Angiographic evaluation and treatment of transplant renal artery stenosis

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.

Detection of transplant renal artery stenosis with contrast-enhanced ultrasound

Transplant renal artery stenosis (TRAS) is a vascular complication occurring during the first 2 years after kidney transplantation, with an incidence and a prevalence ranging from 1% to 23%, and from 1.5% to 4%, respectively. Detection of TRAS is the key, since most stenoses may progress to renal graft loss, however it may be difficult to detect due to its nonspecific clinical manifestations. Although Doppler ultrasound has become a primary imaging technique, digital subtraction angiography (DSA) remains the gold standard for diagnosing TRAS. We present a case of delayed graft function following kidney transplantation complicated by a lateral by-pass with prosthesis upstream and downstream of renal anastomosis, TRAS criteria were unclear using Doppler ultrasound, contrast-enhanced computed tomography-scan, and DSA. Only contrast-enhanced ultrasound (CE-US), observing a delayed and pulsating contest impregnation of renal parenchyma, supported the hypothesis of TRAS that was confirmed by the measurement of trans-anastomosis pressure gradient during DSA.

Transplant renal artery stenosis: Evaluation with contrast-enhanced ultrasound

OBJECTIVE

To assess the efficacy of contrast-enhanced ultrasound (CEUS) in depicting transplant renal artery stenosis (TRAS).

MATERIALS AND METHODS

Seventy-eight patients (56 men and 22 women; aged 36±12.2years) who were suspected of TRAS due to either Doppler ultrasound (DUS) abnormalities or difficult control of blood pressure and/or persistent deterioration of renal function were enrolled to perform CEUS. The reference standard for the TRAS diagnoses was computed tomography angiography (CTA). The diagnostic performance of DUS and CEUS parameters was assessed by the area under the receiver operating characteristic curve (AUC).

RESULTS

TRAS was diagnosed in 32 out of 78 cases by CTA. The AUC, accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CEUS in predicting TRAS were 0.92, 92.3%, 87.5%, 95.7%, 93.3%, and 91.7%, respectively. CEUS rectified 13 (28.3%) false-positive cases on DUS, which were confirmed by CTA. Compared to DUS parameters, CEUS showed the highest AUC, statistically significant differences of AUC were found (P=0.006-0.039), except for that of the PSV ratio in the main transplant renal artery to that in interlobar artery (PSV-ratio) (AUC: 0.92 versus 0.86, P=0.422). However, CEUS showed a significantly higher specificity (95.7% versus 76.1%, P=0.008) and the same sensitivity compared to PSV-ratio.

CONCLUSIONS

CEUS is superior to DUS in depicting TRAS. Moreover, our results suggest that CEUS might potentially be used as a noninvasive tool to spare many patients from unnecessary CTA.

Interventional Therapy for Transplant Renal Artery Stenosis Is Safe and Effective in Preserving Allograft Function and Improving Hypertension

Purpose:

To evaluate the outcomes of percutaneous intervention (PI) for transplant renal artery stenosis (TRAS).

Materials and Methods:

Doppler ultrasonography was used as the screening tool, and angiography was the diagnostic method for TRAS. The indications for PI were (1) a reduction in lumen diameter of >50% or (2) a mean pressure gradient of >15 mm Hg. Technical success was assessed immediately after the procedure. The short-term results of stenosis were evaluated by serum creatinine (Scr) levels and blood pressure (BP). The long-term results were assessed by graft survival and renal function.

Results:

From October 2009 to July 2015, a total of 660 patients had kidney transplantation and 22 cases underwent PI. The technical success was 100%. The mean Scr level preintervention was 321.6 ± 167.2 (range, 171.3-862.0) μmol/L, and it decreased to 145.3 ± 44.7 (range, 74.3-260.8) μmol/L 1 month postintervention ( P < .001). Blood pressure was also improved at 1 month postintervention, as assessed by systolic (157.0 ± 13.0 vs 131.0 ± 11.0 mm Hg, P < .001), diastolic (95.0 ± 5.0 vs 77.0 ± 9.0 mm Hg, P < .001), and mean arterial pressure (116.0 ± 7.0 vs 95.0 ± 9.0 mm Hg, P < .001). The patency rate was 100%, 91.7%, and 85.7% at 1, 3, and 12 months, respectively. The secondary patency rate was 100%. Graft survival was 100% during follow-up. There was no significant deterioration in graft function or BP ( P > .05) postintervention when compared to posttransplantation.

