 interaction in conditions of proteinuria and renal function loss. Treatment with heparin(oids) might be a therapeutic option to improve dyslipidemia and CTD. We investigated the effects of (non-)anticoagulant heparin(oids) on serum lipids, syndecan-1 and PCSK9 levels, and CTD development. Methods: Kidney allotransplantation was performed from female Dark Agouti to male Wistar Furth recipients. Transplanted rats received daily subcutaneous injections of saline, unfractionated heparin, and RO-heparin or NAc-heparin (2 mg heparin(oid)/kg BW) until sacrifice after 9 weeks of treatment. Results: Saline-treated recipients developed hypertension, proteinuria, and loss of creatinine clearance (all p < 0.05 compared to baseline), along with glomerulosclerosis and arterial neo-intima formation. Saline-treated recipients showed significant increase in plasma triglycerides (p < 0.05), borderline increase in non-HDLc/HDLc (p = 0.051), and ∼10-fold increase in serum syndecan-1 (p < 0.05), without significant increase in serum PCSK9 at 8 weeks compared to baseline. Heparin and non-anticoagulant RO-heparin administration in transplanted rats completely prevented an increase in triglycerides compared to saline-treated recipients at 8 weeks (both p < 0.05). Heparin(oids) treatment did not influence serum total cholesterol (TC), plasma syndecan-1 and PCSK9 levels, creatinine clearance, proteinuria, glomerulosclerosis, and arterial neo-intima formation, 8 weeks after transplantation. Combining all groups, increased syndecan-1 shedding was associated with TC (r = 0.5; p = 0.03) and glomerulosclerosis (r = 0.53; p = 0.021), whereas the non-HDLc/HDLc ratio was associated with the neo-intimal score in the transplanted kidneys (r = 0.65; p < 0.001). Conclusion: Prevention of triglyceridemia by (non-)anticoagulant heparin(oids) neither influenced PCSK9/syndecan-1 nor precluded CTD, which however did associate with the shedding of lipoprotein clearance receptor syndecan-1 and the unfavorable cholesterol profile.

Increased migration of antigen presenting cells to newly-formed lymphatic vessels in transplanted kidneys by glycol-split heparin

Background

Chronic renal transplant dysfunction is characterized by loss of renal function and tissue remodeling, including chronic inflammation and lymph vessel formation. Proteoglycans are known for their chemokine presenting capacity. We hypothesize that interruption of the lymphatic chemokine–proteoglycan interaction interferes with the lymphatic outflow of leukocytes from the renal graft and might decrease the anti-graft allo-immune response.

Methods

In a rat renal chronic transplant dysfunction model (female Dark-Agouti to male Wistar Furth), chemokines were profiled by qRT-PCR in microdissected tubulo-interstitial tissue. Disruption of lymphatic chemokine–proteoglycan interaction was studied by (non-anticoagulant) heparin-derived polysaccharides in vitro and in renal allografts. The renal allograft function was assessed by rise in plasma creatinine and urea.

Results

Within newly-formed lymph vessels of transplanted kidneys, numerous CD45⁺ leukocytes were found, mainly MHCII⁺, ED-1^-, IDO^-, HIS14^-, CD103^- antigen presenting cells, most likely representing a subset of dendritic cells. Treatment of transplanted rats with regular heparin and two different (non-)anticoagulant heparin derivatives revealed worsening of kidney function only in the glycol-split heparin treated group despite a two-fold reduction of tubulo-interstitial leukocytes (p<0.02). Quantitative digital image analysis however revealed increased numbers of intra-lymphatic antigen-presenting cells only in the glycol-split heparin group (p<0.01). The number of intra-lymphatic leukocytes significantly correlates with plasma creatinine and urea, and inversely with creatinine clearance.

Conclusions

Treatment of transplanted rats with glycol-split heparin significantly increases the number of intra-lymphatic antigen presenting cells, by increased renal diffusion of lymphatic chemokines, thereby increasing the activation and recruitment of antigen presenting cells towards the lymph vessel. This effect is unwanted in the transplantation setting, but might be advantageous in e.g., dendritic cell vaccination.

Evaluation of Heparin Anticoagulation Protocols in Post-Renal Transplant Recipients (EHAP-PoRT Study)

BACKGROUND

Disturbances in hemostasis are common among renal transplant recipients. Because of the risk of thromboembolism and graft loss after transplant, a prophylactic heparin protocol was implemented at St Paul's Hospital in Vancouver, British Columbia, in 2011. Therapeutic heparin is sometimes prescribed perioperatively for patients with preexisting prothrombotic conditions. There is currently limited literature on the safety and efficacy of heparin use in the early postoperative period.

