Endovascular Treatment of Transplant Renal Artery Stenosis: A Systematic Review and Meta-analysis

Vascular Reconstruction of Multiple Renal Arteries-A Risk Factor for Transplant Renal Artery Stenosis: Insight From a Matched Case-Control Study

Transplant Renal Artery Stenosis (TRAS) is the leading vascular complication following kidney transplantation (KT), causing premature allograft loss and increased post-KT mortality. While risk factors for TRAS, such as prolonged cold ischemia time and delayed graft function, are well-documented in deceased donor-KT, the risk factors remain less clearly defined in living donor-KT. This matched case-control study, conducted at a leading national transplant center predominantly performing living donor-KT, evaluated risk factors and long-term outcomes of clinical TRAS (cTRAS). cTRAS cases diagnosed from January 2009 to December 2022 were matched with four control kidney transplant recipients (KTRs) in a study powered to assess whether ex-vivo arterial vascular reconstruction of multiple renal arteries (VR-MRA) increases the risk of cTRAS. Among 2,454 KTs, 28 KTRs (1.14%) were diagnosed with cTRAS around 3.62 ± 1.04 months post-KT, with renal allograft dysfunction (92.86%) as the most common presenting feature. Notably, 27 cTRAS cases were successfully treated with endovascular intervention, yielding favorable outcomes over a 6-180 months follow-up period. The study identified ex-vivo VR-MRA as an independent risk factor for cTRAS (P < 0.001). cTRAS cases receiving timely treatment exhibited long-term outcomes in graft and patient survival similar to control KTRs. Early screening and timely intervention for cTRAS post-KT may improve graft and patient outcomes.

Endovascular Treatment for Transplant Renal Artery Stenosis: 10 Years' Experience from a Single Center

INTRODUCTION

Transplant renal artery stenosis (TRAS) is a common post-renal transplant complication. Although endovascular treatment is widely used to treat TRAS, previous research has been limited by small sample sizes. This article aimed to present the clinical outcomes of endovascular treatment for TRAS in a large sample.

METHODS

Between January 2010 and December 2019, this study included patients with TRAS who were admitted to our center. All patients' clinical symptoms, comorbidities, imaging data, treatment, and follow-up results were reviewed retrospectively.

RESULTS

Seventy two patients participated in this study. The median time between renal transplantation and TRAS was 5.25 months. Out of 72 patients, 55 (76.4%) received balloon dilatation in conjunction with stent deployment, 10 (13.9%) received drug-coated balloon dilatation alone, and 7 (9.7%) received balloon dilatation alone. The median follow-up period was 27 months. Primary patency rates were 100%, 81.8%, 74.5%, 64.6%, and 61.8% at 1, 3, 6, 12, and 24 months. A total of 23 patients were found to have restenosis during follow-up, with 6 (26.1%) requiring reintervention and none remaining restenosis after the second treatment. In the subgroup analysis of the three types of stenosis, patients with transplant renal stenosis at the anastomosis had a significantly higher rate of primary patency. Between endovascular treatments, the primary patency rate, postoperative creatinine clearance, and mean systolic blood pressure did not differ significantly.

CONCLUSION

Endovascular treatment resulted in favorable short-term patency as well as effective relief of renal dysfunction and renal hypertension in TRAS patients.

Assessment of Transplant Renal Artery Stenosis with Non-contrast-Enhanced Magnetic Resonance Angiography: Comparison with Digital Subtraction Angiography

RATIONALE AND OBJECTIVES

Early diagnosis of transplant renal artery stenosis (TRAS) is crucial for salvaging kidney function and improving patient prognosis. The purpose of this study was to evaluate image quality of non-contrast-enhanced MR angiography (NCE-MRA) and the value of NCE-MRA in evaluating TRAS compared to DSA.

MATERIALS AND METHODS

In 60 patients with TRAS confirmed by DSA, the degree of TRAS was assessed using balanced triggered angiography non-contrast-enhanced (B-TRANCE) MR angiography and was compared to that of DSA. Image quality for NCE-MRA was assessed independently by two radiologists. The Wilcoxon signed-rank test was used to compare NCE-MRA with DSA in assessing TRAS degree. Specificity, sensitivity, accuracy, positive-predictive value (PPV), and negative-predictive value (NPV) of NCE-MRA for the detection of marked (≥50%) TRAS were calculated.

