Renal artery stent placement: long-term results with the Wallstent endoprosthesis

Percutaneous renal artery revascularization after prolonged ischemia secondary to blunt trauma: pooled cohort analysis

PURPOSE

We aimed to identify factors related to technical and clinical success of percutaneous revascularization for blunt renal arterial trauma.

METHODS

All cases of percutaneous revascularization for blunt renal arterial trauma were searched in the available literature. We included a case of iatrogenic renal artery occlusion at our institution treated by percutaneous stenting 20 hours after injury. A pooled cohort analysis of percutaneous revascularization for blunt renal artery injury was then performed to analyze factors related to technical and clinical success. Clinical failure was defined as development of new hypertension, serum creatinine rise, or significant asymmetry in split renal function.

RESULTS

A total of 53 cases have been reported, and 54 cases were analyzed including our case. Median follow-up was 6 months. Technical success was 88.9% and clinical success was 75%. Of 12 treatment failures (25%), 66.7% occurred during the first postprocedure month. Time from injury to revascularization was not a predictor of clinical success (OR=1.00, P = 0.681). Renal artery occlusion was significantly associated with clinical failure (OR=7.50, P = 0.017) and postintervention antiplatelet therapy was significantly associated with treatment success (OR=0.16, P = 0.043). At 37-month follow-up, the stented renal artery in our case remained patent and the patient was normotensive with preserved glomerular filtration rate.

CONCLUSION

Percutaneous revascularization for blunt renal arterial injury resulted in relatively high technical and clinical success. Time-to-revascularization was independent of successful outcomes. Clinical success was significantly associated with a patent renal artery at the time of intervention and with postprocedure antiplatelet therapy.

Hemodynamic Measurements for the Selection of Patients With Renal Artery Stenosis: A Systematic Review

Interventions targeting renal artery stenoses have been shown to lower blood pressure and preserve renal function. In recent studies, the efficacy of catheter-based percutaneous transluminal renal angioplasty with stent placement has been called into question. In the identification of functional coronary lesions, hyperemic measurements have earned a place in daily practice for clinical decision making, allowing discrimination between solitary coronary lesions and diffuse microvascular disease. Next to differences in clinical characteristics, the selection of renal arteries suitable for intervention is currently on the basis of anatomic grading of the stenosis by angiography rather than functional assessment under hyperemia. It is conceivable that, like the coronary circulation, functional measurements may better predict therapeutic efficacy of percutaneous transluminal renal angioplasty with stent placement. In this systematic review, the authors evaluate the available clinical evidence on the optimal hyperemic agents to induce intrarenal hyperemia, their association with anatomic grading, and their predictive value for treatment effects. In addition, the potential value of combined pressure and flow measurements to discriminate macrovascular from microvascular disease is discussed.

Stenting of the Renal Artery to Improve Renal Function Prior to Thoracoabdominal Aneurysm Repair

Purpose:

To report the successful staged treatment of a patient with a thoracoabdominal aortic aneurysm (TAA), who presented with renal insufficiency attributable to renal artery stenosis.

Methods and Results:

A 66-year-old woman with a 6-cm Crawford type IV TAA presented with uncontrolled hypertension (240/130 mmHg), worsening congestive heart failure, and progressive renal insufficiency (serum creatinine 3.8 mg/dL) caused by renal artery stenosis to a solitary functioning kidney. Renal artery stenting restored normal renal and pulmonary function, and elective TAA repair 6 weeks after percutaneous stenting was uneventful. Restenosis (50% diameter reduction) in the renal artery was found 10 months later and treated with repeat dilation. Secondary patency was maintained at follow-up 21 months after redilation.

Conclusions:

It appears feasible to use preliminary renal artery stenting to reduce operative risk in TAA surgical candidates with renal insufficiency secondary to renal artery stenosis.

Successful Wallstent Implantation for Extensive Iatrogenic Renal Artery Dissection in a Patient with Fibromuscular Dysplasia

Purpose:

To describe a case of renal artery stenosis with fibromuscular dysplasia (FMD) and extensive iatrogenic dissection treated with Wallstent implantation.

Methods and Results:

An 83-year-old woman with a history of coronary artery disease and hypertension presented at another facility with exertional angina and poorly controlled hypertension. Renal arteriography uncovered a critical right renal artery stenosis with severe FMD. However, angioplasty resulted in extensive dissection of the renal artery, for which the patient was referred to our institution. The renal artery was recanalized via the left brachial approach with restoration of flow using a Wallstent and a Palmaz stent. The patient's blood pressure was controllable after this procedure, and follow-up duplex imaging with flow velocities at 6 months showed patent right renal artery stents.

Conclusions:

Owing to its length and flexibility, the Wallstent endoprosthesis was a useful treatment modality in this case of extensive renal artery dissection.

Stents in the Treatment of Renal Artery Stenosis: Long-Term Follow-up

Purpose:

To evaluate the role of percutaneous stenting in the treatment of renal arterial lesions after failure of balloon angioplasty.

Methods:

Two hundred ten patients (139 males; mean age 67.7 ± 9.9 years, range 27 to 87) had 259 balloon-expandable stents (165 Palmaz and 94 Renal Bridge stents) implanted in 244 renal artery stenoses (171 ostial and 73 nonostial lesions). The patients were suffering from intractable hypertension (n = 210) and/or renal dysfunction (n = 48). The majority of the lesions (n = 234) were atheromatous in origin. Stents were implanted for suboptimal balloon dilation (n = 182, 75%), restenotic lesions (n = 27, 11%), or dissection (n = 9, 4%); 26 (11%) ostial lesions were stented primarily. Mean lesion length was 11.9 ± 4.4 mm (range 5 to 30) and mean percent stenosis was 81.9% ± 8.25% (range 70 to 100).