Conclusions:

Percutaneous intervention for TRAS is safe and results in significant improvement both in allograft function and in BP.

Evaluation of the Vascular Surgical Complications of Renal Transplantation

BACKGROUND

Renal transplantation is the treatment of choice of end-stage renal failure. However, vascular surgical complications can compromise the functional prognosis of the transplant or even be life threatening in the short term. Since few data are available in the literature, the objective of this study was to evaluate the vascular surgical complications of renal transplantation.

METHODS

In a retrospective and monocentric study, the records of all the patients receiving a kidney transplant between January 2008 and December 2014 were reviewed. The demographic data and the follow-up of the patients who presented a vascular surgical complication in relation to their transplant were collected. Minor, intermediate, or major vascular complications were defined according to the need for monitoring, reoperation, or the risk of transplant loss or a life-threatening situation. Predictive factors of vascular complications were also looked for.

RESULTS

Mean age was 50.9 ± 15.0 years, and 312 kidney transplants were carried out (205 men). Fifty vascular surgical complications (16.0%) were found. Among them, 23 vascular complications (7.4%) were major, including 6 (1.9%) which required transplantectomy, after 4 arterial thromboses (1.3%), 1 early venous thrombosis (0.3%), and 1 injury of the inferior vena cava (0.3%). Twelve complications (3.8%) were minor. Surgical revision was necessary in 76% of the vascular complications (n = 38). The average follow-up of the transplanted population was 37.4 ± 24.0 month, 268 kidney transplants (85.8%) were functional and 21 patients (6.7%) returned to dialysis. Surgical complications were more frequent when the recipient had hypertension (P = 0.02, OR = 2.5; 95% CI [1.1-6.1]), in case of right kidney transplant (P = 0.0004, OR = 3.1; 95% CI [1.6-5.8]) and when the kidney hilum consisted of at least arteries (P = 0.02, OR = 10.0; 95% CI [1.3-34]). Male gender (P = 0.03, OR = 0.5; 95% CI [0.3-0.9]) as well as the choice of the common iliac arterial (P = 0.001, OR = 0.4; 95% IC [0.2-0.7]) and venous (P = 0.002, OR = 0.3; 95% IC [0.2-0.8]) axes to carry out the vascular anastomoses appeared as protective factors.

CONCLUSIONS

The vascular surgical complications of kidney transplantation, especially thromboses, can be serious and lead to transplant loss. The expertise of vascular surgeons finds its place here and makes it possible to maintain low rates of vascular complications and loss of transplants.

Transplant renal artery stenosis: The impact of endovascular management and their outcomes

Introduction:

Transplant renal artery stenosis (TRAS) is a well-known vascular complication of renal transplantation. The aim of this analysis was to assess the short and midterm outcomes of endovascular therapy to salvage transplant kidney.

Methods:

We retrospectively analyzed our transplant database from 2000 to 2015. Percutaneous transluminal angioplasty/stenting was done in 24 patients (22 men and two women) with significant TRAS. The mean age was 59 ± 12 years. The parameters analyzed were: Technical success, pre- and post-treatment serum creatinine and number of antihypertensive drugs before and after treatment and vessel patency on Doppler ultrasonography at 3 and 6 months.

Results:

Overall incidence of TRAS in this study was 5.06%. Incidence of TRAS following live donor transplantation was 4.68% while that in deceased donors was 11.5%. Technical success was 100%. There were no periprocedural deaths. Renal function was improved from 2.32 ± 0.5 mg/dL to 1.72 ± 0.3 mg/dL (P < 0.001) and number of antihypertensive medications after the procedure was reduced from 2.9 ± 0.7 to 2 ± 0.6 (P < 0.001) at 6 months follow-up. One patient developed restenosis within 5 months (4.2%). Clinical success at 6 months follow-up was 79.2%.

