Transplant Renal Artery Stenosis Research Articles

Robotic-Assisted Endovascular Treatment for Transplant Renal Artery Stenosis: A Feasibility Study.

To describe a single-center experience with robotic-assisted endovascular treatment for transplant renal artery stenosis. This is a single-center, retrospective, feasibility study of 4 consecutive cases of robotic-assisted endovascular surgery for transplant renal artery stenosis from October 2021 to August 2022. All lesions were identified, and stenting was performed with no complications. Conversion to manual control was not necessary. The mean fluoroscopy time was 25.25min (range 12-60.9). A control Doppler ultrasound was routinely performed, demonstrating no residual lesions in all cases. There was no reintervention during the follow-up period. The operator learning curve was felt to be acceptable. Robotic-assisted endovascular treatment is a feasible technique for transplant renal artery stenosis.

#2115 Phase-contrast magnetic resonance imaging (PC-MRI) for quantification of volumetric flow in renal transplant arteries: an observational cohort study

Abstract Background and Aims Impaired renal transplant blood flow, a manifestation of severe transplant renal artery stenosis (TRAS), can negatively impact transplant function and survival. Phase-contrast magnetic resonance imaging (PC-MRI) is a non-invasive method of quantifying blood flow volume. Recent work has demonstrated the utility of this technique in measuring native renal blood flow, whilst validating the use of flow measurements taken on the aorta above and below the origin of the renal arteries to calculate flow in the renal arteries [1]. As part of a quality improvement study incorporating PC-MRI into renal transplant assessment, this study set out to (a) establish the normal range for transplant renal blood flow volume and (b) assess whether PC-MRI improved screening for TRAS. Method Between January 2019 and February 2021, PC-MRI sequences were included in the protocols for all magnetic resonance angiograms (MRA) performed as part of clinically-indicated renal transplant assessment. As part of the MRA study, using a coronal localizer MR image, planes were prescribed on the external iliac artery (EIA) both proximal and distal to the transplant artery anastomosis site in a perpendicular orientation (Fig. 1A). Using CV142 software [2], arterial cross-sections were highlighted manually at the pre-determined planes (Fig. 1B) to generate flow curves that coincided with the cardiac cycle (Fig. 1C). Studies were excluded if: the EIA flow waveform was incongruous with the cardiac cycle, contemporaneous heart rate data was not recorded, or the calculated flow volume was a negative value. Results During the study period 392 transplant MRAs were performed, of which 218 were included in this analysis. Potential TRAS was identified in 49 (22.5%) studies, with 19 (8.7%) having this diagnosis confirmed by intra-arterial digital subtraction angiography (IADSA). In the 169 (77.5%) studies without evidence of TRAS, the mean flow in the proximal EIA was 0.90 L/min (95% CI 0.85-0.94 L/min) and in the distal EIA 0.47 L/min (95% CI 0.44-0.50 L/min). The difference between the two measurement points, that is the flow in the transplant renal artery, was 0.42 L/min (95% CI 0.39-0.45 L/min) (Fig. 2A). In the 19 studies with TRAS confirmed by IADSA, mean flow at the time of the initial MRA was 0.34 L/min (95% CI 0.25-0.43 L/min); there was no difference when compared with the group without evidence of TRAS on MRA (p = 0.09) (Fig. 2B). Of the patients who had potential TRAS identified on MRA, 30 patients proceeded to IADSA; there was no difference in PC-MRI flow volume in the 11 who had a diagnosis of TRAS refuted on IADSA and the 19 who had diagnosis of TRAS confirmed (p = 0.97). ROC curve analysis of PC-MRI arterial flow measurement as a diagnostic test for TRAS, whereby the positive group of 19 had IADSA confirmed TRAS, the negative group of 176 had either normal MRA artery appearances or normal IADSA, and the disease prevalence is 13.7% [3], shows AUC 0.62 (95% CI 0.55-0.69) P = 0.09, sensitivity 57.9 specificity 67.1 (Fig. 2C). Conclusion This is the largest study to incorporate functional PC-MRI sequences into MRA protocols for the assessment of people with any form of kidney disease. The results suggest that the blood flow volume in healthy transplant renal arteries lies between 0.39–0.45 L/min. In comparative analysis between patients with healthy transplant arteries and those with IADSA-confirmed TRAS, there was no difference in arterial flow volume, though the study was limited by the small population in the group with IADSA-confirmed TRAS. PC-MRI does not appear to improve the screening accuracy of MRA in identifying TRAS. However, there may be a future role for PC-MRI as part of multi-parametric MR protocols for comprehensive assessment of patients with kidney transplants.

