Divergent outcomes after percutaneous therapy for symptomatic renal artery stenosis

Is stenting for atherosclerotic renal stenosis an effective technique?

INTRODUCTION

One of the treatments for renal artery stenosis is endovascular intervention, but its effectiveness is controversial. The present study aims to analyze the experience of a working group in the endovascular treatment of selected patients with severe obstructive atherosclerotic lesions of the renal arteries, and to characterize early and late results.

METHODS

This is a retrospective study of symptomatic patients with atherosclerotic renal artery stenosis who underwent endoluminal therapy between May 12, 1999 and March 12, 2015 at two institutions. Statistical analysis was performed using the PASW Statistics program.

RESULTS

A total of 99 patients were treated, mean age 66 years and 76.8% male. The mean degree of stenosis measured by renal Doppler echocardiography was 83% and 64.6% were ostial lesions. Mean preoperative creatinine level was higher than the postoperative mean: 1.3 vs. 1.2 mg/dl (p=0.014). The number of antihypertensive drugs in the preoperative period was higher than in the postoperative period: 2.0 vs. 1.3 (p=0.001). The mean follow-up was 40 months (0-164). The mean peak systolic velocity over time in the postoperative period was 77 cm/s (40-250). The restenosis rate was 8%, and 30-day mortality was 0%.

CONCLUSIONS

The results demonstrated that the endovascular technique has a beneficial effect on blood pressure and renal function in selected patients, and is a safe technique associated with a high rate of technical success and few complications.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Resultados a longo prazo da angioplastia de artérias renais com stent na doença aterosclerótica: revisão sistemática

Resumo A doença renovascular aterosclerótica é a principal causa de hipertensão secundária. A história natural da doença demonstra taxas de progressão de 4 a 12% ao ano. Entre os métodos de tratamento existe a angioplastia com stent de artérias renais; porém, poucos estudos clínicos demonstraram seus resultados a longo prazo. Esta revisão sistemática da literatura se propõe a apresentar os resultados a longo prazo (acima de 24 meses) da angioplastia com stent de artérias renais na doença aterosclerótica em relação à função renal e aos níveis pressóricos no controle da hipertensão. Foi realizada uma ampla pesquisa, utilizando os termos apropriados, nas bases de dados LILACS, EMBASE, SCIELO, Cochrane Library e MEDLINE. De um total de 2.170 referências, apenas sete artigos contemplavam todos os critérios de inclusão. Conclui-se que, a longo prazo, há uma estabilização da função renal, redução dos níveis pressóricos e diminuição do número de classes de medicamentos anti-hipertensivos.

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.

Endovascular intervention for renal artery stenosis

Renovascular diseases are common conditions with important implications on cardiovascular morbidity and mortality. Renal artery stenosis (RAS) is present in 1-5% of patients with hypertension (HTN) in the US with the vast majority of caused by atherosclerosis. Atherosclerotic RAS is related not only to uncontrolled HTN, but also to renal dysfunction. Atherosclerotic RAS in the USA has been reported to account for approximately 14-16% of new patients requiring dialysis each year. Hence a concerted effort was made in the last decade to treat renovascular stenosis using newly developed endovascular therapies to improve cardiovascular morbidity and renal function. A review on new advances in the endovascular management of renal artery stenosis with low profile stents, embolic protection devices, and drug eluting stents is presented.

Self-expanding nitinol renal artery stents: comparison of safety and efficacy of bare versus Polyzene-F nanocoated stents in a porcine model

OBJECTIVE

To investigate the safety and efficacy of a Polyzene-F nanocoat on new low-profile self-expandable nitinol stents in minipig renal arteries.

MATERIALS AND METHODS

Ten bare nitinol stents (BNS) and 10 stents coated with a 50 nm-thin Polyzene-F coating were randomly implanted into renal arteries of 10 minipigs (4- and 12-week follow-up, 5 animals/group). Thrombogenicity, on-stent surface endothelialization, vessel wall injury, late in-stent stenosis, and peristrut vessel wall inflammation were determined by quantitative angiography and postmortem histomorphometry.

