How to avoid graft thrombosis requiring graftectomy: immediate posttransplant CT angiography in pancreas transplantation

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.

Heparin Thromboprophylaxis in Simultaneous Pancreas-Kidney Transplantation: A Systematic Review and Meta-Analysis of Observational Studies

Thrombosis is a leading causes of pancreas graft loss after simultaneous pancreas kidney (SPK), pancreas after kidney (PAK), and pancreas transplant alone (PTA). There remains no standardized thromboprophylaxis protocol. The aim of this systematic review and meta-analysis is to evaluate the impact of heparin thromboprophylaxis on the incidence of pancreas thrombosis, pancreas graft loss, bleeding, and secondary outcomes in SPK, PAK, and PTA. Following PRISMA guidelines, we systematically searched BIOSIS®, PubMed®, Cochrane Library®, EMBASE®, MEDLINE®, and Web of Science® on April 21, 2021. Primary peer-reviewed studies that met inclusion criteria were included. Two methods of quantitative synthesis were performed to account for comparative and non-comparative studies. We included 11 studies, comprising of 1,122 patients in the heparin group and 236 patients in the no-heparin group. When compared to the no-heparin control, prophylactic heparinization significantly decreased the risk of early pancreas thrombosis and pancreas loss for SPK, PAK and PTA without increasing the incidence of bleeding or acute return to the operating room. Heparin thromboprophylaxis yields an approximate two-fold reduction in both pancreas thrombosis and pancreas loss for SPK, PAK and PTA. We report the dosage, frequency, and duration of heparin administration to consolidate the available evidence.

Microdialysis and CO2 sensors detect pancreatic ischemia in a porcine model

BACKGROUND

Pancreatic transplantation is associated with a high rate of early postoperative graft thrombosis. If a thrombosis is detected in time, a potentially graft-saving intervention can be initiated. Current postoperative monitoring lacks tools for early detection of ischemia. The aim of this study was to investigate if microdialysis and tissue pCO2 sensors detect pancreatic ischemia and whether intraparenchymal and organ surface measurements are comparable.

METHODS

In 8 anaesthetized pigs, pairs of lactate monitoring microdialysis catheters and tissue pCO2 sensors were simultaneously inserted into the parenchyma and attached to the surface of the pancreas. Ischemia was induced by sequential arterial and venous occlusions of 45-minute duration, with two-hour reperfusion after each occlusion. Microdialysate was analyzed every 15 minutes. Tissue pCO2 was measured continuously. We investigated how surface and parenchymal measurements correlated and the capability of lactate and pCO2 to discriminate ischemic from non-ischemic periods.

RESULTS

Ischemia was successfully induced by arterial occlusion in 8 animals and by venous occlusion in 5. During all ischemic episodes, lactate increased with a fold change of 3.2-9.5 (range) in the parenchyma and 1.7-7.6 on the surface. Tissue pCO2 increased with a fold change of 1.6-3.5 in the parenchyma and 1.3-3.0 on the surface. Systemic lactate and pCO2 remained unchanged. The area under curve (AUC) for lactate was 0.97 (95% confidence interval (CI) 0.93-1.00) for parenchymal and 0.90 (0.83-0.97) for surface (p<0.001 for both). For pCO2 the AUC was 0.93 (0.89-0.96) for parenchymal and 0.85 (0.81-0.90) for surface (p<0.001 for both). The median correlation coefficients between parenchyma and surface were 0.90 (interquartile range (IQR) 0.77-0.95) for lactate and 0.93 (0.89-0.97) for pCO2.

CONCLUSIONS

Local organ monitoring with microdialysis and tissue pCO2 sensors detect pancreatic ischemia with adequate correlation between surface and parenchymal measurements. Both techniques and locations seem feasible for further development of clinical pancreas monitoring.

Technical factors that minimize the occurrence of early graft failure in pancreas transplantation

Pancreatic transplantation is the only treatment for insulin-dependent diabetes resulting in long-term euglycemia without exogenous insulin. However, pancreatic transplantation has become debatable following the improvements in the results of islet transplantation and artificial pancreas. Therefore, surgeons who perform pancreas transplants require the best surgical technique that can minimize technical failure. We aimed to report our experiences with pancreatic transplantations. We transplanted 65 pancreatic grafts between 2015 and 2020. Except for one death due to hypoxic brain damage after surgery, no postoperative technical failure was observed. We usually perform duodeno-duodenal anastomosis using the transperitoneal approach, with retrocolic placement of the graft pancreas. There was no leakage from the duodenum even after immunologic graft failure. To prevent venous thrombosis, which is the most common cause of technical failure, we used the inferior vena cava for anastomosis and added graft venoplasty with a patch of donor vena cava or aortic interposition graft to the bench procedure; subsequently, there were no cases of technical failure due to thrombosis post-transplantation. Therefore, the 1-year graft survival (insulin-free) rate was more than 95%. The improving the surgical technique will maintain pancreatic transplantation as the best treatment for insulin-dependent diabetes. This article is protected by copyright. All rights reserved.