#2741 The interplay between donor & recipient factors, outcomes, and transplant artery flow volume as measured by phase-contrast magnetic resonance imaging

Abstract Background and Aims Cardiovascular health and kidney transplant health are inter-connected [1]. Phase-contrast magnetic resonance imaging (PC-MRI) is a non-invasive means of quantifying blood flow volume within vasculature. Its utility for the assessment of blood flow volumes within the transplant renal artery has not been explored. The aims of this study were to determine if: (A) flow in the transplant artery is influenced by donor and recipients factors, (B) flow in the transplant artery is related to or influences clinical outcomes for transplant recipients. Method Analysis of PC-MRI sequences obtained during 218 kidney transplant magnetic resonance angiograms (MRA) performed at a single centre between 2019 and 2021 was undertaken. All scans were clinically indicated and requested by clinicians to investigate for transplant renal artery stenosis (TRAS). Baseline clinical and demographic data and subsequent clinical outcome data were collected for all study participants. Median follow up was 49 (IQR 40–54) months. For Kaplan-Meier survival analyses, comparison of clinical outcomes by interquartile range of flow volumes was performed, whereby quartile one comprised subjects with the lowest transplant artery blood flow volumes. Statistical analysis was performed using MedCalc Statistical Software version 22.013. Results In this study of 218 subjects, 49 (22.4%) had features of possible TRAS identified on initial MRA. TRAS was subsequently confirmed via intra-arterial digital subtraction angiography in 19 (8.7%) cases. The majority of participants were male 150/218 (68.8%). The commonest cause of ESKD was diabetic kidney disease at 71/218 (32.6%). Living donor transplant recipients were 35/218 (11.5%) of the study population. The median donor age was 55 (IQR 44–65) years. The median time from ESKD to transplantation was 25 (IQR 9–53) months. The median time from transplantation to PC-MRI for all participants was 322 (IQR 81–1744) days; for participants who were ultimately diagnosed with TRAS it was 169 (IQR 76–262) days. The median age of recipients at time of PC-MRI was 56 (IQR 45–64) years. Overall, the mean transplant artery flow volume was 0.41 L/min (95% CI 0.39–0.45 L/min). Rank correlation between age of donor and flow in the transplant artery (L/min) showed r = −0.25 (95% CI −0.37 - −0.12) P = 0.0002. Rank correlation between age of recipient at time of PC-MRI and flow in the transplant artery (L/min) showed r = −0.37 (95% CI −0.48 to −0.25) P ≤ 0.0001. Rank correlation between flow in the transplant artery (L/min) and estimated glomerular filtration rate (mL/min/1.73 m2) showed r = 0.43 (95% CI 0.31–0.53) P < 0.0001. Univariable linear regression analysis of flow in the transplant artery (L/min) and estimated glomerular filtration rate (mL/min/1.73 m2) was R2 0.14, DF regression = 1 DF residual = 214, F = 34.7, P < 0.0001 (Fig. 1). Overall, 35 (16.1%) participants experienced kidney transplant failure and 42 (19.3%) participants died within the study follow up period. Kaplan-Meier analysis showed no significant difference in kidney transplant survival between four groups categorized according to transplant artery flow volumes, logrank test P = 0.93 (Fig. 2A). Subjects in the first quartile were at greater risk of death, logrank test P = 0.01, HR 4.36 (95% CI 1.77–10.74) compared with fourth quartile (Fig. 2B) Conclusion This study has demonstrated that both older donor age and older recipient age negatively correlate with transplant artery flow, and that transplant artery flow is positively correlated and predicts estimated glomerular filtration rate. Finally, recipients with low transplant artery flow volume are at greater risk of death. Neither cause nor effect of low blood flow volume have been elucidated in this study. However, improving transplant blood flow by optimising cardiovascular health may have a positive impact on outcomes for people with kidney transplants and warrants further study.