Conclusions:

Endovascular treatment of TRAS has high technical success with minimal complications. It also provides satisfactory clinical success with improvement in overall transplant renal function and renovascular hypertension in early follow-up.

Renal transplant vascular complications: the role of Doppler ultrasound

Improvements in the care of kidney transplant recipients and advances in immunosuppressive therapy have reduced the incidence of graft rejection. As a result, other types of kidney transplant complications, such as surgical, urologic, parenchymal, and vascular complications, have become more common. Although vascular complications account for only 5-10 % of all post-transplant complications, they are a frequent cause of graft loss. Ultrasonography, both in B-mode and with Doppler ultrasound, is a fundamental tool in the differential diagnosis of renal allograft dysfunction. Doppler ultrasound is highly specific in cases of transplanted renal artery stenosis, pseudoaneurysms, arteriovenous fistulas, and thrombosis with complete or partial artery or vein occlusion. A single measurements of color Doppler indexes display high diagnostic accuracy and in particular cases are more useful during the post-transplantation follow-up period. More recent techniques, such as contrast-enhanced ultrasound, undoubtedly increase the accuracy of ultrasonography in the diagnosis of vascular complications involving the transplanted kidney.

Complications of transplantation. Part 1: renal transplants

Vascular complications after solid-organ transplantation are not uncommon and may lead to graft dysfunction and ultimately graft loss. A thorough understanding of the surgical anatomy, etiologies, and types of vascular complications, their presentation, and the options for management are important for managing these complex patients. This article reviews the basic surgical anatomy, vascular complications, and endovascular management options of vascular complications in patients with renal transplants.

Role of high resolution contrast-enhanced magnetic resonance angiography (HR CeMRA) in management of arterial complications of the renal transplant

INTRODUCTION

Transplant renal artery (RA) stenosis (TRAS) is the most frequent posttransplantation vascular complication. Contrast enhanced magnetic resonance (CeMRA) angiography has been established as the preferred imaging technique for the evaluation of TRAS because it does not require the use of iodinated contrast material and does not expose the patient to ionizing radiation. Digital subtraction angiography (DSA) is the gold standard in the evaluation of arterial tree of the renal allograft.

AIM OF THE WORK

This study was carried out to assess the accuracy of CeMRA in the detection of arterial complications after renal transplantation.

PATIENTS AND METHODS

Thirty renal transplant patients with suspected arterial complications in which both CeMRA and DSA were performed were included in the study. The HR CeMRA shows 93.7% sensitivity, 80% specificity, 88.2% positive predictive value, 88.9% negative predictive value and 88.5% accuracy.

CONCLUSION

HR CeMRA is an accurate reliable tool in the assessment of arterial complications after renal transplantation. It may replace DSA as a diagnostic modality with reservation of interventional techniques for endovascular treatment of suitable cases.

Renal transplant imaging and complications

The management of end stage renal disease has been revolutionised with the advent of renal transplantation, which offers good quality of life with low morbidity. Imaging plays an important role in the diagnosis and management of complications arising in renal transplant recipients. Ultrasound, Doppler and nuclear medicine are the main imaging modalities. CT scan, MRI and angiography are used in indeterminate cases. Interventional radiology plays a vital role in the management of complications. The aim of this pictorial review is to illustrate the role and limitations of imaging in renal transplant. The normal appearances, the spectrum of pathological conditions affecting the transplant and the complications of immunosuppression are discussed and illustrated.

Does peak systolic velocity correlate with renal artery stenosis in a pediatric renal transplant population?

