Renal Revascularization Research Articles

Endovascular Procedures for Renovascular Disease

While open surgical revascularization remains the gold standard, other endovascular techniques for renal revascularization, including percutaneous transluminal angioplasty with or without endoluminal stent placement (PTAS), have emerged as another option. Preoperative evaluation and procedural planning (including patient preparation, correlation of diagnostic images with clinical findings, and materials and instruments) are discussed. The procedural technique is described and includes the steps of securing the renal artery access for therapeutic intervention, transluminal angioplasty, and endoluminal stenting. Postprocedural care, complications, and outcome evaluation are also presented. Nearly one dozen figures show various diagnostic images, including CT scans, aortograms, and arteriography. Tables show the standard equipment for renal PTAS, a summary of trials included in meta-analysis, and results after primary arterial stent placement for atherosclerotic renal artery stenosis. This review contains 71 references.

Addition of endothelial progenitor cells to renal revascularization restores medullary tubular oxygen consumption in swine renal artery stenosis

Renal artery stenosis (RAS) promotes microvascular rarefaction and fibrogenesis, which may eventuate in irreversible kidney injury. We have shown that percutaneous transluminal renal angioplasty (PTRA) or endothelial progenitor cells (EPC) improve renal cortical hemodynamics and function in the poststenotic kidney. The renal medulla is particularly sensitive to hypoxia, yet little is known about reversibility of medullary injury on restoration of renal blood flow. This study was designed to test the hypothesis that PTRA, with or without adjunct EPC delivery to the stenotic kidney, may improve medullary remodeling and tubular function. RAS was induced in 21 pigs using implantation of irritant coils, while another group served as normal controls (n = 7 each). Two RAS groups were then treated 6 wk later with PTRA or both PTRA and EPC. Four weeks later, medullary hemodynamics, microvascular architecture, and oxygen-dependent tubular function of the stenotic kidneys were examined using multidetector computed tomography, microcomputed tomography, and blood oxygenation level-dependent MRI, respectively. Medullary protein expression of vascular endothelial growth factor, endothelial nitric oxide synthase, hypoxia-inducible factor-1α, and NAD(P)H oxidase p47 were determined. All RAS groups showed decreased medullary vascular density and blood flow. However, in RAS+PTRA+EPC animals, EPC were engrafted in tubular structures, oxygen-dependent tubular function was normalized, and fibrosis attenuated, despite elevated expression of hypoxia-inducible factor-1α and sustained downregulation of vascular endothelial growth factor. In conclusion, EPC delivery, in addition to PTRA, restores medullary oxygen-dependent tubular function, despite impaired medullary blood and oxygen supply. These results support further development of cell-based therapy as an adjunct to revascularization of RAS.

Emergent Renal Revascularization of a Simultaneous Pancreas-Kidney Transplant Recipient

Emergent Renal Revascularization of a Simultaneous Pancreas-Kidney Transplant Recipient

Reverse cardiac remodelling and renal functional improvement following bilateral renal artery stenting for flash pulmonary oedema

Acute flash pulmonary oedema (AFPO) is a life-threatening syndrome almost unique to patients with atheromatous renovascular disease (ARVD). Although recurrent AFPO is a widely accepted indication to consider renal revascularization, this is based on a number of case reports/series describing a successful outcome post-procedure. There is limited literature on the pathophysiological mechanisms and treatment effects of revascularization to support this clinical decision making. We report the case of a 65-year-old lady who presented with three episodes of AFPO. Investigations revealed severe bilateral renal artery stenosis. Post-revascularization, she experienced substantial improvement in energy levels and New York Heart Association class, with improvement in her blood pressure and renal function. Post-procedure, there were dramatic improvements in her cardiac morphology and function that were sustained at 1 year (ejection fraction improved from 39 to 65%, left ventricular mass decreased from 161 to 116 g) as well as renal function (isotopic glomerular filtration rate increased from 22.4 to 34.2 mL/min). This report provides new insights into the pathophysiological relationships between renal and cardiac changes in AFPO; the extent of the cardiac morphological changes was striking and unexpected.

