Objectives: Renal artery intimal injury during kidney transplant is infrequent but potentially devastating, especially when situated near the hilar trifurcation, where standard reconstruction techniques are frequ-ently unfeasible. Prompt identification is difficult because the arterial pulse may persist despite significant luminal obstruction. We report a case involving a 24-year-old female living donor whose left kidney was transplanted into a 54-year-old male recipient with end-stage renal disease. Although initial reperfusion appeared satisfactory, the graft gradually became cyanotic and soft during the procedure. Doppler signals remained preserved, and there was no response to vasodilatory interventions. We suspected arterial inflow impairment, and so we proceeded with inspection of the vascular anastomoses and revealed intimal disruption with significant luminal narrowing at the hilar trifurcation. Given the lack of a reconstructible distal arterial segment, patch angioplasty was performed using an expanded polytetrafluoroethylene graft, thereby forming a composite arterial conduit while preserving the posterior native wall. Following reimplantation, graft perfusion improved, showing satisfactory intraoperative Doppler findings. The graft produced immediate urine output, although the postoperative course was complicated by severe acute tubular necrosis due to prolonged warm ischemia time (87 minutes). At 6 weeks, the patient remained independent from dialysis with a serum creatinine of 300 μmol/L (estimated glomerular filtration rate 21 mL/min/1.73 m²). Doppler ultrasonography confir- med sustained graft patency without evidence of stenosis or thrombosis, and a renal allograft biopsy showed no rejection. Further functional recovery remains possible but uncertain. To our knowledge, this is among the first reports of polytetrafluoroethylene patch angioplasty for treatment of near-hilar intimal injury in a living donor transplant. Polytetrafluoroethylene patch angioplasty constitutes a viable salvage methodology for near-hilar renal artery intimal injury in living donor kidney transplant. Polytetrafluoroethylene patch angioplasty achieves graft patency and dialysis-independent survival, even in cases with extended duration of warm ischemia time that may delay functional recovery.

Key words : Graft salvage, Intimal dissection, Living donor kidney transplantation, Renal artery injury, Vascular complications

Introduction

Vascular complications occur in approximately 3% to 15% of kidney transplants and remain a significant cause of early graft dysfunction and loss. Among these vascular complications, renal artery thrombosis is one of the most catastrophic events, which frequently results in immediate graft failure if not promptly recognized and managed.¹ Despite advances in surgical technique and perioperative care, vascular complications continue to carry substantial risks for both graft survival and recipient outcomes. Early diagnosis can be particularly challenging, because arterial pulsatility and Doppler signals may persist despite significant luminal compromise.²
Renal artery intimal injury may occur during donor nephrectomy, back-table preparation, or graft implantation.² Even minor intimal disruption can lead to turbulent flow, thrombosis, or progressive luminal occlusion. Unlike overt arterial thrombosis, which typically presents with sudden anuria and absent Doppler flow, intimal injury may preserve seemingly normal Doppler waveforms, thereby constituting a well-documented diagnostic challenge.³ In such cases, intraoperative visual cues, including progressive graft cyanosis and loss of turgor, may offer more reliable indicators of arterial inflow obstruction versus Doppler findings alone.²
Management strategies for renal artery injury encompass primary repair, arterial shortening, inter-position grafting, and patch angioplasty utilizing either autologous or prosthetic materials. The selection of an appropriate technique is largely contingent upon the location and extent of the injury. Injuries near the hilar trifurcation pose a distinct technical challenge, as such injuries often lack an adequate distal arterial segment for clamping or reconstruction. In such cases, conventional approaches such as resection or inter-position grafting may prove to be anatomically unfeasible.²
Polytetrafluoroethylene (PTFE) grafts have been employed in transplant surgery for vascular reconstruction, including arterial extension and salvage of injured vessels, with acceptable short-term to mid-term outcomes.^2,4 These PTFE grafts possess favorable handling characteristics and an acceptable thrombogenic profile in high-flow environments. Nevertheless, use of PTFE grafts in the acute intraoperative management of intimal injury at or near the renal hilar trifurcation, especially in living donor transplants, is rarely documented.
Presently, no standardized approach exists for management of intimal injuries in this anatomically prohibitive location. This report describes the use of PTFE patch angioplasty to salvage a renal allograft with near-hilar intimal injury, a scenario in which conventional reconstructive options were not feasible. Our study thus underscores a pragmatic, anatomy-driven solution and seeks to broaden the spectrum of surgical options available for graft salvage in complex vascular cases. Nonetheless, there have been no previous reports that explicitly describe the applica-tion of PTFE patch angioplasty for intimal injury at the hilar trifurcation, where anatomic constraints limit reconstruction.