Early protocol computer tomography and endovascular interventions in pancreas transplantation

BACKGROUND

Early vascular complications following pancreatic transplantation are not uncommon (3%-8%). Typically, cross-sectional imaging is requested in response to clinical change. We instituted a change in protocol to request imaging pre-emptively to identify patients with thrombotic complications.

METHODS

In 2013, protocol computer tomography angiography (CTA) at days 3-5 and day 10 following pancreas transplantation was introduced. A retrospective analysis of all pancreas transplants performed at our institution from January 2001 to May 2019 was undertaken.

RESULTS

A total of 115 patients received pancreas transplants during this time period. A total of 78 received pancreas transplant without routine CTA and 37 patients with the new protocol. Following the change in protocol, we detected a high number of subclinical thromboses (41.7%). There was a significant decrease in invasive intervention for thrombosis (78.6% before vs 30.8% after, p = .02), and graft survival was significantly higher (61.5% before vs 86.1% after, p = .04). There was also a significant reduction in the number of graft failures (all-cause) where thrombosis was present (23.4% before vs 5.6% after, p = .02). Patient survival was unaffected (p = .48).

CONCLUSIONS

Implementation of early protocol CTA identifies a large number of patients with subclinical graft thromboses that are more amenable to conservative management and significantly reduces the requirement for invasive intervention.

Fence Angioplasty Prevents Narrowing of Venous Anastomosis in Solitary Pancreas Transplant

Background

Graft thrombosis is the leading cause of early graft failure in pancreas transplants. Direct anastomosis grafting of the portal vein to the iliac vein or vena cava generally appears narrowed on postoperative computed tomography (CT) scans. However, modification of surgical techniques may prevent venous narrowing, which also prevents thrombosis-related graft failure.

Material/Methods

We performed 31 solitary pancreas transplants since 2015. Retrospective analysis of these patients was performed.

Results

Fence angioplasty was applied in the final 12 cases, and no technical failures or early graft losses occurred in these cases. Three graft losses, including 2 immunologic losses and 1 patient death with functioning graft, occurred after at least postoperative 4 months. The venous anastomoses were evaluated via intraoperative Doppler ultrasound and postoperative CT scans. Intraoperative Doppler ultrasound revealed improved spectral waves of venous anastomoses in the fence group (monophasic spectral wave, 42.9% vs. 0%, p=0.017). The fence-graft applied group had no cases of narrowing, whereas the non-fence group had high narrowing rates on CT scans (84.2% vs. 0%, p<0.001). Furthermore, with less use of postoperative heparin, postoperative bleeding rates were lower in the fence group (36% vs. 0%, p=0.026).

Conclusions

Fence angioplasty is a definitive method for avoiding venous anastomotic stenosis and preventing graft failure due to thrombosis.

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.

Techniques of pancreas graft salvage/indications for allograft pancreatectomy

PURPOSE OF REVIEW

Despite improvements in pancreas allograft outcome, graft complications remain a significant cause of morbidity and mortality. This review analyses the issues involved in the management of conditions that may require graft pancreatectomy, including the indications and techniques for graft salvage.

RECENT FINDINGS

With early recognition of graft complications, liberal use of radiological interventions, improved infection control, access to critical care and innovative surgical techniques, graft salvage is now feasible in many circumstances where graft pancreatectomy would previously have been necessary.

SUMMARY

The outcome of pancreas transplantation continues to improve with advances in the management of graft-threatening complications.