PSV of renal transplant vessels, calculated during allograft ultrasonography, has previously been shown to correlate with TRAS. Controversy exists regarding the threshold PSV value (adult range: 1.5-3.0 ms), which should prompt further, more invasive investigations to confirm the diagnosis of TRAS. Furthermore, there is a paucity of literature regarding PSV values in the pediatric renal transplant population. In a group of pediatric renal transplant patients, we correlated post-operative renal transplant PSV values with BP, renal function (serum creatinine) and TRAS. All patients who underwent cadaveric or living-related renal transplantation at the HSC between 2001 and 2004 with at least 6 months of follow-up were reviewed through the HSC multi-organ transplant database. Post-operative allograft Doppler ultrasonography was performed during routine follow-up. PSV values obtained were correlated with BP and serum creatinine performed concomitantly. Finally, we correlated PSV in those patients who underwent more intensive investigations, including magnetic resonance and conventional angiography. Fifty-three patients underwent transplantation during the study period. Complete data available for 50/53 demonstrated a mean PSV of 2.13 m/s (range: 0.9-6.1 m/s) for all patients. Of six patients who underwent MRA for suspicion of TRAS, two (with mean PSV values of 1.93 m/s) were found to have clinically significant stenoses. Four of six without angiographic evidence of TRAS had mean PSV values of 2.22 m/s. Patients suspected of having TRAS demonstrated elevated median serum creatinine values compared with those without clinical suspicion of TRAS. However, both mean PSV and BP were not found to be statistically different in both patient subgroups. Furthermore, there was no correlation identified between PSV and serum creatinine and BP in these patient populations. Despite the utility of PSV for monitoring adult renal transplant patients, we did not find that PSV correlated with BP, nadir creatinine or identify those patients who, through subsequent investigations, were found to have TRAS in this pediatric population. Maintaining cognizance in conjunction with close clinical follow-up may identify patients at risk for this rare but potentially morbid complication of transplantation.

Risk factors and long-term outcome of transplant renal artery stenosis in adult recipients after treatment by percutaneous transluminal angioplasty

Transplant renal artery stenosis (TRAS) is a common complication of kidney transplantation but attempts to identify predisposing risk factors for TRAS have yielded conflicting results. In order to determine the predisposing factors for transplant (TRAS), we retrospectively reviewed the records of 29 renal allograft recipients with TRAS treated with percutaneous transluminal angioplasty (PTA). The TRAS group was compared with a case-control group of 58 patients. Predisposing factors for TRAS included CMV infection (41.4% vs. 12.1% p = 0.0018) and initial delayed graft function (DGF) (48.3% vs. 15.5% p = 0.0018), respectively in the TRAS and the control group. Acute rejection occurred more frequently in patients from the TRAS group (48.3%) compared with the control group (27.6%), although the difference was not significant (p = 0.06). In a multivariate analysis, only CMV infection (p = 0.005) and DGF (p = 0.009) appear to be significantly and independently associated with TRAS. The long-term graft survival was significantly higher in the control group, compared with the TRAS group (p = 0.03). Our study suggests that CMV infection and DGF are two reliable risk factors for TRAS. Despite treatment by PTA with primary successful results, TRAS significantly affects long-term graft outcome.

Current management of transplant renal artery stenosis: clinical utility of duplex Doppler ultrasonography

OBJECTIVES

To perform a retrospective study to determine the clinical utility of Doppler ultrasonography (DUS) and to determine its role in the management of transplant renal artery stenosis (TRAS).

METHODS

Patients undergoing DUS between January 1998 and January 2001 for clinical suspicion of TRAS were included in the study. A total of 51 patients were divided into two groups according to the peak systolic velocity. Additional management was based on the clinical and DUS findings and their congruence. Patients were followed up and their outcome was analyzed.

RESULTS

Of the 51 patients who entered the study, 26 were in the low probability group (LPG) and 25 in the high probability group (HPG). Nine patients in the LPG underwent additional investigations; eight underwent magnetic resonance angiography and one angiography. Of these 9 patients, 6 had stenosis, 4 of whom required angiography. In total, 5 patients from the LPG underwent angioplasty, and 4 of them had stenosis (1 with TRAS, 2 with common iliac artery stenosis, and 1 with renal artery ostial stenosis). Three patients underwent angioplasty and 2 of them improved. In the HPG, 20 of 25 patients underwent additional investigations, including magnetic resonance angiography in 12 and angiography in 8, with stenosis in 15 patients. Of the HPG, 13 of 25 patients underwent angiography, with 10 requiring angioplasty--8 for TRAS and 2 for adjacent renal artery stenosis, with improvement in 8 patients. Congruent clinical and DUS findings were highly predictive of significant stenosis more amenable to improvement.

CONCLUSIONS

The results of our study have shown that high-probability DUS and congruent clinical findings are likely to identify a significant stenosis that is amenable to treatment. Low-probability DUS findings do not eliminate the possibility of stenosis, but intervention in this group is less likely to result in improvement.