RESULTS

In 6 of 10 BNS, >50% stenosis was found, but no stenosis was found in stents with a nanothin Polyzene-F coating. Histomorphometry showed a statistically significant (p < 0.05) different average maximum luminal loss of 55.16% ± 8.43% at 12 weeks in BNS versus 39.77% ± 7.41% in stents with a nanothin Polyzene-F coating. Stents with a nanothin Polyzene-F coating had a significantly (p < 0.05) lower inflammation score after 12 weeks, 1.31 ± 1.17 versus 2.17 ± 0.85 in BNS. The results for vessel wall injury (0.6 ± 0.58 for Polyzene-F-coated stents; 0.72 ± 0.98 for BNS) and re-endothelialization, (1.16 ± 0.43 and 1.23 ± 0.54, respectively) were not statistically significant at 12-week follow-up. No thrombus deposition was observed on the stents at either follow-up time point.

CONCLUSION

Nitinol stents with a nanothin Polyzene-F coating successfully decreased in-stent stenosis and vessel wall inflammation compared with BNS. Endothelialization and vessel wall injury were found to be equal. These studies warrant long-term pig studies (≥120 days) because 12 weeks may not be sufficient time for complete healing; thereafter, human studies may be warranted.

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-splanchnic steal syndrome: the treatment of chronic mesenteric ischemia with renal angioplasty and stenting

The clinical syndrome of chronic mesenteric ischemia classically presents with a combination of involuntary weight loss, post prandial abdominal pain, and food fear. With occlusion or stenosis of the celiac and superior mesenteric arteries (SMA) collateral blood flow between mesenteric vessels is common and frequently act as the sole blood supply to the intestine. We present a rare case of chronic mesenteric ischemia in which the main blood supply to the celiac and SMA were collaterals coming off the right renal artery resulting in renal-splachnic steal. After an unsuccessful attempt to cannulate the SMA and celiac vessels it was possible to relieve this patient's symptoms with renal artery stenting.

Embolic protection device use in renal artery stent placement

PURPOSE

The purpose of the present study was to report safety, efficacy, and renal function outcomes with use of the GuardWire embolic protection device (EPD) in renal artery stent placement for patients with renal artery stenosis (RAS) and chronic renal insufficiency (CRI).

MATERIALS AND METHODS

This was a retrospective study of all patients with RAS and CRI treated concomitantly with a GuardWire EPD and renal artery stents from December 2002 through June 2006. Renal function was determined by calculating the estimated glomerular filtration rate (eGFR) according to the Modification of Diet in Renal Disease formula, and subjects were divided into Kidney Disease Outcomes and Quality Initiative (K-DOQI) classes based on baseline eGFR. After revascularization, an improvement from baseline of at least one K-DOQI class was defined as improvement, unchanged K-DOQI class as stabilization, and worsening of at least one K-DOQI class as deterioration.

RESULTS

There were 63 patients (54% men) with a mean age of 75.2 years +/- 7.7. The mean baseline serum creatinine level and eGFR were 1.87 mg/dL +/- 0.6 (range, 1-3.8 mg/dL) and 36.63 mL/min per 1.73 m(2) +/- 11.42 (range, 13.85-59.99 mL/min per 1.73 m(2)), respectively, and at the last clinical follow-up, the respective measurements were 1.96 mg/dL +/- 0.72 and 38.75 mL/min per 1.73 m(2) +/- 13.25 (P = not significant). Over a mean follow-up period of 16 months +/- 12, 14 patients (25%) showed improvement, 33 (58%) had stable renal function, and 10 (18%) showed deterioration. There was one GuardWire-related dissection, which was successfully treated with a stent.

CONCLUSIONS

The GuardWire EPD, used during renal artery stent placement, is safe and was associated with stabilization or improvement in kidney function in 83% of patients with RAS and CRI.

