Palmaz stent in atherosclerotic stenoses involving the ostia of the renal arteries: preliminary report of a multicenter study

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.

Renal artery stent in solitary functioning kidneys: 77% of benefit: A systematic review with meta-analysis

BACKGROUND

Solitary functioning kidney (SFK) is tough issue to address in clinical, mostly developed from renal artery stenosis (RAS) in adults. Although renal artery stent is widely used to help SFK patients, the efficacy of the stent is still disputable. This study is aimed at reviewing a series of SFK cases to draw a conclusion about the efficacy of renal artery stent.

METHODS

All related papers published in PubMed, Web of Science, EMBASE, and Cochrane Library were searched. Studies or subsets were included only if they satisfied certain criteria. The benefit rate which equaled the rate of improvement subjoining the rate of stabilization was calculated. All analyses were conducted with Stata version 12.0 (Stata Corporation, College Station, TX).

RESULTS

According to 7 papers on the efficacy of renal artery stent, 253 SFK patients were included. The result revealed that the renal artery stent could help SFK patients to improve or stabilize their renal function (RF). The benefit rate was 0.77, with 95% confidence interval between 0.72 and 0.83.

CONCLUSIONS

With proper patient selection, renal artery stent could benefit SFK patients with a percentage odd of 0.77 to improve or stabilize the RF.

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.

Sirolimus-Eluting versus Bare-Metal Low-Profile Stent for Renal Artery Treatment (GREAT Trial): Angiographic Follow-up after 6 Months and Clinical Outcome up to 2 Years

Purpose:

To evaluate the patency of sirolimus-eluting stents (SES) compared to bare-metal stents (BMS) in the treatment of atherosclerotic renal artery stenosis (RAS).

Methods:

Between November 2001 to June 2003, 105 consecutive symptomatic patients (53 men; mean age 65.7 years) with RAS were treated with either a bare-metal (n=52) or a drug-eluting (n=53) low-profile Palmaz-Genesis peripheral stent at 11 centers in a prospective nonrandomized trial. The primary endpoint was the angiographic result at 6 months measured with quantitative vessel analysis by an independent core laboratory. Secondary endpoints were technical and procedural success, clinical patency [no target lesion revascularization (TLR)], blood pressure and antihypertensive drug use, worsening of renal function, and no major adverse events at 1, 6, 12, and 24 months.

Results:

At 6 months, the overall in-stent diameter stenosis for BMS was 23.9%±22.9% versus 18.7%±15.6% for SES (p=0.39). The binary restenosis rate was 6.7% for SES versus 14.6% for the BMS (p=0.30). After 6 months and 1 year, TLR rate was 7.7% and 11.5%, respectively, in the BMS group versus 1.9% at both time points in the SES group (p=0.21). This rate remained stable up to the 2-year follow-up but did not reach significance due to the small sample. Even as early as 6 months, both types of stents significantly improved blood pressure and reduced antihypertensive medication compared to baseline (p<0.01). After 6 months, renal function worsened in 4.6% of the BMS patients and in 6.9% of the SES group. The rate of major adverse events was 23.7% for the BMS group and 26.8% for the SES at 2 years (p=0.80).

Conclusion:

The angiographic outcome at 6 months did not show a significant difference between BMS and SES. Renal artery stenting with both stents significantly improved blood pressure. Future studies with a larger patient population and longer angiographic follow-up are warranted to determine if there is a significant benefit of drug-eluting stents in treating ostial renal artery stenosis.

Stent-Related Iliac Artery and Iliac Vein Infections: Two Unreported Presentations and Review of the Literature

Purpose:

To discuss the presentation, diagnosis, and treatment of stent-related infections on the basis of 2 new cases and historical review.

Case Reports:

Two previously unreported cases of vascular stent infection are presented with a summary of cases from the literature. One case involved an iliac artery stent infection secondary to a remote bacteremia 6 months after stent placement. The other case was an early iliac vein stent infection, a previously unreported site of this complication. Both cases were diagnosed by use of computed tomography and were treated surgically after medical management failed. Both patients survived.

Conclusions:

A high index of suspicion is necessary for the diagnosis of stent infections, and an aggressive treatment is usually necessary for survival. Prophylactic antibiotics should definitely be considered in cases involving repeat interventions and prolonged catheterization, as well as before bacteremia-inducing therapies.

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.

