Renal artery stenosis in kidney transplants

Renal Transplant Arterial Stenosis Treated With Bare-Metal Versus Drug-Eluting Stents: Comparison of Treatment Outcomes

INTRODUCTION

This study aims to evaluate outcomes of bare-metal stents (BMS) versus drug-eluting stents (DES) in patients who undergo stenting for transplant renal arterial stenosis.

MATERIALS AND METHODS

We retrospectively reviewed records of renal transplantation patients who underwent transplant renal arterial stenting from September 2009 to September 2013. All stents greater than 5 mm were excluded to allow for equivalent comparison between the DES and BMS groups. Statistical comparisons were performed using a two-tailed Fischer exact test, and analysis of continuous variables was analyzed using a one-way analysis of variance.

RESULTS

The final study population included a total of 18 patients who received either BMS or DES (11 and 7 patients, respectively) for transplant renal arterial stenosis. The most common indications for stenting were increasing creatinine level and abnormal Doppler velocities. There were more re-interventions with BMS (n = 4/11) than DES (n = 0/7), but the trend was not statistically significant (P = .12). Three patients who received BMS had a clinically significant decrease in blood pressure versus 4 in the DES group (P = .33). Six patients who received BMS had a clinically significant decrease in creatinine level versus 3 in the DES group (P = 1.0).

CONCLUSION

There is an absolute but not statistically significant difference in the incidence of restenosis requiring repeat intervention between the BMS and DES groups. No difference was detected in clinical success as measured by decreases in blood pressure or creatinine. Future larger studies are needed to corroborate these findings.

Revascularization of Kidney Allograft after Renal Artery Occlusion Secondary to Angioplasty

Arterial thrombosis causing complete occlusion is a rare event in the natural history of a transplanted allograft; an incidence of 1.4% has been reported. This condition usually results from technical problems, hyperacute rejection, severe atherosclerosis, or injury to donor or recipient arteries. The treatment of choice is transplant nephrectomy. We report a case of renal artery occlusion after a therapeutic radiological procedure and subsequent salvaging of the graft. The case report shows that an aggressive surgical approach toward restoring circulation is worth the effort.

Management of Hypertension in Solid-Organ Transplantation

Posttransplant hypertension is a major risk factor for cardiovascular disease and chronic renal allograft dysfunction. A significant number of transplant recipients suffer from posttransplant hypertension in part because of corticosteroid and calcineurin inhibitor use. Although the optimal blood pressure range and the antihypertensive agents of choice in the transplant population have not been determined, the guidelines for blood pressure control in the general population can be extrapolated to the transplant population. The choice of an antihypertensive regimen should be tailored on the basis of the individual patient's risk factors and comorbidities.

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.

Imaging Complications of Renal Transplantation

Renal transplant complications are categorized as those related to the transplant vasculature, collecting system, perinephric space, renal parenchyma, and miscellaneous complications including posttransplant lymphoproliferative disorder. Many of these renal transplant complications are diagnosed with imaging. Medical complications including rejection, acute tubular necrosis, and drug toxicity also can impair renal function. These medical complications are typically indistinguishable at imaging, and biopsy may be performed to establish a diagnosis. Normal transplant anatomy, imaging techniques, and the appearances of renal transplant complications at ultrasound, computed tomography, and MR imaging are reviewed.

Graft arterial stenosis in kidney en bloc grafts from very small pediatric donors: incidence, timing, and role of ultrasound in screening

In previous studies with different donor selection criteria and noncontemporary surgical techniques, graft arterial stenosis (GAS) has been reported to occur more frequently in adult recipients of pediatric en bloc renal allografts (EBKT) as compared to single adult donor allografts. The purpose of our study was to evaluate the incidence of GAS within our EBKT recipient population and to evaluate clinical and imaging features of those cases with GAS. In a retrospective cohort study, we analyzed 182 EBKT performed at a single institution. We identified cases of suspected GAS based on clinical factors, lab results, and noninvasive imaging. Diagnosis of GAS was confirmed by digital subtraction angiography. Two EBKT recipients (1.1% of 182) had angiographically confirmed GAS at 2.5 and 4.5 months after transplant. In both cases, the stenoses were short segment within the proximal (perianastomotic) donor aorta, color Doppler ultrasound demonstrated peak systolic velocities of >400 cm/s, and poststenotic parvus tardus waveforms were present. Both patients underwent angioplasty and demonstrated postintervention improvement in renal function and blood pressure. Restenosis did not occur during follow up. In conclusion, recipients of EBKT have a low incidence of GAS, similar to the lowest reported for adult single allografts.