Hepatorenal bypass using autogenous, free internal iliac artery graft: An attractive alternative to revascularize the right kidney in Takayasu′s disease

Nonspecific aortoarteritis or Takayasu's disease (TD) is a chronic pan endarteritis of unknown origin involving the aorta and its major branches affecting young adults especially women. The disease is more common in eastern Asian countries. Hypertension in these patients generally reflects as renal artery stenosis, which is seen in 28–75% of patients. Surgical revascularization is occasionally needed in patients with failed medical management or endovascular interventions. We report two cases of Takayasu's arteritis in young women where renal revascularization was done using free internal iliac artery hepatorenal bypass graft with excellent control of hypertension in the postoperative period.

'String of beads' or 'bunch of grapes': A case report of renal artery fibromuscular dysplasia

Introduction: Fibromuscular dysplasia (FMD), a disease of unknown etiology leading to renovascular hypertension (RVH) usually affects medium and large arteries of young females. Case Report: We report the case of 29­ year­old man in whom fibromuscular dysplasia presented as ‘Bunch of Grapes’ instead of its telltale sign of ‘String of Beads’. To our knowledge it is the first case of renal artery multiple aneurysms arising from single site associated with stenoses. Angioplasty, although standard of care in such lesions, was not feasible and open surgical revascularisation using exclusion of aneurismal segment and renal revascularisation using reversed great saphenous vein graft interposition provided excellent results. Conclusion: The First case of Renal artery Fibromuscular dysplasia presenting as ‘Bunch of Grapes’ sign is reported. Detailed evaluation of renovascular hypertension and its successful surgical correction using vein graft exclusion bypass is described.

The heart in atherosclerotic renovascular disease

Atherosclerotic renovascular disease (ARVD) is associated with a high rate of cardiovascular disease and mortality. ARVD is an independent risk factor for adverse outcome in coronary artery disease and there is a correlation between the presence of ARVD and severity of cardiovascular disease. ARVD is the most common cause of secondary hypertension and can be found in up to half of elderly patients with chronic heart failure. Abnormal cardiac structure and / or function will be present in 95 % of ARVD patients, with left ventricular hypertrophy (LVH) and diastolic dysfunction the predominant abnormalities. These are likely to be due in part to over-activity of the renin-angiotensin pathway. Up to now, randomised trials have shown no benefit of renal artery revascularisation over medical therapy in terms of cardiovascular events but small case series clearly demonstrate situations where cardiac structure and function respond to revascularisation. Future strategies must focus on accurately identifying sub-groups of ARVD patients for whom revascularisation should be first line therapy.

A novel technique for renal stenting in the setting of type‐B aortic dissection

A type-B acute aortic dissection patient required renal artery revascularization for renal artery stenosis resulting from the compression by a false lumen. Renal artery stenting was complicated by unclear opacification of the ostia resulting from the collapsed true lumen of both renal artery and aorta. The use of the "Szabo" technique facilitated this procedure by allowing us to position the stent edge precisely at the ostium. This is the first report of this technique utilized in this lesion subset.

Efficacy of combined renal and mesenteric revascularization

Small numbers of patients have advanced renal and mesenteric vascular disease requiring treatment. Open surgical treatment has been considered high risk, and the advent of endovascular intervention has affected management. This study evaluated the safety and long-term efficacy of concomitant mesenteric and renal revascularization with open techniques. Data from 90 consecutive patients who underwent mesenteric and renal revascularization during a 30-year period were analyzed. Early and late outcomes were evaluated over two intervals: 48 in period A (1978 to 1995), concomitant open renal and mesenteric revascularization (COR; n = 46) and sequential open renal and mesenteric revascularization (SOR; n = 2); 42 in period B (1996 to 2009), 22 COR, 4 SOR, 13 sequential hybrid open/endovascular repairs (SOER), and 3 sequential endovascular repairs (SER). There were 26 men and 64 women (median age, 67 years). Renal insufficiency was present in 24% and coronary artery disease (CAD) in 53%. Open surgical reconstruction was performed in 126 renal and 149 mesenteric arteries, with angioplasty/stenting in 15 and 8, respectively; 58 patients had concomitant aortic reconstruction (AR), and 9 had prior AR (8 in period A, 1 in period B). Hospital mortality was 8.8% overall; seven (14.5%) in period A and one (2.3%) in period B. Causes of early death were hemorrhage in three and multisystem organ failure in five. During a median follow-up of 4.5 years (range, 6 days-26.5 years), 11 patients progressed to hemodialysis (7 COR, 4 SOER), and 6 had recurrent mesenteric ischemia (4 COR, 1 SOER, 1 SER). Eight patients in period A and seven in period B required further procedures (9 renal, 9 mesenteric; 11 COR, 2 SOER, 1 SOR, 1 SER). Univariate analysis of COR patients showed CAD (P = .017) and prior AR (P = .035), but not concomitant AR (P = .366), predicted early death. Five-year survival for COR patients was 65% overall, but 74% in patients who survived the operation, with no difference between time periods (P = .55). Concomitant open mesenteric and renal revascularization is associated with low early mortality and good long-term durability in appropriately selected patients. It remains a viable procedure, especially in patients requiring concomitant aortic reconstruction. High-risk patients with CAD or prior aortic surgery should be considered for endovascular treatment, when anatomically feasible.

