Surgical management of atherosclerotic renovascular disease

Atherosclerotic Renal Artery Stenosis: A Review

Renal artery stenosis (RAS) is associated with hypertension and renal impairment. Atherosclerosis is the leading etiologic factor which accounts for >90% of the cases. Those with atherosclerotic RAS (ARAS) tend to have concomitant atherosclerosis in other vascular beds, so they are at a high risk of adverse coronary and cerebrovascular events. Management of ARAS is controversial, with limited indications for revascularization. In this review, the author aims to discuss the pathophysiology, natural history, diagnosis, and management of ARAS.

The Role of Hypoxia in Ischemic Chronic Kidney Disease

A gradually developing reduction in renal blood flow from atherosclerotic renovascular disease results in loss of kidney volume and a decrease in glomerular filtration rate that eventually becomes irreversible. Whether this process fundamentally reflects tissue hypoxia has been difficult to establish. Studies of human renovascular disease have indicated that reductions in blood flow of up to 30% to 40% can be tolerated with preservation of normal oxygenation and structural integrity. These observations are consistent with remarkable stability of poststenotic kidney function during sustained medical antihypertensive drug therapy in moderate renovascular disease. With more severe and sustained reductions, however, cortical oxygenation decreases and the magnitude of medullary hypoxia expands. These changes are associated with increasing renal venous levels of inflammatory cytokines, angiogenic markers, and infiltration of inflammatory cells, including tissue macrophages and T cells. Although restoring large-vessel blood flow can improve oxygenation, some of these processes reflect microvascular rarefication, remain activated, and do not depend on hemodynamic factors alone. Elucidation of tissue injury pathways associated with hypoxia opens the possibility of adjunctive therapeutic measures beyond renal revascularization. These include cell-based regeneration, mitochondrial protection, and/or angiogenic cytokine therapy to restore or preserve renal function in ischemic nephropathy.

Selection of Patients for Angioplasty for Treatment of Atherosclerotic Renovascular Disease: Predicting Responsive Patients

Atherosclerotic renal artery stenosis (ARAS) can cause secondary hypertension, progressive decline in renal function, and cardiac complications. Recent randomized controlled trials including the Cardiovascular Outcomes in Renal Atherosclerotic Lesions study have not reported the benefit of renal artery stenting compared with medical therapy alone to improve renal function or reduce cardiovascular and renal events in the enrolled patients with ARAS. However, observational evidence indicating the benefits of angioplasty in the selected high-risk patients with ARAS has been increasing. Thus, the timely correction of stenosis through angioplasty may have a beneficial effect in selected patients. However, optimal patient selection for angioplasty has been debated and can be challenging at times. Clinicians must identify the responsive patients who would benefit from angioplasty through risk stratification and the prediction of outcomes. Efforts have been made for the determination of predictors that can identify the subgroups of patients who would benefit from angioplasty. Lower age, more severe stenosis, preserved renal perfusion, and absence of diabetes or generalized atherosclerosis have been reported as the predictors for the improvement of hypertension after angioplasty. Global renal ischemia, rapidly declining renal function over 6-12 months, progressive shrinkage of the affected kidney, lower resistive index, and lower levels of albuminuria have been reported as predictors of improved or preserved renal function after angioplasty. This review discusses the identification of ARAS patients who will potentially respond well to angioplasty.

Restenosis of Aorto-renal Venous Grafts: Report of Two Patients Treated by Endovascular Stenting

Introduction

Renal venous graft restenosis is an uncommon event usually associated with significant clinical impact. Its treatment by endovascular stenting is seldom reported in the literature.

Report

Two cases of successful stenting for restenosis in aorto-renal venous grafts are described, detailing the technique and in one case reporting for the first time the use of a covered stent in this condition.

Discussion

Technical success may be achieved with proper material selection for the patient's anatomy and with dilation at relatively high pressures. The use of a covered stent may provide extra safety when treating vein grafts.

Total Renal Artery Occlusion: Recovery of Function After Revascularization

Current trends in managing atherosclerotic renal artery stenosis favor medical therapy, on account of negative results from prospective trials of revascularization, such as CORAL and ASTRAL. One result of this trend has been encountering occasional patients with progressive disease, sometimes leading to total arterial occlusion. We illustrate a case of accelerated hypertension with complete renal artery occlusion in which the patient recovered function after surgical bypass and we review the clinical approach used and the advanced imaging modalities available to us. A high index of suspicion and careful radiologic imaging play important roles in selecting patients who may have residual function and may benefit from revascularization. This case illustrates an example whereby restoring renal artery perfusion for carefully selected patients can be life changing, with recovery of kidney function and improved blood pressure, pill burden, and overall quality of life.

