Percutaneous transluminal renal angioplasty in management of atherosclerotic renovascular hypertension: results in 100 patients

Percutaneous Endovascular Therapy of Renal Artery Stenosis: Technical and Clinical Developments in the past Decade

Renal artery stenosis may initiate or exacerbate arterial hypertension and/or renal insufficiency. During the last decade, technical improvements of diagnostic and interventional endovascular tools have led to more widespread use of endoluminal renal artery revascularization and broader indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Grüntzig in 1978, numerous single-center studies have documented the benefits of percutaneous renal revascularization. In the early 1990s, stent implantation was added to the interventionist's armamentarium for treating renal artery stenosis due to atherosclerosis or fibromuscular dysplasia. The metaanalysis of 3 randomized studies comparing balloon angioplasty with best medical therapy found intervention to be beneficial for blood pressure control but not for preservation of renal function. Despite the absence of randomized studies, there is mounting evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has a positive impact on blood pressure control and renal function. This article summarizes the technical improvements in these endovascular tools during the last decade and gives an overview concerning their clinical impact on renal artery revascularization.

Percutaneous revascularization for ischemic nephropathy: the past, present, and future

Occlusion of the renal arteries can threaten the viability of the kidney when severe, in addition to accelerating hypertension and circulatory congestion. Renal artery stenting procedures have evolved from a treatment mainly for renovascular hypertension to a maneuver capable of recovering threatened renal function in patients with “ischemic nephropathy” and improving management of congestive heart failure. Improved catheter design and techniques have reduced, but not eliminated hazards associated with renovascular stenting. Expanded use of endovascular stent grafts to treat abdominal aortic aneurysms has introduced a new indication for renal artery stenting to protect the renal circulation when grafts cross the origins of the renal arteries. Although controversial, prospective randomized trials to evaluate the added benefit of revascularization to current medical therapy for atherosclerotic renal artery stenosis until now have failed to identify major benefits regarding either renal function or blood pressure control. These studies have been limited by selection bias and have been harshly criticized. While studies of tissue oxygenation using blood oxygen level dependent (BOLD) MR establish that kidneys can adapt to reduced blood flow to some degree, more severe occlusive disease leads to cortical hypoxia associated with microvascular rarefication, inflammatory injury and fibrosis. Current research is directed toward identifying pathways of irreversible kidney injury due to vascular occlusion and to increase the potential for renal repair after restoring renal artery patency. The role of nephrologists likely will focus upon recognizing the limits of renal adaptation to vascular disease and identifying kidneys truly at risk for ischemic injury at a time point when renal revascularization can still be of benefit to recovering kidney function.

Clinical efficacy of percutaneous renal revascularization with stent placement in hypertension among patients with atherosclerotic renovascular diseases

AIM

The aim was to assess the effect of renal angioplasty with stent on systolic, diastolic, and mean arterial blood pressure (MAP) in awake and sleep time with ambulatory blood pressure (ABP) monitoring (Holter monitoring).

MATERIALS AND METHODS

Patients with angiographically proven atherosclerotic renal artery stenosis (RAS) were referred to the Angiography Department of Imam Hospital for intervention during a 1-year period from June 2008 to December 2009. Primary stent placement was attempted by a single operator in 27 severe RAS cases although 1 case was omitted from the study because of technical failure. Pre- and postprocedure creatinine levels, ejection fraction (EF), history of diabetes mellitus (DM), and ABP were obtained. Twenty-six (17 men, 9 women; average age, 62.6 years; age range, 90-21 years) consecutive patients participated in the study.

RESULTS

All patients had severe hypertension resistant to multiple medications; 10 patients had impaired renal function (serum creatinine level greater than 130 µmol/L). A total of 3 (11.5%) patients had congestive heart failure, and 10 (37.7%) were diabetic. Hypertension was cured in 1 (4%) patient, had improved in 23 (88.4%) patients, and had failed to respond to treatment in 2 (7.6%). Serum creatinine decreased significantly from 1.46 ± 0.89 to 1.35 ± 0.61 mg/dL (P<0.05).

CONCLUSION

Percutaneous transluminal angioplasty for atheromatous RAS rarely cures hypertension, but improved blood pressure control is often achieved.