Percutaneous renal artery intervention versus medical therapy in patients with renal artery stenosis: a meta-analysis

Patients with renal artery stenosis are treated with percutaneous intervention, but randomised studies are inconclusive. We aimed to compare renal percutaneous revascularisation versus medical therapy. A systematic search for randomised controlled studies yielded three studies comparing renal angioplasty and two studies comparing renal angioplasty with stenting versus medical therapy, respectively. Six sets of data were extracted focusing on systolic and diastolic blood pressure as well as serum creatinine at follow-up. The five trials included 1,030 patients with renal artery stenosis. There was a trend toward, but no significant improvement in, systolic blood pressure (weighted mean difference [WMD] -2.76 mmHg, 95% confidence interval (CI) -5.71 to 0.18; p=0.07), diastolic blood pressure, (WMD -1.18 mmHg, 95% CI -2.69 to 0.32; p=0.12), or serum creatinine (WMD -7.26 mmol/L, 95% CI -14.99 to 0.47; p=0.07) in the patients who underwent percutaneous intervention compared to the medical therapy group. All but one trial showed at least a moderate overall bias risk. We did not find a significant improvement in blood pressure or renal function in patients with renal artery stenosis treated with renal artery revascularisation compared to medical therapy alone. However, trial quality was a limitation.

Surgical Treatment of Renal Artery Compression by Diaphragmatic Crus

Symptomatic compression of the renal artery by the diaphragmatic crus is a rare disorder. To our knowledge, renal artery compression by the diaphragmatic crus complicated with poststenosis aneurysm has not been reported. We present the case of a 28-year-old man with refractory hypertension. Extrinsic compression of the bilateral renal arteries and celiac artery and the aneurysm were proven by surgical exploration. We successfully performed left renal artery revascularization and renal autotransplantation in situ. Normal perfusion of the two bypass graft vessels was proven by computed tomography angiography.

Renal artery revascularization after unsuccessful percutaneous therapy: a single centre experience

This retrospective review describes the long time effect of surgical revascularization after unsuccessful early or mid-term failure of percutaneous transluminal renal angioplasty (PTRA). From January 1995 to January 2005, 60 out of 696 patients operated due to renal artery occlusive disease (17 fibromuscular dyplasia (FMD): mean age, 33.4years; 43 atherosclerotic disease (ASD): mean age, 62.46years) after unsuccessful PTRA underwent surgical revascularization for renal artery stenosis at our institution. The mean duration from failed PTRA to operation was 1.74years. Out of the 68 renal arteries, 44 were pretreated with angioplasty alone (19, FMD; 25, ASD), and 24 were treated with PTRA and stent (all ASD). Operative management, response of renal function and hypertension as well as survival were compared to the literature. Fifty-nine per cent (n = 40) of the renal arteries were treated by transaortic thrombendarterectomy, 37% (n = 25) by bypass. Thirty-day and in-hospital mortality was 0% in all pretreated patients; after a mean of 4.16years, it was 16.6% (only atherosclerotic). There was a significant decrease in systolic blood pressure values for all patients early after surgery as well as in follow-up. Creatinine remained stable in the patients with FMD, and there was an insignificant increase in creatinine level in the atherosclerotic patients. Hypertension was improved or healed in 32.5% of all pretreated patients, in cases with FMD in 54%, in atherosclerotic cases in 22.2%. Re-stenoses occurred in 26% of cases with FMD and in 18% of patients with atherosclerotic RAS. Surgical renal artery revascularization after failed PTRA is feasible and safe and systolic blood pressure can be lowered. The higher rate in re-stenoses in both the literature as well as in our own experience may be explained by the alterations in the renal artery after interventional treatment.

