Transplant Renal Artery Stenosis: Association With Acute Vascular Rejection

Transplant renal artery stenosis: Study of incidence using doppler ultrasound, risk factors and analysis is effect in graft outcomes

INTRODUCTION AND OBJECTIVES

Transplant renal artery stenosis (TRAS) is a vascular complication after kidney transplantation which estimated incidence is 13%. It could cause refractory arterial hypertension, kidney dysfunction and premature death in transplant recipients.

METHODS

We carried out a retrospective study including every patient who underwent renal transplantation between 2014 and 2020. They were evaluated with a systematic post-transplant renal Doppler ultrasound. To identify independent risk factors for transplant renal artery stenosis we performed a multivariate analysis.

RESULTS

Seven hundred twenty-four kidney transplants were included, 12% ​​were living donors and 88% were deceased donors. The mean age was 54.8 in recipients and 53 in donors. Transplant renal artery stenosis was diagnosed in 70 (10%) recipients, the majority in the first 6 months after surgery. 51% of patients with transplant renal artery stenosis were managed conservatively. The multivariate analysis showed diabetes mellitus, graft rejection, arterial resuture and donor body mass index as independent risk factors for transplant renal artery stenosis. Survival of the grafts with transplant renal artery stenosis was 98% at 6 months and 95% at two years.

CONCLUSIONS

The systematic performance of Doppler ultrasound in the immediate post-transplant period diagnosed 10% of transplant renal artery stenosis in our cohort. Despite the above risk factors, an adequate monitoring and treatment could avoid the increased risk of graft loss in patients with transplant renal artery stenosis.

Urgent endovascular maneuvers to rescue a failing transplant kidney with a T-stent approach - A case report

Renal artery thrombosis (RAT) is a major cause of renal transplant loss and, for this reason, should be treated promptly. We present a case of a 48-year-old man with external iliac thrombosis associated with thrombosis of a transplant renal artery that led to worsening of renal function. Multiple mechanisms have been identified in the literature as risk factors for RAT. In our patient, a combination of anastomotic stenosis, hypercoagulability, and diabetic nephropathy had resulted in RAT, and an unconventional endovascular revascularization technique with a T-stent approach was needed to guarantee patency of the treated vessels. No 30-day perioperative complications occurred, and the postoperative follow-up examination showed patency of the treated vessels; thus, transplant loss was avoided.

Diagnosis and Treatment of Early Transplant Renal Artery Stenosis: Experience From a Center in Eastern China

Few studies have focused on the clinical characteristics of transplant renal artery stenosis (TRAS) with early onset. Sixteen cases diagnosed with TRAS in our center from January 2014 to August 2018 were retrospectively analyzed. Sixteen transplant patients without TRAS were selected as controls. The median diagnostic time for TRAS was 47.5 days after transplantation. No significant difference was observed between the TRAS group and the control group. The serum creatinine level (Scr), estimated glomerular filtration rate, systolic/diastolic blood pressure, graft artery peak systolic velocity (PSV), and resistive index of intersegmental artery (RI-ISA) between the 2 groups were (5.55 ± 3.49) and (1.89 ± 0.85) mg/dL; (17.83 ± 14.94) and (49.39 ± 19.96) mL/min; (143.50 ± 9.49)/(86.14 ± 7.38) and (130.38 ± 18.86)/(82.81 ± 12.52) mm Hg; (3.39 ± 1.57) and (1.31 ± 0.51) m/s; and (0.51 ± 0.10) and (0.67 ± 0.13), respectively. All showed statistical significance except the diastolic blood pressure. The Scr, estimated glomerular filtration rate, systolic/diastolic blood pressure, graft artery PSV, and RI-ISA in the TRAS group prior and after treatment were (5.55 ± 3.49) and (3.20 ± 1.50) mg/dL; (17.83 ± 14.94) and (25.60 ± 13.29) mL/min; (143.50 ± 9.49)/(86.14 ± 7.38) and (128.07 ± 16.16)/(75.71 ± 7.56) mm Hg; (3.39 ± 1.57) and (2.00 ± 1.04) m/s; and (0.51 ± 0.10) and (0.61 ± 0.10); all showed statistical significance. Receiver operating characteristic analysis showed an area under curve of 0.8616 for PSV and 0.8535 for RI-ISA in diagnosing TRAS. Patients with TRAS in our center showed a unique characteristic of early onset. The most prominent clinical symptom of TRAS is increasing Scr level instead of refractory hypertension. Screening of color Doppler flow imaging with a graft artery PSV >2.5 m/s and RI-ISA <0.5 could yield a preliminary diagnosis of TRAS. Percutaneous transluminal angioplasty/stenting could effectively improve allograft function as well as color Doppler flow imaging indexes.

