Estenosis arterial del injerto renal: evaluación de la incidencia mediante ecografía doppler, factores de riesgo y análisis de las complicaciones que pueden afectar a la supervivencia del injerto / Transplant renal artery stenosis: Study of incidence using doppler ultrasound, risk factors and analysis is effect in graft outcomes

Introducción y objetivos La estenosis de la arteria del injerto renal (EAR) es una complicación vascular del trasplante renal cuya incidencia estimada es del 13%, la cual puede causar hipertensión arterial refractaria, disfunción renal y muerte prematura en los receptores. Métodos Se realizó un estudio retrospectivo que incluyó a todos los pacientes sometidos a trasplante renal entre 2014 y 2020. Los pacientes fueron evaluados mediante ecografía doppler renal sistemática tras el trasplante. Para identificar los factores de riesgo independientes de la estenosis de la arteria renal tras el trasplante, realizamos un análisis multivariante. Resultados Se incluyeron 724 trasplantes renales, el 12% eran de donante vivo y el 88% de donante fallecido. La edad media en los receptores era de 54,8 años y en los donantes era de 53. Se diagnosticó estenosis de la arteria del injerto renal en 70 (10%) receptores, la mayoría durante los primeros 6 meses después de la intervención. El 51% de los pacientes con estenosis de la arteria del injerto renal se manejaron de manera conservadora. El análisis multivariante mostró que la diabetes mellitus, el rechazo del injerto, la resutura arterial y el índice de masa corporal del donante eran factores de riesgo independientes de estenosis de la arteria renal después del trasplante. La supervivencia de los injertos con estenosis de la arteria del injerto renal fue del 98% a los 6 meses y del 95% a los 2 años. Conclusiones El uso sistemático de la ecografía doppler en el período inmediatamente posterior al trasplante permitió diagnosticar un 10% de estenosis de la arteria del injerto renal en nuestra cohorte. A pesar de los factores de riesgo mencionados anteriormente, un seguimiento y tratamiento adecuados podrían reducir el riesgo de pérdida del injerto en pacientes con estenosis de la arteria del injerto renal. (AU)

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. The 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. (AU)

Case report: Endovascular treatment of transplant renal artery stenosis in patient with normal color duplex ultrasound of the renal artery.

Key Clinical Message: Proper diagnosis and treatment of vascular stenosis which is a possible complication of renal transplant is important in improving patients' quality of life and prognosis. Abstract: One known consequence among recipients of renal transplants is graft renal artery stenosis. Early identification and therapy are crucial to avoid graft malfunction and the serious consequences that might arise due to elevated hypertension in several organs. We report a rare case of transplant renal artery stenosis in a mid-aged woman who presented with edema, hypertension, and increased creatinine 2 months after kidney transplant. The patient had normal renal arterial resistive index (RI) and perfusion index (PI), and there was only a modest decrease in perfusion on duplex ultrasound. Following the patient's renal stenting treatment, angiographic resolution was observed. After 14 days of regulated blood pressure following renal artery stenting, she was discharged from the hospital with her edema resolved. Considering complications in patients with clinical manifestations such as hypertension resistant to treatment and graft dysfunction, vascular stenosis is a notable issue to consider even in the context of normal renal arterial RI, PI, and duplex ultrasound. Proper diagnosis and treatment are of importance to improve patients' quality of life and prognosis.

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.

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.

Transplant renal artery stenosis: utilization of machine learning to identify ancillary sonographic and doppler parameters to predict stenosis in patients with graft dysfunction.