Successful technical and clinical outcome using a second generation balloon expandable coronary stent for transplant renal artery stenosis: Our experience

Transplant renal artery stenosis (TRAS) is a vascular complication frequently seen because of increase in the number of renal transplantations. Early diagnosis and management is essential to optimize a proper graft function. Currently, the endovascular treatment of TRAS using angioplasty and/or stenting is considered the treatment of choice with the advantage that it does not preclude subsequent surgical correction. Treatment of TRAS with the use of stents, particularly in tortuous transplant renal anatomy presents a unique challenge to an interventional radiologist. In this study, we present three cases from our practice highlighting the use of a balloon-expandable Multi-Link RX Ultra coronary stent system (Abbott Laboratories, Abbott Park, Illinois, USA) for treating high grade focal stenosis along very tortuous renal arterial segments. Cobalt-Chromium alloy stent scaffold provides excellent radial force, whereas the flexible stent design conforms to the vessel course allowing for optimal stent alignment.

When is contrast-enhanced sonography preferable over conventional ultrasound combined with Doppler imaging in renal transplantation?

Conventional ultrasound in combination with colour Doppler imaging is still the standard diagnostic procedure for patients after renal transplantation. However, while conventional ultrasound in combination with Doppler imaging can diagnose renal artery stenosis and vein thrombosis, it is not possible to display subtle microvascular tissue perfusion, which is crucial for the evaluation of acute and chronic allograft dysfunctions. In contrast, real-time contrast-enhanced sonography (CES) uses gas-filled microbubbles not only to visualize but also to quantify renal blood flow and perfusion even in the small renal arterioles and capillaries. It is an easy to perform and non-invasive imaging technique that augments diagnostic capabilities in patients after renal transplantation. Specifically in the postoperative setting, CES has been shown to be superior to conventional ultrasound in combination with Doppler imaging in uncovering even subtle microvascular disturbances in the allograft perfusion. In addition, quantitative perfusion parameters derived from CES show predictive capability regarding long-term kidney function.

Successful endovascular treatment of transplant intrarenal artery stenosis in renal transplant recipients: Two case reports

Transplant renal artery stenosis (TRAS) is a relatively rare complication after renal transplantation. The site of the surgical anastomosis is most commonly involved, but sites both proximal and distal to the anastomosis may occur, as well. Angioplasty is the gold standard for the treatment of the stenosis, especially for intrarenal lesions. We report two cases of intrarenal TRAS and successful management with angioplasty without stent placement. Both patients were male, 44 and 55 years old respectively, and they presented with elevated blood pressure or serum creatinine within three months after transplantation. Subsequently, they have undergone angioplasty balloon dilatation with normalization of blood pressure and serum creatinine returning to baseline level. Percutaneous transluminal balloon renal angioplasty is a safe and effective method for the treatment of the intrarenal TRAS.

Femoro-femoral Bypass for Graft Salvage in a Renal Transplant Patient With Aorto-iliac Occlusion: A Case Report

As vascular diseases are becoming more prevalent among renal transplant recipients, complications related to renal artery anastomosis are likely to occur more often. Here we report a renal transplant patient treated with femoro-femoral bypass who had renal allograft dysfunction due to aorto-iliac occlusive disease (AIOD) proximal to renal artery anastomosis. We performed living donor renal transplantation in the left iliac fossa of a 41-year-old male. At post-transplant 30 months, he was admitted with hypertension, increase in serum creatinine, and claudication of his left leg. Doppler ultrasonography showed poor flow characteristics of the renal allograft. Total occlusion of the left common iliac artery was diagnosed on angiography. Since endovascular approach was unsuccessful, we performed right-to-left femoro-femoral bypass to provide retrograde blood flow to the renal allograft. The patient was discharged at postoperative day 3 with decreased serum creatinine, normal blood pressure, no claudication, and normal flow characteristics in Doppler ultrasonography. AIOD should be suspected in renal transplant patients in case of hypertension, allograft dysfunction, and ipsilateral leg ischemia. Femoro-femoral bypass is a safe surgical procedure that may be performed in patients who cannot be treated using an endovascular approach.