Risk factors for transplant renal artery stenosis after live donor transplantation

Background

Renal transplant surgeons are making increasing use of live donor kidneys with multiple renal arteries. This study aimed to identify independent risk factors for the development of transplant renal artery stenosis (TRAS) in the modern era of complex arterial reconstruction for multiple vessels.

Methods

Multivariable logistic regression analysis with a stepwise variable deletion model was used to identify risk factors for the development of TRAS in a consecutive series of live donor kidney transplants.

Results

Of 506 kidney transplants, 19 (3·8 per cent) had evidence of significant TRAS on CT angiography. Functional TRAS, defined by improvement in BP control or renal function after correction of a stenosis by angioplasty, occurred in 13 of 506 patients (2·6 per cent). Independent risk factors for TRAS were: use of an explanted internal iliac artery graft from the recipient (odds ratio (OR) 4·95; P = 0·020) and total ischaemia time (OR 1·82; P = 0·010). TRAS was associated with a lower 5-year allograft survival rate (79 versus 88·7 per cent; P = 0·020) but only one graft loss was attributed directly to TRAS. The 5-year allograft survival rate after internal iliac artery grafting was 86 per cent.

Conclusion

Although use of an internal iliac artery graft is an independent risk factor for TRAS after live donor kidney transplantation, this technique is still a useful option for complex arterial reconstruction.

[A high level of high-density lipoprotein cholesterol is a protective factor against transplant renal artery stenosis]

OBJECTIVE

To investigate the factors associated with the occurrence of transplant renal artery stenosis (TRAS).

METHODS

A retrospective analysis was conducted in 26 recipients who developed TRAS and 40 concurrent renal recipients without TRAS. We also conducted a nested case-control study in 14 patients with TRAS (TRAS-SD group) and another 14 non-TRAS recipients who received the allograft from the same donor (non-TRAS-SD group).

RESULTS

Compared with those in the concurrent recipients without TRAS, acute rejection (AR) occurred at a significantly higher incidence (P=0.004) and the warm ischemia time (WIT) was significantly longer (P=0.015) and the level of high?density lipoprotein cholesterol (HDL--C) significantly lower (P=0.009) in the recipients with TRAS. Logistic regression analysis suggested that AR (P=0.007) and prolonged WIT (P=0.046) were risk factors of TRAS while HDL-C (P=0.022) was the protective factor against TRAS. In recent years early diagnosis of TRAS had been made in increasing cases, the interval from transplantation to TRAS diagnosis became shortened steadily, and the recipients tended to have higher estimated glomerular filtration rate at the time of TRAS diagnosis.

CONCLUSION

Apart from the surgical technique, AR and prolonged WIT are also risk factors of TRAS while a high HDL-C level is the protective factor against TRAS. The improvement of the diagnostic accuracy by ultrasound is the primary factor contributing to the increased rate of early TRAS diagnosis in recent years.

Three-Dimensional Computed Tomography Reconstruction in Transplant Renal Artery Stenosis

OBJECTIVES

Transplant renal artery stenosis is a frequently recognized complication of kidney transplant procedures. A single-center retrospective study was conducted to examine the use of 3-dimensional computed tomography reconstruction in diagnosing transplant artery stenosis.