Dispelling the myth: the use of renin-angiotensin blockade in atheromatous renovascular disease

Many physicians retain reservations regarding the routine prescription of renin-angiotensin blockade (RAB) in patients with atheromatous renovascular disease (ARVD). Conversely, these patients are in most need of the cardio- and renal protection offered by RAB. This reservation is mostly because of fear of precipitating acute renal deterioration. We aimed to study whether RAB can be used safely in ARVD patients and whether it altered their outcome. Prospective observational study of all ARVD patients presenting to our tertiary referral centre from 1999-2009. Data capture included usage and tolerability of RAB, and correlation with endpoints of cardiovascular events, dialysis or death. Six hundred and twenty-one subjects were available for analysis. Mean age (SD) of the cohort was 71.3 (8.8) years, median (interquartile range) follow-up 3.1 (2.1, 4.8), range 0.2-10.61 years. Seventy-four patients had an intolerance to RAB at study entry. When utilized prospectively, RAB was tolerated in 357 of 378 patients (92%), and this was even seen in 54/69 (78.3%) patients with bilateral>60% renal artery stenosis (RAS) or occlusion. Patients (4/21) who were intolerant of RAB during follow-up (and 12 retrospectively intolerant), underwent renal revascularization which facilitated safe use of these medications post-procedure. On multivariate time-adjusted analysis, patients receiving RAB were significantly less likely to die (P=0.02). RAB is well tolerated even in patients with bilateral severe RAS and reduced mortality in a large group of ARVD patients. We recommend all ARVD patients be considered for RAB therapy unless an absolute contra-indication exists. Intolerance of these agents due to renal dysfunction should be considered an emerging indication for renal revascularization to facilitate their re-introduction.

Controversies surrounding renal artery intervention: making sense of the confusion

Atherosclerotic renal artery stenosis may manifest as progressive renal dysfunction, difficult-to-manage hypertension and cardiac disturbance syndromes. While dilating the stenotic lesion in the renal artery is a sound choice from a physiologic and anatomic standpoint, endovascular renal artery stent revascularization has not demonstrated clear clinical benefit for these patients. However, as optimal medical therapy has not been shown to halt the progression of atherosclerotic renal artery stenosis or to affect clinical outcomes sufficiently, these interventions are becoming more prevalent in the treatment of this condition. Furthermore, trials comparing medical and endovascular treatments have serious flaws, thereby fostering confusion regarding patient selection. Proponents of endovascular renal artery stent revascularization suggest that technical improvements in the procedure, coupled with better predictors about which patients may truly benefit from endovascular treatment, will yield superior results...

Atherosclerotic renal artery stenosis and renal artery stenting: an evolving therapeutic option

Atherosclerotic renal artery stenosis is a common clinical problem for which the optimal therapeutic strategy remains to be defined. However, renal artery stenting procedures have significantly increased as one approach to treat this clinical problem. Despite improvements in device design and technical performance of the procedure, the benefits and results of randomized clinical trials of renal artery stenting as a therapy remain confusing. Understanding the epidemiology, pathophysiology and natural history of renal artery stenosis are central to improving the outcomes of renal artery stenting. Developing both noninvasive and invasive predictive tools to better identify which patient will respond to renal revascularization will also be beneficial. In this article, we will present an overview of atherosclerotic renal artery disease. The results of renal artery stenting will be discussed and from this, the available noninvasive and invasive tools available to assess the clinical and hemodynamic significance of renal artery stenosis will be presented.

