An Innovative Endovascular Approach to Pancreatic Transplant Artery Y-Graft Aneurysm Complications Using Elective Endovascular Techniques: A Case Report

Introduction

The incidence of pancreatic transplant artery pseudoaneurysm was reported by Yadev and colleagues to be 1%, although it is likely under-reported and has been previously reported to be as high as 8% [1,2]. Arterial pseudoaneurysms are potentially life-threatening when they involve disruption of the vessel wall continuity, resulting in hemorrhage. This can present as gastrointestinal bleeding due to pseudoaneurysm erosion into the adjacent bowel, massive internal abdominal bleeding, or asymptomatic if it is a contained pseudoaneurysm [3]. To the best of our knowledge, this is the first reported case of a chronic transplant pancreas artery aneurysm treated with endovascular stenting.

Case Report

A 54-year-old man underwent a simultaneous pancreas and kidney transplant in 2002 from a donation after brain death donor for end-stage renal failure secondary to type 1 diabetes. The pancreatic transplant artery was anastomosed to the right common iliac artery and was performed at Monash Hospital. He was discharged home with stable pancreatic and renal function after an uneventful postoperative recovery.

In 2023 a computed tomography scan with arterial phased contrast (CT-A) was performed to investigate upper-abdominal pain, which found significant aneurysmal change (40×35 mm) of the transplant pancreatic artery (Figure 1).

The case was discussed in a vascular surgery multidisciplinary meeting. Given the high risk of rupture, both endovascular and open interventions were discussed with the patient. Following the patient’s last surgery, a laparoscopic cholecystectomy in 2022 in which significant adhesions were encountered, an endovascular approach was chosen to treat the pancreatic artery aneurysm. The main risk of endovascular stenting is loss of perfusion to the distal pancreas by sacrificing the splenic artery to allow stenting of the superior mesenteric artery (SMA) to maintain perfusion to the head of the pancreas.

Access was achieved via the right common femoral artery with a 10-French Dryseal sheath. A 10×50 mm Viabahn stent was then deployed into the main artery. The splenic artery and SMA were cannulated with.018 Command wires, and two 6×50 mm Viabahn stents were deployed (Figure 2).

The postoperative period was uneventful and the patient was discharged 2 days after the operation. The patient reported no further abdominal pain and maintained regular transplant pancreatic function. A CT-A 6 weeks after stenting showed no endoleaks and found a reduction in the size of the pseudoaneurysm to 30 mm.

Discussion

Vascular complications from pancreatic transplants are among the most clinically challenging to manage [4]. These complications include arterial and venous thrombus, hemorrhage, and arteriovenous fistulas, but pancreatic transplant aneurysms are rare [3]. The literature on diagnosis and management of pancreatic transplant artery aneurysms is scant and consists of case reports and small case series [3,5]. We believe this is the first published case of a chronic pancreatic aneurysm existing for more than 20 years treated with endovascular stenting.

Although rare, pancreatic transplants have higher rates of pseudoaneurysm than any other visceral transplants (incidence of 1%) and threaten long-tern graft function [1]. Pseudoaneurysms arise from a disruption of arterial continuity and usually arise from technical issues of the vascular anastomosis or are caused by infection. Other etiologies include trauma, vasculitis, chronic rejection, and postoperative pancreatitis [6]. Post-transplant infections or pancreatitis can lead to peripancreatic collections that erode the artery wall, leading to pseudoaneurysm formation [7]. Peripancreatic biopsies or trauma to the transplanted pancreas can cause arterial damage. In addition, chronic inflammation from rejection can result in arterial wall erosion, also leading to pseudoaneurysm formation.

As a potential late-onset complication occurring 3 months after transplantation, termed a chronic pseudoaneurysm, transplant pancreatic artery pseudoaneurysm can be fatal due to hemorrhage. This case report is the first to identify a chronic pseudoaneurysm 20 years after transplantation. Development of late pancreatic artery pseudoaneurysm is thought to be due to weakening of the arterial wall from transient leakage of pancreatic exocrine enzymes, often caused by chronic rejection or pancreatitis [1]. On retrospective review of the case, a clear etiology remains unknown, as for 20 years the allograft function was stable, with no previous episodes of pancreatitis. Additionally, a biopsy was performed after endovascular intervention, which demonstrated no signs of chronic rejection.

Based on the calcified margin, mural thrombus, and eccentric lumen demonstrated on CT-A, we suspect that the pancreatic artery pseudoaneurysm was chronic. Over time, there were likely small sentinel leaks of pancreatic enzymes around the weak point of the original arterial anastomosis of the donor superior mesenteric artery and splenic artery to the donor Y-graft. Luckily, this did not lead to a fatal hemorrhage in this case.

Although the patient presented with upper-abdominal pain, we suspect that this was unrelated to the finding of the transplant pancreatic artery aneurysm, but regardless, the finding of mural thrombus with consequential threat to graft function prompted quick elective intervention.

To maintain graft function, preservation of the pancreatic transplant arterial blood supply is critical. Pancreatic transplant arterial aneurysms can be life-threatening if a complication such as rupture occurs, with resultant high morbidity and high mortality risk [2,8–10]. Consequently, the standard management in these cases is open repair of the aneurysm with or without allograft removal. If patients are asymptomatic and the pseudoaneurysm is stable in size on interval imaging, aneurysms can be managed conservatively [11]. Aneurysm size and location, patient co-morbidities, and the extent of hemorrhage are all critical factors in deciding between open or endovascular management [1,10,12]. Other procedural options include pancreatic transplant artery transposition, endovascular stenting or endovascular coiling, or a combination of both endovascular stenting and coiling [13].

Greater adoption of endovascular repair has occurred, as it is minimally invasive and has lower morbidity compared to open laparotomy to manage bleeding and prevention of aneurysm rupture, particularly in frail and elderly patients. Endovascular stenting has been successful for pseudoaneurysms located away from the arterial anastomosis [13]. Endovascular stents are useful in imminent control of massive hemorrhage, but must be carefully considered with mycotic pseudoaneurysm due to long-term seeding of infection. Endovascular covered stents can be a definitive treatment or a temporization step before open repair in the case of rebleeding, allograft necrosis, or loss of allograft function [3,14]. Customised stents such as those used in this case require time for manufacturing and are not suitable in emergency settings. Furthermore, standard stenting over the arterial anastomosis, including the Y-graft, has a risk of sacrificing or covering a transplant artery and subsequent risk of graft failure and loss.

This case report demonstrates that the use of elective endovascular stenting within the Y-graft aneurysm is achievable and maintains graft function. Future studies should assess the efficacy of endovascular stenting in a larger cohort of patients including the medium- and long-term pancreas allograft outcomes.

Conclusions

Pancreatic transplant artery aneurysms, particularly chronic pseudoaneurysms, can be successfully managed with endovascular stenting to prevent potentially life-threatening hemorrhage. Compared to open treatment, stenting is a less invasive alternative that can successfully preserve graft function.