PURPOSE: To determine if ancillary sonographic and Doppler parameters can be used to predict transplant renal artery stenosis in patients with renal graft dysfunction. MATERIALS AND METHODS: IRB-approved, HIPAA-compliant retrospective study included 80 renal transplant patients who had renal US followed by renal angiogram between January 2018 and December 2019. A consensus read of two radiologists recorded these parameters: peak systolic velocity, persistence of elevated velocity, grayscale narrowing, parvus tardus, delayed systolic upstroke, angle of the systolic peak (SP angle), and aliasing. Univariate analysis using t-test or chi-square was performed to determine differences between patients with and without stenosis. P values under 0.05 were deemed statistically significant. We used machine learning algorithms to determine parameters that could better predict the presence of stenosis. The algorithms included logistic regression, random forest, imbalanced random forest, boosting, and CART. All 80 cases were split between training and testing using stratified sampling using a 75:25 split. RESULTS: We found a statistically significant difference in grayscale narrowing (p = 0.0010), delayed systolic upstroke (p = 0.0002), SP angle (p = 0.0005), and aliasing (p = 0.0024) between the two groups. No significant difference was found for an elevated peak systolic velocity (p = 0.1684). The imbalanced random forest (IRF) model was selected for improved accuracy, sensitivity, and specificity. Specificity, sensitivity, AUC, and normalized Brier score for the IRF model using all parameters were 73%, 81%, 0.82, and 69 in the training set, and 78%, 58%, 0.78, and 80 in the testing set. VIMP assessment showed that the combination of variables that resulted in the most significant change of the training set performance was that of grayscale narrowing and SP angle. CONCLUSION: Elevated peak systolic velocity did not discriminate between patients with and without TRAS. Adding ancillary parameters into the machine learning algorithm improved specificity and sensitivity similarly in the training and testing sets. The algorithm identified the combination of lumen narrowing coupled with the angle of the systolic peak as better predictor of TRAS. This model may improve the accuracy of ultrasound for transplant renal artery stenosis.

Perfusion and oxygenation in allografts with transplant renal artery stenosis: Evaluation with functional magnetic resonance imaging.

BACKGROUND: Transplant renal artery stenosis (TRAS) has been shown to reduce kidney perfusion leading to post-operative hypertension. We aimed to measure the perfusion and oxygenation changes in TRAS with arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) imaging, respectively. METHODS: In this single-center prospective study, a total of seven patients with TRAS and seven age- and sex-matched normal kidney transplant recipients underwent both ASL and BOLD imaging. Moreover, measurements of ASL and BOLD were also performed in five patients after successful angioplasty for TRAS. RESULTS: Allograft cortical perfusion as measured by ASL in the TRAS group was significantly decreased as compared with normal control group (129.9 ± 46.6 ml/100 g vs. 202.4 ± 47.7 ml/100 g, P = .01). Interestingly, allograft oxygenation as indicated by R2* derived from BOLD in both the cortex (16.42 ± 1.90 Hz vs. 18.25 ± 4.34 Hz, P = .33) and the medulla (30.34 ± 2.35 Hz vs. 30.43 ± 6.85 Hz, P = .97) showed no statistical difference between the TRAS and normal control group. In addition, both cortical and medullary oxygenation remained unchanged despite significantly improved cortical perfusion in those undergone successful angioplasty. CONCLUSION: Cortical and medullary oxygenation were preserved in the presence of reduced allograft perfusion in clinically significant TRAS. Prospective larger studies are needed to conclusively establish perfusion and oxygenation changes in TRAS.

Risk factors of transplant renal artery stenosis in kidney transplant recipients.

BACKGROUND: Transplant Renal Artery Stenosis (TRAS) is a recognized vascular complication after kidney transplantation. The overall risk predictors of TRAS are poorly understood. METHODS: Retrospective analysis of patients with suspected TRAS (Doppler ultrasound PSV > 200 cm/s) who underwent angiographic study in a single center between 2007 and 2014. All patients with stenosis > 50% were considered with TRAS. Stenosis restricted in the body of the artery was also analyzed in a subgroup. RESULTS: 274 patients were submitted to a renal angiography and 166 confirmed TRAS. TRAS group featured an older population (46.3 ± 11.0 vs. 40.9 ±14.2 years; p = 0.001), more frequent hypertensive nephropathy (30.1% vs. 15.7%; p = 0.01), higher incidence of Delayed Graft Function (DGF) (52.0% vs. 25.6%; p < 0.001) and longer Cold Ischemia Time (CIT) (21.5 ± 10.6 vs. 15.7 ± 12.9h; p < 0.001). In multivariable analyses, DGF (OR = 3.31; 95% CI 1.78‒6.30; p < 0.0001) was independent risk factors for TRAS. DM and CIT showed a tendency towards TRAS. The compound discriminatory capacity of the multivariable model (AUC = 0.775; 95% CI 0.718‒0.831) is significantly higher than systolic blood pressure and creatinine alone (AUC = 0.62; 95% CI 0.558-0.661). In body artery stenosis subgroup, DGF (OR = 1.86; 95% CI 1.04‒3.36; p = 0.03) and Diabetes Mellitus (DM) (OR = 2.44; 95% CI 1.31‒4.60; p = 0.005) were independent risk factors for TRAS. CONCLUSION: In our transplant population, DGF increased more than 3-fold the risk of TRAS. In the subgroup analysis, both DGF and DM increases the risk of body artery stenosis. The addition of other factors to hypertension and renal dysfunction may increase diagnostic accuracy. TRAS TRIAL REGISTRED: clinicaltrials.gov (n° NCT04225338).