Comparing the diagnostic accuracy of contrast-enhanced computed tomographic angiography and gadolinium-enhanced magnetic resonance angiography for the assessment of hemodynamically significant transplant renal artery stenosis

To compare diagnostic accuracy of contrast-enhanced computed tomographic angiography (CTA) and gadolinium-enhanced magnetic resonance angiography (MRA) for the assessment of hemodynamically significant transplant renal artery stenosis (TRAS). After institutional review board approval, records of 27 patients with TRAS confirmed on digital subtraction angiography (DSA) were retrospectively reviewed. A total of 13 patients had MRA and 14 had CTA before DSA. Two board-certified fellowship-trained radiologists, one each from interventional radiology and body imaging blindly reviewed the DSA and CTA or MRA data, respectively. Sensitivity (SN), specificity (SP), positive predictive value, and negative predictive value of MRA and CTA were estimated using 50% stenosis as the detection threshold for significant TRAS. These parameters were compared between modalities using the Fisher exact test. Bias between MRA or CTA imaging and DSA was tested using the Wilcoxon signed-rank test. Two patients were excluded from the MRA group owing to susceptibility artifacts obscuring the TRAS. The correlation between MRA and DSA measurements of stenosis was r = 0.57 (95% CI:-0.02, 0.87; P = 0.052) and between CTA and DSA measurements was r = 0.63 (95% CI: 0.14, 0.87; P = 0.015); the difference between the 2 techniques was not significant (P = 0.7). Both imaging modalities tended to underestimate the degree of stenosis when compared with DSA. MRA group (SN and SP: 56% and 100%, respectively) and CTA group (SN and SP: 81% and 67%, respectively). There were no significant differences in detection performance between modalities (P>0.3 for all measures). We did not find that either modality had any advantage over the other in terms of measuring or detecting significant stenosis. Accordingly, MRA may be preferred over CTA after positive color Doppler ultrasound screening when not contraindicated owing to lack of ionizing radiation or nephrotoxic iodinated contrast. However, susceptibility of artifacts owing to surgical clips at the anastomosis may limit diagnostic utility of MRA as found in 2 of 13 patients. Trend towards no significant difference between the CTA and enhanced MRA in the detection of hemodynamically significant TRAS.

Hypertension, living kidney donors, and transplantation: where are we today?

Hypertension is a prevalent problem in kidney transplant recipients that is known to be a "traditional" risk factor for atherosclerotic cardiovascular disease leading to premature allograft failure and death. Donor, peritransplant, and recipient factors affect hypertension risk. Blood pressure control after transplantation is inversely associated with glomerular filtration rate (GFR). Calcineurin inhibitors, the most commonly used class of immunosuppressives, cause endothelial dysfunction, increase vascular tone, and sodium retention via the renin-angiotensin-aldosterone system resulting in systemic hypertension. Steroid withdrawal seems to have little impact on blood pressure control. Newer agents like belatacept appear to be associated with less hypertension. Transplant renal artery stenosis is an important, potentially treatable cause of hypertension. Dihydropyridine calcium channel blockers mitigate calcineurin inhibitor nephrotoxicity and may be associated with improved estimated GFR. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are not recommended in the first 3 to 6 months given their effects on reduced estimated GFR, anemia, and hyperkalemia. The use of ß-blockers may be associated with improved patient survival, even for patients without cardiovascular disease. Living donation may increase blood pressure by 5 mm Hg or more. Some transplant centers accept Caucasian living donors with well-controlled hypertension on a single agent if they agree to close follow-up.

Restoration of renal allograft function via reduced-contrast percutaneous revascularization of transplant renal artery stenosis

Transplant renal artery stenosis (TRAS), the most common vascular complication of kidney transplantation, can lead to heart failure, uncontrolled hypertension, and irreversible dysfunction of the transplanted kidney. Percutaneous revascularization can improve outcomes in well-selected patients with symptomatic TRAS, but the intervention itself poses risk to the transplanted kidney because of the quantities of nephrotoxic contrast solution that often are used. We report the case of a patient with TRAS who, 5 months after undergoing a kidney transplant, developed allograft dysfunction and heart failure that required hemodialysis. We performed angioplasty and stenting of the TRAS, using intravascular ultrasonography and fluoroscopy as our primary imaging methods. To minimize further damage to a potentially viable kidney, the volume of intravascular contrast medium used was trivial (a total of 9 cc). Revascularization of the patient's TRAS restored his renal function: within 4 weeks of the procedure, he no longer needed hemodialysis, and his heart failure symptoms had resolved. This case emphasizes the value of early definitive treatment of TRAS and the usefulness of intravascular ultrasonography to minimize the amount of contrast medium used in endovascular procedures.

Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy

Transplant renal artery stenosis (TRAS) is a well-recognized vascular complication after kidney transplant. It occurs most frequently in the first 6 months after kidney transplant, and is one of the major causes of graft loss and premature death in transplant recipients. Renal hypoperfusion occurring in TRAS results in activation of the renin–angiotensin–aldosterone system; patients usually present with worsening or refractory hypertension, fluid retention and often allograft dysfunction. Flash pulmonary edema can develop in patients with critical bilateral renal artery stenosis or renal artery stenosis in a solitary kidney, and this unique clinical entity has been named Pickering Syndrome. Prompt diagnosis and treatment of TRAS can prevent allograft damage and systemic sequelae. Duplex sonography is the most commonly used screening tool, whereas angiography provides the definitive diagnosis. Percutaneous transluminal angioplasty with stent placement can be performed during angiography if a lesion is identified, and it is generally the first-line therapy for TRAS. However, there is no randomized controlled trial examining the efficacy and safety of percutaneous transluminal angioplasty compared with medical therapy alone or surgical intervention.

Acute renal artery thrombosis after kidney transplantation

Early kidney transplant loss as a result of acute thrombosis of the renal artery remains a constant and devastating complication, with an incidence of 0.2-7.5%. While uncommon, arterial obstruction in the early postoperative period is a surgical emergency and must be ruled out if previously established diuresis ceases suddenly. Arterial thrombosis may occur as a result of injury to a diseased artery, problems with anastomoses, hypercoagulability or malpositioning of the allograft. In this study, we analyzed data on a group of 105 renal transplant recipients who presented with acute postoperative graft dysfunction between January 2006 and May 2012, to identify cases of acute renal artery thrombosis. We report on our experience of immediate re-transplantation following early kidney transplant thrombosis. Overall, two (1.9%) patients suffered early (within 48 hours of surgery) allograft renal artery thrombosis. In both patients, transplantation had not been complicated by atherosclerotic lesions or other thrombophilic states and postoperative diuresis had been successfully achieved, but diuresis ceased abruptly during the early postoperative period. Emergent duplex ultrasound scans were performed and acute renal artery thrombosis was detected in both patients. The patients were operated immediately and retransplantation procedures were conducted. We have reported our experience of immediate retransplantation following early primary graft dysfunction due to renal artery thrombosis. In conclusion, close monitoring of postoperative diuresis and, if necessary, immediate retransplantation in this situation can prove to be a successful treatment for preventing graft loss.

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.

Transplant renal artery stenosis in children: risk factors and outcome after endovascular treatment

BACKGROUND

Transplant renal artery stenosis (TRAS) is an increasingly recognised cause of post-transplant hypertension.

METHODS

We retrospectively analysed 216 paediatric renal recipients transplanted between 2001 and 2011 to assess TRAS prevalence and percutaneous transluminal angioplasty (PTA) efficacy. To assess risk factors, we compared children with TRAS with a propensity score-matched cohort of recipients without TRAS.

RESULTS

Of the 216 paediatric patients who were transplanted in the study period, 44 were hypertensive (prevalence 20.3 %) and ten presented with TRAS (prevalence 4.6 %, median age at transplantation 14 years, range 6.78-17.36 years). Hypertensive patients without TRAS were prescribed one to two anti-hypertensive agents, whereas patients with TRAS required one to five medications. In the TRAS group, one recipient presented with vascular complications during surgery, and in three patients the graft had vascular abnormalities. TRAS was detected by Doppler ultrasonography (US) performed due to hypertension in nine of the patients with TRAS, but in the tenth case the TRAS was clinically silent and detected by routine Doppler-US screening. TRAS diagnosis was refined using angio-computed tomography or angio-magnetic resonance imaging. All patients underwent PTA without complications. Significant improvement after PTA was observed in the standard deviation scores for blood pressure [3.2 ± 1.4 (pre-PTA) vs. 1.04 ± 0.8 (post-PTA); p = 0.0006) and graft function [creatinine clearance: 69 ± 17.08 (pre-PTA) vs. 80.7 ± 21.5 ml/min/1.73 m(2) (post-PTA); p = 0.006] We observed no significant differences between the two cohorts for cold ischaemia time, recipient/donor weight ratio, delayed graft function, cytomegalovirus infections and acute rejection episodes.

CONCLUSIONS

Our study reports a low but significant TRAS prevalence among the paediatric patients who were transplanted at our centre in the study period and confirms that PTA is an effective and safe therapeutic option in paediatric renal transplant recipients. Known risk factors do not appear to be related to the development of TRAS.

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.

