Embolic Protection and Platelet Inhibition During Renal Artery Stenting

Interventions for renal artery stenosis: Appraisal of novel physiological insights and procedural techniques to improve clinical outcome

Randomized clinical trials failed to show additional benefit of renal artery stenting on top of medical therapy. Instead of writing an obituary on renal artery stenting, we try to explain these disappointing results. A transstenotic pressure gradient is needed to reduce renal perfusion and to activate the renin-angiotensin-aldosterone system. In only a minority of patients included in trials, a transstenotic pressure gradient is measured and reported. Like the coronary circulation, integration of physiological lesion assessment will allow to avoid stenting of non-significant lesions and select those patients that are most likely to benefit from renal artery stenting. Renal artery interventions are associated with peri-procedural complications. Contemporary techniques, including radial artery access, no-touch technique to engage the renal ostium and the use of embolic protection devices, will minimize procedural risk. Combining optimal patient selection and meticulous technique might lead to a netto clinical benefit when renal artery stenting is added to optimal medical therapy.

Atherosclerotic renovascular disease: a clinical practice document by the European Renal Best Practice (ERBP) board of the European Renal Association (ERA) and the Working Group Hypertension and the Kidney of the European Society of Hypertension (ESH)

Atherosclerotic renovascular disease (ARVD) is the most common type of renal artery stenosis. It represents a common health problem with clinical presentations relevant to many medical specialties and carries a high risk for future cardiovascular and renal events, as well as overall mortality. The available evidence regarding the management of ARVD is conflicting. Randomized controlled trials failed to demonstrate superiority of percutaneous transluminal renal artery angioplasty (PTRA) with or without stenting in addition to standard medical therapy compared with medical therapy alone in lowering blood pressure levels or preventing adverse renal and cardiovascular outcomes in patients with ARVD, but they carried several limitations and met important criticism. Observational studies showed that PTRA is associated with future cardiorenal benefits in patients presenting with high-risk ARVD phenotypes (i.e. flash pulmonary oedema, resistant hypertension or rapid loss of kidney function). This clinical practice document, prepared by experts from the European Renal Best Practice (ERBP) board of the European Renal Association (ERA) and from the Working Group on Hypertension and the Kidney of the European Society of Hypertension (ESH), summarizes current knowledge in epidemiology, pathophysiology and diagnostic assessment of ARVD and presents, following a systematic literature review, key evidence relevant to treatment, with an aim to support clinicians in decision making and everyday management of patients with this condition.

Ultra-Low-Dose Contrast Using Transluminal Renal Angioplasty: The ULTRA Study

BACKGROUND

Although severe atherosclerotic renal artery stenosis (ARAS) is a predictor of future cardiovascular events, large trials have not shown the benefits of percutaneous transluminal renal angioplasty (PTRA). This study aimed to validate the safety and efficacy of PTRA using low-concentration digital subtraction angiography (LC-DSA) in patients with severe ARAS and advanced chronic kidney disease (CKD).

MATERIALS AND METHODS

This prospective study was conducted between August 2018 and October 2021. Eighteen patients with 20 lesions, CKD stage 3b or worse, and significant renal artery stenosis were included and underwent PTRA using ultra-low-dose contrast medium. The primary endpoint was a change in renal function based on serum creatinine (sCr) level.

RESULTS

The mean sCr level significantly improved from 3.34 ± 1.8 mg/dL pre-PTRA to 2.48 ± 1.19 mg/dL at 1 month post-PTRA (P = .02). The mean amount of contrast used was 8.3 ± 3.9 mL per vessel. More severe stenosis and rapid deterioration of renal function before treatment were associated with improved kidney function. No cardiovascular or renal complications such as stroke or contrast-induced nephropathy were observed during the 30-day period.

CONCLUSIONS

PTRA using an ultra-low-dose contrast medium is safe and provides acceptable results.

Six Decades of History of Hypertension Research at the University of Toledo: Highlighting Pioneering Contributions in Biochemistry, Genetics, and Host-Microbiota Interactions

PURPOSE OF REVIEW

The study aims to capture the history and lineage of hypertension researchers from the University of Toledo in Ohio and showcase their collective scientific contributions dating from their initial discoveries of the physiology of adrenal and renal systems and genetics regulating blood pressure (BP) to its more contemporary contributions including microbiota and metabolomic links to BP regulation.