Results:

Immediate technical success was 99% (241 of 244). Three (1.2%) major complications included one intraprocedural stent thrombosis, one arterial perforation manifesting as a perirenal hematoma 24 hours after the procedure, and one renal arterial rupture. Follow-up over a mean 25.4 ± 22.8 months (range 1 to 96) in 185 eligible patients (209 arteries) found 24 cases of restenosis (11.4%). Primary and secondary patencies for all lesions at 60 months were 79% and 98%, respectively, with no significant differences between ostial and nonostial lesions or stent types. Hypertension was reversed in 35 (19%), improved in 112 (61%), and remained unchanged in 37 (20%). Renal function was improved in 29% (14 of 48), unchanged in 67% (32 of 48), and worse in 4% (2 of 48).

Conclusions:

Renal artery stenting is safe, effective, and may be an alternative to surgery, particularly in ostial lesions. Our experience shows reduction in the restenosis rate compared to conventional angioplasty. All ostial stenoses should be stented.

Biocompatible slippery fluid-infused films composed of chitosan and alginate via layer-by-layer self-assembly and their antithrombogenicity

Antifouling super-repellent surfaces inspired by Nepenthes, the pitcher plant, were designed and named slippery liquid-infused porous surfaces (SLIPS). These surfaces repel various simple and complex liquids including water and blood by maintaining a low sliding angle. Previous studies have reported the development of fluorinated SLIPS that are not biocompatible. Here, we fabricated fluid-infused films composed of biodegradable materials and a biocompatible lubricant liquid. The film was constructed using a combination of electrostatic interactions between chitosan and alginate and hydrogen-bonding between alginate and polyvinylpyrrolidone (PVPON) via the layer-by-layer self-assembly method. After chitosan and alginate were cross-linked, the PVPON was removed by increasing the pH to generate porosity from the deconstruction of the hydrogen-bonding. The porous underlayer was hydrophobized and covered by biocompatible almond oil. Blood easily flowed over this biodegradable and biocompatible SLIPS without leaving stains on the surface, and the material is environmentally durable, has a high transmittance of about 90%, and is antithrombogenic. The results of this study suggest that this SLIPS may facilitate the creation of nonfouling medical devices through a low-cost, eco-friendly, and simple process.

Renal artery stenosis: prevalence of, risk factors for, and management of in-stent stenosis

Atherosclerotic renal artery stenosis is common and is associated with hypertension and chronic kidney disease. More frequent use of percutaneous renal artery stent placement for the treatment of renal artery stenosis during the past 2 decades has increased the number of patients with implanted stents. In-stent stenosis is a serious problem, occurring more frequently than earlier reports suggest and potentially resulting in late complications. Currently, there are no guidelines covering the approach to restenosis after renal artery stent placement. This article reviews data on the prevalence of and risk factors for the development of in-stent stenosis and the clinical manifestations, evaluation, and treatment of in-stent stenosis and suggests a strategy for the management of patients after percutaneous renal artery stent placement.

Renal parenchymal preservation after percutaneous renal angioplasty and stenting

BACKGROUND

The intent of endovascular therapy for symptomatic atherosclerotic renal artery stenosis (ARAS) is to preserve parenchyma and avoid renal-related morbidity. The aim of this study is to examine the impact of renal artery intervention on parenchymal preservation.

METHODS

We performed a retrospective analysis of records from patients who underwent endovascular intervention for ARAS and were followed by duplex ultrasound between 1990 and 2008. Renal volume (in cm(3)) was estimated in all patients as renal length (cm) x renal width (cm) x renal depth (cm) x 0.5. The normal renal volume was calculated as 2 x body weight (kg) in cm(3). Failure of preservation was considered to be a persistent 10% decrease in volume. Clinical benefit defined as freedom from renal-related morbidity (increase in persistent creatinine >20% of baseline, progression to hemodialysis, death from renal-related causes) was calculated.

RESULTS

Five hundred ninety-two renal artery interventions were performed. One hundred eighty-six kidneys suffered parenchymal loss (>5%) with an actuarial parenchymal loss rate of 29% +/- 1% at five years respectively. There were no significant differences in age, gender, starting renal volume, or kidney size. However, patients with parenchymal loss had lower eGFR (45 +/- 24 vs 53 +/- 24 mL/min/1.73 m(2); Loss vs noLoss, P = .0002, Mean +/- SD) higher resistive index (0.75 +/- 0.9 vs 0.73 +/- 0.10; P = .0001) and worse nephrosclerosis grade (1.43 +/- 0.55 vs 1.30 +/- 0.49; P = .006) then those not suffering parenchymal loss. Parenchymal loss was associated with significantly worse five-year survival (26% +/- 4% vs 48% +/- 2%; Loss vs noLoss; P < .001) and freedom from renal-related morbidity (70% +/- 5% vs 82% +/- 2%; P < .05) with increased numbers progressing to dialysis (17% vs 7%; P < .006).

CONCLUSION

While parenchymal preservation occurs in most patients, parenchymal loss occurs in 31% of patients and is associated with markers of impaired parenchymal perfusion (resistive index and nephrosclerosis grade) at the time of intervention. Pre-existing renal size or volumes were not predictive of parenchymal loss. Parenchymal loss is associated with a significant decrease in survival and a marked increased renal related morbidity and progression to hemodialysis.

Renal artery revascularization: collaborative approaches for specialists

Endovascular revascularization for atherosclerotic renal artery stenosis (RAS) is the revascularization strategy of choice for patients with hemodynamically and clinically significant renal artery stenosis. Surgical revascularization is reserved for failed endovascular therapy or concomitant abdominal aortic surgery. Endovascular renal artery stenting is associated with excellent technical success, low complication rates, and acceptable long-term patency. This technique has been proven to be beneficial for preserving kidney function and stabilizing or improving blood pressure control in selected patients. Nevertheless, deterioration in kidney function after the procedure in 10% to 20% of cases may limit the immediate benefits of this technique. Atheroembolism appears to play an important role in the cause of kidney dysfunction after renal revascularization. Renal revascularization with a distal embolic protection device is a promising strategy in reducing the risk of atheroembolism and deterioration in kidney function.