Transplant renal artery stenosis secondary to mechanical compression from polycystic kidney disease: A case report

Transplant renal artery stenosis (TRAS) is a potentially treatable cause of allograft dysfunction, hypertension and graft loss. The mainstay of treatment includes angioplasty and endovascular stenting, although observation and surgery are at times indicated. We present an unusual case of TRAS secondary to mechanical compression from a patient's enlarged native polycystic kidneys. This was treated with bilateral native nephrectomy and evidence of TRAS improved both clinically and radiographically. Recognition and treatment are important in preventing irreversible complications of TRAS.

Clinical usefulness of 3-dimensional computerized tomographic renal angiography to detect transplant renal artery stenosis

OBJECTIVE

The aim of this study was to evaluate whether 3-dimensional computerized tomographic angiography (3D-CTA) is useful to detect transplant renal artery stenosis (TRAS).

METHODS

Fourteen patients with clinically suspected TRAS underwent color Doppler ultrasonography (CDU) and 3D-CTA before renal angiography. We compared 3D-CTA and CDU for accuracy based on the results of renal angiography. The safety of 3D-CTA was investigated by measuring the estimated glomerular filtration rate (eGFR) before and after the 3D-CTA examination.

RESULTS

The 10 men and 4 women who participated in this study showed a mean eGFR of 75 mL/min/1.73 m(2) (range 60-94). Of these, 9 patients were diagnosed with TRAS. 3D-CTA detected stenoses in all 9 patients, but CDU failed to detect it in 3, including, 2 with end-to-side arterial anastomoses, which may be more challenging to detect compared with end-to-end anastomoses. The stenotic area in 3D-CTA was similar to that detected by renal angiography (70 ± 12 vs 68 ± 11). The eGFR did not differ significantly before versus after the 3D-CTA examination; 72 ± 13 vs 69 ± 14 mL/min/1.73 m(2).

CONCLUSIONS

3D-CTA was an effective safe method to detect renal artery stenosis among transplant recipients with an eGFR >60 mL/min/1.73 m(2).

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Vascular and haemorrhagic complications of adult and paediatric live-donor renal transplantation: A single-centre study with a long-term follow-up

Objectives

To compare the haemorrhagic and vascular complications between paediatric and adult renal transplant recipients with a long-term follow-up.

Patients and methods

Between March 1976 and December 2006, in all, 1865 live-donor renal transplants were carried out. Patients were stratified according to their ages into two groups; paediatric (⩽18 years; 259) and adult (>18 years; 1606). Variables assessed included incidence, risk factors, management and sequelae of vascular and haemorrhagic complications. The effect of these complications on patient and graft survival was compared.

Results

Haemorrhage requiring active intervention (percutaneous drainage or surgical exploration) was reported in seven children (2.7%) and 29 adults (1.8%), while thrombotic or stenotic complications were recorded in two children (0.77%) and 19 adults (1.18%; P < 0.05). Female gender, delayed onset of diuresis and acute tubular necrosis were significant predictors of vascular complications on univariate analysis, but none remained significant on multivariate analysis. In adults, vascular complications had a significant negative effect on mean (SD) 10-year graft survival compared to patients with no complications, at 19.8 (7.63)% vs. 55.7 (1.66)% (P = 0.01). Children who developed vascular complications had a significantly higher 5- and 10-year graft survival rate than adults (P = 0.01).

Conclusion

The incidence of vascular complications is comparable in paediatric and adult transplants. Vascular complications had a significant negative influence on graft survival in adult recipients. Children who developed vascular complications appear to tolerate its effects and have a better graft survival than have adults.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Detection and treatment of transplant renal artery stenosis

Purpose:

To assess the effects of transplant renal artery stenosis (TRAS) on blood pressure, renal function, and graft survival. To assess the usefulness of Doppler in predicting the clinical significance of TRAS and also to identify the predictive factors in Doppler that correlated with clinical features of TRAS.

Materials and Methods:

A prospective study was done on consecutive renal allograft recipients at Christian Medical College, over a period of 66 months from January 2002. All recipients underwent Doppler ultrasound (DUS) evaluation on the fifth post-operative day. Subsequent evaluation was done if the patients had any clinical or biochemical suspicion of TRAS. Angiogram was done in case of a high index of suspicion of significant stenosis or before angioplasty and stenting. The clinical and radiological outcomes of the patients with symptomatic or asymptomatic TRAS were analyzed.