OBJECTIVES

The primary objectives were to document, for patients who underwent renal transplant, the incidence of major bleeding and of thrombosis in those receiving therapeutic heparin, prophylactic heparin, and no heparin anticoagulation in the early postoperative period and to compare these rates for the latter 2 groups. The secondary objectives included a comparison of the risk factors associated with major bleeding and thrombosis.

METHODS

Adult patients who received a renal transplant at St Paul's Hospital between January 2008 and July 2013 were included in this retrospective cohort study. Electronic health records and databases were used to divide patients into the 3 heparin-use cohorts, to identify cases of major bleeding and thrombosis, and to characterize patients and events. The Fisher exact test was used for the primary outcome analysis, and descriptive statistics were used for all other outcomes.

RESULTS

A total of 547 patients were included in the analysis. Major bleeding was observed in 6 (46%) of the 13 patients who received therapeutic heparin; no cases of thrombosis occurred in these patients. Major bleeding occurred in 8 (3.0%) of the 266 patients who received prophylactic heparin and 9 (3.4%) of the 268 who received no heparin (p > 0.99). Thrombosis occurred in 1 (0.4%) and 3 (1.1%) of these patients, respectively (p = 0.62). Major bleeding occurred more frequently among patients with a low-target heparin protocol, but 61% of values for partial thromboplastin time were above target. A larger proportion of deceased-donor transplant recipients who had major bleeding were taking antiplatelet agents, relative to living-donor transplant recipients.

CONCLUSION

Therapeutic use of heparin increased the risk of bleeding among renal transplant recipients, but there were no cases of thrombosis. Prophylactic use of heparin did not increase the risk of bleeding and prevented proportionately more cases of thrombosis relative to no anticoagulation; this result supports the continued use of prophylaxis.

Risk of major hemorrhage after kidney transplantation

BACKGROUND

Major hemorrhagic events are associated with significant morbidity and mortality. We examined the three-year cumulative incidence of hospitalization with major nontraumatic hemorrhage after kidney transplantation.

METHODS

We performed a retrospective cohort study using healthcare administrative data of all adult-incident kidney-only transplantation recipients in Ontario, Canada from 1994 to 2009. We calculated the three-year cumulative incidence, event rate, and incident rate ratio of hospitalization with major hemorrhage, its subtypes and those undergoing a hemorrhage-related procedure. RESULTS were stratified by patient age and donor type and compared to a random and propensity-score matched sample from the general population.

RESULTS

Among 4,958 kidney transplant recipients, the three-year cumulative incidence of hospitalization with nontraumatic major hemorrhage was 3.5% (95% confidence interval [CI] 3.0-4.1%, 12.7 events per 1,000 patient-years) compared to 0.4% (95% CI 0.4-0.5%) in the general population (RR = 8.2, 95% CI 6.9-9.7). The crude risk of hemorrhage was 3-9-fold higher in all subtypes (upper/lower gastrointestinal, intra-cranial) and 15-fold higher for gastrointestinal endoscopic procedures compared to the random sample from the general population. After propensity score matching, the relative risk for major hemorrhage and its subtypes attenuated but remained elevated. The cumulative incidence of hemorrhage was higher for older individuals and those with a deceased donor kidney.

CONCLUSION

Kidney transplantation recipients have a higher risk of hospitalization with hemorrhage compared to the general population, with about 1 in 30 recipients experiencing a major hemorrhage in the three years following transplant.

Evaluation of bleeding rates in renal transplant patients on therapeutic intravenous heparin

BACKGROUND

It is unknown whether coagulation properties differ between renal transplant and nontransplant patients.

OBJECTIVE

To assess whether renal transplant patients on intravenous (IV) heparin, titrated to therapeutic activated partial thromboplastin times (aPPT; 56-93 seconds), experienced a higher rate of bleeding compared to nontransplant patients.

METHODS

Twenty-nine renal transplant and 29 nontransplant patients receiving IV heparin for a deep vein thrombosis, pulmonary embolism, atrial fibrillation, or acute coronary syndrome were randomly identified through a retrospective chart review.

RESULTS

Renal transplant patients had higher bleeding rates on IV heparin therapy compared to nontransplant patients (31% vs 6.9%, respectively; P = .041). Renal transplant patients experienced a drop in hemoglobin of at least 1 g/dL or the need for a transfusion more often then nontransplant patients (69% vs 45%, respectively; P = .111), although the difference was not statistically significant.