#2169 Transplant renal artery stenosis in recipients with resistant arterial hypertension

Abstract Background and Aims Transplant Renal Artery Stenosis (TRAS) is a vascular complication after kidney transplantation. It worsens the prognosis of the graft and the patient's life. The aim was to study the incidence of TRAS as a cause of resistant arterial hypertension in kidney transplant recipients in the Republic of Belarus and the efficiency of its endovascular treatment. Method The study included 187 kidney transplant recipients. Blood pressure of 72 (38.5%) patients was less than 130/80 mmHg without taking antihypertensive drugs. Arterial hypertension was diagnosed in 115 (61.5%) recipients. The study included clinical, laboratory and instrumental methods (24-hour blood pressure monitoring, Doppler ultrasound, graft scintigraphy with captopril). Results 31 (16.6%) recipients needed to take one antihypertensive drug, 43 (23.0%)—2 drugs, 41 (21.9%)—3 or more. 17 (9.1%) recipients did not have target blood pressure correction while taking more than 4 antihypertensive drugs. There was decreased blood flow in the graft artery with a peak systolic velocity > 200 cm/s in 14 (7.5%) cases. These patients were submitted to the graft nephroscintigraphy with caplopril where 8 grafts (4.3%) were diagnosed signs of TRAS. These recipients were submitted to the renal angiography with the injection of 150 (100; 200) ml of contrast agent. 5 (2.7%) recipients were diagnosed with hemodynamically significant TRAS of more than 70 (65; 75) % and received percutaneous transluminal angioplasty and stenting. All these patients had a decrease of glomerular filtration rate and resistant arterial hypertension before operation. The average age of the patients with TRAS was 57.4 ± 11.0 years, the period after transplantation was 11 ± 3 months. Their blood tests did not show dyslipidemia, but 4 out of 5 cases had diabetes mellitus. Their postoperative period had no complications. The patient was placed on dual antiplatelet therapy with aspirin and clopidogrel. There was an increase in glomerular filtration rate by 27 ± 7 ml/min/1.73 m2 and a decrease in systolic blood pressure by 40 (40; 45) mm Hg in the early postoperative period. Graft artery stenting allowed reducing the number of antihypertensive drugs to one tablet in 4 out of 5 patients. Conclusion Transplant Renal Artery Stenosis is a rare but significant complication of the late postoperative period that may cause resistant hypertension in kidney transplant recipients. Timely identification and stenting of the graft artery improves the graft functioning and reduces blood pressure.