The current state of endovascular therapy in the evaluation and management of renovascular disease

Hypertension is the most common reason for physician office visits among nonpregnant adults in the United States; up to one-third of Americans over the age of 18 have been diagnosed with hypertension. Patients with physiologically significant renal artery stenosis often go unnoticed because hypertension can often be well controlled with antihypertensive medications. As a result, screening for renovascular causes of hypertension is rarely done. However, the likelihood of renovascular disease increases in patients with acute, severe, or refractory hypertension and should be explored in patients who fall into these categories. Renovascular disease is a crucial consideration in the management of hypertension due to its increasing incidence and its potential for reversibility. Although renovascular disease accounts for less than 1% of patients with mild hypertension, it is estimated that between 10 and 45% of white patients with severe or malignant hypertension have renal artery stenosis (RAS). In this population, diagnosing and treating RAS can have a profound and long-lasting effect on the treatment of hypertension.

Cost-effectiveness analysis of treatment of renal-artery stenoses by medication, angioplasty, stenting and surgery

This study analysed the cost-effectiveness of four different treatment modalities (medical therapy, PTA with and without stent, and surgery) for the therapy of renal-artery stenoses in hypertensive patients in Germany. A computerised, predictive decision-analytic model, based on economic input data and the cost of medical care in Germany, and the results of published data from prospective clinical trials, was developed. The economic analysis was performed from the perspective of a third-party payer. The base-case analysis showed that the primary end-point (major vascular bleeding, stroke, dialysis, or repeat arterial revascularisation) was reached at 36 months by 82.4% of the patients in the medical treatment group, 81.4% in the angioplasty group, 52.9% in the surgical group and 27.7% in the stent group. The average reimbursed treatment cost per patient after 3 years was &euro; 9121 (medication), &euro; 17 164 (surgery), &euro; 14 670 (PTA), and &euro; 8437 (stent). This resulted in a cost-effectiveness ratio of &euro; 51 752 (medical treatment), &euro; 36 454 (surgery), &euro; 78 766 (PTA), and &euro; 11 663 (stent) per event-free patient at 3 years. The accelerated cost-development after balloon dilatation was caused by higher rates of restenosis compared with primary stent implantation. The analysis of published prospective clinical data and current economic variables for renovascular interventions leads to the conclusion that a strategy using primary stent implantation is more cost-effective than stand-alone balloon dilatation. Both medical therapy and surgery offer a better cost-effectiveness ratio than PTA treatment alone.

Cutting balloon angioplasty of bilateral renal artery stenosis due to Takayasu arteritis in a 5-year-old child with midterm follow-up

The aim of this report is to demonstrate the successful endovascular treatment of bilateral renal artery stenosis due to Takayasu arteritis by cutting balloon angioplasty in a 5-year-old child with mid-term follow-up.

The role of percutaneous revascularization for renal artery stenosis

Renal artery stenosis (RAS) is usually caused by atherosclerosis or fibromuscular dysplasia. RAS leads to activation of the renin-angiotensin-aldosterone system and may result in hypertension, ischemic nephropathy, left ventricular hypertrophy and congestive heart failure. Management options include medical therapy and revascularization procedures. Recent studies have shown angiotensin receptor blockers (ARB) and angiotensin converting enzyme inhibitors (ACE-I) to be highly effective in treating the hypertension associated with RAS and in reducing cardiovascular events; however, they do not correct the underlying RAS and loss of renal mass may continue. Renal artery angioplasty was first performed by Gruntzig in 1978. The routine use of stents has increased technical success rates compared with angioplasty, and surgery is now only rarely performed. Although numerous case series claimed benefit in terms of blood pressure control, no adequately powered randomized, controlled, prospective study of renal artery interventions has reported their effect on cardiovascular morbidity or mortality. The CORAL trial, an ongoing study of renal artery stent placement and optimal medical therapy (OMT) funded by the National Institutes of Health, is the first study to attempt to do so. Until the CORAL trial results are in, physicians will continue to be faced with difficult choices when determining the optimal management for RAS patients and deciding which, if any, patients should be offered revascularization.

Renal artery stenosis: epidemiology, clinical manifestation, and percutaneous endovascular therapy

Renal artery stenosis may cause or deteriorate arterial hypertension and/or renal insufficiency. Technical improvements of diagnostic and interventional endovascular tools have lead to a more widespread use of endoluminal renal artery revascularization and extension of the indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Grüntzig in 1978, numerous single-center studies have reported the beneficial effect of percutaneous transluminal renal angioplasty, and since the early 1990's stenting of renal artery stenosis caused either by atherosclerosis or by fibromuscular dysplasia. This article summarizes the impact of technical improvements of endovascular tools on interventional techniques during the last decade and gives an overview concerning the clinical impact of renal artery revascularization. Despite the absence of sufficient randomized studies, there is nonetheless evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has an impact on blood pressure control, renal function, and left ventricular hypertrophy.