MATERIALS AND METHODS

During 2013 at our center, 86 patients underwent kidney transplant. All patients underwent ultrasonographic analyses. Patients with clinically suspected transplant renal artery stenosis were examined by 3-dimensional computed tomography reconstruction and were treated with endovascular approaches or medically managed.

RESULTS

Ten patients were diagnosed with transplant renal artery stenosis by 3-dimensional computed tomography reconstruction. No evidence of contrast-induced nephrotoxicity was observed. Nine of the 10 patients underwent percutaneous transluminal angio-plasty, whereas the remaining patient was treated conservatively. Procedural success rate was 100%. Patients were followed for a mean period of 20 ± 3 months. Blood pressure improved from a mean of 163/90 to 132/73 mm Hg at the end of the follow-up period. In the 9 patients who underwent angioplasty, serum creatinine improved from 198 ± 24 to 134 ± 16 μmol/L at the end of the follow-up period. The cystatin C level in some patients declined after interventional therapy.

CONCLUSIONS

Three-dimensional computed tomography reconstruction is a safe choice for patients who present with increased serum creatinine levels and refractory hypertension. Percutaneous transluminal angioplasty is the preferred therapeutic technique for transplant renal artery stenosis.

Detection of transplant renal artery stenosis: determining normal velocities at the renal artery anastomosis

PURPOSE

Renal artery anastomosis peak systolic velocity (RAA PSV) exceeding 250 cm/s and a ratio of the renal artery to the adjacent external iliac artery (RAA:EIA) exceeding 1.8 historically suggest significant transplant renal artery stenosis (TRAS). However, the range of RAA PSV in transplants without TRAS has not been established.

METHODS

A retrospective review of renal transplants at a single institution over 5 years was performed identifying patients without graft dysfunction, failure, or refractory hypertension. RAA PSV obtained during interval postoperative sonograms was recorded.

RESULTS

Of 1141 patients, 844 met the inclusion criteria. Mean RAA PSV for 377 patients evaluated within 2 days of transplant measured 195 cm/s; RAA PSV exceeded 250 cm/s in 97 patients (26%). Mean RAA PSV for 820 patients evaluated 1-month post-transplant measured 206 cm/s; RAA PSV exceeded 250 cm/s in 224 patients (27%). Mean RAA PSV for 785 patients evaluated 4-month post-transplant measured 203 cm/s; RAA PSV exceeded 250 cm/s in 201 patients (26%). Mean RAA PSV for 766 patients evaluated 1-year post-transplant measured 189 cm/s; RAA PSV exceeded 250 cm/s in 141 patients (18%). At each of the given time points, 24%-34% of normal patients had RAA-to-EIA ratios greater than 1.8.

CONCLUSION

Approximately, 26% of patients without TRAS have RAA PSV > 250 cm/s in the first 9 months, and 18% do at 1 year. Similar findings also occurred with regards to the RAA-to-EIA ratio threshold of 1.8. In isolation, a PSV over 250 cm/s or 1.8 ratio threshold for suspicion of TRAS will lead to a large number of false-positive assessments.

Artery Stenosis of the Renal Graft: Experience of a Center of Northeastern Brazil

BACKGROUND

Transplant renal artery stenosis (TRAS), the most common vascular complication after transplant (Tx), leads to resistant hypertension, impaired renal function, and even loss of the graft. The purpose of the study was to investigate the prevalence and factors associated with TRAS in northeastern Brazil.

METHODS

The study was conducted as a retrospective case-control study in a population of Tx recipients in a renal Tx center in northeastern Brazil. Demographic and clinical characteristics of the recipients and donors, data related to the surgery, laboratory data, and number of anti-hypertensive drugs were assessed. Statistical analysis was performed with the use of SPSS 17.0.