Stenting for Stenoses of the Proximal Vertebral Artery

We report our initial experience of stenting for symptomatic stenoses of the proximal vertebral artery. A total of 25 lesions affecting the proximal vertebral artery were treated by PTA with stent in 23 patients. The lesions involved the vertebral artery ostium in 20 lesions and the nonostial V1 portion in five lesions. The mean stenosis rate of those lesions was 81% pre-stenting and was reduced to 4% post-stenting.

There were two transient neurological complications: hemiparesis in one patient and visual acuity disturbance in another. Angiographic follow-up studies more than three months after treatment demonstrated restenosis in three patients. One of these patients was symptomatic. These restenoses were successfully treated by PTA.

Our initial results demonstrated that stenting is a feasible and safe method of treating stenosis of the proximal vertebral artery.

Stenting for Extracranial Stenotic Lesions of Carotid and Vertebral Arteries

We evaluated the feasibility of stenting in four patients. Two cases were vertebral osteal stenosis and the others were carotid stenosis at high position with ulcers. We placed balloon expandable coronary stents by a bared stent technique. The mean preprocedural stenosis (86.58%) was reduced to 13.05%. Patients were examined clinically and angiographically at 1, 3 and 6 months after stenting. There was no minor nor major stroke during and after the procedures. Asymptomatic restenosis occurred in the cases of proximal vertebral arteries. One of these patients needed to repeat balloon dilatation. There were no angiographic restenoses in the location of stenting in the carotid artery.

In the treatment for atherosclerotic stenoses, stent placement is a feasible and safe method. However restenosis in a vertebral osteal lesion should be carefully followed after stent placement.

What Interventional Cardiologists Are Still Leaving to the Surgeons?

Nowadays, development of new technologies is still ongoing with the ultimate goal of maximizing treatment outcomes with less invasiveness and reduced procedural risk. This review is intended to update on when interventionalists need surgical support in common or emerging problems in congenital heart disease.

A Novel Approach to Overcome Stent Strut Entrapment of the Distal Filter Retrieval Catheter during Vertebral Artery Stenting: The "Olive-Tipped" Technique

We developed an "olive-tipped" technique for preventing the distal filter retrieval catheter from entrapment in the stent struts during retrieval procedures after stent deployment and which we used in 2 vertebral artery stenting cases. A new wire entry port was made in the catheter at the transition of larger and smaller lumen to permit passage of a low-profile balloon into the lumen of the retrieval catheter. When the balloon was inflated across the retrieval catheter tip, a smoother profile was created which eliminated the sharp step between the catheter tip and the filter wire. The retrieval catheter could then be advanced easily through the stent struts using this modified system.

Ultrasonographic evaluation of the renal transplant

Ultrasonography is an excellent tool for evaluation of the renal transplant in the immediate postoperative period and for long-term follow-up. In this article, normal imaging findings and complications of renal transplantations are described. Disease processes are divided into vascular, perinephric, urologic and collecting system, and parenchymal abnormalities. Attention is paid to the time of occurrence of each complication, classic imaging findings, and potential pitfalls.

Infections of intravascular bare metal stents: a case report and review of literature

OBJECTIVE

The objective of the paper is to present a case of an infected bare metal stent in the left common iliac artery that was removed by an urgent operation, and to review the literature on diagnosis and outcome of infected coronary and non-coronary metal stents.

METHODS

A systematic search of the Medline database was performed with the purpose of identifying risk factors, signs and symptoms, imaging strategies, and treatment modalities of bare metal stent infections, both coronary and peripheral.

RESULTS

In total, 76 additional studies/case reports (48 non-coronary; 29 coronary) were included and analyzed. Intravascular bare metal stent infections are a rare but serious complication, often leading to emergency surgery (overall: 75.3%; non-coronary cases: 83.3%; coronary cases: 62.1%). In 25.0% of the non-coronary cases, infection led to amputation of an extremity or removal of viscera. Reported mortality was up to 32.5% of the cases (non-coronary: 22.9%; coronary 48.3%). Physicians should always be suspicious of a stent infection when patients present with aspecific symptoms such as fever and chills after stent placement. Additional imaging can be used to detect the presence of a pseudoaneurysm. A PET-CT is an ideal medium for identification of a stent infection.

CONCLUSIONS

Intravascular stent infection is associated with a high risk of morbidity and mortality. Surgery is the preferred treatment option, but not always possible, especially in patients with a coronary stent. In selected cases, bare metal stent infections may be prevented by the use of prophylactic antibiotics at stent placement.

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.

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.