Case Report

The living donor was a 24-year-old woman with a body mass index (measured as kilograms body mass per height in meters squared) of 16.6 who underwent a left laparoendoscopic single-site donor nephrectomy.⁵ Predonation evaluation revealed no vascular anomalies, and the left kidney was selected based on standard anatomic and functional criteria. Her baseline serum creatinine was 62 μmol/L (estimated glomerular filtration rate [eGFR] 118 mL/min/1.73 m²). The procedure was completed uneventfully, with a donor warm ischemia time of 2 minutes. The retrieved graft had a single renal artery and a single renal vein.
The recipient of the preemptive living related kidney transplant was a 54-year-old man with a body mass index of 33.6 and diabetes, hypertension, and end-stage renal disease. His pretransplant serum creatinine was 812 μmol/L, with eGFR of 7 mL/min/-1.73 m². Vascular exposure was technically difficult, due to obesity.
After induction with thymoglobulin, a standard retroperitoneal approach was employed. The renal vein was anastomosed to the external iliac vein with continuous 5-0 polypropylene sutures, and the renal artery was anastomosed to the external iliac artery with 6-0 polypropylene sutures. Initial reperfusion was deemed satisfactory, which was confirmed by appropriate graft coloration and palpable arterial pulsation.
However, during ureteroneocystostomy, the graft exhibited progressive cyanosis and softening approximately 20 minutes following reperfusion. Handheld Doppler assessment indicated preserved arterial pulsation, and systemic blood pressure re-mained stable. Empirical interventions to mitigate suspected vasospasm, including the administration of papaverine, lidocaine, nitroglycerin, and intra-renal verapamil, as well as systemic heparin (3000 U), did not result in an improvement of the graft appearance.
The discrepancy between preserved Doppler signals and the ongoing graft ischemia prompted an immediate suspicion of mechanical arterial inflow obstruction rather than vasospasm. The graft was explanted and flushed on the back table using histidine-tryptophan-ketoglutarate solution with 10 000 U of heparin. The previously small-caliber renal artery was incised longitudinally, revealing intimal disruption with significant luminal compromise imme-diately proximal to the hilar trifurcation (Figure 1). The artery was divided into 3 segmental branches immediately distal to the injured segment; as such, no adequate distal stump was available for clamping or interposition grafting.
In light of the unavailability of a reconstructible distal arterial segment, patch angioplasty was deemed to be the most practicable reconstructive strategy. An expanded PTFE graft (Acuseal Vascular Graft, 4-7 mm; Gore Medical) was meticulously tailored and sutured with continuous 7-0 polypropylene, forming a com-posite arterial conduit while conserving the posterior native wall and augmenting the anterior wall. The reconstructed artery exhibited satisfactory geometry, with no signs of leakage (Figure 2). The graft was reimplanted utilizing the same vascular configuration. Reperfusion was initially postponed, which resulted in the kidney remaining cyanotic for approximately 20 minutes before a gradual improvement in coloration and turgor was observed. Intraoperative Doppler assessment confirmed sufficient arterial inflow, with cortical and hilar resistive indexes measuring 0.5 (Figure 3). Subsequently, uretero-neocystostomy was completed, and a double-J ureteric stent was inserted. Urine output reached 600 mL within the first postoperative hour.
The total duration of warm ischemia time was 87 minutes, calculated as follows: donor warm ischemia time was 2 minutes, first implantation was 28 minutes, interval from reperfusion to reexploration was 20 minutes, explantation and back-table flush was 6 minutes, and second implantation was 31 minutes. The total duration of cold ischemia time was 67 minutes, comprising 35 minutes of storage and 32 minutes for back-table reconstruction.

Postoperative course
In the absence of standardized guidelines, antithrom-botic therapy was individualized based on perceived thrombotic risk and institutional practice. On postoperative day 0, treatment was initiated with enoxaparin 20 mg daily and aspirin (acetylsalicylic acid) 81 mg daily. On postoperative day 1, serum creatinine peaked at 660 μmol/L, urine output was 400 to 500 mL/h, and Doppler ultrasonography demonstrated preserved perfusion (main renal artery resistive index 0.7, cortical resistive index 0.6), with a peak systolic velocity of 44 cm/s proximally and 33 cm/s distally and no waveform abnormalities. Enoxaparin was increased to 30 mg daily, and aspirin was continued.
The identical regimen was maintained during the first 2 days after surgery, with stable hemoglobin levels. During postoperative day 2 and postoperative day 3, clopidogrel 75 mg daily was incorporated, given the confirmed absence of bleeding and a desire to mitigate the elevated thrombotic risk. The maintenance immunosuppression protocol included prednisolone, mycophenolate mofetil, and tacrolimus.
During the initial 72 hours, supportive manage-ment focused on maintenance of mean arterial pressure within the range of 80 to 90 mmHg, to ensure adequate intravascular volume status and to prevent hypotension, preclude the need for vasoconstrictor agents, and avoid elevated calcineurin inhibitor levels.
The postoperative course was complicated by severe acute tubular necrosis caused by extended warm ischemia time, manifested by polyuria ave-raging approximately 400 mL/h during the initial 8 days. Serial Doppler ultrasonography examinations consistently demonstrated resistive index values ranging from 0.6 to 0.7, indicating preserved vascular patency. These findings remained stable on daily monitoring for the subsequent 2 to 3 days.
Following the initial postoperative week, enoxa-parin was discontinued, while dual antiplatelet therapy was maintained for 4 to 6 weeks. The patient was discharged on postoperative day 10 with a serum creatinine level of 300 μmol/L. After this period, dual antiplatelet therapy was transitioned to a lifelong regimen of aspirin.