Management of atherosclerotic renovascular disease: the effect of renal artery stenting on renal function and blood pressure

In the last few years, renal artery stenting has gradually evolved into one of the most important therapeutic modalities in the management of atherosclerotic renovascular disease. Stenting is nowadays preferred by a steadily increasing number of physicians, not only because of its significant contribution to blood pressure control, but also because of its documented ability to maintain, and even improve, renal function. At the same time, procedure-related morbidity and mortality rates are extremely low, while recurrent stenosis rates have been repeatedly reported to be minimal. Percutaneous transluminal renal angioplasty (PTRA) and stenting are nowadays considered by many physicians to be the treatment of choice for atherosclerotic renovascular disease.

A clinical survey of vascular stents

As a result of the many different potential locations to be treated, it is still difficult to evaluate the indications for efficacy and safety of non-coronary percutaneous transluminal angioplasty (PTA) and stenting versus surgical methods, such as endarterectomy or bypass grafts. This paper reviews pertinent data published in the last 5-10 years and gives an overview of the main peripheral minimally invasive vascular interventional fields.

Restenosis after stenting of atherosclerotic renal artery stenosis: Is there a rationale for the use of drug-eluting stents?

Percutaneous stent-angioplasty has become an accepted therapy for the treatment of atherosclerotic renal artery stenosis (RAS) because of higher acute and long-term success rates compared with balloon angioplasty alone. Restenosis rates after successful renal stent placement vary from 6 to 20% and depend mainly on the definition of restenosis and the vessel diameter of the renal artery or stent. We recommend that restenosis should be defined as >70%. The safety and efficacy of drug-eluting stents for the treatment of RAS is poorly defined. The currently partially published GREAT study (Palmaz Genesis peripheral stainless steel balloon expandable stent: comparing a sirolimus-coated vs. a bare stent in REnal Artery Treatment) examined the effect of a sirolimus-coated stent on restenosis rate in 102 patients and found a relative risk reduction of angiographic binary in-stent restenosis by 50% (7% versus 14%, P = ns). Given the lack of outcome data, the considerable expenses associated with drug-eluting stents, morbidity, and cost associated with prolonged dual antithrombotic therapy, the use of drug-eluting stents in RAS should be restricted to clinical trials. This is a review on restenosis rate following renal stenting, its definition, and the potential use for implantation of a drug-eluting stent in RAS, which so far for this indication is not yet commercially available.

Renal artery stenting in solitary functioning kidneys: Technical and clinical results

OBJECTIVE

To evaluate the clinical and technical results of renal artery stenting for the treatment of renovascular hypertension and renal failure in patients with solitary functioning kidney.

MATERIALS AND METHODS

Fifteen patients with solitary functioning kidney underwent renal artery stenting and were followed up for 12-60 months. Before the procedures, systolic and diastolic blood pressures and serum creatinine levels were measured and the number of antihypertensive drugs was recorded and followed up after stenting. In case of restenosis, either in-stent percutaneous transluminal renal angioplasty or stent-in-stent placement was performed.

RESULTS

Primary technical success rate was 100%. One lesion was nonostial while 14 were ostial. Primary patency rates were 100% for 6 months, 92.3% for 12 months, and 69.2% for 24 months. The secondary patency rate at 24 months was 100%. The differences between the baseline and postprocedural values of systolic blood pressures, diastolic blood pressures and the number of antihypertensive drug were statistically significant (P < 0.05), except the values of serum creatinine. Hypertension was cured in 1 (6.7%) patient, improved in 4 (26.6%) and stabilized in 10 (66.7%) patients. Renal function improved in 9 (60%), stabilized in 4 (26.6%), and deteriorated in 2 (13.4%) patients. Minor complication rate was 13.4% and major complication rate was 13.4%.

CONCLUSION

Revascularization of renal artery stenosis using stent in solitary functioning kidneys is a safe and efficient procedure with high primary technical results, low restenosis rates and acceptable complication rates. It has an improving and controlling effect on blood pressure and renal functions.

Quand, comment et pourquoi réaliser une exploration des artères rénales ?

The objectives of this course are both: to describe acquisition, injection and reconstruction parameters of volumic images for renal arteries examination and specific signs; to discuss the role of the different images in the diagnosis and in the therapeutic management. Ultrasound is one of the best imaging for the analysis of renal arteries in the detection of stenosis even if the sensitivity is less (around 85%)compared to CT Angiography (95%) and MR Angiography (90%). Because of this advantage and of 3D evaluation, CTA and MRA are sometimes in the first line for renal artery evaluation and can assess morphology before angioplasty. Renal scintigraphy with Captopril test and renin dosage are only used for small kidney evaluation. Arteriogram is systematically followed by angioplasty if possible. With the new endovascular materials, complications decrease (less than 5% with a major reduction in cholesterol emboli) and indications of endoprosthesis increase (71% of stenting with half of it in direct stenting technique). This course will give practical tools for imaging acquisition, specifically 3D imaging, for indications and management of lesion in accordance to symptoms and morphology.

Guidelines for the Reporting of Renal Artery Revascularization in Clinical Trials

Although the treatment of atherosclerotic renal artery stenosis with use of percutaneous angioplasty, stent placement, and surgical revascularization has gained widespread use, there exist few prospective randomized controlled trials (RCTs) comparing these techniques to each other or against the standard of medical management alone. To facilitate this process as well as help answer many important questions regarding the appropriate application of renal revascularization, well-designed and rigorously conducted trials are needed. These trials must have clearly defined goals and must be sufficiently sized and performed so as to withstand intensive outcomes assessment. Toward this end, this document provides guidelines and definitions for the design, conduct, evaluation, and reporting of renal artery revascularization RCTs. In addition, areas of critically necessary renal artery revascularization investigation are identified. It is hoped that this information will be valuable to the investigator wishing to conduct research in this important area.

The diagnosis and management of renovascular disease: a primary care perspective. Part II. Issues in management

Renovascular disease is a complex disorder, most commonly caused by fibromuscular dysplasia and atherosclerotic disease. It usually presents in one of three forms: asymptomatic renal artery stenosis, renovascular hypertension, or ischemic nephropathy. This complexity may make diagnostic and management decisions difficult for the primary care physician. In Part I of this review (presented in the May/June 2003 issue of The JCH), the authors discussed when to consider and how to go about making a diagnosis of renovascular disease. In Part II, the authors review the management of this complex condition. There is a debate concerning the optimal treatment of patients with renovascular disease. Management options include medical, surgical, or percutaneous approaches (angioplasty and stenting). Generally in patients with fibromuscular disease, the results of surgery and percutaneous approaches appear superior. In patients with atherosclerotic disease, the data are less consistent, and there does appear to be a group of patients who will respond well to medical management. A potential management algorithm is presented.