Stent placement for atherosclerotic stenosis of the vertebral artery ostium: angiographic and clinical outcomes in 117 consecutive patients

BACKGROUND

Although it is thought to be a safe treatment option, the main concerns related to treating vertebral artery ostium (VAO) stenosis with stents have been the rate of restenosis and the uncertain long-term results.

OBJECTIVE

To evaluate the angiographic and clinical results of stent placement for atherosclerotic stenosis of the VAO.

METHODS

One hundred seventeen consecutive patients with atherosclerotic VAO stenosis were treated with stent placement over a period of 12 years. All patients were retrospectively analyzed through the use of a prospectively collected database. The indication criteria for this treatment protocol were symptomatic severe VAO stenoses (> 60%) and asymptomatic severe VAO stenoses (> 60%) with incidentally detected infarction in the posterior circulation. The target diameter of stent dilatation from 1997 to 2000 was the normal vessel diameter just distal to the lesion. Moderate overdilation in the proximal portion of the stents has been performed since 2001.

RESULTS

Successful dilatation was obtained in 116 of 117 cases. Transient neurological complications developed in 2 patients; however, no patients experienced any permanent neurological complications. One hundred four patients underwent follow-up angiography at 6 months after stenting. The restenosis rate at the 6-month follow-up was 9.6% (10 of 104). Until 2000, the restenosis rate after stenting was 13.3%. Since 2001, the restenosis rate has decreased to 4.5%. The median clinical follow-up period was 48 months. The annual rate of strokes in the posterior circulation was 0.95%.

CONCLUSION

Stent placement for atherosclerotic VAO stenosis is considered to be a feasible and safe treatment and may be effective for stroke prevention. The moderate overdilation of stents may be an effective modality for the prevention of restenosis.

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.

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.

Percutaneous revascularization of persistent renal artery in-stent restenosis

Abstract

Percutaneous renal artery stenting is a common means of treating atherosclerotic renal artery stenosis. However, renal artery restenosis remains a frequent problem. The optimal treatment of restenosis has not been established and may involve percutaneous renal artery angioplasty or deployment of a second stent. Other modalities include cutting balloon angioplasty, repeat stenting with drug-eluting stents or endovascular brachytherapy. Most recently, use of polytetrafluoroethylene (PTFE)-covered stents may offer a new and innovative way to treat recurrent renal artery stenosis. We describe a case in a patient who initially presented with renal insufficiency and multi-drug hypertension in the setting of severe bilateral renal artery stenosis. Her renal artery stenosis was initially successfully treated by percutaneous deployment of bilateral bare metal renal artery stents. After initial improvement of her hypertension and renal insufficiency, both parameters declined and follow-up duplex evaluation confirmed renal artery in-stent restenosis. Owing to other medical co-morbidities she was felt to be a poor surgical candidate and was subsequently treated first with bilateral cutting balloon angioplasty and second with drug-eluting stent deployment. Each procedure was associated with initial improvement of renal function and blood pressure control, which then later deteriorated with the development of further significant in-stent restenosis. It was then decided to treat the restenosis using PTFE-covered stents. At 12 months of follow-up, the blood pressure had remained stable and renal function had normalized. The covered stents remained free of any significant neointimal tissue or obstruction.

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.

Bare metal stent infections: Case report and review of the literature

Infection of bare metal stents in the vasculature is rare, but associated with significant morbidity and mortality. We report two cases of bare metal stent infections and review the literature regarding infected bare metal stents with respect to risk factors, pathophysiology, diagnosis, treatment, and prevention. Overall, this article highlights the need to have a high index of suspicion of bare metal stent infection, since prompt diagnosis and treatment can ultimately decrease the morbidity and mortality associated with this devastating problem.

Renal artery stenosis

Fibromuscular dysplasia (FMD) and aortoarteritis are the most frequent causes of secondary hypertension induced by renal artery stenosis (RAS). Revascularization of this disease entity usually cures arterial hypertension. Demographic evolution leads to an increasing incidence of atherosclerotic RAS, one of the major causes of end-stage renal failure. Furthermore, atherosclerotic RAS leads to deterioration of primary hypertension, progression of atherosclerosis manifestation such as occlusive and aneurysmatic peripheral artery disease, and chronic or acute organ damage such as left ventricular hypertrophy and recurrent flash pulmonary edema. Despite the lack of sufficiently powered randomized controlled trials, each hemodynamically relevant RAS (eg, > or = 70%) should be considered for stent angioplasty in patients without end-stage ischemic nephropathy or limited life expectancy due to concomitant disease (eg, cancer). Drug-eluting stents will probably reduce the overall low in-stent restenosis rate of 10% to 20%. Interventions in patients with dialysis-dependent end-stage nephropathy are left to appropriate clinical study protocols.