Follow-up at 6 weeks
At the 6-week follow-up, the patient remained with dialysis-independent status, and serum creatinine remained at 300 μmol/L (eGFR 21 mL/min/1.73 m²). Doppler ultrasonography demonstrated a patent renal artery with a peak systolic velocity of 60 cm/s, no evidence of stenosis, and a resistive index of 0.65. Good cortical perfusion with no waveform abnorma-lities indicated sustained vascular patency without complications. A renal allograft biopsy showed no evidence of rejection or significant chronic injury, consistent with ongoing recovery from prolonged ischemic acute tubular necrosis. Further gradual improvement in renal function is anticipated over the subsequent months.

Discussion

This case underscores several crucial technical and clinical considerations for management of renal artery intimal injury during kidney transplant, parti-cularly when the lesion is situated at or near the hilar trifurcation, which is a challenging anatomic location where conventional reconstructive strategies may prove unfeasible.
Renal artery intimal injury constitutes a recog-nized diagnostic challenge. Unlike overt arterial thrombosis, which generally manifests with abrupt cessation of blood flow and absence of Doppler signals, intimal disruption may maintain arterial pulse and Doppler waveforms despite significant luminal narrowing.^2,3 In this case, the preservation of Doppler signals initially obscured the severity of the arterial lesion, whereas the progressive development of graft cyanosis and loss of turgor served as critical clinical indicators of inflow deficiency. These circums-tances emphasize the primacy of intraoperative visual assessment over Doppler findings in cases of suspected arterial compromise.²
The location of the injury in this case, imme-diately proximal to the hilar trifurcation, posed a unique reconstructive challenge. Conventional techniques such as segmental resection with reanastomosis or interposition grafting require an adequate distal arterial segment for clamping and reconstruction. However, when the artery divides early into multiple segmental branches, as in this case, no suitable distal target exists. Primary repair is similarly limited to minor, non-flow-limiting injuries and is not appli-cable in the presence of significant luminal narrowing.² These anatomic constraints render standard approaches ineffective and necessitate alternative strategies.
Patch angioplasty provides a notable technical benefit in this scenario. By expanding the arterial lumen without the necessity of distal anastomosis, patch angioplasty preserves the posterior native arterial wall and maintains the integrity of segmental branch origins. The patch angioplasty method is especially appropriate for near-hilar injuries, where the arterial length is limited and further shortening could impair perfusion. In this case, patch angioplasty reestablished luminal geometry while avoiding additional anastomotic sites, thereby minimizing additional difficulty to the well-known technical challenges associated with such unexpected scenarios.²
The selection of an appropriate conduit for arterial reconstruction is of paramount importance. Autologous vein grafts are conventionally preferred due to the biocompatibility and reduced thrombo-genic potential; nonetheless, such grafts possess certain limitations. Reports have documented late complications such as aneurysmal degeneration and rupture, including the rupture of a saphenous vein aortorenal graft several years after implantation,⁶ aneurysmal degeneration subsequent to renal artery reconstruction,⁷ and the formation of graft-enteric fistulas.⁸ These risks are especially pertinent to younger recipients, for whom long-term durability is critical.²
In contrast, PTFE grafts offer advantageous handling characteristics, structural stability, and a satisfactory thrombogenic profile within high-flow vascular beds.⁴ The PTFE graft has been effectively employed in transplant procedures for arterial exten-sion and vascular salvage, demonstrating acceptable short-term to mid-term outcomes.^2,4 In the acute intraoperative setting, for which prompt and reliable reconstruction is imperative to avert graft loss, these attributes make PTFE an appealing option. Although concerns persist regarding prosthetic infection and thrombosis, these concerns must be considered against the almost certain loss of the graft if reconstruction is not attempted.² In this scenario, the risk assessment favors prosthetic reconstruction.
Heparin-bonded PTFE grafts have exhibited pro-mising patency rates in peripheral vascular surgery, approaching those of autologous vein grafts in certain contexts.⁹ Although direct comparative data in renal transplants are lacking, the high-flow conditions of the renal artery may further support the use of PTFE in this context.² Notably, the lack of aneurysmal degeneration in PTFE grafts signifies a potential long-term benefit over vein conduits.
The total duration of warm ischemia time in this case was 87 minutes, exceeding the widely recognized threshold of 30 minutes, which is correlated with an elevated risk of delayed graft function.² Extended ischemia exceeding 60 minutes has been associated with increased incidence of delayed graft function, prolonged hospitalization, and potential long-term decline in graft performance.¹⁰ Nevertheless, the graft exhibited immediate urine production, signifying maintained functional viability.