RECENT FINDINGS

The University of Toledo College of Medicine and Life Sciences (UTCOMLS), previously known as the Medical College of Ohio, has contributed significantly to our understanding of the etiology of hypertension. Two of the scientists, Patrick Mulrow and John Rapp from UTCOMLS, have been recognized with the highest honor, the Excellence in Hypertension award from the American Heart Association for their pioneering work on the physiology and genetics of hypertension, respectively. More recently, Bina Joe has continued their legacy in the basic sciences by uncovering previously unknown novel links between microbiota and metabolites to the etiology of hypertension, work that has been recognized by the American Heart Association with multiple awards. On the clinical research front, Christopher Cooper and colleagues lead the CORAL trials and contributed importantly to the investigations on renal artery stenosis treatment paradigms. Hypertension research at this institution has not only provided these pioneering insights, but also grown careers of scientists as leaders in academia as University Presidents and Deans of Medical Schools. Through the last decade, the university has expanded its commitment to Hypertension research as evident through the development of the Center for Hypertension and Precision Medicine led by Bina Joe as its founding Director. Hypertension being the top risk factor for cardiovascular diseases, which is the leading cause of human mortality, is an important area of research in multiple international universities. The UTCOMLS is one such university which, for the last 6 decades, has made significant contributions to our current understanding of hypertension. This review is a synthesis of this rich history. Additionally, it also serves as a collection of audio archives by more recent faculty who are also prominent leaders in the field of hypertension research, including John Rapp, Bina Joe, and Christopher Cooper, which are cataloged at Interviews .

Revascularization for Renovascular Disease: A Scientific Statement From the American Heart Association

Renovascular disease is a major causal factor for secondary hypertension and renal ischemic disease. However, several prospective, randomized trials for atherosclerotic disease failed to demonstrate that renal revascularization is more effective than medical therapy for most patients. These results have greatly reduced the generalized diagnostic workup and use of renal revascularization. Most guidelines and review articles emphasize the limited average improvement and fail to identify those clinical populations that do benefit from revascularization. On the basis of the clinical experience of hypertension centers, specialists have continued selective revascularization, albeit without a summary statement by a major, multidisciplinary, national organization that identifies specific populations that may benefit. In this scientific statement for health care professionals and the public-at-large, we review the strengths and weaknesses of randomized trials in revascularization and highlight (1) when referral for consideration of diagnostic workup and therapy may be warranted, (2) the evidence/rationale for these selective scenarios, (3) interventional and surgical techniques for effective revascularization, and (4) areas of research with unmet need.

Endovascular interventions in main renal artery pathologies: an overview and update

Renal arteries are involved in a wide spectrum of pathologies including atherosclerosis, fibromuscular dysplasia, Takayasu arteritis, aneurysms, and aortic type B dissections extending into main renal arteries. They manifest as renovascular hypertension, renal ischemia, and cardiovascular dysfunction. The location of the renal arteries in relation to the abdominal aortic aneurysm is a critical determinant of interventional options and long-term prognosis. This article provides a comprehensive review of the role of interventional radiologists in transcatheter interventions in various pathologies involving the main renal arteries with analysis of epidemiology, pathophysiology, newer interventional techniques, and management options.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet agents may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the benefits and harms of antiplatelet agents in people with any form of CKD, including those with CKD not receiving renal replacement therapy, patients receiving any form of dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 13 July 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet agents versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data were pooled using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 113 studies, enrolling 51,959 participants; 90 studies (40,597 CKD participants) compared an antiplatelet agent with placebo or no treatment, and 29 studies (11,805 CKD participants) directly compared one antiplatelet agent with another. Fifty-six new studies were added to this 2021 update. Seven studies originally excluded from the 2013 review were included, although they had a follow-up lower than two months. Random sequence generation and allocation concealment were at low risk of bias in 16 and 22 studies, respectively. Sixty-four studies reported low-risk methods for blinding of participants and investigators; outcome assessment was blinded in 41 studies. Forty-one studies were at low risk of attrition bias, 50 studies were at low risk of selective reporting bias, and 57 studies were at low risk of other potential sources of bias. Compared to placebo or no treatment, antiplatelet agents probably reduces myocardial infarction (18 studies, 15,289 participants: RR 0.88, 95% CI 0.79 to 0.99, I² = 0%; moderate certainty). Antiplatelet agents has uncertain effects on fatal or nonfatal stroke (12 studies, 10.382 participants: RR 1.01, 95% CI 0.64 to 1.59, I² = 37%; very low certainty) and may have little or no effect on death from any cause (35 studies, 18,241 participants: RR 0.94, 95 % CI 0.84 to 1.06, I² = 14%; low certainty). Antiplatelet therapy probably increases major bleeding in people with CKD and those treated with haemodialysis (HD) (29 studies, 16,194 participants: RR 1.35, 95% CI 1.10 to 1.65, I² = 12%; moderate certainty). In addition, antiplatelet therapy may increase minor bleeding in people with CKD and those treated with HD (21 studies, 13,218 participants: RR 1.55, 95% CI 1.27 to 1.90, I² = 58%; low certainty). Antiplatelet treatment may reduce early dialysis vascular access thrombosis (8 studies, 1525 participants) RR 0.52, 95% CI 0.38 to 0.70; low certainty). Antiplatelet agents may reduce doubling of serum creatinine in CKD (3 studies, 217 participants: RR 0.39, 95% CI 0.17 to 0.86, I² = 8%; low certainty). The treatment effects of antiplatelet agents on stroke, cardiovascular death, kidney failure, kidney transplant graft loss, transplant rejection, creatinine clearance, proteinuria, dialysis access failure, loss of primary unassisted patency, failure to attain suitability for dialysis, need of intervention and cardiovascular hospitalisation were uncertain. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, including prasugrel, ticagrelor, different doses of clopidogrel, abciximab, defibrotide, sarpogrelate and beraprost.