Transplant renal artery stenosis: outcome after percutaneous intervention

PURPOSE

To assess the outcome of percutaneous transluminal angioplasty (PTA) and stent placement as the primary treatment for transplant renal artery stenosis (TRAS).

MATERIALS AND METHODS

A retrospective review of PTA and stent placement procedures performed for TRAS from April 1997 to July 2003 was conducted. Reviewed parameters included technical success, date of transplantation, dates of percutaneous intervention, mean arterial blood pressure, number of blood pressure medications, and serum creatinine level before and after intervention. Twenty-one interventions were performed in 18 allografts. The primary clinical indication for imaging and treatment was increased creatinine level in 12 allografts and hypertension in six allografts. Patency rates were estimated with use of the Kaplan-Meier method.

RESULTS

The technical success rate of PTA/stent placement was 100% and the clinical success rate was 94% (17 of 18 allografts). Thirteen interventions involved PTA alone, with eight combined PTA and stent insertions. The mean preintervention serum creatinine level among 12 allografts presenting with elevated creatinine levels was 2.8 mg/dL +/- 1.4 (SD), compared with a 1-month postintervention mean of 2.2 mg/dL +/- 0.7 (P = .03). Of six allografts that presented with hypertension, significant improvement was seen between the preintervention and 1-month postintervention mean systolic (174 mm Hg vs 135 mm Hg, P = .003) and diastolic (99 mm Hg vs 82 mm Hg, P = .02) pressures. These patients required a mean of 2.3 medications for blood pressure control before intervention, compared with a mean of 1.0 medications at 1 month after intervention (P = .002). Primary patency rates at 3, 6, and 12 months (+/-95% CI) were 94% +/- 6%, 72% +/- 12%, and 72% +/- 12%, respectively. Secondary patency rates at 3, 6, and 12 months (+/-95 CI) were 100%, 85% +/- 10%, and 85% +/- 10%, respectively. Mean follow-up time was 27 months. Of the eight allografts that underwent stent placement, all eight remained patent at last follow-up (mean, 18.3 months +/- 9.2). One major complication of a puncture site pseudoaneurysm occurred (5%).

CONCLUSION

Primary treatment of TRAS with PTA with or without stent placement has good intermediate-term patency and is associated with significant early improvement in blood pressure and creatinine level.

Duplex Doppler sonography of transplant renal artery stenosis

PURPOSE

The aim of this study was to evaluate the accuracy of duplex Doppler sonography in diagnosing transplant renal artery stenosis (TRAS) and to determine which parameter is the most reliable for making that diagnosis.

METHODS

Over a 3-year period, we sonographically evaluated patients who were referred for investigation of possible TRAS. We investigated the following parameters: peak systolic velocity (PSV) in the external iliac and renal arteries, acceleration time and acceleration in the intrarenal arteries, acceleration time in the renal artery, resistance index, and the ratio of the PSVs in the renal and external iliac arteries. We also used MR angiography and digital subtraction arteriography to verify the degree of stenosis. After the evaluations, the patients were classified into 2 groups, 1 with and the other without significant stenosis (> 50% narrowing of the lumen) on digital subtraction arteriography. We also included a control group of patients who had undergone renal transplantation at least 6 months before, had had a good course after transplantation, had a diastolic blood pressure of 90 mm Hg or less, and were taking a maximum of 1 antihypertensive drug.

RESULTS

Our study population consisted of 22 patients suspected to have TRAS (10 without and 12 with confirmed significant stenosis) and 19 control patients. We found statistically significant differences between the mean values of these 3 groups except for the PSV in the iliac artery and the resistance index in the intrarenal arteries. The most accurate parameters to use in diagnosing TRAS were an acceleration time of 0.1 second or higher in the renal and intrarenal arteries, a PSV of greater than 200 cm/second in the renal artery, and a ratio of PSVs in the renal and external iliac arteries of greater than 1.8.

CONCLUSIONS

Duplex Doppler sonography is an excellent method for screening patients suspected to have TRAS and can help select which of those patients should undergo digital subtraction arteriography.