Clinical Experience with Pancreas Graft Rescue From Severe Thrombus After Simultaneous Pancreas-Kidney Transplantation by Early Detection with Doppler Ultrasound: A Case Report

Patient: Female, 41

Final Diagnosis: Graft thrombosis

Symptoms: None

Medication: —

Clinical Procedure: Doppler ultrasound

Specialty: Transplantology

Pancreas Transplantation From Living Donors: A Single Center Experience of 20 Cases

Living donor pancreas transplantation (LDPT) has several advantages over deceased donor pancreas transplantation (DDPT), including better HLA matching, shorter ischemic time, and shorter waiting time. It remains an attractive option for diabetes mellitus (DM) patients with end stage renal disease. We reviewed 20 cases of LDPT performed in Asan Medical Center between October 1992 and March 2015. Six cases (30%) were pancreas transplantation alone (PTA), and the rest (70%) were simultaneous pancreas and kidney transplantation (SPK). Relations of donor and recipient were parents in 7 (35%), siblings in 6 (30%), spouse in 6 (30%), and cousin in 1 (5%). Graft survival in SPK at 1, 3, 5, and 10 years was 91.7%, 83.3%, 83.3%, and 83.3%, respectively, and that in PTA recipients was 50%, 33.3%, 16.7%, and 16.7%, respectively (p = 0.005). Causes of graft failure in SPK were thrombosis (one case), and rejection (one case), whereas those in PTA were noncompliance (two cases), thrombosis (one case), reflux pancreatitis (one case), and chronic rejection (one case). In terms of pancreas exocrine drainage, two grafts (25%) maintained their function in bladder drainage, while all grafts maintained in enteric drainage p < 0.05). Seven (35%) donors experienced minor pancreatic juice leakage and one underwent reoperation due to postoperative hematoma. Most donors maintained normoglycemia and normal renal function. However, two donors developed DM (at 1 and 90 months postdonation), and were treated with oral hypoglycemic agents. Graft survival in PTA recipients was poorer than in SPK due to poor compliance and bladder drainage-related problems. The surgical and metabolic complication rates of donors can be minimized by applying strict donor criteria. Therefore, LDPT with enteric drainage is an acceptable treatment for SPK.

Formation of Collateral Veins in a Graft Pancreas After a Simultaneous Pancreas and Kidney Transplantation: A Case Report

A graft vein thrombosis is the main cause of early graft failure after pancreas transplantation. We report a case of formation of collateral veins in a graft pancreas after transplant. A 30-year-old woman underwent simultaneous pancreas and kidney transplantation. She was discharged 16 days after the operation with good pancreas and kidney function. A total occlusion of the portal vein was discovered on computed tomography (CT) performed at an outpatient clinic. She had no symptoms or signs of hyperglycemia. Venography was attempted for vein thrombectomy but failed. After 2 weeks of heparinization therapy, the edema disappeared and perfusion of the graft pancreas improved. However, the thrombotic occlusion was not resolved on CT. Arteriography of the Y-graft revealed collateral veins. She was discharged with warfarin. She is currently doing well without any symptoms or signs. This is the first reported case of collateral vein formation in a grafted pancreas after pancreas transplantation.

Endovascular Management for the Treatment of Pancreas Transplant Venous Thrombosis: A Single-Center Experience

PURPOSE

To investigate the safety and efficacy of mechanical thrombectomy used as a tool for graft rescue in patients with pancreas graft venous thrombosis (PGVT).

MATERIALS AND METHODS

Graft venous thrombosis was discovered in 36 (33%) of 110 patients who underwent pancreas transplantation. Percutaneous aspiration thrombectomy was performed in seven patients (mean age, 31 y; range, 15-36 y) who had complete or severe thrombosis of the splenic vein or superior mesenteric vein seen on postoperative computed tomography.

RESULTS

Successful evacuation of PGVT was possible in six of seven patients; the thrombus was partially evacuated in one patient. In this patient, subsequent anticoagulation salvaged the graft, rendering primary and secondary technical success rates as 86% and 100%, respectively. As pancreas grafts were successfully functioning in all seven patients within 1 month after endovascular treatment, the clinical success rate was 100%. There were no procedure-related complications. At the last follow-up evaluation, all seven patients were alive with no graft loss (mean follow-up time, 9.4 mo; range, 3.6-22.2 mo).

CONCLUSIONS

Endovascular treatment may be considered in patients with severe PGVT to prevent early graft loss.