Various Techniques and Outcomes of Arterial Anastomosis in Live Renal Transplant: An Institutional Experience.

Introduction Renal transplantation with multiple arteries is associated with a major index of surgical complications. Relevant papers and meta-analyses have shown relatively more vascular and urological complications in transplant of donor kidneys with multiple arteries. In live donor grafts due to the unavailability of a carrel patch, several techniques for bench and in situ reconstruction have been described in order to reduce the incidence of these vascular complications. In this study, the short and long-term results of living donor kidney transplants with multiple renal arteries (MRAs) versus single renal artery (SRA) were compared retrospectively. Methods This is a retrospective study done on patients who received a living donor kidney between January 2012 and January 2018 at the Institute of Urology, Madras Medical College, Chennai. We have excluded deceased donor kidney transplants and ABO-incompatible cases done in the same time period. The study was approved by the Institutional Ethics Committee (Approval No: IES-MMC-008) and performed in accordance with the guidelines of the Declaration of Helsinki. Open live donor nephrectomy was performed through an extra-peritoneal flank incision in all cases. In the SRA group, the renal artery was anastomosed end to end to the Internal iliac artery, while the renal vein was anastomosed to the external iliac vein in the end to side fashion. Urinary tract reconstruction was accomplished by the Gregoir technique in both groups. We looked at recipient complications, baseline and postoperative serum creatinine, total ischemia time, mean operating time, and short- and long-term graft and patient survival as postoperative outcomes. Results In a six-year period (2012-2018) at our institute, 256 living donor transplantations were performed; 36 (14%) kidneys had two or more renal arteries which were anastomosed using various techniques. Cold ischemia time was relatively longer in the MRA group (45 mins vs 28 mins in the SRA group) (p-value <0.05). while warm ischemia time was comparable in both groups (2.5 vs 2.9 mins) serum creatinine was comparable in both groups at the 30th postoperative day (1.4 in SRA group vs 1.2 in MRA group) (p-value >0.05). Incidence of surgical complications in SRA and MRA groups was: vascular - 3.6% and 2.7%; urological - 3.2% and 2.7%; the incidence of lymphocele was 4.5% and 5.5% and delayed graft function 4.5% and 5.5% respectively. Conclusion Multiple renal arteries are no longer a relative contraindication with advanced surgical techniques. in renal grafts with multiple arteries, all techniques of vessel anastomosis are comparable in terms of post-surgical complications.

Percutaneous transluminal interventions of transplant renal artery stenosis: A case series study.

Introduction: and importance: Transplant renal artery stenosis (TRAS) is a well-recognized vascular complication after kidney transplant that can lead to graft loss, when it is diagnosed early and treated appropriately it may prevent kidney damage and related systemic squeals. Case presentation: This case-series represents our center experience in managing TRAS using percutaneous transluminal angioplasty [either balloon angioplasty (PTA) or stent placement (PTAS)] in 11 patients. Clinical discussion: All treated patients experienced immediate total recovery of renal function and normalization of arterial blood pressure without any drug or reducing the number of drugs used; no complications related to the intervention were reported. Conclusion: PTA or PTAS of TRAS can be considered safe and effective when it diagnosed and treated early.

Long-term clinical outcomes of patients with nonsignificant transplanted renal artery stenosis.