Coronary bypass procedures in patients with renal artery stenosis

BACKGROUND AND AIM OF THE STUDY

We present our experience on patients with renal artery stenosis undergoing myocardial revascularization procedures.

METHODS

Eighteen patients with varying degrees of renal artery stenosis were operated for coronary artery bypass grafting between 1996 and 2003. The overall incidence was 0.15%. There were nine male and nine female patients with a mean age of 62 +/- 8.2 (40-72 years). Four had bilateral and eight had significant unilateral (>50%) renal artery stenoses. Preoperatively, three patients had renal arterial intervention (stenting), and one patient was on hemodialysis. The mean preoperative creatinine value was 2.6 +/- 2.7 mg/dL (range 0.7 to 9.3). The patients were followed medically: two patients underwent off-pump coronary bypass grafting and the others were operated on-pump.

RESULTS

There was only one mortality and two patients required hemodialysis postoperatively. The postoperative mean creatinine values were 3.4 +/- 4.9 mg/dL (range 1.0 to 12.5). No electrolyte imbalances were noted except that one case revealed a transient metabolic acidosis. Five patients required inotropic support with dopamine and two needed diuretic infusions. Only five patients demonstrated a refractory hyper tensive period postoperatively.

CONCLUSIONS

The concomitant correction of renal artery stenosis with CABG is usually not necessary, but the principles for renovascular diseases must be kept in mind and individually oriented strategies must be planned.

Prospective evaluation of aggressive medical therapy for atherosclerotic renal artery stenosis, with renal artery stenting reserved for previously injured heart, brain, or kidney

Sixty-six patients with atherosclerotic renal artery stenosis (RAS) and serum creatinine < or =2.0 mg/dl were treated with antihypertensive therapy, a statin, and aspirin. Renal stenting was reserved for patients with injuries to the heart, brain, or kidneys. The primary end point was stenotic kidney glomerular filtration rate (GFR) at 21 months; secondary end points included major adverse clinical events, serum creatinine, total GFR, and blood pressure (BP). After baseline evaluation, 26 of 66 patients underwent renal stenting because of injuries to the heart, brain, or kidneys. After 21 months, 6 medical patients required renal stenting, and 5 patients experienced late clinical events (2 medical patients, 3 stent patients). There was no difference in final BP between groups. Whereas medical patients experienced 6% and 8% decreases in total and stenotic kidney GFR, stent patients experienced 7% and 11% increases in total kidney (p = 0.006) and stenotic kidney (p = 0.02) GFR. There was no difference in final serum creatinine. In conclusion, patients with atherosclerotic RAS and baseline creatinine < or =2.0 mg/dl can be safely managed with aggressive medical therapy, with a small decrease in GFR. For patients who develop injuries to the heart, brain, or kidneys, renal artery stenting may further reduce hypertension and improve renal function.

Low-profile Stent System for Treatment of Atherosclerotic Renal Artery Stenosis: The GREAT Trial

PURPOSE

The Palmaz Genesis Peripheral Stainless Steel Balloon Expandable Stent in Renal Artery Treatment (GREAT) Trial was designed to assess the safety and performance of a low-profile stent for the treatment of obstructive renal artery disease by looking at 6-month renal artery patency uniformly analyzed by a Core Lab.

MATERIALS AND METHODS

Fifty-two consecutive patients (mean age, 63.7 years) were successfully treated with the Palmaz Genesis Peripheral Stent (Cordis, Miami, FL) on the Slalom 0.018-inch Delivery System (Cordis Europe N.V., Oosteinde 8, NLO-9301 LJ Roden, The Netherlands) at 11 investigational centers. Patients with severe renal failure and > 8-mm renal artery were excluded. Primary endpoint was angiographic determination of in-stent percent diameter stenosis at 6 months. Fifty-one patients were treated with one stent, one patient was treated with two stents to cover the complete lesion.

RESULTS

Mean percentage diameter stenosis before renal angioplasty was 68.2% +/- 12.0%. No stent implantation failure, displacement, need for additional stent implantation, or procedural complication was observed. Six-month angiography was performed in 41 of 52 patients (79%) resulting in a mean in-stent percent diameter stenosis or Quantitative Vessel analysis (QVA) at 6 months of 23.9%. The in-stent binary (percent diameter stenosis > 50%) restenosis rate at 6 months was 14.3%. No fatal events occurred up to 6 months after implantation. Major adverse events occurred in five patients: four patients (7.7%) required a revascularization and one patient (1.9%) experienced a cerebrovascular event, which regressed spontaneously.

CONCLUSIONS

The Palmaz Genesis stent (Cordis) provides good results for renal artery stent placement, with an in-stent binary restenosis rate (percent diameter stenosis > 50%) at 6 months of 14.3% as determined with angiography.