AUTHORS' CONCLUSIONS

Antiplatelet agents probably reduced myocardial infarction and increased major bleeding, but do not appear to reduce all-cause and cardiovascular death among people with CKD and those treated with dialysis. The treatment effects of antiplatelet agents compared with each other are uncertain.

When and How Should We Revascularize Patients With Atherosclerotic Renal Artery Stenosis?

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension and may lead to resistant (refractory) hypertension, progressive decline in renal function, and cardiac destabilization syndromes (pulmonary edema, recurrent heart failure, or acute coronary syndromes) despite guideline-directed medical therapy. Although randomized controlled trials comparing medical therapy with medical therapy and renal artery stenting have failed to show a benefit for renal artery stenting, according to comparative effectiveness reviews by the Agency for Healthcare Research and Quality, the trials may not have enrolled patients with the most severe atherosclerotic renal artery stenosis, who would be more likely to benefit from renal stenting. Because of limitations of conventional angiography, it is critical that the hemodynamic severity of moderately severe (50% to 70%) atherosclerotic renal artery stenosis lesions be confirmed on hemodynamic measurement. The authors review techniques to optimize patient selection, to minimize procedural complications, and to facilitate durable patency of renal stenting. The authors also review the current American College of Cardiology and American Heart Association guidelines and the Society for Cardiovascular Angiography and Interventions appropriate use criteria as they relate to renal stenting.

Renal and Mesenteric Artery Intervention

Atherosclerotic renal artery stenosis is the most common cause of secondary hypertension and may cause progressive renal disease and cardiac destabilization syndromes. Guideline-directed medical therapy is advised in all patients. Patients with refractory symptoms and hemodynamically significant stenoses are more likely to benefit from renal artery stent placement. Chronic mesenteric ischemia (CMI) is an infrequent and difficult to diagnose illness. Due to robust collateralization, clinical symptoms from mesenteric artery stenosis or occlusion is uncommon. Atherosclerosis is the most common etiology of CMI. Current evidence suggests that, compared with open surgical repair, endovascular therapy is the most cost-effective choice for CMI.

Is there still a role for renal artery stenting in the management of renovascular hypertension - A single-center experience and where do we stand?

BACKGROUND

Renal artery (RA) stenosis has been implicated in the pathophysiological mechanism for resistant hypertension. Despite the increasingly diagnosed frequency of hemodynamically significant lesions, the value of RA revascularization remains controversial. Our group had previously demonstrated significant blood pressure (BP) reduction in a retrospective cohort of appropriately selected patients undergoing RA stenting up to 18-months of follow-up. We herein present long-term clinical outcomes data 5-years post revascularization on 26 subjects who continued follow-up at our institution.

METHODS

Retrospective analysis was performed on subjects who underwent RA stenting at our institution for hemodynamically significant (≥70%) RA stenosis and systolic hypertension on ≥3 antihypertensive agents. Clinical outcome data for systolic blood pressure (SBP), diastolic blood pressure (DBP), creatinine level and number of antihypertensive drugs was assessed prior to and then later at 6-12 months and 3-5 years post RA stenting.

RESULTS

Mean age was 69 ± 9 years; 27% (7/26) were male. Median follow-up was 5.1 years. Blood pressure reduction was sustained at long-term follow-up (135/70 ± 18/11 mmHg) compared to initial reduction noted at 6-months (136/69 ± 16/8 mmHg; p ≤0.01 for both) and from baseline (162/80 ± 24/18 mmHg; p ≤0.001 for both). The number of antihypertensive agents also decreased from 4.1 ± 1.0 to 2.7 ± 2.1 (p = 0.002) at 6-months and was sustained at long-term follow-up, 3.4 ± 1.2 (p = 0.03) with no difference in renal function between short- and long-term follow-up compared to baseline.

CONCLUSIONS

This study shows sustained benefit of RA stenting in BP reduction in an appropriately selected cohort with significant stenosis ≥70% and uncontrolled hypertension on multiple medications on long-term follow-up.