[Hypertension in patients with renal artery stenosis]

Renal artery stenosis (RAS) is often present in patients with severe hypertension and atherosclerotic vascular disease. In this setting it is important to screen patients for renovascular disease, e.g. with Duplex-ultrasound, CT- or MR-angiography. The challenge of treating these patients is to find the evidence proving that the RAS is responsible for hypertension and/or renal dysfunction. Measurement of the intra-arterial pressure gradient is necessary in order to determine hemodynamic relevance. On the other side, in these patients hypertension is often of primary and/or renoparenchymatous origin and is aggravated by a renovascular disease. This explains why hypertension cannot be cured even if a high grade stenosis has been removed. In addition, thromb- and cholesterol-embolic material is often mobilized during an invasive procedure and leads to renaparenchymatous ischemia which sustains hypertension after intervention. An individual evaluation of profit versus risk is important for the decision for or against an invasive procedure, especially since there is no sufficient evidence for a decrease of mortality after interventions of RAS. The optimal conservative treatment, including the treatment of atherosclerotic risk factors is recommended.

Embolic protection devices in patients with renal artery stenosis with chronic renal insufficiency: a clinical study

PURPOSE

To present clinical outcomes with the use of embolic protection devices (EPDs) and renal artery stents in patients with chronic renal insufficiency (CRI) and renal artery stenosis (RAS).

MATERIALS AND METHODS

A retrospective study was conducted in 23 patients with RAS and CRI who were treated with renal artery stent placement with an EPD. Follow-up data were obtained through medical records.

RESULTS

In 23 patients (18 men; 78%) with an average age of 69.4 years +/- 11 (range, 46-86 y), 32 renal arteries were treated for worsening renal function (n = 17; 74%) or uncontrolled hypertension and worsening renal function (n = 6; 26%). Nine FilterWire EZ devices were used in eight patients (35%) and 17 SpideRX devices were used in 15 patients (65%). The average follow-up was 8 months +/- 5. After the stent procedure, the mean systolic blood pressure decreased significantly (P < .05) whereas the diastolic pressure remained unchanged. There was a significant increase in the mean estimated glomerular filtration rate from 32.9 mL/min +/- 12.9 at baseline to 41.3 mL/min +/- 13.7 at last follow-up (P < .05). In 96% of patients, there was improvement or stabilization of kidney function. In six of the 17 SpideRX devices (35%), macroscopically evident embolic material was observed in the device after stent placement. There were two minor and two major complications.

CONCLUSIONS

Renal artery stent placement combined with the use of a SpideRX or FilterWire EZ device is associated with an good clinical outcome with a reasonable safety profile.

Tratamento endovascular da estenose da artéria renal em rim único

CONTEXTO: O tratamento endovascular da doença renal hipertensiva, em doentes com rim único, conseqüente à estenose de artéria renal, mostrou ser efetivo na prevenção da falência do órgão, sua função e controle da hipertensão. Quando indicado após avaliação criteriosa, tanto bioquímica como por imagens e sinais do doente, o tratamento endovascular apresenta benefícios clínicos de forma efetiva e pouco invasiva. OBJETIVO: Estudar a doença hipertensiva renovascular e avaliar a eficácia do tratamento endovascular no controle da hipertensão arterial sistêmica e da insuficiência renal secundárias à estenose da artéria renal e como medida de prevenção de falência renal em doentes com rim único funcionante. MÉTODO: Estudo realizado com protocolo de atendimento previamente elaborado, no Centro de Referência de Alta Complexidade em Cirurgia Endovascular do Hospital de Clínicas da Universidade de Campinas, de abril de 1997 a junho de 2005, em 10 doentes com diagnóstico de estenose da artéria renal em rim único funcionante, submetidos ao tratamento endovascular. Foi avaliada a melhora da hipertensão e função renal através de seguimento clínico e laboratorial com medidas de pressão arterial, dosagens séricas de uréia, creatinina e clearance. Exames pelo eco-color-Doppler foram realizados no pós-operatório de 30 dias, 3 meses, 6 meses e anualmente; no caso de haver alguma dúvida na obtenção de imagens ou sinais, foi realizada a aortografia e arteriografia seletiva renal. Nesta casuística, 90% dos doentes apresentavam hipertensão arterial, 70% eram tabagistas, 40%, hiperlipidêmicos, 30% apresentavam doença oclusiva cerebral extracraniana, 60%, obstrução arterial crônica nos membros inferiores, e 20%, diabetes melito. RESULTADOS: O sucesso inicial foi de 100%. O seguimento médio foi de 40 meses. Houve controle da pressão arterial em 90%, diminuição significativa dos níveis de uréia e creatinina após procedimento e piora do quadro de hipertensão em 10%. CONCLUSÃO: O tratamento endovascular da estenose da artéria renal é uma técnica que apresenta benefícios clínicos no controle da hipertensão arterial, preserva a função renal e desacelera a progressão da insuficiência renal crônica de origem renovascular, porém sem melhora desta.