Evaluation of the patients with renovascular hypertension after percutaneous revascularization by Doppler ultrasonography

OBJECTIVE

Evaluation of the effectiveness of percutaneous revascularization is based primarily on clinical criteria, and laboratory findings rather than direct investigation of luminal width. The purpose of this study was to evaluate the success of endovascular revascularization with serial Doppler ultrasound (US) examinations.

METHODS AND MATERIAL

19 patients (14 were atherosclerotic, five were with fibromuscular dysplasia) with suspected renovascular hypertension treated by percutaneous revascularization were included in a prospective study. Patients had 23 renal artery stenoses reducing the diameter by more than 50%. Doppler US examinations were performed before intervention, and 1 day, 3 and 6 months after intervention.

RESULTS

Initial revascularization was technically successful in 21 of 23 stenoses (91.3%) (18 PTRA, three stent placement). Hypertension was cured in five atherosclerotic and in five fibromuscular dysplasia (FMD) patients, and improved in four atherosclerotic patients. Residual stenosis was determined in six patients and the others were evaluated as normal by initial postprocedure Doppler US. As based on Doppler US, restenosis (>60%-narrowing) was depicted in four of six (66.6%) renal arteries with residual stenosis, and one of 15 (6.6%) normal renal arteries at 1 year. This difference in restenosis rates (residual stenosis vs. normal) was significant (P<0.05).

CONCLUSION

Positive predictor for recurrence was a residual renal artery stenosis documented by Doppler US 1 day after percutaneous revascularization in atherosclerotic cases.

Repeated intervention for in-stent restenosis of the renal arteries

PURPOSE

To assess the long-term technical success of repeated endovascular intervention in stenosed renal artery stents.

MATERIALS AND METHODS

Fifteen patients with stenoses >or=50% in a renal stent placed because of an ostial atherosclerotic renal artery stenosis were included in this study. In the presence of increased blood pressure or decreased renal function, the in-stent restenosis was treated with percutaneous transluminal angioplasty (PTA) in the stent or placement of a second stent if the stenosis was located too distally in the stent. The results of these repeat interventions were evaluated by angiography.

RESULTS

The 15 patients had a total of 20 stenosed stents. Eighteen of these in-stent stenoses were treated with PTA and two were treated with placement of a second stent. Angiographic follow-up was available in 16 arteries, showing in-stent restenosis in four (25%; mean follow-up, 11 mo). The cumulative patency rates after repeat endoluminal intervention were 93% (95% CI: 80%-106%) and 76% (95% CI: 52%-101%) after 6 and 12 months, respectively. Renal function remained stable or improved in most patients (80%) after repeated intervention in the stent, and hypertension was classified as improved or cured in 47% of patients after 1 year.

CONCLUSION

Patients with stenosed renal artery stents can be treated successfully with PTA in a majority of cases, with a long-term success rate of 75% and stable renal function 1 year after repeated intervention.

Chronic renal ischemia: implications for cardiovascular disease risk

Chronic renal ischemia caused by atherosclerotic renal artery stenosis (RAS) is gaining recognition as a potentially important risk factor for cardiovascular (CV) morbidity and mortality. The etiology of increased risk of CV events is multifaceted and includes direct physiologic changes that increase risk as well as intermediate clinical effects that are associated with worse outcome. Physiologic changes associated with increased CV risk in patients with RAS include increased production of fibrogenic and vasoactive peptides such as renin, angiotensin, endothelin, and catecholamines, as well as endothelial cell dysfunction. Clinical intermediate conditions associated with higher incidences of CV events seen in patients with renal ischemia include hypertension, systemic atherosclerosis, chronic renal failure, and left ventricular hypertrophy and dysfunction. More thorough understanding of the myriad physiologic changes seen in patients with RAS will likely improve patient selection for renal artery revascularization. Clinical trials should examine a full range of CV and renal outcomes, not just blood pressure, to adequately assess the merits of revascularization.

Guidelines for the reporting of renal artery revascularization in clinical trials

Although the treatment of atherosclerotic renal artery stenosis with use of percutaneous angioplasty, stent placement, and surgical revascularization has gained widespread use, there exist few prospective randomized controlled trials (RCTs) comparing these techniques to each other or against the standard of medical management alone. To facilitate this process as well as help answer many important questions regarding the appropriate application of renal revascularization, well-designed and rigorously conducted trials are needed. These trials must have clearly defined goals and must be sufficiently sized and performed so as to withstand intensive outcomes assessment. Toward this end, this document provides guidelines and definitions for the design, conduct, evaluation, and reporting of renal artery revascularization RCTs. In addition, areas of critically necessary renal artery revascularization investigation are identified. It is hoped that this information will be valuable to the investigator wishing to conduct research in this important area.

3D MR angiography of renal arteries: comparison of volume rendering and maximum intensity projection algorithms

PURPOSE

To compare volume rendering (VR) and maximum intensity projection (MIP) as postprocessing techniques of magnetic resonance (MR) angiography for detection and quantification of renal artery stenosis.

MATERIALS AND METHODS

Twenty-seven patients underwent three-dimensional contrast material-enhanced MR angiography of the renal arteries with a 1.5-T imager. For each renal artery, targeted MIP and VR images were reconstructed in oblique coronal and transverse orientations. For each modality, image generation and evaluation were performed interactively by two independent radiologists blinded to angiographic results. In comparison with digital subtraction angiography (DSA) findings, stenosis quantification and detection by using MIP and VR were evaluated with the use of 50% and 70% cutoff points by using linear regression analysis and 2 x 2 tables. Overall image quality and vascular delineation on MIP and VR images were also compared.