Issues related to renal artery angioplasty and stenting

Renal artery stenosis may play a significant role in the pathogenesis of secondary hypertension, renal dysfunction, and flash pulmonary edema. Currently correction of renal arterial inflow stenosis is reserved for resistant hypertension patients who have failed maximal medical therapy, have worsening renal function and/or unexplained proximal congestive failure. With the recent advances in minimally invasive percutaneous stent placement techniques, open surgical revascularization has been largely replaced by renal artery stenting. The potential benefit of revascularization seemed intuitive; however, the initial enthusiasm and rise in the number of percutaneous interventions have been tempered by many subsequent negative randomized clinical trials that failed to prove the proposed benefits of the percutaneous intervention. The negative randomized trial results have fallen under scrutiny due to trial design concerns and inconsistent outcomes of these studies compared to pivotal trials undertaken under US Food and Drug Administration scrutiny. Treatment of atherosclerotic renal artery occlusive disease has become one of the most debatable topics in the field of vascular disease. The results from recent randomized clinical trials of renal artery stenting have basically limited the utilization of the procedure in many centers, but not every clinical scenario was covered in those trials. There are potential areas for improvement focusing mainly on procedural details and patient selection with respect to catheter based treatment of atherosclerotic renal artery stenosis. We believe, limiting patient selection, enrollment criteria and outcomes measured functioned to reduce the benefit of renal artery stenosis stenting by not enrolling patients likely to benefit. Future studies incorporating potential procedural improvements and that include patients more likely to benefit from renal stenting than were included in ASTRAL and CORAL are needed to more carefully examine specific patient subgroups so that “the baby is not thrown out with the bath water.” We also discuss several other concerns related to renal artery stenting which include diagnostic, procedure, indication, and reimbursement issues.

Issues related to renal artery angioplasty and stenting

Renal artery stenosis may play a significant role in the pathogenesis of secondary hypertension, renal dysfunction, and flash pulmonary edema. Currently correction of renal arterial inflow stenosis is reserved for resistant hypertension patients who have failed maximal medical therapy, have worsening renal function and/or unexplained proximal congestive failure. With the recent advances in minimally invasive percutaneous stent placement techniques, open surgical revascularization has been largely replaced by renal artery stenting. The potential benefit of revascularization seemed intuitive; however, the initial enthusiasm and rise in the number of percutaneous interventions have been tempered by many subsequent negative randomized clinical trials that failed to prove the proposed benefits of the percutaneous intervention. The negative randomized trial results have fallen under scrutiny due to trial design concerns and inconsistent outcomes of these studies compared to pivotal trials undertaken under US Food and Drug Administration scrutiny. Treatment of atherosclerotic renal artery occlusive disease has become one of the most debatable topics in the field of vascular disease. The results from recent randomized clinical trials of renal artery stenting have basically limited the utilization of the procedure in many centers, but not every clinical scenario was covered in those trials. There are potential areas for improvement focusing mainly on procedural details and patient selection with respect to catheter based treatment of atherosclerotic renal artery stenosis. We believe, limiting patient selection, enrollment criteria and outcomes measured functioned to reduce the benefit of renal artery stenosis stenting by not enrolling patients likely to benefit. Future studies incorporating potential procedural improvements and that include patients more likely to benefit from renal stenting than were included in ASTRAL and CORAL are needed to more carefully examine specific patient subgroups so that "the baby is not thrown out with the bath water." We also discuss several other concerns related to renal artery stenting which include diagnostic, procedure, indication, and reimbursement issues.

Renal Artery Stenosis: When to Revascularize in 2017

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension; it can also cause progressive renal insufficiency and cardiovascular complications such as refractory heart failure and flash pulmonary edema. Medical therapy including risk factor modification, renin-angiotensin-aldosterone system antagonists, lipid lowering agents, and antiplatelet therapy is the first line of treatment in all patients. Patients with uncontrolled renovascular hypertension despite optimal medical therapy, ischemic nephropathy, and cardiac destabilization syndromes who have severe renal artery stenosis are likely to benefit from renal artery revascularization. Screening for renal artery stenosis can be done with Doppler ultrasonography, computed tomographic angiography and magnetic resonance angiography. Invasive physiologic measurements are useful to confirm the severity of renal hypoperfusion and therefore improve the selection patients likely to respond to renal artery revascularization. Primary patency exceeds 80% at 5 years and surveillance for in-stent restenosis can be done with periodic clinical, laboratory, and imaging follow-up.