Percutaneous endovascular therapy of renal artery stenosis: technical and clinical developments in the past decade

Renal artery stenosis may initiate or exacerbate arterial hypertension and/or renal insufficiency. During the last decade, technical improvements of diagnostic and interventional endovascular tools have led to more widespread use of endoluminal renal artery revascularization and broader indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Gruntzig in 1978, numerous single-center studies have documented the benefits of percutaneous renal revascularization. In the early 1990s, stent implantation was added to the interventionist's armamentarium for treating renal artery stenosis due to atherosclerosis or fibromuscular dysplasia. The meta-analysis of 3 randomized studies comparing balloon angioplasty with best medical therapy found intervention to be beneficial for blood pressure control but not for preservation of renal function. Despite the absence of randomized studies, there is mounting evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has a positive impact on blood pressure control and renal function. This article summarizes the technical improvements in these endovascular tools during the last decade and gives an overview concerning their clinical impact on renal artery revascularization.

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.

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.

[Percutaneous transluminal renal angioplasty in hypertension]

The aim of our study was assess anatomical and functional results of renal artery angioplasty with and without stenting in 25 hypertensive patients (8 female and 16 male, 42.6 and 61.6 years old respectively) with significative renal artery stenosis (RAS) (atherosclerotic: 22; fibrodysplastic: 3). Eleven patients had simple angioplasty and 13 had stenting. The rate of angioplasty success was 96%. In the stent group, the anatomical result was better: 2% of residual stenosis versus 24% in the other group (p < 0.001). Restenosis occurred in 2 patients. Immediately after revascularisation arterial blood pressure decreased from 195/105 +/- to 150/85 +/- mmHg in-group without stent (p < 0.001) and from 190/100 to 145/85 mmHg in the group (p < 0.001). The value of serum creatinine concentration in patient with renal failure didn't change after revascularization.

Renal angioplasty and stenting under protection: The way for the future?

The purpose of this study was to evaluate the feasibility and safety of renal artery angioplasty and stenting utilizing a distal protection device to reduce the risk of intraprocedural artery embolism and avoid deterioration of the renal function. Fifty-six hypertensive patients (32 men; mean age, 66 +/- 11.8 years; range, 22-87) with atherosclerotic renal artery stenosis (8 bilateral) underwent angioplasty and stenting with distal protection in 65 renal arteries (58 ostial lesions). Five patients had a solitary kidney, 18 a renal insufficiency. The lesion was crossed either with a GuardWire temporary occlusion balloon (n = 38), which was inflated to provide parenchyma protection or with a filter (EPI Filter; n = 26), or with Angioguard (n = 1), which allows a continuous flow. Generated debris was aspirated and analyzed. Blood pressure and serum creatinine levels were followed. Immediate technical success was 100%. All lesions except one were stented, either directly (43 ostial lesions) or after predilatation (22 ostial lesions). Visible debris were aspirated with the PercuSurge in all patients or removed with filters in 80% of the patients. Mean particle number and diameter were 98.1 +/- 60.0 per procedure (range, 13-208) and 201.0 +/- 76.0 microm (range, 38-6,206), respectively. Mean renal artery occlusion time was 6.55 +/- 2.46 min (range, 2.29-13.21) with the PercuSurge device. Mean time in situ (filters) was 4.25 +/- 1.12 min. Mean follow-up was 22.6 +/- 17.6 months (range, 1-47). Systolic and diastolic blood pressure declined from 169.0 +/- 15.2 and 104.0 +/- 13.0 mm Hg, respectively, to 149.7 +/- 12.4 and 92.7 +/- 6.7 mm Hg after the procedure. The mean creatinine level remains constant during the follow-up. At 6-month follow-up (45 patients), renal function did not deteriorate in any patient, whereas 8 patients with baseline renal insufficiency improved after the procedure. At 3 years (19 patients), renal function deteriorated only in 1 patient with renal insufficiency and in 1 patient treated for bilateral renal stenosis, one side without protection. These preliminary results suggest the feasibility and safety of distal protection during renal interventions to protect against atheroembolism and to avoid renal function deterioration. This technique's beneficial effects should be evaluated by randomized studies.

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.

Nitric oxide and oxidative stress in atherosclerotic renovascular hypertension: effect of endovascular treatment

PURPOSE

Because activation of the renin-angiotensin system leads to an increase in oxidative stress, the authors investigated nitric oxide (NO; nitrite + nitrate), superoxide dismutase (SOD), catalase, and malondialdehyde (MDA) levels and the effect of endovascular treatment on these parameters in patients with atherosclerotic renovascular hypertension. The relationship of NO with blood pressure and renal functional indexes was also investigated.