RESULTS

All main and accessory renal arteries depicted at DSA were also demonstrated on MIP and VR images. VR performed slightly better than MIP for quantification of stenoses greater than 50% (VR: r(2) = 0.84, P <.001; MIP: r(2) = 0.38, P =.001) and significantly better for severe stenoses (VR: r(2) = 0.83, P <.001; MIP: r(2) = 0.21, P =.1). For detection of stenosis, VR yielded a substantial improvement in positive predictive value (VR: 95% and 90%; MIP: 86% and 68% for stenoses greater than 50% and 70%, respectively). Image quality obtained with VR was not significantly better than that with MIP; however, vascular delineation on VR images was significantly better.

CONCLUSION

The VR technique of renal MR angiography enabled more accurate detection and quantification of renal artery stenosis than did MIP, with significantly improved vascular delineation.

Renal artery stenting for renal insufficiency in solitary kidney in 26 patients

OBJECTIVE

to present our experience with stent placement in renal arteries in solitary kidneys for treating renal insufficiency.

DESIGN

retrospective analysis.

MATERIALS

in 26 patients with solitary kidney (17 men, 9 women, mean age: 63 years), presented with renal insufficiency (se-creat >0.144 mmol/l), stent was placed in a stenosed renal artery. We analysed the clinical outcome, based on the level of creatinine at 3 months following the procedure. Clinical benefit was considered when there was a decrease compared to the baseline creatinine by >20% or a stabilisation of the creatinine value (+/-20% of the baseline).

RESULTS

in 16 of the 26 patients (62%), clinical benefit was achieved. However, 38% of the study population, renal function continued to deteriorate. Baseline creatinine value was the single best predictor for clinical benefit achievement (odds ratio: 13; 95% confidence intervals: 1.6-107, p=0.01).

CONCLUSION

renal stenting results in improvement or stabilisation of renal function in the majority of the patients with solitary kidneys and renal artery stenosis, presenting with renal insufficiency. Because best outcome was observed mainly in those patients with not progressed renal insufficiency, intervention should be focused on that group.

Renal artery stenosis: duplex US after angioplasty and stent placement

PURPOSE

To evaluate the hemodynamic outcome of technically successful percutaneous transluminal renal artery angioplasty and stent placement (PTRAS) with duplex ultrasonography (US).

MATERIALS AND METHODS

Eighteen patients who underwent PTRAS in 22 renal arteries were prospectively examined. All had abnormal preprocedural duplex US findings. Those who had significant renal artery stenosis (>70%) at angiography and underwent technically successful percutaneous interventions were enrolled. Standard intrarenal duplex US parameters (acceleration index [AI], acceleration time, waveform morphology grade, and resistive index) were compared before and after interventions.

RESULTS

A significant AI increase occurred after PTRAS (9.02 m/sec(2) +/- 4.85 [SD]), as compared with before intervention (2.34 m/sec(2) +/- 2.03; P <.001). Acceleration time significantly decreased from 0.084 second +/- 0.049 to 0.032 second +/- 0.008 (P <.01). There was also a significant resistive index increase from 0.69 +/- 0.12 to 0.79 +/- 0.12 (P <.01). Abnormal waveform morphology (modified Halpern waveform grade 3-6) was present in 19 (86%) of 22 intrarenal arteries prior to intervention, as compared with one (5%) after PTRAS (P <.001). In the instance in which an abnormal waveform persisted after intervention, waveform morphology improved from grade 6 to grade 3, with a concomitant AI increase from 0.96 to 5.1 m/sec(2).

CONCLUSION

The findings suggest an important potential role for duplex US in noninvasive assessment of the immediate hemodynamic outcome and long-term follow-up of PTRAS.

Long-term effects of arterial stenting on kidney function for patients with ostial atherosclerotic renal artery stenosis and renal insufficiency

It is uncertain whether renal artery stent placement in patients with atherosclerotic renovascular renal failure can prevent further deterioration of renal function. Therefore, the effects of renal artery stent placement, followed by patency surveillance, were prospectively studied in 63 patients with ostial atherosclerotic renal artery stenosis and renal dysfunction (i.e., serum creatinine concentrations of >120 micromol/L (median serum creatinine concentration, 171 micromol/L; serum creatinine concentration range, 121 to 650 micromol/L). Pre-stent renal (dys) function was stable for 28 patients and declining for 35 patients (defined as a serum creatinine concentration increase of > or =20% in 12 mo). The median follow-up period was 23 mo (interquartile range, 13 to 29 mo). Angioplasty to treat restenosis was performed in 12 cases. Five patients reached end-stage renal failure within 6 mo, and this was related to stent placement in two cases. Two other patients died or were lost to follow-up monitoring within 6 mo, with stable renal function. For the remaining 56 patients, the treatment had no effect on serum creatinine levels if function had previously been stable; if function had been declining, median serum creatinine concentrations improved in the first 1 yr [from 182 micromol/L (135 to 270 micromol/L ) to 154 micromol/L (127 to 225 micromol/L ); P < 0.05] and remained stable during further follow-up monitoring. In conclusion, stent placement, followed by patency surveillance, to treat ostial atherosclerotic renal artery stenosis can stabilize declining renal function. For patients with stable renal dysfunction, the usefulness is less clear. The possible advantages must be weighed against the risk of renal failure advancement with stent placement.

Endovascular revascularization of renal artery stenosis: technical and clinical results

PURPOSE

The natural history of renal artery stenosis is progression with subsequent deterioration of kidney function and development of renovascular hypertension. Percutaneous transluminal renal angioplasty is effective in the treatment of nonostial lesions but less effective for ostial stenoses. Because of the poor technical success experienced with percutaneous transluminal renal angioplasty, stenting of ostial stenoses is becoming the standard of endovascular care. In this retrospective study we analyzed the technical and clinical outcomes after renal artery stenting in 73 consecutive patients.

PATIENTS AND METHODS

From July 1992 to January 1999, 88 Palmaz stents were deployed in 85 renal artery stenoses in 73 patients, with a mean age of 67.9 +/- 9.4 years. Twelve patients (16%) underwent bilateral stent placement. Atheromatous lesions were the most prevalent (99%: 82% ostial, 16% nonostial). Most stents were implanted for suboptimal balloon dilation (52%) or dissection (24%). Mean percent stenosis was 86% +/- 12%. Renal insufficiency (creatinine level > or = 1.5 mg/dL) was present in 50 (68%) patients, and uncontrolled hypertension (systolic > or = 160 mm Hg or diastolic > or = 90 mm Hg with more than two medications) was present in 57 (78%).