Results:

Five hundred and forty three consecutive renal allograft recipients were analyzed, of whom, 43 were found to have TRAS. Nine recipients (21%) were detected to have TRAS on first evaluation. All had a high peak systolic velocities (PSV) recorded while 25 of them had other associated features. Patients with only high PSV required no further intervention and were followed up. They had a pretransplant mean arterial pressure (MAP) of 107.83 mmHg (SD = 13.32), ranging from 90 to 133 mm Hg and a posttransplant MAP of 106.56 mmHg (SD =16.51), ranging from 83 to 150 mm Hg. Their mean nadir serum creatinine was 1.16 mg% (SD = 0.24), at detection was 1.6 mg% (SD = 1.84) and at 6 months follow-up was 1.26 mg% (SD=0.52). Of the remaining 25 patients with other associated Doppler abnormalities, 11 required further intervention in the form of re-exploration in 2, angioplasty in 3 and stenting in 6 patients. One patient in the group of patients intervened, expired in the immediate post-operative period due to overwhelming urosepsis and consumption coagulopathy. The mean creatinine clearance (Cockroft-Gault method) in this group of remaining 10 patients, before and after intervention was 44.75 ml/min (SD=17.85) and 68.96 ml/min (SD = 10.56), respectively, with a mean increase by 24.21 ml/min (P=0.000). The mean arterial pressure before and after intervention in this group were 132.80 mm Hg (SD = 13.22) and 102 mm Hg (SD = 10.55), with a decline in the MAP by 30.80 mmHg (P=0.017). The haemoglobin levels also increased from 11.72 (SD=2.13) to 12.48 gm% (SD = 1.75), with a mean increase by 0.76 gm% (P=0.05).

Conclusions:

Patients with isolated high PSV do not have a significant alteration of blood pressure or allograft function and required no intervention. Although high PSV with associated Doppler anomalies are more suggestive of significant TRAS, the decision regarding surgical intervention is largely based on clinical assessment.

[Vascular complications following renal transplantation: diagnostic evaluation]

Vascular complications after renal transplantation are the most frequent type of complication following urological complications. They may affect the function of the transplant. Early vascular complications include renal artery or vein thrombosis, lesions to the iliac vessels and cortical necrosis. Delayed complications mainly include renal artery stenosis, arteriovenous fistula, and rarely false aneurysm. Doppler sonography, sometimes with the use of intravenous contrast, is the imaging modality of choice in the acute setting or routine follow-up. MRI may be performed for additional morphological and functional evaluation while CT may provide additional evaluation of the arterial supply. Angiography is performed prior to endovascular treatment.

Hypertension after kidney transplant

Hypertension in kidney transplant recipients is a major "traditional" risk factor for atherosclerotic cardiovascular disease. Importantly, atherosclerotic cardiovascular disease is the leading cause of premature death and a major factor in death-censored graft failure in transplant recipients. The blood pressure achieved after transplant is related inversely to postoperative glomerular filtration rate (GFR), with many patients experiencing a significant improvement in blood pressure control with fewer medications within months of surgery. However, the benefits of improved GFR and fluid status may be affected by the immunosuppression regimen. Immunosuppressive agents affect hypertension through a variety of mechanisms, including catechol- and endothelin-induced vasoconstriction, abrogation of nitric oxide-induced vasodilatation, and sodium retention. Most notable is the role of calcineurin inhibitors in promoting hypertension, cyclosporine more so than tacrolimus. Additionally, the combination of calcineurin- and mammalian target of rapamycin (mTOR)-inhibitor therapy is synergistically nephrotoxic and promotes hypertension, whereas steroid withdrawal and minimization strategies seem to have little or no impact on hypertension. Other important causes of hypertension after transplant, beyond a progressive decrease in GFR, include transplant renal artery stenosis and sequelae of antibody-mediated rejection. Calcium channel blockers may be the most useful medication for mitigating calcineurin inhibitor-induced vasoconstriction, and use of such agents may be associated with improvements in GFR. Use of inhibitors of the renin-angiotensin system, such as angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, remains an attractive strategy for many transplant recipients, although some recipients may have significant adverse effects associated with these medications, including decreased GFR, hyperkalemia, and anemia. In conclusion, hypertension control affects both patient and long-term transplant survival, and its best management requires careful analysis of causes and close monitoring of therapies.

Hypertension following kidney transplantation

The majority of patients become hypertensive following kidney transplantation. Its occurrence is associated not only with increased fatal and nonfatal cardiovascular events but also with decreased allograft survival. This review summarizes the current knowledge of the epidemiology, etiology, pathophysiology, and management of post-transplant hypertension.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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