MATERIALS AND METHODS

In this prospective cohort study, serum creatinine, NO, SOD, catalase, plasma MDA, urinary microalbumin, and NO levels, and blood pressure were determined in 21 patients with hypertension and unilateral renal artery stenosis caused by atherosclerosis at entry and after 24 hours, 2 weeks, and 6 weeks of endovascular treatment.

RESULTS

MDA concentrations decreased 24 hours after intervention and remained low 2 and 6 weeks later. In addition, serum SOD and NO and urine NO levels were increased significantly 24 hours after endovascular treatment and decreased after 2 and 6 weeks. However, serum catalase levels did not differ after the intervention. Blood pressures decreased after treatment. There were no significant differences in urinary microalbumin levels, estimated glomerular filtration rates, and creatinine levels after endovascular treatment.

CONCLUSIONS

Endovascular treatment decreases oxidative stress and may offer new benefits in the treatment of patients with hypertension associated with renal artery stenosis. The decrease in oxidative stress and/or the upregulation of SOD may increase the bioavailability of NO, which in turn may lead to the rapid hypotensive response.

Atherosclerotic Renal Artery Stenosis

The clinical diagnosis of renal artery stenosis relies on a high index of suspicion and confirmation by noninvasive imaging modalities. There are three distinct clinical syndromes associated with renal artery stenosis: renin-dependent hypertension, essential hypertension, and ischemic nephropathy. Clinical features that should heighten suspicion for renal artery stenosis include abrupt-onset or accelerated hypertension at any age, unexplained acute or chronic azotemia, azotemia induced by angiotensin-converting enzyme (ACE) inhibitors, asymmetric renal dimensions, and congestive heart failure with normal ventricular function. Patients with true renin-dependent (renovascular) hypertension are typically young or middle-age women with renal fibromuscular dysplasia (FMD). Initial therapy for renovascular hypertension associated with FMD is an ACE inhibitor; refractory hypertension responds readily to balloon angioplasty without stenting. Elderly patients with generalized atherosclerosis and hypertension often have atherosclerotic renal artery stenosis (ARAS); hypertension in these patients is usually not renin dependent (ie, essential hypertension). Hypertension alone, even if treated with multiple medications, is not a compelling indication for renal artery revascularization; these patients should be treated aggressively with antihypertensive medical therapy. Renal artery revascularization with stenting may be considered for refractory severe hypertension, and would be expected to improve blood control and modestly reduce medication requirements. Renal revascularization rarely cures hypertension in patients with ARAS. Patients with ARAS, hypertension, and end-organ injury should be considered for renal revascularization. Manifestations of end-organ injury include nonischemic pulmonary edema; hypertensive crisis associated with acute coronary syndrome, aortic dissection, or neurologic impairment; and renal insufficiency. Ischemic nephropathy is best treated before the development of advanced renal failure. The best candidates for revascularization are those with baseline serum creatinine less than 2.0 mg/dL, bilateral renal artery stenosis, normal renal resistive indices, no proteinuria, and one or more manifestations of end-organ injury. In these patients, renal revascularization is best accomplished by stenting, although surgical revascularization may be considered in patients with concomitant severe aortic aneurysmal or occlusive disease.

Atherosclerotic renal arterial stenosis: clinical outcomes of stent placement for hypertension and renal failure

PURPOSE

To assess technical success rates and long-term clinical outcomes of primary renal arterial stent placement in atherosclerotic renal arterial stenosis (RAS).

MATERIALS AND METHODS

Primary stent placement was performed in 100 consecutive patients with atherosclerotic RAS. Indications for treatment were resistant hypertension (n = 25), impaired renal function, (n = 50), and both (n = 25). Immediate technical results were evaluated with angiography. Clinical outcomes were assessed with serial systolic and diastolic blood pressure and serum creatinine values obtained from retrospective review of case notes. Results obtained every 6 months after the procedure were compared with those obtained at the time of the procedure with the paired t test. Radiologic reports were evaluated for immediate and case notes for delayed complications.

RESULTS

Technical success was achieved in 120 (95.2%) of 126 RAS in 95 patients. Mean follow-up was 25 months (median, 24 months; range, 1-66 months). Resistant hypertension was cured in two (4.2%) of 48 patients, had improved in 38 (79.1%), and had failed to respond to treatment in eight (16.7%). Mean systolic and diastolic blood pressures were significantly lower at 6, 12, 18, 24, and 30 months (P <.01) than before the procedure. Among 65 patients treated for renal impairment, renal function improved in 20 (30.8%), stabilized in 25 (41.7%), and continued to deteriorate in 20 (30.8%). The mean serum creatinine level did not show significant change with time for this group. In the improved subgroup, it was significantly higher at 6, 12, 18, 24, 36, and 42 months (P <.05) than prior to the procedure. Procedure-related complications occurred in 18 (18%) cases: Ten were minor and self-limiting and eight were major and included two procedure-related deaths.