Serum Creatinine Stabilization Following Renal Artery Stenting

The impact of renal artery stenting on renal function in a subgroup of consecutive de novo patients with atherosclerotic renal artery stenosis from the single operator, single center, retrospective renal stent trial is defined. Patients with inadequate preprocedure and/or follow-up renal function studies were excluded. Abnormal baseline serum creatinine (sCr) was defined as ≥1.5 mg/dL. Follow-up sCr was improved, unchanged, or worsened if the variance from baseline decreased by >20%, stayed within 20%, or increased >20%, respectively. For the total cohort (194 patients), renal function stabilized or improved in 72% of patients. Plotting 1/sCr demonstrated a decline in renal function before the procedure that stabilized following renal artery stenting. Bilateral renal artery stenting predicted normal follow-up sCr, and baseline sCr >2.1 mg/dL was associated with improvement in sCr long-term. In conclusion, renal artery stenting results in overall stabilization of renal function, and bilateral renal artery stenting seems to have added benefit.

Branch renal artery repair with cold perfusion protection

PURPOSE

This retrospective review describes the use and clinical outcome of cold perfusion protection during branch renal artery (RA) repair in 77 consecutive patients.

METHODS

From July 1987 through November 2006, 874 patients had open operative RA repair to 1312 kidneys. Seventy-seven patients (62 women, 15 men; mean age, 44 +/- 17 years) had branch RA reconstruction using ex vivo or in situ cold perfusion protection for 78 kidneys. Demographic data and surgical technique were examined. Blood pressure response and renal function were estimated. Patency of repair was determined by angiography and renal duplex ultrasound (RDUS) imaging. Primary RA patency was estimated by life-table methods.

RESULTS

Seventy-eight RAs were repaired using ex vivo (49 kidneys) or in situ (29 kidneys) cold perfusion protection. Bilateral RA repair was performed in eight patients, with 13 repairs to solitary kidneys. RA disease included aneurysm (RAA) in 50, fibromuscular dysplasia (FMD) in 37, atherosclerosis in 5, and arteritis in 2; 16 patients had both FMD and RAA. Hypertension was present in 93.5% (mean blood pressure, 184 +/- 35/107 +/- 19 mm Hg; mean of 1.9 +/- 1.1 drugs). RA repair included bypass using saphenous vein in 69, hypogastric artery in 3, polytetrafluoroethylene (PTFE) in 2, composite vein/PTFE in 2, cephalic vein in 1, or aneurysmorrhaphy in 1. The eight bilateral RA repairs were staged. One patient required bilateral cold perfusion protection. One planned nephrectomy was performed at the time of contralateral ex vivo reconstruction. No primary nephrectomies were required for intended reconstruction. Each RA reconstruction required branch dissection and reconstruction (mean of 2.8 +/- 1.6 branches were repaired). Mean cold ischemia time was 125 +/- 40 minutes. Each kidney was reconstructed in an orthotopic fashion. Five early failures of repair required three nephrectomies and one operative revision. Based on postoperative angiography or RDUS, or both, primary patency of RA repair at 12 months was 85% +/- 5%; assisted primary patency was 93% +/- 4%. Among patients with preoperative hypertension, 15% were cured, 65% were improved, and 20% were considered failed. Early renal function was improved in 35%, unchanged in 48%, and worse in 17%. Four patients had perioperative acute tubular necrosis. No patient progressed to dialysis-dependence.