BACKGROUND: Transplant renal artery stenosis (TRAS) is the main vascular complication of kidney transplantation. For research and treatment purposes, several authors consider critical renal artery stenosis to be greater than 50%, and percutaneous intervention is indicated in this scenario. However, there are no reports in the current literature on the evolution of patients with less than 50% stenosis. METHOD: This retrospective study included data from all patients who underwent kidney transplantation and were suspected of having TRAS after transplantation with stenosis under 50% independent of age and were referred for angiography at a single centre between January 2007 and December 2014. RESULTS: During this period, 6,829 kidney transplants were performed at Hospital do Rim, 313 of whom had a clinical suspicion of TRAS, and 54 of whom presented no significant stenosis. The average age was 35.93 years old, the predominant sex was male, and most individuals (94.4%) underwent dialysis before transplantation. In most cases in this group, transplants occurred from a deceased donor (66.7%). The time between transplantation and angiography was less than one year in 79.6% of patients, and all presented nonsignificant TRAS. Creatinine levels, systolic blood pressure, diastolic blood pressure and glomerular filtration rate improved over the long term. The outcomes found were death and allograft loss. CONCLUSION: Age, sex and ethnic group of patients were factors that did not interfere with the frequency of renal artery stenosis. The outcomes showed that in the long term, most patients evolve well and have improved quality of life and kidney function, although there are cases of death and kidney loss.

Intravascular ultrasound-supported percutaneous angioplasty of post-kidney transplant renal artery bifurcation stenosis.

BACKGROUND: Transplant renal artery stenosis (TRAS) is an uncommon complication following renal transplantation. Its usual clinical presentation includes worsening hypertension and/or renal function, without any evidence of graft rejection. Bifurcation renal artery stenosis of the transplanted renal artery is rarely encountered. METHODS: Percutaneous transluminal renal angioplasty (PTRA) with or without stenting is the procedure of choice to treat TRAS. We hereby describe a patient, who presented with impaired renal functions, four months following the renal transplantation. He underwent intravascular ultrasound-guided PTRA of the bifurcation lesion of TRAS.Results and conclusion: Superior renal artery had coronary drug-eluting stent implantation, while inferior renal artery and side branch of the superior renal artery had balloon angioplasty, alone. Post-intervention, the raised serum creatinine level decreased from 2.9 mg% to 1.7 mg%. The index case described the successful PTRA and stenting of the bifurcation lesion of TRAS, the technical results of which was optimized with the use of intravascular ultrasound.

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

OBJECTIVE: Endovascular treatment through either percutaneous transluminal angioplasty (PTA) alone or stenting has been previously used as a treatment for transplant renal artery stenosis (TRAS). This review aimed to investigate the results of endovascular treatment for renal artery stenosis in transplanted kidneys as compared with the outcomes of interventions, medical management, and graft survival in non-TRAS patients. METHODS: A systematic review of PubMed, Google Scholar, Cochrane, and Scopus was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in which studies that reported outcomes of the treatment of TRAS via the endoluminal approach were identified, and their results were meta-analyzed. RESULTS: Fifty-four studies with a total of 1522 patients were included. A significant reduction of serum creatinine level was found, favoring the stenting group, with a mean difference of 0.68 mg/dL (95% confidence interval (CI), 0.17-1.19; Z=2.60, p=0.0009). Comparison of pre- and post-intervention values of any intervention revealed a significant decrease in overall serum creatinine level (0.65 mg/dL; 95% CI, 0.40-0.90; Z=5.09, p=0.00001), overall blood pressure, with a mean difference of 11.12 mmHg (95% CI, 7.29-14.95; Z=5.59, p=0.00001), mean difference in the use of medications (0.77; 95% CI, 0.29-1.24; p=0.002), and peak systolic velocity (190.05; 95% CI, 128.41-251.69; p<0.00001). The comparison of serum creatinine level between endovascular interventions and best medical therapy favored endovascular intervention, with a mean difference of 0.23 mg/dL (95% CI, 0.14-0.32; Z=5.07, p<0.00001). Graft survival was similar between the treated patients and those without TRAS (hazard ratio, 0.98; 95% CI, 0.75-1.28; p=0.091). The overall pooled success rate was 89%, and the overall complication rate was 10.4%, with the most prevalent complication being arterial dissection. CONCLUSION: The endovascular treatment of TRAS improves graft preservation and renal function and hemodynamic parameters. PTA + stenting appears to be a more effective option to PTA alone in the stabilization of renal function, with additional benefits from decreased restenosis rates. Further high-quality studies could expand on these findings.