Spleno-renal artery transposition in a solitary functioning kidney for treatment-resistant hypertension and acute kidney injury

Renal Artery Stenosis (RAS) is an important cause of treatment-resistant hypertension. Uncontrolled hypertension with RAS can cause progressive chronic kidney disease (CKD) leading to end-stage kidney disease. Therapeutic revascularisation can be helpful in appropriate circumstances where pharmaceutical intervention has failed and significant renovascular disease contributes to resistant hypertension. We present an interesting case of a Caucasian male with peripheral vasculopathy, abdominal aortic aneurysm (AAA), single functioning kidney and ostial RAS caused by stent struts from an endovascular AAA stent graft. He had escalating medications requirement, with repeated failed attempts at percutaneous radiological intervention that led to an episode of contrast-induced acute kidney injury (AKI), before undergoing successful surgical revascularisation by a splenic artery transposition graft to the left renal artery that was performed to improve kidney function and the blood pressure. This report highlights the challenges faced with regard to the management of severe hypertension and progressive CKD.

Surgical Treatment of Abdominal Aortic Aneurysm with Congenital Solitary Pelvic Kidney and Superior Mesenteric Artery Stenosis

We report the rare case of a 54-year-old man with uncontrolled renovascular hypertension, who was found to have an abdominal aortic aneurysm with congenital solitary pelvic kidney and superior mesenteric artery stenosis. A single renal artery branched from aneurysmal aortic bifurcation, and both the renal artery and the superior mesenteric artery (SMA) had severe stenosis at their origins. The aneurysm was repaired with a bifurcated Dacron graft, to which the renal artery was anastomosed. SMA bypass was created between the graft's left limb and the SMA using another Dacron graft. The operation was successful, with improvement in renal functions and control of hypertension.

The use of intrarenal Doppler ultrasonography as predictor for positive outcome after renal artery revascularization

Whether patients with renal artery stenosis should undergo therapeutic revascularization is controversial. In this retrospective study, we evaluated prognostic intrarenal Doppler ultrasound parameters that might have a predictive value for a beneficial response after renal revascularization. From January 2003 until December 2012, all renovascular interventions for renal artery stenosis were analyzed. The resistive index and the maximal systolic acceleration were determined by Doppler ultrasonography prior to intervention. Thirty-two patients who underwent a renal revascularization procedure were included: 13 combined positive responders and 19 combined non-responders. The combined positive responders had a significant lower resistive index than the combined non-responders (0.5 vs. 0.6, P = 0.001) and a significant lower maximal systolic acceleration (1.0 vs. 3.8, P = 0.001) before revascularization. A prediction model (RI ≤ 0.5 and ACC_max ≤ 1.3 m/s²) was formulated to identify a subgroup that benefits from renal revascularization. This model has an expected sensitivity of 69% and specificity of 89% for improvement in renal function and/or blood pressure after revascularization. The non-invasive intrarenal Doppler ultrasound parameters resistive index and maximal systolic acceleration can be used as tools to predict improvement in renal function and/or blood pressure after revascularization of renal artery stenosis. The clinical value of this prediction model should be evaluated in a prospective trial.

Renal artery stenting may not be appropriate for patients with atherosclerotic renal artery stenosis

INTRODUCTION

This study compared aortorenal bypass to renal artery stenting to determine the most efficacious and financially sound method for treating patients with atherosclerotic renal artery stenosis (RAS).

METHODS

A decision analysis using direct and indirect costs, and value of statistical life (VSL) was completed. Direct costs were obtained using the Nationwide Inpatient Sample (NIS), indirect costs from the National Institute of Diabetes and Digestive and Kidney Diseases, and VSL from the Department of Transportation. A variance-based sensitivity analysis was completed to assess the accuracy of the decision analysis.