CONCLUSION

Both ex vivo and in situ cold perfusion protection extend the safe renal ischemia time for complex branch RA repair and avoid the need for nephrectomy.

Use of Endovascular Stents in Atherosclerotic Renovascular Stenosis: Blood Pressure and Renal Function Changes in Hypertensive Patients

Atherosclerotic renal artery stenosis may result in hypertension and ischemic nephropathy. Renal artery endovascular stenting has emerged as current therapy; however, the percentage of patients who benefit from this procedure is still not well established. The authors studied 116 hypertensive patients with atherosclerotic renovascular stenosis who underwent successful renal artery stenting for the first time. At 1 year, there was a significant overall decrease in blood pressure in the group after stenting; however, there was no change in renal function. Also, no significant change in the number of antihypertensive drugs was noted. Blood pressure improved in 55% of the patients, worsened in 14%, and remained unchanged in 31%. Renal function improved in 16% of the patients, worsened in 30%, and remained stable in 54%. In relation to blood pressure control, patients with resistant or difficult-to-control hypertension showed the most improvement in blood pressure control after stenting.

Renal artery stent revascularization with embolic protection in patients with ischemic nephropathy

A prospective analysis of renal artery stent revascularization with distal embolic protection in a high-risk patient population with ischemic nephropathy is presented. A total of 63 patients (median age 70.2 years, range 54-86 years) had significant atherosclerotic stenosis of 83 renal arteries documented on pre-procedural imaging. All patients had baseline chronic renal insufficiency with a documented deterioration in renal function in the 6 months before revascularization. The endovascular technique used in all patients involved primary passage of an embolic filter into the distal main renal artery followed by primary stent deployment with a balloon expandable stainless steel stent. The filter baskets were recaptured and contents submitted for pathological analysis. At 6 months post-intervention, 97% of patients demonstrated stabilization or improvement in renal function. Only 3% of patients had an inexorable decline in renal function, unchanged by the intervention. After a mean follow up of 16.0 months (6-27), 94% of patients demonstrated stabilization or improvement in renal function. One patient suffered an acute post-procedural deterioration in renal function. In total, 60% of the filter baskets contained embolic material. This study confirms the technical feasibility of renal artery stent deployment with adjuvant embolic protection. The excellent results for renal preservation at 6 months post-intervention also suggest that a distal embolic protection device may improve the impact of percutaneous renal revascularization on progressive deterioration in renal function. The postulated mechanism is through the prevention of atheromatous embolization and the embolic yield from the distal filters supports this hypothesis. Patients most likely to receive the greatest benefit are those with mild baseline chronic renal insufficiency and a recent decline in renal function.

A Study on the Outcome of Percutaneous Transluminal Renal Angioplasty in Patients with Renal Failure

BACKGROUND

The indications for percutaneous transluminal renal angioplasty (PTRA) in renovascular disease, as well as its benefits, remain a matter of debate. The aim of this study was to evaluate the outcome of angioplasty and to identify risk factors associated with less successful outcomes in patients with atheromatous renal artery stenosis and renal failure of varying degrees.

METHODS

The results of PTRA were analyzed retrospectively in 144 patients with serum creatinine levels of >130 micromol/l. Patients were divided into 5 groups according to their indication for angioplasty: (1) deteriorating renal function; (2) accelerating hypertension; (3) a combination of 1 and 2; (4) peripheral vascular disease, and (5) miscellaneous conditions.