Do patients undergoing renal revascularization outside of the ASTRAL trial show any benefit? Results of a single-centre observational study

Though recent research has concluded that revascularization of atherosclerotic renal artery stenosis has no benefit for most patients, negative findings of the Angioplasty and STent for Renal Artery Lesions (ASTRAL) trial have been criticized in professional fora. Aim of the current study was to determine whether patients undergoing renal revascularization outside of ASTRAL showed any benefit. If so, could we determine a patient group that would benefit from intervention? Patients undergoing renal revascularization outside of the ASTRAL trial between 2003 and 2007 at our institution were reviewed. The primary comparison was the rate of decline of renal function based on individual reciprocal creatinine plots for the periods leading up to and following revascularization. Those who showed any improvement in the mean slope were compared to those with a negative or neutral response. One hundred and twenty-seven patients underwent renal revascularization outside of ASTRAL. The majority [79 (62%)] showed some improvement in the rate of change in renal function, though overall this failed to reach statistical significance. Those who responded positively tended to be declining faster prior to intervention; they were less likely to require RRT (6 versus 29%), and if they did, it was significantly later (3.6 versus 0.7 years). Mortality was, however, similar in both groups. Subgroup analysis was undertaken of patients in whom kidney function was rapidly deteriorating prior to revascularization. The rate of change in this group showed a more sizeable improvement (P = 0.05). Nonetheless, a similar proportion of both groups required RRT and there was no evidence of improvement in overall mortality. In keeping with ASTRAL's findings, our use of renal revascularization has produced no demonstrable benefit overall. There was a suggestion of benefit in patients with rapidly declining renal function in terms of delaying the need for renal replacement therapy, but improvements in cardiovascular outcomes have yet to be proven.

Acute renal artery occlusion: making the case for renal artery revascularization

Atherosclerotic renal artery disease is a common disease entity that may be identified in patients with difficult-to-control hypertension and/or chronic kidney disease but is probably underdiagnosed. Current evidence from both observational and randomized studies offers mixed results regarding the support for renal artery revascularization. There is lack of equipoise with regard to the efficacy of renal artery revascularization among the interventional and renal communities, as well as disagreements on the appropriate endpoints to measure in clinical trials, which have led to selection bias confounding the scant available data. We report a patient who does not fit any clinical trial inclusion criteria with acute on chronic kidney injury and new-onset heart failure whose symptoms and renal function improved significantly after renal artery intervention.

A Novel Approach to the Management of an Inflammatory Abdominal Aortic Aneurysm Associated With Crossed-Fused Renal Ectopia

Crossed-fused renal ectopia is a rare anomaly that poses a therapeutic challenge in the management of abdominal aortic aneurysms (AAAs). Such challenges include preservation of renal blood flow in the setting of multiple aberrant renal arteries and ureteral anomalies. Several surgical approaches to this dilemma, including the use of traditional surgical techniques, have been described in the literature. We describe a novel approach to the management of a 7-cm inflammatory AAA associated with crossed renal ectopia with fusion. During routine surveillance computed tomography angiography (CTA) in a 63-year-old man, a rapidly enlarging AAA with new inflammatory changes was detected. The aneurysm had increased in size from 4.8 to 7 cm over a period of 6 months. At the time of presentation, he was found to be hemodynamically stable. Findings from the laboratory tests conducted at the time of admission were normal, with a baseline glomerular filtration rate of 91.2 mL/min and creatinine of 1. The CTA revealed significant thickening of the aortic wall, suggestive of aortic inflammation, the presence of crossed renal ectopia with fusion, and numerous anomalous renal arteries. We identified two right renal arteries arising from the proximal aneurysm sac and three left renal arteries arising from the common iliac arteries. Given the aortic inflammation, an open repair approach was considered high risk compared with an endovascular aneurysm repair (EVAR). However, given the uncharacteristic arterial anatomy, a staged surgical and endovascular management option was selected. We performed an aortic debranching and renal artery revascularization, followed by an EVAR. We preserved renal function and excluded the aneurysm. The patient was discharged on the postoperative day 6 without periprocedural complications. A CTA was performed at 1- and 6-month follow-up period. This revealed a type 2 endoleak, which was confirmed by MR angiography. However, the aneurysm diameter had decreased in size from 7 to 6.3 cm in 1 month, and from 6.3 to 5.5 cm in 6 months. No further intervention was performed. Inflammatory AAAs associated with crossed-fused renal ectopia can be successfully managed with aortic debranching and renal artery revascularization followed by an EVAR. This epitomizes the growing role for advanced endovascular therapies in conjunction with open surgical techniques.