Novel stent system for accurate placement in aorto-ostial renal artery disease: preclinical study in porcine renal artery model

BACKGROUND

Treatment of aorto-ostial renal artery stenosis has been associated with a lower procedural success and higher complication and restenosis rate, as compared to nonostial lesions. The design and delivery of currently available stent systems in ostial lesions can result in inaccurate stent positioning and placement leading to stent protrusion into the parent vessel lumen or geographic miss. A novel stent system (SquareOne Inc., Campbell, CA, USA) has been designed specifically for aorto-ostial lesions in the renal artery. This stent system aims to provide both tactile and visual confirmation of the ostium at the aorta, allow for improved accuracy during stent positioning and placement, provide complete scaffolding of the lesion at the aortic junction to the native vessel, and enable future vessel reaccess.

METHODS

Stents (n=12) were implanted in both renal arteries of six swine. For histology, two animals were euthanized immediately after stent implantation, and each two animals were then followed up at 2 and 4 weeks, respectively. Intravascular ultrasound (IVUS) studies were performed immediately after stent implantation and at follow-up.

RESULTS

Proper stent positioning and implantation was obtained in all animals. Angiographic and IVUS assessments indicated no dissection or thrombus formation. Histology demonstrated good apposition and endothelialization of the stent strut surface.

CONCLUSION

The unique flared shape of this novel ostial stent system allows for improved accuracy during stent positioning and placement, as well as complete apposition and coverage/scaffolding of the similarly-shaped luminal ostium. Future studies will determine if this novel stent system fulfills the unmet clinical need in aorto-ostial stenoses.

Long-Term Follow-up of Renal Artery Stenting in an Australian Population

BACKGROUND

Renal artery stenosis comprises both atherosclerotic renovascular disease and fibromuscular dysplasia, and may be associated with refractory hypertension, acute 'flash' pulmonary oedema and renal failure. The long-term clinical effects of renal artery stenting remain unclear.

AIM

To assess the procedural and long-term safety and efficacy of renal artery stenting and its effect on blood pressure, antihypertensive medication usage and serum creatinine.

METHODS

All patients referred for renal artery stenting at our institution between September 1997 and December 2003 were entered into a prospectively collected database. Systolic and diastolic blood pressure, number of antihypertensive medications, serum creatinine and estimated glomerular filtration rate (eGFR) were recorded. Patients were followed-up at least six months post-procedure.

RESULTS

Eighty-nine patients underwent renal arteriography, with 110 stents deployed in 102 lesions. The procedural success rate was 99% with no procedural mortality. There were two cases of peri-procedural haemorrhage and one of sepsis. One patient developed renal and peripheral atheroemboli.

FOLLOW-UP

Mean follow-up was 28 months (range 6 months-7 years). Eight patients were lost to follow-up. There were nine deaths with a mean time to death of 20.7 months (range 12 months-3 years). There was a highly statistically significant fall in systolic blood pressure (BP) from 161.7+/-29.5 mmHg pre-procedure to 138.7+/-17.9 mmHg at long-term follow-up post-procedure (p<0.0001). The clinical restenosis rate was 6.2%. Renal function and eGFR remained stable and there was a borderline significant decrease in the number of antihypertensive medications used (p=0.05).

CONCLUSION

Renal artery stenting is safe and appears effective for the treatment of clinically significant renal artery stenosis.

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.

Stent revascularization for the prevention of cardiovascular and renal events among patients with renal artery stenosis and systolic hypertension: rationale and design of the CORAL trial

BACKGROUND

Atherosclerotic renal artery stenosis is a problem with no consensus on diagnosis or therapy. The consequences of renal ischemia are neuroendocrine activation, hypertension, and renal insufficiency that can potentially result in acceleration of atherosclerosis, further renal dysfunction, myocardial infarction, heart failure, stroke, and death. Whether revascularization improves clinical outcomes when compared with optimum medical therapy is unknown.

METHODS

CORAL is a randomized clinical trial contrasting optimum medical therapy alone to stenting with optimum medical therapy on a composite cardiovascular and renal end point: cardiovascular or renal death, myocardial infarction, hospitalization for congestive heart failure, stroke, doubling of serum creatinine, and need for renal replacement therapy. The secondary end points evaluate the effectiveness of revascularization in important subgroups of patients and with respect to all-cause mortality, kidney function, renal artery patency, microvascular renal function, and blood pressure control. We will also correlate stenosis severity with longitudinal renal function and determine the value of stenting from the perspectives of quality of life and cost-effectiveness. The primary entry criteria are (1) an atherosclerotic renal stenosis of > or = 60% with a 20 mm Hg systolic pressure gradient or > or = 80% with no gradient necessary and (2) systolic hypertension of > or = 155 mm Hg on > or = 2 antihypertensive medications. Randomization will occur in 1080 subjects. The study has 90% power to detect a 28% reduction in primary end point hazard rate.