RESULTS

Aortorenal bypass has a 95% five-year patency, a 98% 30-day survival, a 26% rate of overall complications, and a 70% five-year dialysis-free survival. Renal artery stenting has a 56% five-year patency, a 99% 30-day survival, a 40% rate of complications, and a 65% five-year dialysis-free survival. Renal artery stenting has an overall cost of $305,370 and aortorenal bypass has an overall cost of $103,453 per patient. After accounting for VSL, renal artery stenting has a negative value of -$182,270 and aortorenal bypass has a value of $415,881.

CONCLUSIONS

Lower five-year patency and higher rate of complications from renal artery stenting that ultimately lead to significantly lower five-year dialysis-free survival.

Results of the major randomized clinical trials of renal stenting and implications for future treatment strategies

The management of atherosclerotic renovascular disease remains an area of controversy. This review details the results of major clinical trials and their implications for contemporary treatment recommendations for affected patients.

Cardiac function in renovascular hypertensive patients with and without renal dysfunction

BACKGROUND

Hypertension impairs left ventricular (LV) diastolic and systolic function, which might be aggravated by inflammation or neurohumoral activation. We hypothesized that LV diastolic dysfunction is more common in patients with renovascular hypertension (RVHT) compared with essential hypertension (EHT).

METHODS

Hypertensive patients who underwent both renal imaging to exclude RVHT and cardiac echocardiography within a 3-year period were identified retrospectively. Patients with significant renovascular disease were included in the RVHT group (n = 75); those without significant renovascular disease were included in the EHT group (n = 69). Cardiac function and structure were compared.

RESULTS

Baseline renal function was preserved (serum creatinine ≤ 2mg/dl) in EHT patients and impaired (serum creatinine > 2mg/dl) in only 9 RVHT patients. RVHT patients had higher systolic blood pressure, E/e' ratio, and greater prevalence of concentric hypertrophy but lower estimated glomerular-filtration-rate (eGFR) compared with EHT patients. Increased prevalence of LV diastolic dysfunction remained statistically significant in patients with RVHT after multivariable adjustment for age, sex, blood pressure, eGFR, diabetes, smoking, and statin use, with a relative risk (95% CI) for abnormal E/e' of 1.70 (95% confidence interval = 1.05-2.90; P = 0.03) compared with EHT. RVHT patients with severe renal dysfunction showed greater impairments in cardiac systolic and diastolic function compared with those in EHT patients or preserved renal function RVHT patients.

CONCLUSIONS

Among hypertensive patients undergoing echocardiography, cardiac structure and diastolic function are impaired in RVHT patients compared with EHT patients and remain different after adjustment for multiple significant covariables. When associated with significant renal dysfunction, RVHT aggravates LV hypertrophy and both systolic and diastolic dysfunction. Hence, identification of RVHT and renal dysfunction warrants development of targeted management strategies.

Renovascular hypertension: is there still a role for stent revascularization?

PURPOSE OF REVIEW

Management of renovascular hypertension remains controversial and problematic, in part, due to failure of prospective trials to demonstrate added benefit to revascularization.

RECENT FINDINGS

Effective drug therapy often can achieve satisfactory blood pressure control, although concerns persist of the potential for progressive, delayed loss of kidney function beyond a stenotic lesion. Recent studies highlight benefits of renal artery stenting in subsets of patients including those with recurrent pulmonary edema and those intolerant to blockade of the renin-angiotensin system. Occasional patients with recent deterioration in renal function recover sufficient glomerular filtration rate after stenting to avoid requirements for renal replacement therapy. Emerging paradigms from both clinical and experimental studies suggest that hypoxic injury within the kidney activates inflammatory injury pathways and microvascular rarification that may not recover after technically successful revascularization alone. Initial data suggest that additional measures to repair the kidney, including the use of cell-based therapy, may offer the potential to recover kidney function in advanced renovascular disease.

SUMMARY

Specific patient groups benefit from renal revascularization. Nephrologists will increasingly be asked to manage complex renovascular patients, different from those in randomized trials, that require intensely individualized management.

Combined open and endovascular treatment of thoracoabdominal aortic pathologies: a systematic review and meta-analysis

BACKGROUND

A combined open-endovascular technique has emerged as an alternative treatment option for thoracoabdominal pathologies. However, reported experiences from various medical centers have been contradictory and heterogeneous. The aim of this study is to assess the mortality rate and various complication rates associated with this approach.