Transplant Renal Artery Stenosis with Varied Clinical Presentations

Renal vascular complications constitute a clinically significant cause of morbidity following renal transplantation. Transplant renal artery stenosis (TRAS) is a well-recognized complication accounting for ~75% of posttransplant vascular complications. Early recognition and prompt correction of TRAS can prevent adverse outcomes, including graft loss. This series is a summary of four renal transplant recipients who developed TRAS at varied time periods and with varied clinical presentations. A 23-year-old male who presented after 1½ months of renal transplantation with accelerated hypertension was diagnosed with TRAS and was treated successfully with percutaneous transluminal angioplasty with stenting. A 26-year-old male with acute allograft dysfunction after 1 month of transplantation without worsening hypertension was diagnosed with TRAS, which was treated successfully with angioplasty and stenting. A 49-year-old male who presented to the emergency with pulmonary edema secondary to accelerated hypertension (Pickering syndrome) after 2 months of transplantation was diagnosed to have TRAS, which was treated successfully with angioplasty with stenting. A 44-year-old male with an incidentally detected TRAS-like clinical picture secondary to kinking in the transplant renal artery in the immediate posttransplant period was successfully treated with re-exploration and repair. All the patients were screened with Doppler ultrasonogram and computed tomogram-angiography supported the diagnosis in three of the cases. None of the cases developed procedure-related complications including contrast-associated nephropathy. All the patients on follow-up after 6 months of the intervention are normotensive with normal renal function. A high index of suspicion is required in the early identification of TRAS, which is a reversible cause of hypertension and graft dysfunction. The risk of contrast-associated nephropathy cannot hinder or delay the diagnosis especially, in emerging transplant centers. The endovascular procedures used today for the treatment of TRAS are safe with high technical success rates.

Multiple Renal Arteries in Live Donor Renal Transplantation and Impact on Graft Function and Outcome: A Retrospective Study

Objective: The objective of the study is to evaluate the outcomes of live-donor renal allografts with multiple and single renal arteries taking into consideration ischemia times, graft function, and other complications including vascular and urological. Materials and Methods: We conducted a retrospective study by analyzing a prospectively maintained database from January 2021 to December 2021 of all patients undergoing live-related renal allograft transplants at a tertiary care center in North India. A total of 239 live donor kidney transplants were performed during this period. Patients were divided into two groups – Group 1: Single artery single anastomosis and Group 2: Multiple arteries with two or more anastomoses. Duplex imaging of the graft was done at 6 months. Recipients were followed up for possible graft dysfunction, arterial insufficiency, and major urological complications. Results: Mean ischemia times in the two groups were 20.62 ± 1.05 and 30.45 ± 1.77 min, respectively. Failure to normalize creatinine (<1.2 mg/dl) within 72 h was seen in 6/183 and 3/56 (P > 0.05). Slow graft function was encountered in 6 cases in Group 1 and 3 cases in Group 2. Delayed graft function occurred in two patients in both groups. One-year graft survival among the groups was 5/183 and 2/56, respectively (P > 0.05). One patient from Group 1 developed transplant renal artery stenosis. Six patients from Group 1 developed ureteric complications. Conclusion: Donor grafts with multiple renal arteries may be accepted safely with careful surgical reconstruction and close surveillance posttransplant.

Retrospective analysis of percutaneous intervention of the renal artery in transplanted kidneys in children and adolescents at a tertiary public hospital.

This study evaluated the long-term effects of percutaneous intervention in children and adolescents with transplant renal artery stenosis (TRAS). Twenty patients had significant stenosis (>50%) and underwent percutaneous transluminal angioplasty (PTA/stenting) (TRAS group-intervention); 14 TNS (non-significant group -control) patients did not have significant stenosis (≤50%) and were treated clinically. The combined primary endpoints were death from all causes and late graft failure. The secondary endpoints were serum creatinine (SCr), systolic blood pressure (SBP), and diastolic blood pressure (DBP). No statistically significant difference was found between TRAS-Intervention(N = 20) and TNS groups-Control (N = 14) for these clinical parameters: deaths, 1 (5.0%) vs. 0 (0.0%) (p = 1.000) and graft loss, 4 (20.0%) vs. 2 (14.3%) (p = 1.000). For the secondary endpoints, after 1 month and 1 year the values of SCr, SBP, and DBP were similar between the two groups but not statistically significant. In the TRAS group (intervention), the stent implantation was beneficial for treating refractory hypertension and reducing blood pressure (BP) in children and adolescents. Despite the outcomes being similar in the two groups, it can be inferred that the patients in the TRAS group (intervention) would have had a worse outcome without the percutaneous intervention. TRAS treatment with stenting can be considered for children and adolescents. Because the sample in the present study comprised of only a specific population, further studies are needed for generalization. The trial was registered at clinictrials.gov with trial registration number NCT04225338.