CONCLUSION

In atherosclerotic RAS, primary stent deployment has a high technical success rate, producing clinical benefits in the majority of patients when performed for resistant hypertension and recovery of renal function.

Endovascular Therapies for Vascular Disease

Endovascular techniques including angioplasty, stenting, and endoluminal stent grafts represent important therapeutic options for the treatment of vascular disease. Technologic advances have allowed for the treatment of aneurysmal disease as well as extra-cranial carotid disease that previously required surgical methods. The success of various endovascular therapies varies based on anatomic location and extent of disease. The clinical results in different arterial segments are increasingly recognized in the published literature. The aortoiliac arterial bed appears to respond most favorably, with less favorable results observed in the infra-inguinal and infrapopliteal locations. There is increasing evidence that stent-supported carotid angioplasty using cerebral protection will play an important future role in the treatment of carotid artery stenosis. Less invasive techniques to treat abdominal aortic aneurysms with endoluminal stent grafts have dramatically changed the available therapeutic options. Improved devices and delivery systems will likely increase the number of patients who can be successfully treated in this manner. The evolution of endovascular therapies will continue to change the way we treat vascular disease.

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.

Successful management of a resistant renal artery stenosis in a child using a 4 mm cutting balloon catheter

Percutaneous transluminal renal angioplasty (PTRA) is a well-established method to treat renal artery stenosis (RAS) in children and adults. However, a significant number of stenoses might not be treated by interventional techniques due to the inability to dilate the RAS. Conventional balloon angioplasty with a high-pressure coronary angioplasty balloon at 20 atm was unable to dilate a significant RAS in a 12-year-old child with severe renovascular hypertension (RR 195/125 mm Hg). After using a 4 mm cutting balloon, we achieved wide patency of the renal artery and an instant normalization of blood pressure without further need of antihypertensive therapy. PTRA using the cutting balloon technique may offer an additional therapeutic option for selected patients in whom conventional balloon angioplasty was not able to dilate RAS.

Resistant hypertension

Recent clinical trials suggest that resistant hypertension is increasingly common. In the majority of patients, uncontrolled hypertension is due to persistent elevation of the systolic blood pressure. Older age and obesity are associated with poor blood pressure control. Other contributing factors include severity of the underlying hypertension and renal insufficiency. Poor patient adherence is thought be a common cause of medication resistance. Exogenous substances such as nonsteroidal anti-inflammatory drugs, oral contraceptives, and sympathomimetic agents can interfere with treatment. The prevalence of secondary causes of hypertension increases with age, especially atherosclerotic renal artery stenosis. Recent reports suggest that primary aldosteronism may be the most common secondary cause of hypertension. It should be considered in all patients with resistant hypertension. Effective treatment of resistant hypertension requires identification and reversal of contributing factors and/or secondary causes of hypertension. Pharmacologic therapy should utilize combination therapy, including a long-acting diuretic.

Multicenter Palmaz stent renal artery stenosis revascularization registry report: four-year follow-up of 1,058 successful patients

Palmaz-Schatz stent revascularization of renal artery stenosis was successfully performed on 1,058 patients who were entered into a voluntary, multicenter registry. The revascularization procedures were performed because of poorly controlled hypertension, preservation of renal function, and congestive heart failure. All 1,058 patients were eligible for > or =6-month clinical follow-up, which focused on subsequent renal function, blood pressure, number of antihypertensive medications, and survival. At 4-year follow-up, systolic and diastolic blood pressures had significantly decreased (168 +/- 27 mm Hg to 147 +/- 21 mm Hg, and 84 +/- 15 to 78 +/- 12 mm Hg; P < 0.05) and the blood pressure appeared to be more facilely controlled as indicated by the concomitant decrease in number of antihypertensive medications (2.4 +/- 1.1 to 2.0 +/- 1.0; P < 0.05). Serum creatinine had also significantly decreased (1.7 +/- 1.1 to 1.3 +/- 0.8 mg/dl; P < 0.05). The cumulative probability of survival was 74% +/- 3% at 4 years. Survival was good for patients with normal (85% +/- 3%) baseline renal function, fair (78% +/- 5%) with mildly impaired renal function, and poor (49% +/- 5%) with severely impaired renal function (baseline creatinine > or =2.0 mg/dl). The combination of impaired renal function and bilateral disease adversely effected survival (unilateral 55% +/- 6% vs. bilateral 36% +/- 11%; P < 0.05). Renal artery stent revascularization, in the presence of normal or mildly impaired renal function, had a beneficial effect on blood pressure control and on renal function (through stabilization or improvement). Survival was adversely effected by renal dysfunction despite adequate revascularization. Perhaps early diagnosis of renal artery stenosis and adequate revascularization prior to the onset of renal dysfunction could beneficially impact blood pressure control, preserve or prevent deterioration of renal function, and improve patient survival.