METHODS

An electronic health database search was performed on all articles published up to March of 2012 describing combined open-endovascular repair of thoracoabdominal pathologies. Studies were included in the meta-analysis if they had ≥10 patients and reported the basic outcome criteria. End points of the meta-analysis were defined as primary technical success, endoprosthesis related complications, 30-day/in-hospital mortality, symptoms of spinal cord ischemia (SCI) and irreversible paraplegia, permanent renal function impairment, and other major complications.

RESULTS

Fourteen studies were deemed eligible for this meta-analysis with a total of 528 patients (68.0% male, mean age 70.5 years). The mean follow-up period was 34.2 months. The pooled estimate for primary technical success and visceral graft patency was 95.4% and 96.5% respectively. An endoleak developed in 106 (21.1%) patients in whom both stages had been completed. The pooled rate for symptomatic SCI was 7.0% and for irreversible paraplegia 4.4%. The pooled proportion for permanent renal failure was 7.0% and for mesenteric ischemia 4.5%. Prolonged respiratory support and cardiac complications were observed in a pooled rate of 7.8% and 4.6% respectively. The meta-analysis for 30-day/in-hospital mortality revealed a pooled rate of 14.3%.

CONCLUSIONS

Although the hybrid technique for thoracoabdominal aortic pathology provides a less invasive approach, the technique is still associated with a considerable morbidity and mortality rates. High risk patients unfit to withstand open repair, are equally likely to suffer significant complications with the hybrid procedure. The choice of the optimal treatment strategy for thoracoabdominal pathologies should be carefully made on a patient to patient basis, assessing the clinical fitness and the anatomical suitability of each patient. The hybrid approach should be reserved for high volume centers with accumulated experience and high standards of perioperative management.

Early duplex predicts restenosis after renal artery angioplasty and stenting

OBJECTIVE

To examine the relationship between early renal duplex sonography (RDS) and restenosis after primary renal artery percutaneous angioplasty and stenting (RA-PTAS).

METHODS

Consecutive patients undergoing RA-PTAS for hemodynamically significant atherosclerotic renal artery stenosis with hypertension and/or ischemic nephropathy between September 2003 and July 2010 were identified from a prospective registry. Patients had renal RDS pre-RA-PTAS, within 1 week of RA-PTAS and follow-up RDS examinations after the first postoperative week for surveillance of restenosis. Restenosis was defined as a renal artery peak systolic velocity (PSV) ≥ 180 cm/s on follow-up RDS. Associations between RDS and restenosis were examined using proportional hazards regression.

RESULTS

Eighty-three patients (59% female; 12% nonwhite; mean age, 70 ± 10 years; mean pre-RA-PTAS PSV, 276 ± 107 cm/s) undergoing 91 RA-PTAS procedures comprised the sample for this study. All procedures included a completion arteriogram demonstrating no significant residual stenosis. Mean follow-up time was 14.9 ± 10.8 months. Thirty-four renal arteries (RAs) demonstrated restenosis on follow-up with a median time to restenosis of 8.7 months. There was no significant difference in the mean PSV pre-RA-PTAS in those with and without restenosis (287 ± 96 cm/s vs 269 ± 113 cm/s; P = .455), and PSV pre-RA-PTAS was not predictive of restenosis. Within 1 week of RA-PTAS, mean renal artery PSV differed significantly for renal arteries with and without restenosis (112 ± 27 cm/s vs 91 ± 34 cm/s; P = .003). Proportional hazards regression analysis demonstrated increased PSV on first post-RA-PTAS RDS was significantly and independently associated with subsequent restenosis during follow-up (hazard ratio for 30 cm/s increase, 1.81; 95% confidence interval, 1.32-2.49; P = .0003). There was no difference in pre- minus postprocedural PSV in those with and without restenosis on follow-up (175 ± 104 cm/s vs 179 ± 124 cm/s; P = .88), nor was this associated with time to restenosis. Best subsets model selection identified first postprocedural RDS as the only factor predictive of follow-up restenosis. A receiver-operating characteristic curve was examined to assess the first week PSV post-RA-PTAS most predictive of restenosis during follow-up. The ideal cut point for RA-PSV was 87 cm/s or greater. This value was associated with a sensitivity of 82.4%, specificity of 52.6%, and area under the receiver-operating characteristic curve of 69.3%. Increased first postprocedural RA-PSV was predictive of lower estimated glomerular filtration rate in the first 2 years after the procedure (-1.6 ± 0.7 mL/min/1.73 m(2) lower estimated glomerular filtration rate per 10 cm/s increase in RA-PSV; P = .010).