Unusual Endovascular Treatment of Iliac Occlusive Disease With a Physician-Modified Endograft to Preserve a Transplant Renal Artery.

PURPOSE: We describe the feasibility and early results of iliac stenting using a physician-modified endograft (PMEG) to preserve a transplant renal artery in patient with iliac occlusive disease. CASE REPORT: A 70-year-old male patient, with sub-occlusive left common iliac artery stenosis at the level of the transplanted kidney arterial anastomosis, presented with left critical limb ischemia (CLI) and pseudo-transplant renal artery stenosis (pseudo-TRAS) symptoms. He was treated with a physician-modified fenestrated covered stent introduced percutaneously via ipsilateral femoral artery after failure of simple angioplasty (percutaneous transluminal angioplasty, PTA). The modified graft was created by performing a square fenestration graftotomy on a Medtronic iliac limb stent graft (Medtronic Cardiovascular, Santa Rosa, CA, USA). The procedure was technically successful with no intraoperative complications. Procedural time was 110 minutes, including 35 minutes for device modification. On short-term follow-up, the patient had early improvement of renal function and resolution of CLI. The iliac and transplant renal artery remained patent with no sign of stent migration or kinking on 6 months surveillance computed tomography angiography and 1 year color Doppler ultrasonography. CONCLUSION: Use of PMEG to preserve visceral branches in occlusive iliac disease is a feasible endovascular technique with encouraging technical success and satisfying early results.

Risk factors of transplant renal artery stenosis in kidney transplant recipients

Abstract Background: Transplant Renal Artery Stenosis (TRAS) is a recognized vascular complication after kidney transplantation. The overall risk predictors of TRAS are poorly understood. Methods: Retrospective analysis of patients with suspected TRAS (Doppler ultrasound PSV > 200 cm/s) who underwent angiographic study in a single center between 2007 and 2014. All patients with stenosis > 50% were considered with TRAS. Stenosis restricted in the body of the artery was also analyzed in a subgroup. Results: 274 patients were submitted to a renal angiography and 166 confirmed TRAS. TRAS group featured an older population (46.3 ± 11.0 vs. 40.9 ±14.2 years; p = 0.001), more frequent hypertensive nephropathy (30.1% vs. 15.7%; p = 0.01), higher incidence of Delayed Graft Function (DGF) (52.0% vs. 25.6%; p < 0.001) and longer Cold Ischemia Time (CIT) (21.5 ± 10.6 vs. 15.7 ± 12.9h; p < 0.001). In multivariable analyses, DGF (OR = 3.31; 95% CI 1.78-6.30; p < 0.0001) was independent risk factors for TRAS. DM and CIT showed a tendency towards TRAS. The compound discriminatory capacity of the multivariable model (AUC = 0.775; 95% CI 0.718-0.831) is significantly higher than systolic blood pressure and creatinine alone (AUC = 0.62; 95% CI 0.558-0.661). In body artery stenosis subgroup, DGF (OR = 1.86; 95% CI 1.04-3.36; p = 0.03) and Diabetes Mellitus (DM) (OR = 2.44; 95% CI 1.31-4.60; p = 0.005) were independent risk factors for TRAS. Conclusion: In our transplant population, DGF increased more than 3-fold the risk of TRAS. In the subgroup analysis, both DGF and DM increases the risk of body artery stenosis. The addition of other factors to hypertension and renal dysfunction may increase diagnostic accuracy.