The subsequent development of severe acute tubular necrosis, characterized by a prolonged polyuric phase and a delayed decline in serum creatinine, was consistent with ischemia-reperfusion injury. However, graft function recovered over time, with stable renal function at 6 weeks. This case also illustrates that technical success in vascular reconstruction does not guarantee immediate functional recovery. Despite a patent allograft and the absence of rejection, severe acute tubular necrosis resulting from prolonged warm ischemia time (87 minutes) led to delayed and incomplete renal recovery at 6 weeks. Nonetheless, the patient remains with dialysis-independent statis, and graft survival has been achieved, which is a favorable and successful outcome given the other-wise inevitable risk of graft loss. Extended follow-up is necessary to ascertain the final extent of functional recovery, which may continue for 12 to 24 months following severe ischemic injury.
Several factors likely contributed to this favorable outcome, including the use of a living donor graft with substantial nephron reserve,¹¹ meticulous hemodynamic optimization, and confirmation of sustained vascular patency through serial Doppler assessments.¹² This case underscores that even in the setting of prolonged warm ischemia time, successful graft salvage is achievable when technical reconstruc-tion is effective and postoperative management is optimized.
The use of prosthetic material in a recently transplanted kidney requires a delicate balance between preventing thrombosis and minimizing bleeding risk. Presently, there are no standardized antithrombotic protocols tailored to this particular clinical situation. Existing guidelines predominantly focus on venous thromboembolism rather than on arterial reconstruction within the context of transplantation.¹³ Moreover, patients with advanced chronic kidney disease pose additional complexities due to altered hemostasis and their underrepresen-tation in anticoagulation trials, leading to an absence of validated risk stratification tools.¹⁴
The antithrombotic regimen used in this case, comprising staged anticoagulation and dual antipla-telet therapy, aligns with institutional protocols rather than evidence-based consensus. Personalization accor-ding to bleeding risk, graft attributes, and intraope-rative observations remains crucial.² The lack of comprehensive comparative data underscores a significant gap in the literature and emphasizes the need for further investigation in this domain. Further prospective studies are necessary to delineate opti-mal antithrombotic strategies within this high-risk subgroup.
Reconstruction using PTFE requires diligent long-term monitoring to identify potential complications, such as stenosis, thrombosis, or pseudoaneurysm formation. Doppler ultrasonography continues to serve as the primary modality for surveillance. Established parameters, including peak systolic velocity, velocity ratios, and resistive indexes, serve as reliable indicators of graft perfusion and vascular integrity. Early detection of abnormalities should lead to prompt imaging and intervention to maintain graft functionality.
The utilization of PTFE in kidney transplants has been documented in various contexts, including arterial extension for short renal arteries, interposition grafting, and vascular salvage.^2,4,9,15 Nonetheless, application of PTFE as a patch angioplasty for intimal injury at or near the hilar trifurcation remains infrequ-ently reported. This case illustrates that, even in anatomically challenging situations typically deemed inappropriate for reconstruction, graft salvage can be accomplished through an anatomy-driven approach.
To the best of our knowledge, this report is the first to demonstrate the feasibility of PTFE patch angiop-lasty in a context for which no distal arterial target exists, a scenario seldom addressed in the literature. This methodology broadens the reconstructive options accessible to transplant surgeons and offers a practical solution in situations where traditional techniques are unsuitable.
This report possesses inherent limitations, inclu-ding its single-case design and absence of long-term follow-up beyond a 6-week period. Furthermore, the lack of comparative data constrains the ability to generalize these findings. Additional research is necessary to assess durability and reproducibility.

Conclusions

Renal artery intimal injury near the hilar trifurcation is an uncommon and complex scenario in kidney transplants, wherein conventional reconstruction techniques are frequently unfeasible. This case demonstrates that the presence of preserved Doppler signals does not necessarily exclude significant compromise of blood inflow and that immediate surgical reexploration remains crucial. The PTFE patch angioplasty offers a practical and effective salvage technique to facilitate the restoration of arterial flow and graft patency even in anatomically challen-ging situations. This approach successfully restored graft function, prevented immediate graft loss, and enabled dialysis-independent survival despite pro-longed warm ischemia time. Additionally, the PTFE patch angioplasty technique broadens the recons-tructive options available to transplant surgeons when standard methods are not attainable.