CONCLUSIONS

Early renal artery PSV within 1 week after RA-PTAS predicted renal artery restenosis and lower postprocedure renal function. Recurrent stenosis demonstrated no association with absolute elevation in PSV prior to RA-PTAS nor with the change in PSV after RA-PTAS. These data suggest that detectable differences exist in renal artery flow parameters following RA-PTAS that are predictive of restenosis during follow-up but are not apparent on completion arteriography or detectable by intra-arterial pressure measurements. Further study is warranted.

Revascularization in renal artery stenosis

The predominant cause of renal artery stenosis (RAS) is atherosclerosis. Clinical manifestations of atherosclerotic RAS are both direct (hypertension and kidney dysfunction) and indirect (increased cardiovascular events and mortality). However, in many cases, atherosclerotic RAS seems to be an incidental finding with no discernable effects. Antihypertensive medications such as renin-angiotensin-aldosterone system inhibitors, along with statins and aspirin, have significantly improved the medical treatment of atherosclerotic RAS. However, revascularization is still advocated in a variety of clinical settings such as the preservation of renal function, recurrent episodes of "flash" pulmonary edema, and in patients with refractory hypertension. Current management guidelines indicate "resistant hypertension" as an indication for renal artery revascularization. A large number of observational studies support revascularization for both control of high blood pressure and/or preservation of renal function. Unfortunately, the favorable effects of revascularization on these end points seen in the observational studies were not reproduced in randomized controlled trials compared to medical therapy alone. The ability for revascularization to improve control of congestive heart failure or to prevent hard cardiovascular end points (eg, myocardial infarction or stroke) has not been tested in the randomized clinical trials published to date. Hence, the efficacy of intervention remains controversial, which poses a dilemma, especially given the large number of elderly patients with resistant systolic hypertension.

Hybrid Open Endovascular Technique for Aortic Thoracoabdominal Pathologies

Background—

Many authors using a hybrid debranching strategy for the treatment of thoracoabdominal pathologies have reported disappointing results and the initial enthusiasm for the technique has given way to criticism and ambiguity. The aim of the present meta-analysis study was to assess the safety and efficacy of the technique in patients with thoracoabdominal aortic aneurysms or other aortic pathologies.

Methods and Results—

A multiple electronic search was performed on all articles describing hybrid open endovascular repair. Separate meta-analyses were conducted for technical success, visceral graft patency, spinal cord ischemia symptoms, renal insufficiency, and other complications as well as 30-day/in-hospital mortality.

Nineteen publications with a total of 507 patients were analyzed. The pooled estimates for primary technical success and visceral graft patency were 96.2% (95% CI, 93.5%–98.2%) and 96.5% (95% CI, 95.2%–97.8%) respectively. A pooled rate of 7.5% (95% CI, 5.0%–11.0%) for overall spinal cord ischemia symptoms was observed; whereas for irreversible paraplegia the pooled rate was 4.5% (95% CI, 2.5%–7.0%). The pooled estimate for renal failure was 8.8% (95% CI, 3.9%–15.5%). The pooled 30-day/in-hospital mortality rate was 12.8% (95% CI, 8.6%–17.0%). During the mean follow-up period of 34.5 (95% CI, 31.5–37.5) months, a total of 119 endoleaks were identified in 111 patients (22.7%).

Conclusions—

The repair of thoracoabdominal pathologies by means of hybrid procedures in patients who are poor surgical candidates is still associated with significant morbidity and mortality rates. Future studies may substantiate whether the technique is amenable to amelioration and improvement.

Efficacy of combined renal and mesenteric revascularization

OBJECTIVE

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.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.

Renal artery stenosis: optimizing diagnosis and treatment

Renal artery stenosis (RAS) is the most commonly caused by atherosclerosis, with fibromuscular dysplasia being the most frequent among other less common etiologies. A high index of suspicion based on clinical features is essential for diagnosis. Revascularization strategies are currently a topic of discussion and debate. When revascularization is deemed appropriate, atherosclerotic RAS is most often treated with stent placement, whereas patients with fibromuscular dysplasia are usually treated with balloon angioplasty. Ongoing randomized trials should help to better define the optimal management of RAS.