CONCLUSIONS

CORAL represents a unique opportunity to determine the incremental value of stent revascularization, in addition to optimal medical therapy, for the treatment of atherosclerotic renal artery stenosis.

Treatment of severe renal artery stenosis by percutaneous transluminal renal angioplasty and stent implantation: review of the pediatric experience: apropos of two cases

The clinical course of two children with mid-aortic syndrome and renal artery stenosis (RAS) who suffered from severe arterial hypertension is described. Hypertension was uncontrollable by antihypertensive medication and was managed by percutaneous transluminal renal angioplasty (PTRA) with stent implantation. The pediatric experience with PTRA is limited, and there are only few cases reported with additional stent implantation. Complications of these procedures are well known from experience with adult patients. However, since surgical revascularization may be technically difficult especially in small children, PTRA with or without stenting should be considered as a valuable treatment option in pediatric RAS.

Complications of renal transplantation

Continued improvements in graft survival have led to widespread acceptance of renal transplantation as the preferred treatment for the majority of patients with end-stage renal disease. The long-term care of these patients is often provided away from transplantation centers. This article presents both the clinical and imaging features of renal transplantation complications and their interventional management. Urologic and vascular complications may occur. Vascular complications include renal artery stenosis and renal artery and renal vein thrombosis. Ultrasound can accurately depict and characterize many of the potential complications of renal transplantation and increasingly magnetic resonance imaging also facilitates this role. In addition, interventional radiologic techniques allow nonsurgical treatment.

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.

Evaluation of the Safety and Effectiveness of Renal Artery Stenting After Unsuccessful Balloon Angioplasty

OBJECTIVES

This study sought to define the safety and durability of renal stenting after suboptimal/failed renal artery angioplasty in patients with suspected renovascular hypertension.

BACKGROUND

Few prospective multicenter studies have detailed the safety, efficacy, and long-term clinical benefits of renal artery stent revascularization in hypertensive patients with aorto-ostial atherosclerotic renal artery lesions.

METHODS

This non-randomized study enrolled 208 patients with de novo or restenotic > or = 70% aorto-ostial renal artery stenoses, who underwent implantation of a balloon-expandable stent after unsuccessful percutaneous transluminal renal angioplasty (PTRA), which was defined as a > or = 50% residual stenosis, persistent translesional pressure gradient, or a flow-limiting dissection. The primary end point was the nine-month quantitative angiographic or duplex ultrasonography restenosis rate adjudicated by core laboratory analysis. Secondary end points included renal function, blood pressure, and cumulative incidence of major adverse events and target lesion revascularization at 24 months.

RESULTS

The stent procedure was immediately successful in 182 of 227 (80.2%) lesions treated. The nine-month restenosis rate was 17.4%. Systolic/diastolic blood pressure decreased from 168 +/- 25/82 +/- 13 mm Hg (mean +/- standard deviation) at baseline to 149 +/- 24/77 +/- 12 mm Hg at 9 months (p < 0.001 vs. baseline), and 149 +/- 25/77 +/- 12 mm Hg at 24 months (p < 0.001 vs. baseline). Mean serum creatinine concentration was unchanged from baseline values at 9 and 24 months. The 24-month cumulative rate of major adverse events was 19.7%.

CONCLUSIONS

In hypertensive patients with aorto-ostial atherosclerotic renal artery stenosis in whom PTRA is unsuccessful, Palmaz (Cordis Corp., Warren, New Jersey) balloon-expandable stents provide a safe and durable revascularization strategy, with a beneficial impact on hypertension.

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.

Intravascular ultrasound-guided cutting balloon angioplasty for renal artery stent restenosis

Renal artery stenting is the procedure of choice for treating atherosclerotic renal artery stenosis; it improves the acute results of percutaneous balloon angioplasty and has a better long-term outcome, particularly a reduced risk of restenosis. However, the treatment of renal artery stent restenosis is not well established and it is challenging because of limited therapeutic options. A novel technique of treating renal artery stent restenosis using cutting balloon angioplasty guided by intravascular ultrasound is presented.