US Findings in Patients at Risk for Pancreas Transplant Failure

Purpose To determine if ultrasonographic (US) findings, including Doppler US findings, are associated with subsequent pancreas transplant failure. Materials and Methods A cohort of adult patients who underwent pancreas transplantation at a tertiary institution over the course of 10 years (from 2003 to 2012) was retrospectively evaluated for failure, which was defined as return to insulin therapy or surgical graft removal. The institutional review board provided a waiver of informed consent. All US images obtained within the 1st postoperative year were reviewed for three findings: arterial flow (presence or absence of intraparenchymal forward diastole flow), splenic vein thrombus, and edema. These findings were correlated with pancreas graft failure within 1-year after surgery by using Cox proportional hazards models and hazard ratios. Results A total of 228 transplants were included (mean patient age, 41.6 years; range, 19-57 years; 122 men, 106 women). Absent or reversed arterial diastolic flow was identified in nine of 20 failed transplants (sensitivity, 45%; 95% confidence interval [CI]: 23, 68) and in 15 of 208 transplants that survived (specificity, 93% [193 of 208]; 95% CI: 89, 96). The Cox proportional hazard ratio was 6.2 (95% CI: 3.1, 12.4). Splenic vein thrombus was identified in 10 of 20 failed transplants (sensitivity, 50%; 95% CI: 27, 73) and in 25 of 208 transplants that survived (specificity, 88% [183 of 208]; 95% CI: 83, 92). The Cox proportional hazard ratio was 4.2 (95% CI: 2.4, 7.4). Edema had the lowest specificity (Cox proportional hazard ratio, 2.0; 95% CI: 1.3, 2.9). In the multivariate analysis, only absent or reversed arterial diastolic flow remained significantly associated with transplant failure (adjusted hazard ratio, 3.6; 95% CI: 1.0, 12.8; P = .045). Conclusion Absent or reversed diastolic arterial Doppler flow has a stronger association with transplant failure than does splenic vein thrombus or edema. (©) RSNA, 2016.

Multivariate analysis of complications after simultaneous pancreas and kidney transplantation

OBJECTIVE

Identification of factors that have an impact on postoperative complications after simultaneous pancreas and kidney transplantation (SPKTx) could help overcome limitations of this kind of treatment.

METHODS

Postoperative complications among 112 SPKTx recipients were divided into 3 groups: related to transplanted pancreas (n = 66), related to transplanted kidney (n = 23) and general surgical complications (n = 31) 120 refers to complications among 112 recipients. According to the modified Clavien-Dindo scale, complications were classified according to their severity for each group. Risk factors for complication development related to donor, recipient, surgical technique, and immunosuppression were included to establish the multivariable model using logistic regression.

RESULTS

Multiple regression analysis showed the following independent factors influenced mortal complications due to transplanted pancreas: age of donor (OR, 1.07; P < .04), duration of vascular pancreas anastomosis above 35 minutes (OR, 3.94; P < .04) and duration of recipient dialysis above 24 months before transplantation (OR, 0.14; P < .01). Area under receiver operating characteristic curve for this model was 0.8.

CONCLUSION

To improve results, the following modification of identified risk factors should be assumed: selection of donor in term of age, shortening of the second warm ischemia time, and adjustment of the waiting list to avoid prolongation of recipient dialysis before SPKTx.

Multi detector computed tomography (MDCT) for the diagnosis of early complications after pancreas transplantation

PURPOSE

Solitary Pancreas (SPT) and simultaneous kidney-pancreas (SPKT) transplants carry a high risk of surgical complications that may lead to the loss of the pancreas graft and impact later kidney function. The purpose of this study was to investigate the role of MDCT in the diagnosis of early complications and its impact on kidney function.

METHODS

All patients receiving SPT or SPKT over 5 years were retrospectively included. Complications that occurred within the first 15 days were registered and MDCT data analyzed. Data regarding donor, transplant, and recipient characteristics as well as transplantation procedures were analyzed according to the occurrence of early complications. Kidney function at day 3 following MDCT was evaluated.

RESULTS

One hundred and forty-one patients were included (85 men, 56 women; mean age 40.1 years, SD 7.7) with 119 SPKT and 22 SPT. Sixty-four complications were registered in 50 patients. Partial (P-) or complete venous thrombosis (C-VT) occurred in 12.1 % (n = 17), arterial thrombosis (AT) in 1.4 % (n = 2), and hemorrhage in 8.5 % (n = 12) of all patients. For venous thrombosis, the predominant risk factor was body mass index (BMI) for either recipients (P < 0.05) or donors (P < 0.01). Median time for venous thrombosis diagnosis with MDCT was 4 days. Kidney function was not altered following MDCT. Fourteen pancreatectomies were necessary. All patients with C-VT and AT had to undergo graftectomy.

CONCLUSION

Vascular complications occurred early following grafting. Systematic early-enhanced MDCT at day 2-3 should be adequate to detect early thrombosis, especially if risk factors have been identified, without induced kidney function alteration.