RESULTS

Primary technical success was achieved in 89%. At the initial procedure, three additional stents were placed for residual stenoses, and urokinase was used to treat one intraprocedural stent thrombosis, resulting in an assisted primary technical success rate of 94%. Major complications occurred in 9.1% of stents placed: access artery thrombosis (n = 4), renal artery extravasation (n = 1), renal artery thrombosis (n = 1), and hematoma requiring operation (n = 2). Long-term clinical data were available on 69 (95%) patients at 20 +/- 17 months. Overall, a significant decrease in systolic and diastolic pressures (P <.001) and reduction of medication (P <.01) were noted without a change in renal function (P = NS). Angiography was performed on 22 patients at 11.3 +/- 10.3 months for persistent or worsening renal function or hypertension or for other reasons; 10 patients had significant restenoses in 14 renal arteries.

CONCLUSION

Our retrospective analysis demonstrates that endovascular stenting of renal artery stenosis in patients with poorly controlled hypertension or deteriorating renal function is a safe and effective alternative treatment to surgical management.

Stent placement for renal arterial stenosis: where do we stand? A meta-analysis

PURPOSE

To perform a meta-analysis of renal arterial stent placement in comparison with renal percutaneous transluminal angioplasty (PTA) in patients with renal arterial stenosis.

MATERIALS AND METHODS

Studies dealing with renal arterial stent placement (14 articles; 678 patients) and renal PTA (10 articles; 644 patients) published up to August 1998 were selected. A random-effects model was used to pool the data.

RESULTS

Renal arterial stent placement proved highly successful, with an initial adequate performance in 98% and major complications in 11%. The overall cure rate for hypertension was 20%, whereas hypertension was improved in 49%. Renal function improved in 30% and stabilized in 38% of patients. The restenosis rate at follow-up of 6-29 months was 17%. Stent placement had a higher technical success rate and a lower restenosis rate than did renal PTA (98% vs 77% and 17% vs 26%, respectively; P <.001). The complication rate was not different between the two treatments. The cure rate for hypertension was higher and the improvement rate for renal function was lower after stent placement than after renal PTA (20% vs 10% and 30% vs 38%, respectively; P <.001).

CONCLUSION

Renal arterial stent placement is technically superior and clinically comparable to renal PTA alone.

Percutaneous revascularization of the renal arteries: predictors of outcome

PURPOSE

To identify predictors of clinical outcome after percutaneous revascularization of the renal arteries.

MATERIALS AND METHODS

In 63 patients, the therapeutic response was retrospectively assessed after percutaneous revascularization of the renal arteries indicated for hypertension (41.3%), renal failure (4.8%), or both (53.9%). All patients underwent percutaneous transluminal renal angioplasty, complemented by stent insertion in 30 patients. The authors analyzed the role of clinical and imaging factors, including scintigraphy, Doppler sonography, and angiography for predicting clinical success.

RESULTS

In the hypertensive population, there were three cures (5.6%), 26 improvements (48.1%), and 25 failures (46.3%). Among patients with renal insufficiency, 12 were improved (37.5%), 11 were stabilized (34.4%), and nine deteriorated (28.1%). Predictors of favorable outcome for hypertension were shorter duration of hypertension, higher diastolic blood pressure, fibromuscular dysplasia, abnormal Doppler study, higher percentage of angiographic stenosis, and lower grade of aortic atheromatous disease. Predictors of favorable outcome for renal failure were nondiabetic status, abnormal Doppler study, and higher percentage of angiographic stenosis. Abnormal Doppler and scintigraphic examinations predicted successful treatment of hypertension in 60% and 53.8% of cases, respectively, and renal insufficiency in 85% and 60% of cases, respectively.

CONCLUSION

Clinical and angiographic variables were the best predictors of therapeutic success for hypertension. Doppler sonography was useful in patients with renal failure.

Outpatient percutaneous transluminal renal artery angioplasty: a Canadian experience

PURPOSE

The authors performed a retrospective study of their experience and complication rate while performing outpatient percutaneous transluminal renal artery angioplasty (PTRA) during a 5-year period.

MATERIALS AND METHODS

From July 1992 to July 1997, 87 PTRAs were performed. Of these, 62 PTRA procedures were performed on 53 outpatients. In total, 66 arteries were dilated in 62 PTRA sessions using standard, established techniques. During the same period, only 25 PTRAs were performed on inpatients. Angioplasties were performed on those patients with demonstrated renal artery stenosis and poorly controlled hypertension and/or renal failure. Patients chosen for PTRA were picked by a team that included a vascular surgeon, a nephrologist, and a radiologist. Patients who were deemed suitable for an outpatient procedure were recommended by a nephrologist. Radiological input was sought at that time. Specific guidelines were used to select these patients who were otherwise healthy, well-orientated, and able to respond to an emergency situation. None of the subjects had significant risk factors. All were accompanied by an adult for the first 24 hours and all lived no more than an hour's travel time from a hospital. All were stable on discharge and were seen within 24 hours by a nephrologist.

RESULTS

The technical success rate, defined as a residual stenosis on imaging of less than 30% and/or by a pressure gradient of less than 10 mm Hg across the stenosis, was 85%. The early complication rate was 5.6%, including two patients who developed a localized hematoma. In all, four patients were admitted to the hospital rather than being discharged to home after an average of 4.2 hours of observation. The late complication rate was 3% and involved two patients. One patient, who reported pain after balloon deflation, was readmitted 6 hours after discharge with hypotension, and a diagnosis of renal artery rupture was confirmed with computed tomography. Another patient developed peripheral atheroemboli 20 days after the procedure.

CONCLUSION

Outpatient PTRA can be performed on selected patients. In this study, late complications occurred in only 3% of patients. Early complications were readily recognized in 5.6% of patients, and these patients were admitted for observation after the procedure.

