Prevention and management of graft thrombosis in pancreatic transplant

Ultrasound of pancreatic transplant complications: a primer for radiologists

Pancreatic transplantation is an established treatment for patients with type 1 diabetes patients and select type 2 diabetes patients, with excellent survival rates as graft health is evaluated through regular imaging and early detection of complications. Amongst the various imaging methods that may aid in diagnosis of pancreatic transplant complications, ultrasound is a widely available, quick, portable, and cost-effective technique, often used as the sole method to assess for pancreatic transplant complications. When assessing a patient with a pancreatic transplant, the radiologist should be methodical in assessing the vasculature, the pancreatic parenchyma, and the peripancreatic regions. Complications can be categorised based on time from transplant and type of complications, and include vascular, parenchymal, and enteric/anastomotic complications. Doppler has a major role in the diagnosis of vascular complications including arterial and venous thrombosis, arterial stenosis, pseudoaneurysms, and haematomas. Pancreatic complications include rejections and pancreatitis, and are often diagnosed through a combination of clinical, laboratory, and imaging findings, such as pancreatic heterogeneity or the presence of pancreatic pseudocysts. Enteric/anastomotic complications include leaks and bowel obstructions, and may require cross-sectional imaging in addition to ultrasound. This review covers the most common and high-impact vascular, parenchymal, and enteric/anastomotic complications that should be considered in every radiologist's search pattern when assessing a pancreatic graft, as well as their respective postoperative timeframes.

Pancreatic Allograft Thrombosis: Implementation of the CPAT-Grading System in a Retrospective Series of Simultaneous Pancreas-Kidney Transplantation

Pancreatic graft thrombosis (PAT) is a major surgical complication, potentially leading to graft loss. The recently proposed Cambridge Pancreas Allograft Thrombosis (CPAT) grading system provides diagnostic, prognostic and therapeutic recommendations. The aim of the present study was to retrospectively assess computed tomography angiography (CTA) examinations performed routinely in simultaneous pancreas-kidney (SPK) recipients to implement the CPAT grading system and to study its association with the recipients' outcomes. We retrospectively studied 319 SPK transplant recipients, who underwent a routine CTA within the first 7 postoperative days. Analysis of the CTA scans revealed PAT in 215 patients (106 grade 1, 85 grade 2, 24 grade 3), while 104 showed no signs. Demographic data of the patients with and without PAT (thrombosis and non-thrombosis group) were not significantly different, except for the higher number of male donors in the thrombosis group. Pancreatic graft survival was significantly shorter in the thrombosis group. Graft loss due to PAT was significantly associated with grade 2 and 3 thrombosis, while it did not differ for recipients with grade 0 or grade 1 thrombosis. In conclusion, the CPAT grading system was successfully implemented in a large series of SPK transplant recipients and proved applicable in clinical practice.

Different timing and risk factors of cause-specific pancreas graft loss after simultaneous pancreas kidney transplantation

In cases after pancreas transplantation (PTx), the pancreas graft might be lost for various reasons, including a pancreatoduodenal graft-related complication or patient death with a functioning graft. Although the causes seem to have distinct characteristics, the causes of pancreas graft loss have not been characterized. This study aimed to characterize the causes of pancreas graft loss by analyzing data from a Japanese nationwide registry. This study included 391 patients who received simultaneous pancreas-kidney transplantation among 461 patients with PTx during the study period in approved institutions in Japan. We characterized each cause in terms of the timing of the cause-specific graft loss and preoperative factors associated with graft loss based on nationwide data from a Japanese nationwide registry. Among the 391 cases, 113 lost the pancreas graft due to patient death with a functioning graft (DWFG; n = 34, 44.2%), graft thrombus (n = 22, 28.6%), or chronic rejection (CR; n = 7, 9.1%). Average (± standard deviation) time from PTx to graft loss due to DWFG, graft thrombus, and CR was 3.70 ± 4.36, 0.02 ± 0.01, and 2.37 ± 2.08 years, respectively. Duration of type 1 diabetes mellitus and donor body mass index were significantly associated with pancreas graft loss due to DWFG and graft thrombus, respectively. This characterization showed that the timing and preoperative factors associated with pancreas graft loss were significantly different for different causes of graft loss. These results may inform PTx follow-up protocols to ensure that appropriate care is based on the cause of graft loss.