Diastolic function predicts survival after renal revascularization

PURPOSE

The purpose of this study was to define the relationship between left ventricular diastolic function and survival after renal revascularization.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Atherosclerotic renovascular disease among hypertensive adults

PURPOSE

This report describes the change in atherosclerotic renovascular disease (AS-RVD) among hypertensive adults referred for renal duplex sonography (RDS) scan.

METHODS

From Oct 1993 through July 2008, 20,994 patients had RDS at our center. A total of 434 hypertensive patients with two or more RDS exams without intervention comprised the study cohort. Patient demographics (blood pressures, medications, serum creatinine levels, and data from RDS) were collected. Analyses of longitudinal changes in Doppler scan parameters, blood pressures, and renal function were performed by fitting linear growth-curve models. After confirming the linearity of change in Doppler scan parameters among patients with variable number of studies, estimates of mean slopes were calculated using maximum likelihood techniques. For changes in renal function, quadratic growth curves were required to describe longitudinal change.

RESULTS

A total of 434 subjects (212 men [49%] and 222 women [51%]; mean age, 64.6 +/- 12.2 years) provided 1351 studies (mean, 3.2 +/- 2.4; range, 2 to 18) for 863 kidneys over a mean follow-up of 34.4 +/- 25.1 months. At baseline, 20.6% of kidneys demonstrated hemodynamically significant stenosis. On follow-up, 72 kidneys (9.1%) demonstrated anatomic progression of disease. A total of 54 kidneys (6.9%) progressed to significant stenosis and 18 (2.3%) progressed to occlusion. Controlling for progression of disease, baseline renal artery status demonstrated a strong association with baseline kidney length (P = .0006). Significant annualized change in renal length was observed (cm change/year +/- standard error of the mean [SEM]: 0.042 +/- 0.011; P = .0002) among both kidneys with and without critical disease at baseline, however, decline in length was significantly greater among kidneys exhibiting progression of renovascular disease (-0.152 +/- 0.028 cm/year; comparison of slopes between groups P = .0005). In the absence of progression, the presence or absence of critical renal artery stenosis at baseline did not affect the rate of decline in renal length. Fitted models for the natural log transform of serum creatinine demonstrated a significant increase during follow-up (P < .0001). No association was observed between change in serum creatinine and baseline renovascular disease status, or its progression.

CONCLUSION

A total of 32% of hypertensive adults referred for RDS demonstrated hemodynamically significant renal artery stenosis. Regardless of the presence or absence of baseline disease, a small percentage of patients demonstrated anatomic progression of AS-RVD. A total of 9.1% demonstrated anatomic progression and 2.3% progressed to occlusion. Although anatomic progression of AS-RVD was associated with an increased rate of decline in renal length, progression did not predict a decline in excretory renal function. Intervention for AS-RVD should be selective and reserved for strict indications.

Effect of hospital volume on in-hospital mortality for renal artery bypass

BACKGROUND

A recent report determined that the nationwide mortality for renal artery bypass (RAB) is surprisingly high-10%. We hypothesized that operative mortality for RAB is related to the volume of such operations performed in each center.

METHODS

The Nationwide Inpatient Sample was analyzed to identify patients undergoing RAB for the years 2000-2005. In-hospital mortality for RAB was compared between hospitals.

RESULTS

During the study period, RAB was performed on 7413 patients with an overall in-hospital mortality of 9.6%. The multivariate logistic regression analyses revealed that after adjusting for surgical risk, increasing hospital volume was significantly associated with decreased in-hospital mortality for RAB (odds ratio 0.98; 95% confidence interval, 0.96-0.99; P=.015).

CONCLUSIONS

Patient risk profile and hospital volume are critical determinants of in-hospital mortality for RAB, which should be factored into decision making for patients requiring intervention for renovascular disease.

[Hypertension in patients with renal artery stenosis]

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

Clinical utility of the resistive index in atherosclerotic renovascular disease

OBJECTIVE

This retrospective study examines the relationship between the renal resistive index (RI) and blood pressure and renal function response after open and percutaneous intervention for atherosclerotic renovascular disease (AS-RVD).