Renal Artery Stenosis: Optimal Therapy and Indications for Revascularization

Atherosclerotic renal artery stenosis (ARAS) is associated with increased cardiovascular risk and overall mortality. Manifestations of ARAS include resistant or malignant hypertension, progressive deterioration of renal function, and cardiac dysfunction syndromes of flash pulmonary edema and angina. Diagnosis rests upon non-invasive studies such as duplex ultrasonography and is confirmed using invasive renal arteriography. Regardless of the severity of ARAS, management of this entity has been a topic of contentious debate. For over two decades, the use of percutaneous revascularization to treat ARAS has been studied with various clinical trials. Though case series seem to demonstrate favorable clinical response to revascularization, the overwhelming majority of randomized clinical trials have not mirrored a robust outcome. In these trials, poor correlation is noted between the reduction of stenosis and the improvement of renovascular hypertension and glomerular filtration rate, and decrease in cardiovascular outcomes and mortality. With dichotomizing results, the explanation for these discrepant findings has been attributed to improper trial design and inappropriate patient selection. An overview of the treatment options available will be provided, with a focus on the methodology and design of clinical trials investigating the efficacy of percutaneous revascularization. Emphasis is placed on appropriate patient selection criteria, which may necessitate the use of hemodynamic lesion assessment and clinical correlation based on individualized care. When clinical equipoise exists between optimal medical therapy and revascularization, the current paradigm supports ongoing medical therapy as the treatment of choice. However, renal artery stenting remains a viable therapeutic option for those who continue to have clinical syndromes consistent with renal hypoperfusion while adequately treated with optimal medical therapy. Despite observational studies suggesting clinical benefit for this specific patient population, there remains a paucity of randomized clinical trial data. Further trials targeting the patients who are inadequately treated with optimal medical therapy need to be undertaken to confirm the efficacy of revascularization.

Associations of antiplatelet therapy and beta blockade with patient outcomes in atherosclerotic renovascular disease

Randomized trials have shown a neutral effect of percutaneous revascularization compared with optimal medical therapy in patients with atherosclerotic renovascular disease (ARVD). However, there are few data to define what constitutes optimal medical therapy. We present a retrospective analysis of 529 ARVD patients. Separate analyses were performed comparing outcomes in patients prescribed/not prescribed beta blocker and antiplatelet agents. Analyses were adjusted for effects of baseline covariates on probability of treatment and on clinical outcome. Over a median follow-up period of 3.8 years, antiplatelet therapy was associated with a reduced risk for death (relative risk, 0.52 [95% confidence interval {CI}: 0.31-0.89]; P = .02). Beta blocker therapy was associated with a reduced for death (relative risk, 0.45 [95% CI: 0.21-0.97]; P = .04) and nonfatal cardiovascular events (relative risk, 0.74 [95% CI: 0.60-0.90]; P = .003). Although limited by small patient numbers, this study suggests that in ARVD, treatment with antiplatelet therapy and beta blockade may associate with a prognostic benefit.

Endovascular versus medical therapy for atherosclerotic renovascular disease

The diagnosis of renal artery stenosis (RAS) has become increasingly common in part due to greater awareness of ischemic renal disease and increased use of diagnostic techniques. Over 90 % of RAS cases are caused by atherosclerotic renovascular disease (ARVD). Patients with ARVD are at high risk for fatal and nonfatal cardiovascular and renal events. The mortality rate in patients with ARVD is high, especially with other cardiovascular or renal comorbidities. Recent clinical studies have provided substantial evidence concerning medical therapy and endovascular interventional therapeutic approaches for ARVD. Despite previous randomized clinical trials, the optimal therapy for ARVD remained uncertain until the results of the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial were released recently. CORAL demonstrated that optimal medical therapy was equally effective to endovascular therapy in the treatment of ARVD. Clinicians can now practice with more evidence-based medicine to treat ARVD and potentially decrease mortality in patients with ARVD using optimal medical therapy.

Transradial access for renal artery intervention

INTRODUCTION

Percutaneous interventional procedures in the renal arteries are usually performed using a femoral or brachial vascular access. The transradial approach is becoming more popular for peripheral interventions, but limited data exists for renal artery angioplasty and stenting.

METHODS

We have analyzed the clinical, angiographic and technical results of renal artery stenting performed from radial artery access between 2012 and 2013. The radial artery anatomy was identified with aortography using 100 cm pig tail catheter. After engagement of the renal artery ostium with a 6F Multipurpose or 6F JR5 guiding catheter, the stenosis was passed with a 0.014" guidewire followed by angioplasty and stent implantation.

RESULTS

In 27 patients (mean age: 65.4 ± 9.17) with hemodynamically relevant renal artery stenosis (mean diameter stenosis: 77.7 ± 10.6%; right, n = 7; left, n = 20), interventional treatment with angioplasty and stenting was performed using a left (n = 3) or right (n = 24) radial artery access. Direct stenting was successfully performed in 13 (48%) cases, and predilatations were required in ten cases 10 (37%). Primary technical success (residual stenosis <30%) could be achieved in all cases. The mean contrast consumption was 119 ± 65 ml and the mean procedure time was 30 ± 8.2 min. There were no major periprocedural vascular complications and in one patient transient creatinine level elevation was observed (3.7%). In one patient asymptomatic radial artery occlusion was detected (3.7%).