RESULTS

The image quality of NCE-MRA based on the B-TRANCE technology of transplanted renal arteries was sufficient (excellent in 81.67%, good in 8.33%, moderate in 6.67%, and non-diagnostic in 3.33%) and had a high inter-observer reproducibility (Kappa=0.836). DSA helped identify severe, moderate, and mild stenosis in 6, 32, and 22 arteries, respectively. No significant difference in the extent of TRAS between NCE-MRA and DSA were observed (P = 0.317). The specificity, sensitivity, accuracy, PPV, and NPV of NCE-MRA in detecting marked (≥50%) TRAS were 90.91%, 100%, 96.55%, 94.74%, and 100%, respectively.

CONCLUSION

NCE-MRA based on B-TRANCE technology has shown promising consistency with DSA in evaluating TRAS and yielding high sensitivity, specificity, and accuracy in assessing the severity of TRAS.

Endovascular treatment of renal artery stenosis in Germany: a retrospective analysis of the DEGIR registry 2018-2021

PURPOSE

To provide an overview of endovascular treatment of renal artery stenosis (RAS) using the data of the Deutsche Gesellschaft für interventionelle Radiologie (DeGIR) quality management system.

MATERIALS AND METHODS

A retrospective analysis was performed. Pre-, peri- and postprocedural data, technical success rates, complication rates, and clinical success rates at dismissal were examined.

RESULTS

Between 2018 and 2021, 2134 angiography examinations of the renal arteries were performed: diagnostic angiography in 70 patients (3 %), balloon angioplasty in 795 (37 %), stent implantation in 1166 (55 %) and miscellaneous procedures in 103 (5 %). The lesion length was less than or equal to 5 mm in 1837 patients (87 %), between 5 and 10 mm in 197 (9 %), and between 10 and 20 mm in 62 (3 %). The degree of stenosis was less than 50 % in 156 patients (7 %), greater than 50 % in 239 (11 %), and greater than 70 % in 1472 (70 %). Occlusion was treated in 235 patients (11 %). Symptoms at discharge resolved in 600 patients (29 %), improved in 1012 (49 %), were unchanged in 77 (4 %), and worsened in 5 (0.2 %). Complications were reported in 51 patients (2.5 %) and the mortality rate was 0.15 %.

CONCLUSION

A substantial number of patients with RAS and occlusions were treated by radiologists in Germany, with high technical success rates and low complication rates. The indication should be determined carefully as the current European guidelines for the treatment of RAS suggest that only carefully selected groups of patients will benefit from recanalizing treatment.

KEY POINTS

· Carefully selected patient groups may benefit from endovascular treatment of renal artery stenosis.. · Analysis of the DEGIR quality management database shows that treatment of renal artery stenosis was performed by radiologists in Germany with high technical success rates and low complication rates.. · Recanalization even led to symptom improvement in a large proportion of patients with occlusions..

Percutaneous transluminal angioplasty with stenting for transplant renal artery stenosis at the anastomosis site in a young female patient: A case report

INTRODUCTION

Transplant renal artery stenosis (TRAS) is one of the major vascular complications and is mostly reported within six months following kidney transplant.

CASE PRESENTATION

The present case was a 16-year-old female whose blood urea nitrogen (BUN) and creatinine rose seven days after a kidney transplant. Ultrasound investigation revealed well-prefusion with a 90-degree angle anastomosis, apparent narrowing, and peak systolic velocity of 300 cm/s. Fourteen days after the transplant, with pre-and post-intervention hemodialysis and well hydration, an angiography with diluted iodinated contrast was done for the patient, which revealed >80 % narrowing at the anastomosis site. Percutaneous transluminal angioplasty (PTAS) with stenting was carried out for the patient, resulting in normal levels of BUN, creatinine, and urinary output.

CLINICAL DISCUSSION

While the patient did not have any risk factors for TRAS and was young, an early stenosis occurred in her left internal iliac artery one week after the kidney transplant. Due to the lower accuracy of CO2 angiography, diluted iodinated contrast angiography with well hydration and pre- and post-intervention dialysis was preferred. Endovascular treatment was preferred by the patient and attending physician due to possible adhesion and complications of open surgery and the possibility of arterial rupture.

CONCLUSION

Performing PTAS two weeks after the renal transplantation at the anastomosis site can be a treatment in patients with early TRAS. However, due to the higher risk of rupture at the anastomosis site, it should be carried out carefully and with consideration of the need for open surgery.

Value and limitations of sonography in kidney transplant recipients with special attention to the resistive index - An update

Kidney transplantation has become the standard treatment for end-stage renal disease. Even though the success rates are high, early and late post-transplant complications remain a major clinical problem due to the risk of graft failure. Therefore, it is of highest interest to early diagnose post-transplant complications. Ultrasound with color coded Duplex analysis plays a crucial role in imaging mechanical and vascular complications. In this article, we give an update of the visualizable complications in kidney transplant recipients and discuss the value of resistive index (RI) measurement with its limitations in allograft rejection.