RESULTS

The baseline mean (+/- SD) systolic and diastolic blood pressures of the entire group were lowered from 180 +/- 32 and 95 +/- 16 mm Hg to 162 +/- 23 and 86 +/- 12 mm Hg, respectively (p < 0.0005), 12 months after angioplasty. The blood pressure level was unaffected by angioplasty in patients with claudication. The mean number of antihypertensive drugs was reduced in the group with accelerating hypertension from 2.9 +/- 0.8 to 2.4 +/- 1.2 (p = 0.019), and in the group with unilateral renal artery stenosis and two kidneys from 2.4 +/- 1.0 to 1.8 +/- 1.1 (p = 0.002), 12 months after PTRA. Glomerular filtration rate at 3-month follow-up had increased from 23 +/- 11 to 27 +/- 14 ml/min/1.73 m(2) (p = 0.021) in group 1, from 25 +/- 11 to 28 +/- 14 ml/min/1.73 m(2) (p = 0.031) in the combined group of patients consisting of groups 1 and 3, and from 32 +/- 13 to 35 +/- 14 ml/min/1.73 m(2) (p = 0.019) in the group with unilateral renal artery stenosis. No statistically significant difference was found in any of these 3 groups 1 year after angioplasty. The first patient group had an increased prevalence of cardiovascular disease, aortic aneurysm, carotid occlusive disease, and peripheral vascular disease compared to the other patient groups (p < 0.05). Patients with baseline creatinine levels of >300 micromol/l had a lower survival rate at 12, 60, and 120 months after PTRA than patients with serum creatinine levels of <300 micromol/l (p < 0.005). Survival was also lower in patients with bilateral renal artery stenosis and those with a single kidney, compared to patients with a unilateral stenosis at both 5 and 10 years after PTRA (p < 0.05). Regression analysis of predictor variables of mortality rate showed that the relative risk (RR) associated with increased serum creatinine was 4.7 (CI 2.0-11.0; p < 0.0005). The RR for older patients was 1.1 (CI 1.0-1.2; p = 0.008), and the RR for former smokers was 6.0 (CI 1.6-24.0; p = 0.009).

CONCLUSION

The results of the present study indicate that glomerular filtration can be improved in patients who primarily undergo angioplasty to rescue renal function. Renal function with creatinine levels of >300 micromol/l was associated with a lower survival rate. It is, therefore, possible that patients selected after a thorough evaluation of their renal function and comorbid disease factors may benefit from PTRA, even when the indication for angioplasty is to salvage renal function.

A Review of the Current Treatment of Renal Artery Stenosis

PURPOSE

Atherosclerotic renal artery stenosis (ARAS) is associated with morbidity and mortality consequent to progressive ischemic renal failure and the cardiovascular consequences of hypertension. There is considerable uncertainty concerning the optimal management of patients with this condition. This review considers the aetiological factors and the physiologic consequences of ARAS and compares the results of clinical studies of medical and endovascular therapies on blood pressure control and preservation of renal function.

RESULTS

Although, in patients with fibromuscular disease the results of percutaneous transluminal angioplasty (PTA) are clearly superior to medical therapy and surgery, in asymptomatic patients with ARAS the antihypertensive benefits and preservation of renal function of endovascular, surgical and medical therapies appear similar. In selected symptomatic patients interventions may, however, be life-saving. Surgery is generally reserved for arterial occlusions with preserved renal parenchyma and function.

CONCLUSIONS

The results of larger, multicentre, randomised, controlled trials are required to clearly clarify the role of interventional therapy in asymptomatic patients.

Percutaneous and Open Renal Revascularizations Have Equivalent Long-Term Functional Outcomes

Atherosclerotic renal artery stenosis is a significant cause of poorly controlled hypertension and progressive renal dysfunction leading to ischemic nephropathy and other end-organ damage. The optimal treatment of renovascular disease contributing to hypertension and renal dysfunction is not known. This study compares the anatomic and functional outcomes of both open and endovascular therapy for chronic, symptomatic atherosclerotic renal artery disease. We performed a retrospective analysis of records from patients who underwent renal arterial interventions, endovascular or open bypass, between January 1984 and January 2004. Principal indications for intervention were hypertension (51%), chronic renal insufficiency (13%), and hypertension and elevated creatinine (36%). A total of 247 patients (109 males; mean age 69 +/- 10, range 44-89 years) underwent 314 interventions (109 open procedures; 205 angioplasties, 71% with stent placement). There was a significant difference in 30-day mortality (4% vs. <1%; p < 0.005) between the open and endoluminal groups, but not at 1, 3, or 5 years. Patients in the open group had a higher primary patency rate at 5 years (83 +/- 5% vs. 76 +/- 6%; p = 0.03), but patients in the endoluminal group had a higher assisted primary patency rate at 5 years (92 +/- 5% vs. 84 +/- 5; p = 0.03). There was no significant difference between both treatment groups in cumulative freedom from presenting symptom or in freedom from dialysis and renal-related death. Patients who presented with hypertension were more likely to have shown improvement in their blood pressure with endoluminal intervention at 1, 3, and 5 (59 +/- 6% endoluminal vs. 83 +/- 5% open; p = 0.01) years. From these results we conclude that open repair and endoluminal repair of atherosclerotic renal artery stenosis have similar immediate and long-term functional and anatomic outcomes. Patients who present with hypertension may have greater benefit with an endoluminal repair.