CONCLUSION

Transradial renal artery angioplasty and stenting is technically feasible and safe procedure.

Technical discussion of diagnostic angiography and intervention of atherosclerotic renal artery stenosis

Renal artery stenting remains an important adjuvant treatment for true-resistant hypertension, although recent disappointing randomized trials highlight the importance of careful patient selection. Safe and successful renal interventions begin with critical core knowledge regarding renal artery anatomy and understanding the often hostile nature of the parent vessel (pararenal aorta). Armed with fundamental knowledge about anatomy and renal ostial disease pathology, it becomes easier to understand the advantages of less traumatic access techniques and how low-profile contemporary flexible stents have enhanced outcomes. In addition to suggested techniques based on detailed understanding of the vessel architecture and pathology, we will review the current available US Food and Drug Administration-approved balloon-expandable on-label renal stents and discuss the role of intravascular ultrasound for definition of lesion severity, stent sizing, and stent apposition. The durability of renal stenting will also be discussed, as will the velocity criteria for duplex surveillance. Lastly, the current empirical data related to renal embolic protection is provided, along with insight into technical issues in this domain.

SCAI expert consensus statement for renal artery stenting appropriate use

The pathophysiology of atherosclerotic renal artery stenosis (RAS) includes activation of the renin-angiotensin-aldosterone axis with resultant renovascular hypertension. Renal artery stenting has emerged as the primary revascularization strategy in most patients with hemodynamically significant atherosclerotic RAS. Despite the frequency with which hemodynamically significant RAS is observed and high rates of technical success of renal artery stenting, there remains considerable debate among experts regarding the role of medical therapy versus revascularization for renovascular hypertension. Modern, prospective, multicenter registries continue to demonstrate improvement in systolic and diastolic blood pressure with excellent safety profiles in patients with RAS. Modern randomized, controlled clinical trials of optimal medical therapy versus renal stenting particularly designed to demonstrate preservation in renal function after renal artery stenting have demonstrated limited benefit. However, these trials frequently excluded patients that may benefit from renal artery stenting. This document was developed to guide physicians in the modern practical application of renal stenting, to highlight the current limitations in the peer-reviewed literature, to suggest best-practices in the performance of renal stenting and to identify opportunities to advance the field.

Management of Renal Arterial Disease

Severe atherosclerotic renal artery stenosis can manifest as treatment-resistant hypertension, ischemic nephropathy and/or cardiac disturbance syndromes of recurrent flash pulmonary edema and refractory angina. Renal artery revascularization can dramatically impact patient outcome. However, patient selection for revascularization can be challenging. Renal artery stenting is most commonly used for renal revascularization and is a safe procedure when performed in carefully selected patients. This review addresses the pathophysiology of renal artery stenosis and the data supporting revascularization in such patients.

Revascularization as a treatment to improve renal function

An aging atherosclerosis-prone population has led to an increase in the prevalence of atherosclerotic renovascular disease (ARVD). Medical management of this disease, as with other atherosclerotic conditions, has improved over the past decade. Despite the widespread availability of endovascular revascularization procedures, there is inconsistent evidence of benefit in ARVD and no clear consensus of opinion as to the best way to select suitable patients for revascularization. Several published randomized controlled trials have attempted to provide clearer evidence for best practice in ARVD, but they have done so with varying clarity and success. In this review, we provide an overview of ARVD and its effect on renal function. We present the currently available evidence for best practice in the management of patients with ARVD with a particular focus on revascularization as a treatment to improve renal function. We provide a brief overview of the evidence for revascularization in other causes of renal artery stenosis.

Roll-in experience from the Cardiovascular Outcomes with Renal Atherosclerotic Lesions (CORAL) study

PURPOSE

To describe the experience and results from the roll-in phase of the Cardiovascular Outcomes with Renal Atherosclerotic Lesions (CORAL) study.

MATERIALS AND METHODS

The CORAL roll-in database was used to describe the baseline characteristics of the patients in the roll-in cohort, all of whom underwent renal artery stent placement; to evaluate CORAL site performance; to compare estimates of lesion (stenosis) severity made by site interventionalists with the central CORAL angiographic core laboratory readings; and to report outcomes after renal artery stent placement. During the roll-in phase, 239 patients (mean age, 70.2 y ± 9.0; 49% male) underwent renal artery stent procedures. Angiographic core laboratory analysis of renal arteriograms was done, and participants were followed at 1 month and 9 months.