Risk Factors for Early Pancreatic Allograft Thrombosis Following Simultaneous Pancreas-Kidney Transplantation: A Systematic Review

Simultaneous pancreas-kidney (SPK) transplantation remains the most effective treatment for providing consistent and long-term euglycemia in patients having type 1 diabetes with renal failure. Thrombosis of the pancreatic vasculature continues to contribute significantly to early graft failure and loss. We compared the rate of thrombosis to graft loss and systematically reviewed risk factors impacting early thrombosis of the pancreas allograft following SPK transplantation. We searched the MEDLINE, EMBASE, The Cochrane Library, and PREMEDLINE databases for studies reporting thrombosis following pancreas transplantation. Identified publications were screened for inclusion and synthesized into a data extraction sheet. Sixty-three studies satisfied eligibility criteria: 39 cohort studies, 22 conference abstracts, and 2 meta-analyses. Newcastle-Ottawa Scale appraisal of included studies demonstrated cohort studies of low bias risk; 1127 thrombi were identified in 15 936 deceased donor, whole pancreas transplants, conferring a 7.07% overall thrombosis rate. Thrombosis resulted in pancreatic allograft loss in 83.3% of reported cases. This review has established significant associations between donor and recipient characteristics, procurement and preservation methodology, transplantation technique, postoperative management, and increased risk of early thrombosis in the pancreas allograft. Further studies examining the type of organ preservation fluid, prophylactic heparin protocol, and exocrine drainage method and early thrombosis should also be performed.

Susceptibility-directed anticoagulation after pancreas transplantation: A single-center retrospective study

Pancreas transplant achieves consistent long-term euglycemia in type 1 diabetes. Allograft thrombosis (AT) causes the majority of early graft failure. We compared outcomes of four anticoagulation regimens administered to 95 simultaneous kidney-pancreas or isolated pancreas transplanted between 1/1/2015 and 11/20/2018. Early postoperative anticoagulation regimens included the following: none, subcutaneous heparin/aspirin, with or without dextran, and heparin infusion. The regimens were empirically selected based on each surgeon's assessment of hemostasis of the operative field and personal preference. A sonographic-based global scoring system of AT is presented. The 47-month recipients and graft survival were 95% and 86%, respectively. Recipients with or without AT had similar survival. Five and four grafts were lost due to death and AT, respectively. Outcomes of prophylaxis regimens correlated with intensity of anticoagulation. Compared with no anticoagulation, an increase in hemorrhagic complications occurred exclusively with iv heparin. The higher arterial AT score found in regimens lacking antiplatelet therapy highlights the importance of early antiaggregants therapy. Abnormal fibrinolysis was associated with an increase in AT score. Platelet dysfunction, warm ischemia time, and enteric drainage were predictive of AT and, along with other known risk factors, were incorporated into an algorithm that matches intensity of early postoperative anticoagulation to the thrombotic risk.

Pancreatic allograft thrombosis: Suggestion for a CT grading system and management algorithm

Pancreatic allograft thrombosis (PAT) remains the leading cause of nonimmunologic graft failure. Here, we propose a new computed tomography (CT) grading system of PAT to identify risk factors for allograft loss and outline a management algorithm by retrospective review of consecutive pancreatic transplantations between 2009 and 2014. Triple-phase CT scans were graded independently by 2 radiologists as grade 0, no thrombosis; grade 1, peripheral thrombosis; grade 2, intermediate non-occlusive thrombosis; and grade 3, central occlusive thrombosis. Twenty-four (23.3%) of 103 recipients were diagnosed with PAT (including grade 1). Three (2.9%) grafts were lost due to portal vein thrombosis. On multivariate analysis, pancreas after simultaneous pancreas-kidney transplantation/solitary pancreatic transplantation, acute rejection, and CT findings of peripancreatic edema and/or inflammatory change were significant risk factors for PAT. Retrospective review of CT scans revealed more grade 1 and 2 thromboses than were initially reported. There was no significant difference in graft or patient survival, postoperative stay, or morbidity of recipients with grade 1 or 2 thrombosis who were or were not anticoagulated. Our data suggest that therapeutic anticoagulation is not necessary for grade 1 and 2 arterial and grade 1 venous thrombosis. The proposed grading system can assist clinicians in decision-making and provide standardized reporting for future studies.

Successful Combined Pancreas Fourth-Kidney Third and Pancreas Third-Kidney Second Transplantation: A Case Report

Extremely few reports have been published on experience with multiple combined pancreas-kidney re-transplantation including long-term results. We here analyze our experience with two patients following successful combined pancreas fourth-kidney third and pancreas third-kidney second transplantation.

METHODS

Patient and graft survival as well as graft function and major complications were recorded. Patient 1 (women, 47 years) underwent combined pancreas fourth-kidney third transplantation after previous removal of the first and second renal and the second pancreatic grafts. Patient 2 (men, 51 years) underwent combined pancreas third-kidney second transplantation after nephrectomy of the first renal graft. Immunosuppression consisted of induction with alemtuzumab and maintenance with tacrolimus, mycophenolate mofetil/mycophenolic acid and steroids.

RESULTS

After a follow-up of 44 and 49 months, respectively, both patients are doing well with stable graft function. Leukopenia, thrombocytopenia, bacterial sepsis, and chronic hepatitis C as major complications were controllable.

CONCLUSIONS

Multiple pancreas-retransplantations combined with simultaneous renal transplantation are feasible. Meticulous immunosuppression, careful monitoring, and excellent patient adherence are of crucial importance.