Percutaneous intervention for renovascular disease: rationale and patient selection

PURPOSE OF REVIEW

The anatomic diagnosis of renovascular disease is increasing in frequency due to the advent of sophisticated non-invasive imaging modalities such as MRA (Magnetic Resonance Angiography) and renal angiography at the time of cardiac catheterization. Despite this fact, the investigation and appropriate management of renovascular disease has remained a controversial topic. This review addresses the clinical syndromes associated with renal artery stenosis (RAS) and the published data guiding appropriate patient selection for revascularization.

RECENT FINDINGS

There is a growing literature in support of renal revascularization as an aid in improving anti-hypertensive control, preserving renal function, and easing the management of congestive heart failure. Meanwhile, technological advances have allowed intervention in an expanding pool of eligible patients. One such technology is the atheroembolic protection device, which may soon allow renal salvage in patients with significant baseline renal impairment that were previously denied intervention for fear of worsening renal function.

SUMMARY

The data reviewed herein helps to identify patients that will benefit from renal revascularization. Large-scale, randomized data further defining the role of renal revascularization and optimal patient selection is still needed.

Current endovascular management of atherosclerotic renal artery stenosis

The recent advances in stent technology and renal endovascular management have provided a technically reproducible method of percutaneously treating atherosclerotic renal artery stenosis (RAS). In many centers, this has resulted in endovascular management being the primary therapy for atherosclerotic RAS. Although still controversial, it appears that endovascular management of RAS by primay stent deployment provides better blood pressure control than that afforded by best medical management. The impact on renal function is less than that found for hypertension, but there is evidence to suggest that the use of protection devices and primary stenting may enhance renal function outcomes. Whether the ultimate benefit of enhanced survival follows remains an important question and should be the subject of future prospective studies.

Diffusion of new technology for the treatment of renovascular hypertension in the United States: Surgical revascularization versus catheter-based therapy, 1988-2001

BACKGROUND

Trends in the management of renovascular hypertension were evaluated by using a representative national database to determine whether a shift in treatment technology and outcomes has occurred.

METHODS

Clinical information regarding the treatment of renovascular hypertension in 5433 patients from 1988 to 2001 was derived from the Nationwide Inpatient Sample (NIS) database. Patients were classified into 3 groups: combined aortic and renal revascularization, isolated renal revascularization, and catheter-based procedures (angioplasty with or without stenting). Population-based trends were determined by using sampling weights for each year to estimate the total number of each intervention in the United States. Outcomes were compared using multivariate logistic regression analysis for risk-adjustment.

RESULTS

A 73% decrease in combined aortic and renal revascularizations ( P = .033) and a 56% decrease in isolated renal revascularizations ( P < .001) occurred during the study period. Catheter-based procedures have increased 173% from 0.4 to 1.1 procedures per 100,000 adults during this same time period ( P < .001). Predictors favoring catheter-based treatment were admission acuity, increasing age, nonwhite race, and high socioeconomic status. Predictors of mortality for all 3 treatment groups included increasing age, emergent admission, and nonwhite race.

CONCLUSIONS

A significant change in the management of patients with renovascular hypertension has occurred, with a shift towards less invasive catheter-based interventions. A better understanding of the diffusion of this technology in the treatment of individuals with renovascular hypertension will influence the training and distribution of future vascular specialists responsible for these patients.