Treatment of renal artery fibromuscular dysplasia with balloon angioplasty: a prospective follow-up study

OBJECTIVES

to assess restenosis rates and blood pressure response after percutaneous transluminal renal angioplasty (PTRA) in patients treated for fibromuscular dysplastic renal artery stenosis.

METHODS

a prospective 12-month follow-up study of 27 patients with 31 treated renal artery stenosis. Follow-up assessment included colour-coded duplex sonography (CCD) of renal arteries, monitoring of blood pressure, antihypertensive medication, and creatinine measurements before discharge and at 3, 6, and 12 months. Primary end point was defined as a haemodynamically significant restenosis >60% assessed by CCD.

RESULTS

there was a cumulative 23% restenosis rate at 12 months. Arterial hypertension was cured or improved in 93% of patients immediately after the intervention and remained cured/improved in 74% of patients at 12 months of follow-up. Renal failure present in five patients before PTRA stabilised or improved in all patients.

CONCLUSION

although restenosis rate after PTRA in fibromuscular dysplasia is as high as in non-ostial atherosclerotic lesions, there remains a considerable higher therapeutic effect. Profound pressure response and recurrent arterial hypertension with restenosis support the high probability of a renovascular origin of arterial hypertension in this young and otherwise healthy population compared to patients with atherosclerotic renal artery lesions.

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.

Transradial renal angioplasty: initial experience

We report our early experience of a new technique of renal angioplasty utilizing the radial approach. Certain anatomic considerations continue to make access from above via the arm the preferable approach in selected patients in renal artery stenosis. We have utilized the transradial technique for renal artery angioplasty and stenting successfully in four patients. The development of coronary guidewire (0.014")-based peripheral balloons and stent delivery systems has miniaturized equipment sufficiently to make the transradial approach attractive. Present equipment allows for stenting of renal arteries of up to 7 mm with the use of 6 Fr guiding catheters. Present equipment length remains a limitation in taller patients. The transradial approach should be considered in those patients with renal artery or aortoiliac anatomy favoring an approach from the arm.

Endovascular treatment of renal artery stenosis

Significant changes have occurred in the treatment of renal artery disease over the past few years. Although excellent clinical results can be obtained with surgery, percutaneous transluminal renal angioplasty has proved similarly efficacious and is now the treatment of choice for nonostial atherosclerotic stenoses and fibromuscular dysplasia. The introduction of stents has become a valuable adjunctive therapy for postangioplasty restenosis and dissection.

Renal artery stenosis: a disease worth pursuing

Consider renovascular hypertension (HT) when: Newly diagnosed hypertension presents with features that are atypical of essential hypertension; Resistant hypertension is associated with risk factors for atheroma; or Angiotensin-converting enzyme (ACE) inhibitor or angiotensin-II-receptor antagonist therapy is associated with increasing plasma creatinine levels. Atheromatous renovascular HT can often be managed medically, which includes intensive correction of cardiovascular risk factors. ACE inhibitors are probably second-line antihypertensives for patients with unilateral renal artery stenosis and two kidneys. First-line antihypertensives are diuretics, beta-blockers and calcium-channel blockers. Bilateral renal artery stenosis, or a unilateral stenosis in a patient with only one kidney, is an absolute contraindication to ACE inhibition.

Protected renal stenting with the PercuSurge GuardWire device: a pilot study

PURPOSE

To evaluate the feasibility and safety of renal artery angioplasty and stenting utilizing a distal protection device to reduce the risk of intraprocedural atheroembolism.

METHODS

Twenty-eight hypertensive patients (18 men; mean age 71.3 +/- 8.6 years, range 49-87) with atherosclerotic renal artery stenosis (4 bilateral) underwent angioplasty and stenting with distal protection in 32 renal arteries (29 ostial lesions). The lesion was crossed with a GuardWire temporary occlusion balloon, which was inflated to provide parenchymal protection. Generated debris was aspirated and analyzed. Blood pressure and serum creatinine levels were followed.