Renal graft artery stenosis associated with pediatric kidney / 中华器官移植杂志

Objective:To retrospectively summarize the clinical experiences of managing renal artery stenosis after donor kidney transplantation in children.Methods:From January 2018 to October 2021, 114 pediatric kidney transplants(donor/recipient aged <18 years)were performed.According to the findings of color Doppler ultrasonography, they were divided into two groups of normal( n=80)and rapid flow( n=34). Rapid flow group were assigned into symptomatic( n=13)and asymptomatic( n=21)sub-groups based upon clinical features of hypertension and renal instability. Results:Among them, there were 65 males and 49 females.A significant inter-gender difference existed in the proportion of higher arterial flow rate of transplanted kidney(38.5% and 18.4%, P=0.02). No significant difference existed in age or body weight of transplant recipients among all groups( P>0.05). The mean age(10.4 months)and body weight(9 kg)of donors were significantly lower in symptomatic group than those in normal group(65.3 months, 21 kg)and asymptomatic group(64.4 months, 21.2 kg). The mean velocity of symptomatic group was significantly higher than that of asymptomatic group(363.5 vs 228.8 cm/s)( P<0.001). In symptomatic group, 6 cases received medications and their clinical manifestations were completely relieved.Among 7 patients invasively treated, one percutaneous transluminal angioplasty(PTA)was offer once( n=2), twice( n=2)and triple( n=1)with clinical relief and stable renal function.One case of bleeding at puncture site during PTA had treatment failure with a gradual loss of graft function.One ineffective case of PTA was subsequently placed with an endovascular stent.However, repeated stent dilation failed due to restenosis.After surgical exploration, vascular stent removal and transplantation of renal artery clipping, clinical symptoms were relieved. Conclusions:Male recipient, low body weight or young donor may be risk factors for transplant renal artery stenosis(TRAS)during pediatric donor renal transplantation.A higher flow rate of transplanted renal artery on ultrasonography could not confirm the diagnosis of TRAS.Greater arterial flow and associated clinical manifestations often hint at a strong possibility of TRAS, requiring drug or invasive treatment interventions.If PTA efficacy is not satisfactory, multiple treatments should be performed.Nevertheless, stenting should be avoided as far as possible to prevent in-stent restenosis.

Endovascular stenting with a drug-eluting stent of transplanted renal artery stenosis in a dual kidney transplanted patient.

Renal transplant remains the preferred therapy for end-stage renal disease (ESRD). Given the shortage of suitable donor kidneys, use of an expanded criteria donor (ECD) allows marginal kidneys to be transplanted; albeit at risk of increased graft failure due to lower nephron mass. To reduce the risk of graft failure, double kidney transplant (DKT) is advocated, with favorable outcomes. Transplant renal artery stenosis (TRAS) is one of the most common vascular complications following renal transplant. Unlike single kidney transplants, where TRAS usually presents with fluid overload, uncontrolled hypertension, and worsening kidney functions; it may be clinically silent in DKT patients since they have two functional transplanted kidneys. We hereby report a case of TRAS in a DKT patient who had 2 years of favorable clinical outcomes following successful endovascular stenting. He however recently died of COVID-19 associated pneumonitis.

O transplante renal continua sendo a terapia preferida para doenças renais em fase terminal. Dada a escassez de rins de doadores adequados, o doador com critérios expandidos permite que rins marginais sejam transplantados, embora haja um maior risco de falha do enxerto devido à diminuição da massa nefrótica. Para diminuir o risco de falha do enxerto, recomenda-se o transplante renal duplo (TRD), com resultados favoráveis. A estenose de artéria renal transplantada (EART) é uma das complicações vasculares mais comuns após o transplante renal. Ao contrário dos transplantes de rim simples, nos quais a EART geralmente se manifesta como sobrecarga de fluido, hipertensão descontrolada e piora das funções renais, ela pode ser clinicamente silenciosa em pacientes com TRD, pois eles têm dois rins funcionais transplantados. Relatamos aqui um caso de EART em um paciente com TRD que teve resultados clínicos favoráveis por dois anos após o sucesso do implante de stent endovascular. No entanto, ele morreu recentemente de pneumonite associada à covid-19.

Visualization of the renal artery in kidney transplant patients using time-resolved computed tomography angiography.