Diastolic function predicts survival after renal revascularization

The purpose of this study was to define the relationship between left ventricular diastolic function and survival after renal revascularization. Seventy-six adult patients (49 women, 27 men; mean age: 63 ± 13 years) with preoperative echocardiography who underwent renal revascularization for atherosclerotic disease were identified. Diastolic function was estimated from the early diastolic transmitral flow velocity (E), the atrial transmitral flow velocity (A), and the mitral annular tissue doppler velocity (e'). Patients were divided into two groups of diastolic dysfunction as either none/mild (E/A ≤ 0.75, E/e' <10) or moderate/severe (E/A >0.75, E/e' ≥ 10). Perioperative and follow-up mortality were determined from a prospective vascular database and the National Death Index. Descriptive statistics were calculated and postoperative survival was estimated by product-limit methods. Associations between preoperative factors, perioperative factors, and follow-up survival were examined using proportional hazards regression models. A forward stepwise variable selection procedure was used to select a "best" model to predict follow-up survival. Seventy-six patients were followed for an average of 41.9 months after renal revascularization. Within this group, 47 of 76 patients (61.8%) were identified as having moderate or severe diastolic dysfunction. Diastolic dysfunction had no apparent association with abnormal systolic function. The mean ejection fraction for those with moderate/severe diastolic dysfunction was 57.7% ± 11.5%. When comparing the moderate/severe and none/mild groupings of diastolic dysfunction, there was a significant difference in left ventricular mass index (151.9 ± 48.9 vs 125.3 ± 31.7; P = .0087). There were five deaths in the perioperative period and 20 deaths on follow-up. Among perioperative survivors, hypertension was cured or improved in 82% of the none/mild group and 53% of the moderate/severe group (P = .012). In multivariable analysis, none/mild diastolic dysfunction was significantly and independently associated with an improvement in blood pressure after revascularization (odds ratio [OR], 6.2; 95% confidence interval [CI], 1.4-28.6; P = .018). Ejection fraction was not associated with survival. After forward variable selection, moderate/severe diastolic dysfunction (hazard ratio [HR], 5.8; 95% CI 1.4-25; P = .018) was the only variable to demonstrate a significant and independent association with follow-up survival. Diastolic dysfunction, but not systolic dysfunction, was frequent in patients with renovascular disease. Blood pressure response and follow-up survival after renal revascularization demonstrated significant and independent associations with diastolic function. Consideration of diastolic function should be included in the management of patients with atherosclerotic renovascular disease.

Platelet Activation in Patients with Atherosclerotic Renal Artery Stenosis Undergoing Stent Revascularization

Soluble CD40 ligand (sCD40L) is a marker of platelet activation; whether platelet activation occurs in the setting of renal artery stenosis and stenting is unknown. Additionally, the effect of embolic protection devices and glycoprotein IIb/IIIa inhibitors on platelet activation during renal artery intervention is unknown. Plasma levels of sCD40L were measured in healthy controls, patients with atherosclerosis without renal stenosis, and patients with renal artery stenosis before, immediately after, and 24 hours after renal artery stenting. Soluble CD40L levels were higher in renal artery stenosis patients than normal controls (347.5 ± 27.0 versus 65.2 ± 1.4 pg/ml, P < 0.001), but were similar to patients with atherosclerosis without renal artery stenosis. Platelet-rich emboli were captured in 26% (9 of 35) of embolic protection device patients, and in these patients sCD40L was elevated before the procedure. Embolic protection device use was associated with a nonsignificant increase in sCD40L, whereas sCD40L declined with abciximab after the procedure (324.9 ± 42.5 versus 188.7 ± 31.0 pg/ml, P = 0.003) and at 24 hours. Atherosclerotic renal artery stenosis is associated with platelet activation, but this appears to be related to atherosclerosis, not renal artery stenosis specifically. Embolization of platelet-rich thrombi is common in renal artery stenting and is inhibited with abciximab.