RESULTS

Major angiographic complications were identified in 28 (13%) subjects. Kidney function remained unchanged at the short (2-4 weeks) follow-up interval. Improvement in systolic blood pressure with use of distal embolic protection devices (n = 161) did not show any clinical benefit over nonuse of such devices (n = 78) in this small series. At 9 months, there were significantly more endpoints reported by site in subjects with bilateral renal artery stenosis (P = .01) and prior history of stroke (P = .03).

CONCLUSIONS

In the roll-in phase of the CORAL study, a significant number of angiographic complications were identified. No effect was seen on estimated glomerular filtration rate after renal artery stent placement, but systolic blood pressure decreased significantly.

Use of embolic protective devices in treating acute arterial occlusions: an interventional radiology and vascular surgery collaborative learning experience

A 43-year-old man presented to the emergency department with left leg claudication. CT angiogram confirmed an acute left leg arterial occlusion from a left ventricular thrombus. During intra-arterial thrombolysis, he developed severe abdominal pain and a CT angiogram confirmed an acute occlusive thromboembolism to his left renal artery. Prior to left renal artery intra-arterial embolectomy, temporary intra-arterial occlusion balloons were inflated within his (1) right renal artery to protect this kidney from acute embolism and (2) left iliac artery to protect his left leg from further clot burden. Following the left renal embolectomy, an angiogram demonstrated patent renal arteries, acute occlusion of the right common iliac artery and persistent clot in his left iliac/lower limb. These occlusions were retrieved by surgical embolectomy. Final angiogram demonstrated patent bilateral iliac/lower limb arteries. The patient was discharged on lifelong anticoagulation and remains asymptomatic with bilateral palpable distal pulses and normal serum creatine.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet treatment may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased.

OBJECTIVES

To summarise the effects of antiplatelet treatment (antiplatelet agent versus control or other antiplatelet agent) for the prevention of cardiovascular and adverse kidney outcomes in individuals with CKD.

SEARCH METHODS

In January 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Cochrane Renal Group's Specialised Register without language restriction.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet treatment versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data was pooled using the random-effects model.

MAIN RESULTS

We included 50 studies, enrolling 27,139 participants; 44 studies (21,460 participants) compared an antiplatelet agent with placebo or no treatment, and six studies (5679 participants) directly compared one antiplatelet agent with another. Compared to placebo or no treatment, antiplatelet agents reduced the risk of myocardial infarction (17 studies; RR 0.87, 95% CI 0.76 to 0.99), but not all-cause mortality (30 studies; RR 0.93, 95% CI 0.81 to 1.06), cardiovascular mortality (19 studies; RR 0.89, 95% CI 0.70 to 1.12) or stroke (11 studies; RR 1.00, 95% CI 0.58 to 1.72). Antiplatelet agents increased the risk of major (27 studies; RR 1.33, 95% CI 1.10 to 1.65) and minor bleeding (18 studies; RR 1.49, 95% CI 1.12 to 1.97). In terms of dialysis access outcomes, antiplatelet agents reduced access thrombosis or patency failure but had no effect on suitability for dialysis. Meta-regression analysis indicated no differences in the relative benefit or harms of treatment (risk of all-cause mortality, myocardial infarction, or major bleeding) by type of antiplatelet agent or stage of CKD. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, treatment in kidney transplant recipients, primary prevention, or risk of ESKD.

AUTHORS' CONCLUSIONS

Antiplatelet agents reduce myocardial infarction but increase major bleeding. Risks may outweigh harms among people with low annual risks of cardiovascular events, including those with early stages of CKD who do not have clinically-evident occlusive cardiovascular disease.

Effect of CD40 and sCD40L on renal function and survival in patients with renal artery stenosis

Activation of the CD40 receptor on the proximal tubular epithelium of the kidney results in fibrosis and inflammation in experimental models of kidney injury. Soluble CD40 ligand is released by activated platelets. The role of CD40-soluble CD40 ligand in patients with ischemic renal disease is unknown. Plasma levels of CD40 and soluble CD40 ligand were measured by enzyme-linked immunosorbent assay in a single center cohort of 60 patients with renal artery stenosis recruited from Salford Royal Hospital, Manchester, United Kingdom. A natural log transformation of CD40 and soluble CD40 ligand was performed to normalize the data. Estimated glomerular filtration rate was used as the primary indicator of renal function. By univariate analysis, low baseline levels of circulating CD40 (R(2)=0.06; P<0.05) and baseline creatinine (R(2)=0.08; P=0.022) were associated with loss of kidney function at 1-year follow-up, whereas soluble CD40 ligand was not (R(2)=0.02; P=ns). In a multiple linear regression model, CD40 (P<0.02) and baseline creatinine (P<0.01) continued to be significantly associated with a decline in renal function (model R(2)=0.17; P<0.005). Baseline CD40 levels were somewhat lower in patients who died during follow-up (survivors, 7.3±0.9 pg/mL, n=48 versus nonsurvivors, 6.7±1.0 pg/mL, n=12; P=0.06). The CD40/soluble CD40 ligand signaling cascade may be a novel mechanism contributing to the development and progression of renal injury in patients with atherosclerotic renal artery stenosis.