Laparoscopic aortorenal bypass

BACKGROUND AND PURPOSE

Open surgical renovascular repair, although producing excellent results, confers significant operative morbidity. As a result, less morbid procedures such as percutaneous balloon angioplasty and stenting have gained increasing acceptance. Laparoscopic techniques have not previously been applied to renal revascularization. The aim of this study was to demonstrate the technical feasibility and the long-term clinical and pathologic outcomes of laparoscopic aorto-left renal artery bypass in a chronic porcine model.

MATERIALS AND METHODS

Eight animals were used in the study. All laparoscopic suturing and knot-tying were performed intracorporeally using free-hand techniques. The following operative steps were employed: (1) aortic dissection and cross-clamping; (2) transection and refashioning of the left renal artery ostium; (3) in-situ renal hypothermia; (4) end-to-side aorto-left renal artery anastomosis; and (5) aortic unclamping. In situ renal hypothermia was achieved laparoscopically by infusion of ice-cold heparinized saline into the renal artery through a balloon catheter.

RESULTS

All eight pigs underwent laparoscopic aortorenal bypass successfully. The median surgical time was 110 minutes, and the aortic cross-clamping time was 45.5 minutes. The median anastomotic time was 40 minutes, and the renal warm ischemia time was 9 minutes. The median estimated blood loss was 30 mL. An intraoperative complication of suture breakage leading to anastomotic hemorrhage occurred in one animal; the problem was corrected laparoscopically. Postoperatively, one animal died from pneumonia. The remaining seven animals experienced no postoperative complications and were euthanized, one each at postoperative day 0 and 1 and week 1, 2, 3, 4, and 6. The median preoperative and postoperative (at euthanasia) serum creatinine values (1.15 mg/dL v 1.2 mg/dL; P = 0.39) were similar. However, compared with preoperative peripheral renin activity (0.25 microg/L per hour), the postoperative peripheral renin activity was elevated (0.9 microg/L per hour; P = 0.047). Autopsy revealed a grossly normal left kidney, with Doppler confirmation of flow in the repaired renal artery in all seven animals. Ex vivo angiography confirmed a patent anastomosis. On histopathology examination, the early left renal parenchymal specimens revealed transient, mild acute tubular necrosis that resolved over sequential specimens without significant long-term sequelae. Histologic analysis of the aorto-left renal artery anastomotic site revealed gradual endothelialization with time.

CONCLUSIONS

Laparoscopic aortorenal artery revascularization is technically feasible. Our chronic animal model has demonstrated durable success over a 6-week follow-up. This study represents the initial report in the literature.

Laparoscopic aortorenal bypass: a feasibility study

PURPOSE

To demonstrate the technical feasibility of laparoscopic aortorenal bypass in an acute porcine model.

MATERIALS AND METHODS

An aorta-to-left renal artery bypass using an interposition Dacron graft was performed in five pigs. Intracorporeal laparoscopic free-hand suturing and knot-tying were employed exclusively. Renoprotective in-situ regional hypothermia was achieved intracorporeally by infusing ice-cold heparinized saline into the renal artery using a balloon catheter.

RESULTS

The mean total surgical time was 325 minutes, and the mean renal ischemia time was 61 minutes. The end-to-side graft-to-aorta and end-to-end graft-to-renal artery anastomosis times were 34 minutes and 40 minutes, respectively. The mean estimated blood loss was 66 mL. On revascularization, prompt reperfusion of the kidney and Doppler-confirmed pulsation of the renal artery was noted. Graft patency was confirmed on autopsy.

CONCLUSION

Laparoscopic aortorenal bypass is feasible. This study represents the initial report in the literature. A long-term animal survival study is planned.

Doppler ultrasound (pre- and post-contrast enhancement) for detection of recurrent stenosis in stented renal arteries: preliminary results

The purpose of the present paper was to assess whether conventional renal Doppler ultrasound and the commonly used parameters of peak systolic velocity and renal aortic ratio may be an appropriate modality for the follow-up of renal artery stents. A total of 19 arteries in 15 patients was examined with both renal Doppler ultrasound and angiography for the presence or absence of recurrent renal artery stenosis. Disease was considered present on angiography if the arterial diameter was more than 60% stenotic. Doppler criteria for stenosis were either a peak systolic velocity of > 180 cm/s or a renal aortic ratio of > 3.0. Echo enhancement with Levovist (Schering, Berlin, Germany) was used if studies were technically unsuccessful or to improve diagnostic confidence. Renal Doppler ultrasound detected 100% of renal artery stenoses. The specificity was 75%, the positive predictive value was 67% and the negative predictive value was 100%. Echo enhancement improved the technical success rate from 89 to 95% and also increased diagnostic confidence in six examinations. The present limited study suggests that similar renal Doppler parameters as used for the study of unstented renal arteries may be applied to the examination of renal arteries with renal stents in situ. It therefore suggests that Doppler ultrasound may provide an adequate non-invasive means of renal artery stent follow-up, particularly when combined with echo-enhancing agents. Further study is warranted to confirm these initial conclusions.

Outcome of renal artery reconstruction: analysis of 687 procedures

OBJECTIVE

To evaluate the short- and long-term results of surgical reconstruction of the renal arteries, the authors review their experience with more than 600 reconstructions performed over a 12-year period.

SUMMARY BACKGROUND DATA

Reconstruction of the renal arteries, whether for primary renal indications or concomitantly with aortic reconstruction, has evolved over the past 40 years. There is concern that renal artery reconstructions carry significant rates of mortality and morbidity and may fare poorly compared with less-invasive procedures.

METHODS

From 1986 to 1998, 687 renal artery reconstructions were performed in 568 patients. Of these, 105 patients had simultaneous bilateral renal artery reconstructions. Fifty-six percent of the patients were male; 11% had diabetes; 35% admitted to smoking at the time of surgery. Mean age was 67 (range, 1 to 92). One hundred fifty-six (23%) were primary procedures and the remainder were adjunctive procedures with aortic reconstructions; 406 were abdominal aortic aneurysms and 125 were aortoiliac occlusive disease. Five hundred procedures were bypasses, 108 were endarterectomies, 72 were reimplantation, and 7 were patch angioplasties. There were 31 surgical deaths (elective and emergent) in the entire group for a mortality rate of 5.5%. Predictors of increased risk of death were patients with aortoiliac occlusive disease and patients undergoing bilateral simultaneous renal artery revascularization. Cause of death was primarily cardiac. Other nonfatal complications included bleeding (nine patients) and wound infection (three patients). There were 9 immediate occlusions (1.3%) and 10 late occlusions (1.5%). Thirty-three patients (4.8%) had temporary worsening of their renal function after surgery.