CONCLUSIONS

Further research is necessary to identify the factors contributing to increased rates of bleeding in renal transplant patients on IV heparin and to determine the ideal aPTT to appropriately balance anticoagulation in renal transplant patients.

Surgical complications and graft survival in pediatric kidney transplant recipients treated with a steroid-free protocol: experiences from a Danish university hospital

BACKGROUND

The outcome of pediatric kidney transplantation depends on several factors, among these are the complications, which occur in relation to the surgical procedure. In this study, we present our experience with pediatric kidney transplantation in a steroid-free immunosuppression regimen, from a surgical point of view.

METHODS

Patient charts of pediatric kidney transplantations in the period 1998-2011 were reviewed. Surgical complications, acute rejection, and patient and graft survivals were recorded.

RESULTS

Sixty-one renal transplantations were performed in 58 patients. Thirty patients (49.1%) experienced a surgical complication, of which 11 (18%) required an explorative laparotomy. Overall the five-year Kaplan-Meier patient survival rate was 96.2% and the graft survival rate was 88.6%. Nine patients (14.7%) had an acute rejection episode within the first year after transplantation. No correlation was observed between surgical complications and acute rejection episodes or graft loss.

CONCLUSIONS

This study indicated a high incidence of surgical complications among pediatric kidney transplantations when using a steroid-free immunosuppression regimen. Despite this, we observed high overall patient and graft survival, supporting the trend toward steroids avoidance in pediatric kidney transplantation.

Risk factors for early hemorrhagic and thrombotic complications after kidney transplantation

INTRODUCTION

Clotting disturbances resulting from chronic renal failure do not remit immediately after successful kidney transplantation (KTx). Hemorrhagic and thrombotic complications after KTx increase the risk of transplanted kidney loss. The aim of the study was to analyze the influence of clotting system disturbances and applied antithrombotic prophylaxis on the development of hemorrhagic and thrombotic complications among KTx patients in the early postoperative period.

MATERIALS AND METHODS

Sixty seven KTx patients underwent measurement of plasma activated partial thromboplastin time (APTT); international normalized ratio; fibrinogen and D-dimer concentration; activity of antitrombin III; protein C and S, VIII, IX; and von Willebrand factors, as well as platelet counts.

RESULTS

A perigraft hematoma developed in 25.4% patients, of whom 4.5% required reoperation. Lower antithrombin III activity (96.2±27.6 vs 112.3±17.4, P=.02) on postoperative day (POD) 7 and higher fibrinogen concentration (4.41±2.03 vs 3.35±0.87, P=.01) and platelet count (269.8±117.5 vs 215.8±64.8, P=.03) on POD 14 were noted in recipients with a hematoma compared to those free of this complication. A perigraft hematoma developed in 57.9% patients undergoing antithrombotic prophylaxis and in 12.5% without this treatment (P=.0002). Among patients receiving unfractionated heparin, we observed extension of APTT on POD 1 (45.9±53.2 vs 30.9±7.5 seconds, P=.04), higher von Willebrand factor activity on POD 7 (348.8±122.2 vs 218.5±125.5, P=.02), and higher D-dimer concentrations POD 7 and 14 (1662±894 vs 757±708, P=.002 and 1614±1372 vs 672±532, P=.003, respectively). No significant differences were observed as regards to analyzed parameters between patients receiving low-molecular-weight heparin versus those not receiving antithrombotic prophylaxis.

CONCLUSIONS

Disturbances in analyzed parameters of hemostasis did not increase the risk of hemorrhagic and thrombotic complications in the early period after KTx. Antithrombotic prophylaxis increases the risk of hemorrhagic complications and should be introduced only for selected renal transplant recipients.

Recurrence of focal segmental glomerulosclerosis in renal allograft: an in-depth review

Focal segmental glomerulosclerosis is a major cause of chronic kidney disease requiring transplantation in children. Recurrence rate in the renal allograft transplantation is as high as 50%. Recurrence of FSGS is associated with renal dysfunction and early graft loss. To date, there is no established therapy for recurrent FSGS after renal transplant. We have reviewed the current English literature in order to summarize current practices with emphasis on graft outcome. We conclude that despite multiple approaches to the post transplant management of recurrent FSGS, none have been shown to be consistently beneficial. Currently, pheresis combined with high dose anti-calcineurin with or without rituximab seems to be the most promising. Further controlled studies are needed to define the optimal therapeutic regimens to treat recurrent of FSGS.