A Case Report of Concurrent Transplant Renal Artery Stenosis, Renal Cell Carcinoma, and Papillary Thyroid Cancer After Renal Transplantation: A Literature Review

BackgroundKidney transplantation is the preferred treatment option for eligible patients with end-stage renal disease. With the advanced transplantation technology and the novel immunosuppressive agents, kidney transplant recipients survive significantly longer. But the chance of developing malignant tumors has increased, posing a serious challenge to the survival of transplanted kidneys and patients. Case presentationWe report a male patient (the patient's informed consent has been obtained) who underwent kidney transplantation 23 years ago. Subsequently appeared transplant renal artery stenosis (TRAS) , primary renal clear cell carcinoma(RCCC), and papillary thyroid cancer(TC). The narrowed blood vessels were dilated through percutaneous transluminal angioplasty (PTA), and the malignant tumor was removed surgically. Currently, anti-rejection drugs are regularly taken, and the transplanted kidney function is good. Satisfied with living conditions. ConclusionHypertension that is difficult to control after kidney transplantation should be suspected as a possibility of graft vascular stenosis. When B-ultrasound cannot accurately diagnose it, magnetic resonance angiography should be used as early as possible to clarify the diagnosis and relieve the stenosis before graft dysfunction. Transplantation patients have a high incidence of malignant tumors after surgery, and the risk increases with the prolongation of the disease course. Focus on symptomatic treatment of related diseases, and anti-rejection drugs can be reduced or not reduced as appropriate.

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

Key Clinical MessageProper diagnosis and treatment of vascular stenosis which is a possible complication of renal transplant is important in improving patients' quality of life and prognosis.AbstractOne 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.

Renal Transplant Artery Stenosis: Clinical Manifestations, Diagnosis and Treatment

Renal Transplant Artery Stenosis: Clinical Manifestations, Diagnosis and Treatment

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

ObjectivesEarly 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 MethodsIn 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 with 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. ResultsThe 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. ConclusionNCE-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.

Renal Transplant Artery Stenosis and Kinking: An Unusual Association

Renal artery stenosis of the kidney allograft associated with kinking is not a frequent finding. As a correctable cause of graft dysfunction, it is important to diagnose it as soon as possible to avoid further graft damage and improve graft and patient survival. As pulsed wave Doppler ultrasound mapping of the graft’s renal arteries is essential to diagnose possible alterations, point of care ultrasound (POCUS) is a highly useful tool for early diagnosis. We present a case in which nephrologists performed this examination promptly allowing a timely diagnosis and treatment plan.

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

Introduction and objectivesTransplant 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. MethodsWe 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. ResultsSeven 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. ConclusionsThe 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.

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

Introduction and objectivesTransplant 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. MethodsWe 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. ResultsSeven 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. ConclusionsThe 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.

Contemporary and Emerging MRI Strategies for Assessing Kidney Allograft Complications: Arterial Stenosis and Parenchymal Injury, From the AJR Special Series on Imaging of Fibrosis.

MRI plays an important role in the evaluation of kidney allografts for vascular complications as well as parenchymal insults. Transplant renal artery stenosis, the most common vascular complication of kidney transplant, can be evaluated by MRA using gadolinium and nongadolinium contrast agents as well as by unenhanced MRA techniques. Parenchymal injury occurs through a variety of pathways, including graft rejection, acute tubular injury, BK polyomavirus infection, drug-induced interstitial nephritis, and pyelonephritis. Investigational MRI techniques have sought to differentiate among these causes of dysfunction as well as to assess the degree of interstitial fibrosis or tubular atrophy (IFTA)-the common end pathway for all of these processes-which is currently evaluated by invasively obtained core biopsies. Some of these MRI sequences have shown promise in not only assessing the cause of parenchymal injury but also assessing IFTA noninvasively. This review describes current clinically used MRI techniques and previews promising investigational MRI techniques for assessing complications of kidney grafts.