CONCLUSION

Renal artery revascularization is a safe and durable procedure. It can be performed in selected patients for primary renovascular pathology. It can also be an adjunct to aortic reconstruction with acceptable mortality and morbidity rates.

Surgery after failed percutaneous renal artery angioplasty

PURPOSE

This retrospective review describes the surgical management of 51 patients after failed percutaneous renal artery angioplasty (F-PTRA).

METHODS

From January 1987 through June 1998, 51 consecutive patients underwent surgical repair of either atherosclerotic (32 patients) or fibromuscular dysplastic (FMD; 19 patients) renovascular vascular disease after F-PTRA. These patients form the basis of this report. Surgical repair was performed for hypertension (29 patients with atherosclerosis: mean blood pressure, 205 +/- 34/110 +/- 23 mm Hg; 18 patients with FMD: mean blood pressure, 194 +/- 24/118 +/- 18 mm Hg) or ischemic nephropathy (20 patients with atherosclerosis: mean serum creatinine level, 2.0 +/- 0.8 mg/dL; three patients with FMD: mean serum creatinine level, 2.0 +/- 1.1 mg/dL). Emergency operation was required in four patients for acute renal artery thrombosis (one patient with atherosclerosis, one patient with FMD), renal artery rupture (one patient with atherosclerosis), or infected pseudoaneurysm (one patient with atherosclerosis). Operative management, blood pressure and renal function response to operation, and dialysis-free survival rate were examined and compared with 487 patients (441 patients with atherosclerosis, 46 patients with FMD) treated by operation alone.

RESULTS

Among the patients with atherosclerotic renovascular disease, there were three postoperative deaths (9.4%) after repair for F-PTRA. Secondary operative repair was associated with emergent repair or nephrectomy in 16% of cases, while more extensive renal artery exposure and more complex operative management was required in 50% of patients with atherosclerosis and 65% of patients with FMD repaired electively. Among the 28 operative survivors with hypertension and atherosclerotic renovascular disease, blood pressure benefit after F-PTRA was significantly lower when compared with patients with atherosclerosis who underwent treatment with operation only (57% vs 89%; P <.001). However, blood pressure benefit in the 19 patients with FMD did not differ (89% vs 96%). Among the 28 patients with atherosclerosis, preoperative estimated glomerular filtration rate (EGFR) as compared with postoperative EGFR was significantly increased (47.4 +/- 4.2 mL/min/1.73m(2) vs 56. 6 +/- 5.1 mL/min/1.73m(2); P =.002). However, EGFR prior to PTRA was not significantly different from postoperative EGFR (51.6 +/- 3.4 mL/min/1.73m(2) vs 56.6 +/- 4.9 mL/min/1.73m(2); P =.121). As compared with patients with atherosclerosis who underwent treatment with operation alone, there was no difference in the dialysis-free survival rate.

CONCLUSION

Operative repair after F-PTRA was altered in 59% of the patients with atherosclerosis and in 68% of patients with FMD. Blood pressure benefit for patients with FMD was unchanged after F-PTRA. However, the blood pressure benefit was significantly decreased among patients with atherosclerosis. Decreased EGFR after F-PTRA was recovered with operative renal artery repair. However, postoperative EGFR as compared with EGFR prior to PTRA was unchanged. Blood pressure and renal function response after F-PTRA for atherosclerotic renovascular disease warrants further study.

Subclavian artery stenosis caused by non-specific arteritis (Takayasu disease): treatment with Palmaz stent

A 32-year old woman was admitted to the hospital with a sudden onset of right-sided hemiplegia and aphasia. Immediate angiographic examination revealed a severe form of type I Takayasu arteritis with occlusion of all supra-aortic vessels, with the exception of the left subclavian artery which was, however, almost completely occluded 1 cm proximal to the origin of the left vertebral artery. Since the latter provided the entire blood supply to the brain tissues, an immediate attempt was undertaken to dilate the left subclavian artery; when this was unrewarding, stenting of the lesion was successfully accomplished with excellent primary and 6-month follow-up results.

Outcome and cost comparison of percutaneous transluminal renal angioplasty, renal arterial stent placement, and renal arterial bypass grafting

PURPOSE

To compare the outcomes and costs of percutaneous transluminal renal angioplasty (PTRA), percutaneous transluminal stent placement (PTSP) of renal arteries, and renal arterial bypass grafting (RABG) in treatment of renovascular hypertension.

MATERIALS AND METHODS

Medical records and angiograms of 130 patients who underwent PTRA, PTSP, or RABG were retrospectively studied to determine success and complication rates, angiographic stenoses, blood pressures, antihypertensive medications, and serum creatinine levels. Actual costs were analyzed in detail.

RESULTS

Technical success rates for PTRA, PTSP, and RABG were 91%, 98%, and 92%, respectively. Complication rates were 13%, 16%, and 38%, respectively. The mean arterial pressure was initially lowered by 29.2 mm Hg, 30.3 mm Hg, and 27.3 mm Hg, respectively, and maintained at 21.0 mm Hg, 19.8 mm Hg, and 20.2 mm Hg below baseline at 12 months. The number of antihypertensive medications was initially reduced on average by 0.63, 0.72, and 0.58, respectively, but returned to baseline in all patients by 12 months. The serum creatinine level did not change substantially with any treatment. Initial treatment costs were $1,402, $2,573, and $15,393, respectively.

CONCLUSION

PTRA, PTSP, and RABG were equally efficacious for control of renovascular hypertension. The initial treatment cost for bypass grafting was substantially higher than that for PTRA and PTSP of renal arteries.