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.

Current debate on the role of embolic protection devices

The role of embolic protection devices (EPDs) during percutaneous arterial revascularization is still debated. This article discusses the use, the limitations, and issues of the variety of EPDs in different vascular beds, with a particular focus on the lower extremity arterial interventions.

Clinical outcomes in patients with renal artery stenosis treated with stent placement with embolic protection compared with those treated with stent alone

PURPOSE

To compare the clinical outcomes in patients with chronic renal insufficiency (CRI) and renal artery stenosis (RAS) following renal artery (RA) stent placement with and without embolic protection device (EPD) usage.

MATERIALS AND METHODS

Eighteen patients who had RA stent placement with EPD were matched to control patients (RA stent only). Blood pressure, number of hypertensive medications, and estimated glomerular filtration rate (eGFR) at 3 months before the procedure and after 12 months were determined. An increase of ≥ 20% in eGFR at 12 months from baseline was defined as "improvement," decrease of ≥ 20% as "deterioration," and an eGFR change between those values as "stabilization" at 12 months.

RESULTS

At 12 months, stage 4 patients treated with EPD had significantly higher eGFR than controls (P = .01). There was no statistical difference in blood pressure outcomes between the 2 groups.

CONCLUSIONS

Patients with stage 4 CRI did significantly better with EPD than those treated without it.

Current views on the management of atherosclerotic renovascular disease

Atherosclerotic renovascular disease (ARVD) is a common condition in both elderly patients and those with other vascular disease. No published randomized controlled trial has demonstrated an overall benefit of revascularization on any clinical or biochemical end-point, and optimal medical therapy in this condition is not clearly defined. In this review we consider the epidemiology of ARVD and discuss the evidence for current medical treatment. We also address the literature on revascularization, consider settings in which an interventional approach may still be considered, and touch upon on-going areas of research.

Comparison of embolic load in femoropopliteal interventions: percutaneous transluminal angioplasty versus stenting

PURPOSE

To compare the incidence of distal emboli occurring during percutaneous transluminal angioplasty (PTA) and primary stent on the superficial femoral artery (SFA) METHODS: A total of 50 consecutive patients were entered in a prospective, randomized trial. Inclusion criteria were the presence of symptomatic limb ischemia due to stenosis or occlusion of the SFA. An embolic protection device was placed in the popliteal artery. The patients were then randomly assigned to undergo primary stent implantation or PTA. The filters were retrieved and sent for histologic examination.

RESULTS

Stenting in the SFA produced more emboli (1.44 mm(3)) than PTA (0.772 mm(3)), P = .031. Reanalyzing the patients according to actual treatment performed, volume of debris in the stent group was 1.271 mm(3) and in the PTA group was 0.191 mm(3), P = .00087.

CONCLUSION

Volume of embolized material during endovascular interventions in the SFA-above-knee popliteal artery is higher when a stent is used.

Endothelialization and in-stent restenosis on the surface of glycoprotein IIIa monoclonal antibody eluting stent

Since the percutaneous transtuminal coronary angioplasty was introduced into China in 1984, this procedure has become widely accepted as an important step in coronary revascularization. This study shows the effect of the monoclonal antibody (mAb) on the platelet glycoprotein IIIa receptor during endothelialization and in-stent restenosis by implanting the mAb-eluting stents into iliac arteries of rabbits. The hard tissue cross sections of the stent-implanted arterial segments were made by polymethylmethacrylate embedding. Arterial intima proliferation was observed and analyzed. The endothelialization of the stent surface was observed using scanning electron microscope, whereas the ultrastructure of the neointima was observed using transmission electron microscope. After one month of stent implantation, the surfaces of both groups were covered by intact endothelial layers, but the neointimal areas and the ratio of stenosis were significantly lesser in the mAb-eluting stent group (p < 0.01). After 3 months, the ratio of stenosis in the mAb-eluting stent group was 14.67 ± 0.79, whereas that of the bare stent group was 21.58 ± 1.76 (p < 0.01). Therefore, the mAb eluting from the stent surface has the potential to accelerate endothelialization, prevent thrombosis formation due to the interaction of stent with blood, and decrease the stenosis ratio by inhibiting neointima proliferation.

Renal intervention to treat hypertension

Renal artery intervention to treat hypertension is one of the frontiers of ongoing research in combating this epidemic. This article focuses on recent data regarding PTRS and catheter-based renal sympathetic denervation. Despite progress in this field large multicenter, randomized trials that compare these treatment modalities with medical therapy for hypertension are lacking.