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

To determine if ancillary sonographic and Doppler parameters can be used to predict transplant renal artery stenosis in patients with renal graft dysfunction. 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. 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. 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.

Clinical Outcomes of Intravascular Ultrasound-confirmed Symptomatic Transplant Renal Artery Stenosis after Endovascular Treatment

Clinical Outcomes of Intravascular Ultrasound-confirmed Symptomatic Transplant Renal Artery Stenosis after Endovascular Treatment

Endovascular Treatment of Transplant Renal Artery Stenosis: A Single-Center Retrospective Cohort Study

Endovascular therapy is the most common treatment for transplant renal artery stenosis; however, its long-term outcomes remain controversial, with no uniform standard for percutaneous transluminal angioplasty versus percutaneous transluminal stenting. We retrospectively analyzed 26 patients with transplant renal artery stenosis who underwent endovascular therapy. We evaluated long-term efficacy of endovascular therapy and the reasonable choice of treatment. Serum creatinine increased significantly at onset of transplant renal artery stenosis (113.88 ± 37.573 before vs 279.31 ± 94.98 μmol/L during stenosis; P1 < .001), and endovascular therapy had a good short-term effect (279.31 ± 94.98 during stenosis vs 139.54 ± 124.40 μmol/L at 2 weeks posttreatment; P2 = .002). Long-term efficacy of endovascular therapy was stable (139.54 ± 124.40 at 2 weeks posttreatment vs 150.69 ± 180.72 at 6 months vs 161.58 ± 174.49 μmol/L at last follow-up; P3 > .05). Blood pressure increased significantly at onset of transplant renal artery stenosis (126.65 ± 16.11 before vs 159.62 ± 25.84 mm Hg during stenosis; P1 < .001). Moreover, the short-term effect of endovascular therapy was good (159.62 ± 25.84 during stenosis vs 128.73 ± 14.22 mm Hg at 2 weeks posttreatment; P2 < .001). Long-term effects remained stable (128.73 ± 14.22 at 2 weeks posttreatment vs 131.15 ± 14.55 at 6 months vs 138.50 ± 16.82 mm Hg at last follow-up; P3 > .05). Peak systolic velocity decreased significantly after endovascular therapy (176.6 ± 67.93 during stenosis vs 114.24 ± 67.93 cm/s at 2 weeks posttreatment; P < .001). Endovascular therapy is effective in transplant renal artery stenosis treatment and has a low incidence of complications. Percutaneous transluminal angioplasty should be performed routinely during endovascular therapy. After dilation, if stenosis remains >25% or retracted, then percutaneous transluminal stenting is recommended. Otherwise, percutaneous transluminal angioplasty is preferred.

Ультразвуковая диагностика цитомегаловирус индуцированного стеноза трансплантационной почечной артерии

Transplant renal artery stenosis (TRAS) is a well-known vascular complication after kidney transplantation. Most often, this occurs in the first 6 months after kidney transplantation and is one of the main causes of graft loss and premature death of transplant recipients. Renal hypoperfusion, which occurs with TRAS, leads to activation of the renin-angiotensin-aldosterone system. Patients usually have worsening or refractory hypertension and often dysfunction of the allograft. Timely diagnosis and treatment of TRAS can prevent allograft damage and systemic consequences. We report a patient with stenosis of the renal artery graft associated with cytomegalovirus infection. Cytomegalovirus is involved in the pathogenesis of renal artery stenosis in a transplant. During the serological determination of examination, cytomegalovirus positive titers of IgG antibodies to cytomegalovirus and quantitative DNA in blood serum by polymerase chain reaction were revealed. Duplex sonography is the most frequently used screening method, while angiography provides the final diagnosis. The results of the Doppler study of the renal allograft were compatible with critical stenosis of the renal artery. Angiography of the renal allograft revealed a critical stenosis of the anastomosis.

Editorial introductions.

Editorial introductions.