METHODS

From March 1997 to December 2005, 86 patients (46 women, 40 men; mean age, 68 +/- 10 years) underwent renal duplex sonography (RDS), including main renal artery and hilar vessel Doppler interrogation, before treatment of AS-RVD. Of these, 56 patients had open operative repair, and 30 had percutaneous intervention. The RI (1-[EDV/PSV]) was calculated from the kidney with the highest peak systolic velocity (PSV). Hypertension response was graded from preprocedural and postprocedural blood pressure measurements and medication requirements. Renal function response was graded by a >or=20% change in estimated glomerular filtration rate (eGFR) calculated from the serum creatinine concentration.

RESULTS

Comorbid conditions, baseline blood pressure, and preoperative renal function were not significantly different between open and percutaneous groups. Baseline characteristics that differed between the percutaneous vs open group were higher mean age (71 +/- 11 years vs 67 +/- 9 years; P = .05), kidney length (11.3 +/- 1.3 cm vs 10.7 +/- 1.2 cm; P = .02), proportion of patients with RI >or=0.8 (50% vs 21%; P = .01), and proportion of bilateral AS-RVD (37% vs 80%; P < .01). After controlling for preintervention blood pressure and extent of repair, postoperative eGFR differed significantly for RI <0.8 or >or=0.8 when all patients (P = .003) and percutaneous intervention (P = .008) were considered. Specifically, eGFR declined from preprocedure to postprocedure in the patients with RI >or=0.8 after percutaneous repair and in the group analyzed as a whole. Neither systolic nor diastolic pressure after intervention demonstrated an association with RI. Considering all patients and both groups, multivariable proportional hazards regression models demonstrated that RI was predictive of all-cause mortality. RI was the most powerful predictor of death during follow-up (hazard ratio, 6.7; 95% confidence interval, 2.6-17.2; P < .001).

CONCLUSION

After intervention for AS-RVD, RI was associated with renal function, but not blood pressure response. A strong, independent relationship between RI and mortality was observed for all patients and both treatment groups.

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.

Endovascular management of atherosclerotic renovascular disease: early results following primary intervention

OBJECTIVE

This retrospective review examines periprocedural morbidity and early functional responses to primary renal artery angioplasty and stenting (RA-PTAS) for patients with atherosclerotic renovascular disease (RVD).

METHODS

Consecutive patients undergoing primary RA-PTAS for hemodynamically significant atherosclerotic RVD with hypertension and/or ischemic nephropathy were identified from a prospectively maintained registry. Hypertension responses were determined based on pre- and post-intervention blood pressure measurements and medication requirements. Estimated glomerular filtration rate (eGFR) was used to determine renal function responses. Both hypertension and renal function responses were assessed at least three weeks after RA-PTAS. Stepwise multivariable regression analysis was used to examine associations between blood pressure and renal function responses to RA-PTAS and select clinical variables.

RESULTS

One-hundred ten primary RA-PTAS were performed on 99 patients with atherosclerotic RVD with a mean angiographic diameter-reducing stenosis of 79.2 +/- 12.9%. All patients had hypertension (mean of 3.4 +/- 1.3 antihypertensive agents). Mean pre-intervention eGFR was 49.9 +/- 22.7 mL/min/1.73 m(2), and 74 patients had a pre-intervention eGFR < 60 mL/min/1.73 m(2). The technical success rate for RA-PTAS was 94.5%. The periprocedural complication rate was 5.5%; there were no periprocedural deaths. Statistically significant decreases in mean systolic blood pressure (161.3 +/- 25.2 vs. 148.5 +/- 25.2 post-intervention, P < .0001), diastolic blood pressure (78.6 +/- 13.3 versus 72.5 +/- 13.5 post-intervention, P < .0001), and number of antihypertensive agents (3.3 +/- 1.2 versus 3.1+/- 1.3 post-intervention, P = .009) were observed. Assessed categorically, hypertension response to RA-PTAS was cured in 1.1%, improved in 20.5%, and unchanged in 78.4%. Categorical eGFR response to RA-PTAS was improved in 27.7%, unchanged in 65.1%, and worsened in 7.2%. Multivariable stepwise regression revealed associations between pre- and post-intervention systolic blood pressure (P < .0001), diastolic blood pressure (P < .0001), and eGFR (P < .0001), as well as a trend toward improved diastolic blood pressure response among patients managed with staged bilateral intervention (P = .0589).