RESULTS

A total of 494 of 529 recipients were assessed, of which 24 had TRAS. The prevalence of TRAS was 4.8%. Twelve patients (50%) were men with a mean age of 46.7 ± 13.5 years. The mean time of diagnosis was 89.9 days after Tx. The risk factors associated with TRAS were number of anti-hypertensive drugs ≥2 (odds ratio, 17.0; confidence interval, 4.1 to 70.4; P = .001) and grafting with 2 or more arteries (odds ratio, 8.9; confidence interval, 1.4 to 56.6; P = .021). There was a significant reduction in mean systolic blood pressure (147.1 ± 23.7 to 127.8 ± 15.2 mm Hg, P = .001) and diastolic blood pressure (86.6 ± 13.0 to 77.6 ± 9.4 mm Hg, P = .001) after TRAS repair and in serum creatinine (2.8 ± 2.4 to 1.9 ± 1.8 mg/dL, P = .04).

CONCLUSIONS

Grafts with 2 or more arteries are associated with TRAS, as well as patients who use a higher number of anti-hypertensive drugs. TRAS repair was associated with improved blood pressure control and renal function.

Postanastomotic transplant renal artery stenosis: association with de novo class II donor-specific antibodies

In this study, we analyze the outcomes of transplant renal artery stenosis (TRAS), determine the different anatomical positions of TRAS, and establish cardiovascular and immunological risk factors associated with its development. One hundred thirty-seven of 999 (13.7%) patients had TRAS diagnosed by angiography; 119/137 (86.9%) were treated with angioplasty, of which 113/137 (82.5%) were stented. Allograft survival in the TRAS+ intervention, TRAS+ nonintervention and TRAS- groups was 80.4%, 71.3% and 83.1%, respectively. There was no difference in allograft survival between the TRAS+ intervention and TRAS- groups, p = 0.12; there was a difference in allograft survival between the TRAS- and TRAS+ nonintervention groups, p < 0.001, and between the TRAS+ intervention and TRAS+ nonintervention groups, p = 0.037. TRAS developed at the anastomosis, within a bend/kink or distally. Anastomotic TRAS developed in living donor recipients; postanastomotic TRAS (TRAS-P) developed in diabetic and older patients who received grafts from deceased, older donors. Compared with the TRAS- group, patients with TRAS-P were more likely to have had rejection with arteritis, odds ratio (OR): 4.83 (1.47-15.87), p = 0.0095, and capillaritis, OR: 3.03 (1.10-8.36), p = 0.033. Patients with TRAS-P were more likely to have developed de novo class II DSA compared with TRAS- patients hazard ratio: 4.41 (2.0-9.73), p < 0.001. TRAS is a heterogeneous condition with TRAS-P having both alloimmune and traditional cardiovascular risk factors.

Presensitization revisited: pitfalls of vascular allografts in transplant candidates

Vascular allografts in end-stage renal disease (ESRD) patients represent a particular immunological challenge. A broad HLA immunization led us to study in depth the history of two patients with vascular allografts. In Case 1 the allograft was added to a Gore-Tex graft used for haemodialysis access and no immunosuppression was administered. In Case 2 the allograft was used to prolong a renal artery from living donor and immunosuppression was suboptimal. In vascular surgery, immunosuppression is mainly used to improve graft patency. ESRD patients are potential organ recipients and immunosuppression should therefore be tailored to reduce HLA immunization.

[Endovascular treatment of stenosis of the renal artery in transplanted kidney]

INTRODUCTION

The incidence of renal artery stenosis in the transplanted kidney (TRAS) varies between 2 and 23%, being the most frequent vascular complication following renal trasplantation. The delay in diagnosis and treatment can lead to functional graft loss. Percutaneous trasluminal angioplasty with stent (PTAS) is the treatment of choice to restore kidney perfusion.

MATERIALS AND METHODS

Retrospective review of renal transplant casuistic in our institution between September 2005 and August 2009. Were included patients with greater than 70% TRAS and impaired graft function, treated with PTAS. Follow-up at 3, 12 and 36 months was done with creatinine, glomerular filtration rate (GFR) and Doppler ultrasonography (DUS). Technical success was defined as correct stent placement associated with decreased flow, and clinical success as improve renal function during follow-up.