BACKGROUND: Transplant renal artery stenosis (TRAS) is a post-operative complication which most often occurs between 3 months and 2 years after transplantation. TRAS is associated with kidney failure and hypertension and, thereby, with an increased risk of cardiovascular events. PURPOSE: The purpose of this retrospective study was to report our experience of perfusion computed tomography angiography (P-CTA) to identify a 50% lumen reduction (as compared to digital subtraction angiography, DSA), assess its subjective image quality and evaluate if contrast-induced acute kidney injury (CI-AKI) occurred. MATERIAL AND METHODS: All 13 patients who had undergone P-CTA for suspected TRAS at our institution were retrospectively evaluated. At P-CTA, eight or 12 g of iodine were administered intravenously, and five to seven scan sequences were merged into time-resolved images after motion correction. Eight patients underwent subsequent DSA. RESULTS: The average patient weight was 76 kg (range 55-97 kg). Image quality was rated as good or excellent for all patients, and pathological changes were shown in 10 of 13 patients undergoing P-CTA. Two patients had a serum creatinine increase of >26 µmol/L during the first 3 days, but serum creatinine was significantly lower in all patients 1 month after P-CTA (165+/-69 µmol/L versus 232+/-66 µmol/L, P < .01). The diagnosis at P-CTA was verified in all eight patients who underwent DSA. However, in two cases with suspected stenosis, renal function was restored without angioplasty. CONCLUSION: Anatomy and blood flow of the transplant renal artery can be visualized using less than a third of the standard contrast media dose by using P-CTA technique.

Kidney allograft infarction associated with transplant renal artery stenosis in a COVID-19 kidney transplant recipient.

Kidney allograft infarction is rare, but an urgent condition that requires prompt intervention to avoid allograft loss. Renal artery thrombosis is the leading cause of infarction. Apart from traditional risk factors for thrombosis, emerging SARS-CoV-2 predisposes patients to thrombotic diseases both in arterial and venous vasculatures. We report a case of kidney transplant recipient with known transplant renal artery stenosis (TRAS) status post angioplasty with severe COVID-19, complicated by oliguric acute kidney injury requiring continuous renal replacement therapy (CRRT). She did not have a history of thromboembolic disease. The hospital course was complicated by new-onset atrial and ventricular fibrillation and cardiac arrest requiring multiple rounds of cardiopulmonary resuscitation. She had no signs of renal recovery, and an abdominal CT scan showed evidence of allograft infarcts. She underwent an allograft nephrectomy. Pathology revealed diffuse thrombotic microangiopathy involving glomeruli, arterioles, and arteries associated with diffuse cortical infarction with negative SARS-CoV-2 immunostain and in situ hybridization. This is the first case of kidney allograft infarct with a history of TRAS in a COVID-19 patient. Underlying TRAS and COVID-19-associated thrombosis in this patient are unique and likely play a key role in allograft infarction from arterial thrombosis. Recognizing risk factors and early therapy for allograft infarction may improve transplant outcomes.

Peripheral Vascular Disease Involving Transplant Renal Artery.

BACKGROUND: Transplant renal artery stenosis (TRAS) can afflict up-to one-fifth of patients with a transplanted kidney. It is associated with uncontrolled hypertension, loss of precious transplanted organs, and mortality. Pathophysiology, diagnosis, and treatment of TRAS is distinct from vascular diseases of the native kidney. The value of preservation of a transplanted kidney is unique, considering the emotional and surgical stakes involved. This field lacks large randomized trials, and ethically it may never be possible to randomize patients with a solitary transplanted kidney. Therefore, vascular interventionalists have to rely on treating factors that can cause graft malfunction like uncontrolled hypertension and renal ischemia, considering that sufficiently large, prospective, randomized data indicating that treating these factors make a difference may never emerge.

Acute Page kidney after angioplasty in kidney transplant allografts.

Acute Page kidney (APK) in kidney transplantation is a rare entity often related to interventional techniques. Percutaneous angioplasty remains an exceptional cause of APK. Herein we describe the clinical course and outcome of APK following percutaneous angioplasty for transplant renal artery stenosis in four kidney transplant recipients, where external compression of the graft was caused by subcapsular haematomas. All patients were treated with surgical drainage, after which two cases recovered baseline kidney function, one developed advanced chronic kidney disease and one remained dialysis-dependent. To our knowledge, the present series is the largest to describe APK in kidney allografts after percutaneous angioplasty.