Long-term Effects of Delayed Graft Function on Pancreas Graft Survival After Pancreas Transplantation

BACKGROUND

Compared with the impact of delayed graft function (DGF) after renal transplantation, DGF after pancreas transplantation has not been fully evaluated.

METHODS

We retrospectively verified the impact of DGF on long-term pancreas graft survival in surgically successful cases. Pancreas graft failure was defined by the recipient's return to exogenous insulin administration.

RESULTS

Between May 2004 and April 2013, we performed 135 technically successful primary pancreas transplantations. Delayed graft function was defined as a total cumulative insulin requirement of 19 UI or greater within postoperative 7 days. Of the 135 recipients in our study cohort, 47 (34.8%) developed DGF after the pancreas transplantation. By multivariate analysis, DGF was found to be associated with a donor age of 30 years or older (odds ratio, 3.4; 95% confidence interval, 1.50-7.69; P=0.003) and the increased ratio of body mass index in a recipient to a donor (odds ratio, 26.1; 95% confidence interval, 2.53-270.0; P=0.006). There was a trend toward higher acute rejection (P=0.622) and mortality (P=0.49) rates in recipients with versus without DGF, although this did not reach statistical significance. Delayed graft function was found to be associated with a greater risk of overall pancreas graft failure (P=0.016) and death-censored graft failure (P=0.037).

CONCLUSION

Delayed graft function after pancreas transplantation was found to be associated with a greater risk of overall pancreas graft failure and death-censored graft failure.

Simultaneous pancreas-kidney transplantation: lessons learned from the initial experience of a single center in Korea

Purpose

The purpose of this study is to report the results of simultaneous pancreas-kidney (SPK) transplantations and describe the lessons learned from the early experiences of a single center.

Methods

Between January 2002 and June 2013, a total of 8 patients underwent SPK transplantation. Clinical and radiologic data were reviewed retrospectively.

Results

Seven patients were diagnosed with type I diabetes mellitus and one patient became insulin-dependent after undergoing a total pancreatectomy because of trauma. Pancreas exocrine drainage was performed by enteric drainage in 4 patients and bladder drainage in 4 patients. Three patients required conversion from initial bladder drainage to enteric drainage due to urinary symptoms and duodenal leakage. Four patients required a relaparotomy due to hemorrhage, ureteral stricture, duodenal leakage, and venous thrombosis. There was no kidney graft loss, and 2 patients had pancreas graft loss because of venous thrombosis and new onset of type II diabetes mellitus. With a median follow-up of 76 months (range, 2-147 months), the death-censored graft survival rates for the pancreas were 85.7% at 1, 3, and 5 years and 42.9% at 10 years. The patient survival rate was 87.5% at 1, 3, 5, and 10 years.

Conclusion

The long-term grafts and patient survival in the current series are comparable to previous studies. A successful pancreas transplant program can be established in a single small-volume institute. A meticulous surgical technique and early anticoagulation therapy are required for further improvement in the outcomes.

Role of 16-multidetector computerized tomography in evaluation of graft failure risk in patients with pancreatic graft thrombosis after simultaneous pancreas and kidney transplantation

BACKGROUND

Thrombosis of the pancreatic graft vessels is a common complication in patients after pancreas transplantation. The aim of this study was to evaluate the usefulness of 16-multidetector computerized tomography (16-MDCT) with volume rendering (VR) and maximum intensity projection (MIP) reconstruction as a predicting method of pancreatic graft loss after simultaneous pancreas and kidney transplantation.

METHODS

Within 6-8 days after combined kidney-pancreas transplantation, MDCT was performed in 60 patients. Secondary reconstructions were obtained with the application of VR and MIP algorithms. Vessel anastomosis, extra- and intrapancreatic arteries, venous morphology, and enhancement of graft's parenchyma were evaluated. The stenosis grade of pancreatic graft vessels and the areas of graft parenchyma malperfusion were evaluated.

RESULTS

Thrombosis of pancreatic graft vessels was recognized in 26 patients (43%), however only one-half of them required graftectomy. There were 17 cases of large vessel thrombosis and 9 cases of small intragraft vessel thrombosis. In 13 (86.6%) out of 15 recipients parenchymal malperfusion resulted in graft lost. It appeared that vessel narrowing >40% was a threshold for pancreatic graft loss with sensitivity and false positive values of 100% and 9%, respectively. For parenchyma nonenhancement >60% the sensitivity and false positive values of 100% and 0% were significantly associated with pancreatic graft loss (P < .0001).

CONCLUSIONS

Vascular occlusion of >40% and necrosis >60% of parenchymal volume correspond with pancreatic graft loss.