RESULTS

Incidence of TRAS was 7.3% (22/298), 60% PTAS subsidiary. 100% technical success and 84.6% clinical success, 15.4% without changes in renal function. 84% decreases flow rate greater than 70% by DUS, and 26% up to 60%. Wave changes from type III to type II were recorded in 69% and to type I in 33%.

CONCLUSIONS

The PTAS is a safe and effective procedure for the treatment of selected TRAS patients, as it preserves vascular permeability in short and medium term, ensuring the functionality of the graft. DUS is the method of choice for diagnosis and monitoring TRAS.

Renal artery stenosis in kidney transplants: assessment of the risk factors

BACKGROUND

Transplant renal artery stenosis (TRAS) is an important cause of hypertension and renal allograft dysfunction occurring in kidney transplant recipients. However, conflicting predisposing risk factors for TRAS have been reported in the literature.

OBJECTIVE

The aim of the present study was to assess the potential correlation between possible risk factors and TRAS in a group of living donor renal transplant recipients 1 year after the renal transplantation.

METHODS

We evaluated the presence of renal artery stenosis in 16 recipients who presented with refractory hypertension and/or allograft dysfunction 1 year after renal transplantation. Screening for TRAS was made by magnetic resonance angiography and diagnosis was confirmed by conventional renal angiography. Age, gender, history of acute rejection, plasma lipid profile, serum creatinine, blood urea nitrogen, serum uric acid, calcium phosphate (CaPO₄) product, alkaline phosphatase, fasting blood sugar, hemoglobin, and albumin were compared between the TRAS and non-TRAS groups.

RESULTS

Of 16 kidney transplant recipients, TRAS was diagnosed in three patients (two men and one woman). High levels of calcium, phosphorous, CaPO₄ product, and low-density lipoprotein (LDL) cholesterol were significantly correlated with the risk of TRAS 1 year after renal transplantation (P < 0.05). Serum level of uric acid tended to have a significant correlation (P = 0.051).

CONCLUSION

Correlation between high CaPO₄ product, LDL cholesterol, and perhaps uric acid and TRAS in living donor renal transplant recipients 1 year after renal transplantation might suggest the importance of early detection and tight control of these potential risk factors.

Management of transplant renal artery stenosis and its impact on long-term allograft survival: a single-centre experience

BACKGROUND

Transplant renal artery stenosis (TRAS) is a recognized complication resulting in post-transplant hypertension associated with allograft dysfunction. It is a commonly missed but potentially treatable complication that may present from months to years after transplant surgery. In this retrospective study, we compared management strategies and outcomes of TRAS from 1990 to 2005.

METHODS

Case notes of transplant recipients with TRAS demonstrated by angiography were reviewed. Angiography and was carried out when there was a clinical or Doppler ultrasound suspicion of TRAS. The clinical diagnosis of TRAS was based on uncontrolled refractory/new-onset hypertension and/or unexplained graft dysfunction in the absence of another diagnosis, such as rejection, obstruction or infection. The two-tailed Student t-test was used to analyse the differences between mean arterial pressure, serum creatinine, and estimated glomerular filtration rate before and after the intervention.

RESULTS

Sixty-seven patients with angiogram-confirmed TRAS were included. Forty-four, 9 and 14 patients were managed with primary percutaneous transluminal renal angioplasty (PTRA), surgical intervention and conservative treatment, respectively. Uncontrolled hypertension was the most common presentation noted in 74.62%. Post-anastamotic single stenosis was the commonest occurrence (n = 53). Angioplasty had the highest 1- and 5-year graft survival rate of 91% and 86%, respectively. The worst prognosis was noted in patients treated with secondary PTRA after failed surgery or secondary surgery after failed primary PTRA.

CONCLUSIONS

TRAS is a recognized complication resulting in loss of renal allografts. Early Doppler ultrasound is a good primary diagnostic tool. Early intervention is associated with a good long-term graft function.