RESULTS

Immediate technical success was 100%. All lesions were stented, either directly (14 ostial lesions), after predilation (15 ostial lesions), or owing to suboptimal angioplasty (3 nonostial lesions). Visible debris was aspirated from all patients. Mean particle number and diameter were 98.1 +/- 60.0 per procedure (range 13-208) and 201.2 +/- 76.0 microm (range 38-6206), respectively. Mean renal artery occlusion time was 6.55 +/- 2.46 min (range 2.29-13.21). Mean follow-up was 6.7 +/- 2.9 months (range 2-17). Systolic and diastolic blood pressure declined from 167.0 +/- 15.2 and 103.0 +/- 12.0 mm Hg, respectively, to 154.7 +/- 12.3 and 93.2 +/- 6.8 mm Hg after the procedure. The mean creatinine level dropped from 1.34 +/- 0.35 mg/dL preprocedurally to 1.22 +/- 0.36 mg/dL at 24 hours and remained constant. At 6-month follow-up, renal function did not deteriorate in any patient, whereas 5 patients with baseline renal insufficiency improved after the procedure.

CONCLUSIONS

These preliminary results suggest the feasibility and safety of distal balloon occlusion during renal interventions to protect against atheroembolism. This technique's beneficial effects should be evaluated by randomized studies.

Renal Artery Stenosis

Renal artery stenosis (RAS) can accelerate or generate progressive hypertension and renal dysfunction. The goals for treating patients with RAS are to reduce cardiovascular morbidity and mortality attributable to elevated arterial pressure and to preserve renal function beyond critical stenosis. Recent, randomized trials with current antihypertensive agents indicate that many patients with RAS can be managed for years without renal artery revascularization. As it does elsewhere, atherosclerotic disease can progress to more severe occlusion in the renal arteries. Rapid advances in endovascular techniques, including stenting, make restoration of renal blood flow possible in more patients than before. Therapeutic goals are achieved by 1) avoidance of tobacco, 2) reducing arterial pressure with antihypertensive drug therapy, particularly those agents capable of blocking the renin-angiotensin system, and 3) renal revascularization, using balloon angioplasty and stent placement, surgical bypass, or endarterectomy. The major clinical challenges are to identify progressive occlusive disease and to determine appropriate timing for vascular intervention.

Safety of CO(2)- and gadodiamide-enhanced angiography for the evaluation and percutaneous treatment of renal artery stenosis in patients with chronic renal insufficiency

OBJECTIVE

The objective of our study was to evaluate the safety of CO(2) and gadodiamide angiography for diagnosing and percutaneously treating renal artery stenosis in patients with chronic renal insufficiency and presumed ischemic nephropathy.

SUBJECTS AND METHODS

One hundred forty-six consecutive patients with chronic renal insufficiency (serum creatinine > 1.5 mg/dL) were examined for renal artery stenosis using CO(2) and gadodiamide as the angiographic contrast agents. If renal artery stenosis was detected, percutaneous balloon angioplasty with or without stenting was performed. In patients for whom 48-hr creatinine levels were available, we performed an analysis to determine the incidence of contrast-involved nephropathy (increase in serum creatinine of 0.5 mg/dL at 48 hr without identifiable cause). Major complications were reported up to 1 week, and mortality was reported up to 30 days after the procedure.

RESULTS

Ninety-five patients had serum creatinine levels available at 48 hr. An increase in creatinine of greater than 0.5 mg/dL at 48 hr occurred in three patients (3.2%), presumably caused by CO(2), by gadodiamide, or by both. Neither diabetes nor the degree of preexisting chronic renal insufficiency was a predictor of worsening renal function 48 hr after the procedure. The volumes of CO(2) and gadodiamide used for diagnostic studies alone versus the volume used for interventional studies was not significantly different (for CO(2), p = 0.09; for gadodiamide, p = 0.30). Eleven major complications occurred in eight patients (5.5%). Two deaths (1.4%) occurred within 30 days. One death was due to cholesterol embolization and the other was not believed to be related to the procedure.

CONCLUSION

Angiography and percutaneous treatment of renal artery stenosis in patients with chronic renal insufficiency and suspected ischemic nephropathy can be performed relatively safely using CO(2) and gadodiamide as angiographic contrast agents without an increased risk of complications. Contrast-induced nephropathy potentially occurred in 3.2% of patients. Neither the degree of underlying renal insufficiency nor diabetes was a risk factor for predicting a greater likelihood of renal function worsening at 48 hr of follow-up. The volumes of CO(2) and gadodiamide used in this study did not result in an increased risk of contrast-involved nephropathy.