CONCLUSION

Primary RA-PTAS for atherosclerotic RVD was associated with low peri-procedural morbidity and mortality but only modest early improvements in blood pressure and renal function. Results from ongoing prospective trials are needed to assess the long term outcomes associated with RA-PTAS and clarify its role in the management of atherosclerotic RVD.

Tratamento endovascular da estenose da artéria renal em rim único

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

Atheroembolism during percutaneous renal artery revascularization

INTRODUCTION

Atheroembolization during renal artery angioplasty and stenting (RA-PTAS) has been postulated as a cause for the inferior renal function results observed when compared with those with surgical revascularization. To further characterize procedure-associated atheroembolism, we analyzed recovered atheroembolic debris and clinical data from patients undergoing RA-PTAS with distal embolic protection (DEP).

METHODS

RA-PTAS procedures were performed with DEP using a commercially available temporary balloon occlusion and aspiration catheter system between July 2005 and December 2006. Following RA-PTAS but prior to deflation of the distal occlusion balloon, the static column of blood proximal to the balloon was aspirated and submitted for embolic particle analysis. Angiograms, demographics, and laboratory data were reviewed. Glomerular filtration rate (eGFR) was estimated before RA-PTAS and at 4 to 8 weeks postintervention using the abbreviated Modification of Diet in Renal Disease formula. Associations between clinical factors, captured particle counts, and changes in renal function were examined using univariate techniques and multiple linear regression.

RESULTS

Twenty-eight RA-PTAS procedures were performed with DEP. Mean total number of embolic particles counted per procedure was 2033 +/- 1553 for particles 20-60 microm and 265 +/- 132 for particles >60 microm. Significant positive associations with quantity of captured particles 20 to 60 microm were observed for African American race (P = .002), predilation (P = .005), and stent diameter (P < .001); a significant negative association was observed for preoperative aspirin use (P =.016). Quantity of captured particles >60 microm was positively associated with ratio of stent to renal artery diameter (P =.009). Change in eGFR was positively associated with preoperative aspirin use (P = .006) and preoperative eGFR (P < .001), while a negative association was observed for captured particle counts >60 microm (P = .015).

CONCLUSION

These results demonstrate the liberation of thousands of atheroembolic particles during RA-PTAS. Clinical, anatomic, and device-related factors may be predictive of procedural embolization, and increasing captured particle counts >60 microm were associated with inferior renal function results. Further investigation is warranted to establish relationships between atheroembolism, end organ functional impairment, and clinical responses.

The management of renal artery atherosclerosis for renal salvage: Does stenting help?

OBJECTIVE

The use of endovascular techniques to treat renal artery stenosis (RAS) has increased in recent years but remains controversial. The purpose of this study was to review the outcomes and durability of percutaneous transluminal angioplasty and stenting (PTA/S) for patients with RAS and decreasing renal function.

METHODS

Between 1999 and 2004, 125 consecutive patients underwent angiography and intervention for renal salvage and formed the basis of this study. Inclusion criteria for this study included serum creatinine greater than 1.5 mg/dL, ischemic nephropathy, and high-grade RAS perfusing a single functioning kidney. Patients undergoing PTA/S for renovascular hypertension or fibromuscular dysplasia or in conjunction with endovascular stent grafting for aneurysm repair were excluded. The original angiographic imaging was evaluated for lesion grade and parenchymal kidney size. All medical records and noninvasive testing were reviewed. Preoperative and postoperative patient data were standardized and analyzed by using chi(2) tests for nominal values and t tests for continuous variables. The Modification of Diet in Renal Disease equation was used to estimate glomerular filtration rate (GFR), and univariate analysis was performed.

RESULTS

Preoperative variables included the presence of coronary artery disease (93%), diabetes (44%), tobacco use (48%), and hypercholesterolemia (70%). RAS was suspected on the basis of preoperative duplex imaging or magnetic resonance angiography. Aortography and PTA/S were performed in 125 patients (mean age, 71 years; 59% male) with a mean baseline creatinine level of 2.2 mg/dL. There were two mortalities (1.6%) in the 30-day postoperative period, but there was no case of acute renal loss. Blood pressure decreased after PTA/S (151/79 mm Hg before vs 139/72 mm Hg after 1 month; P < .03). For all patients, the estimated GFR went from 33 +/- 12 mL . min(-1) . 1.73 m(-2) (mean +/- SD) to 37 +/- 19 mL . min(-1) . 1.73 m(-2) at 6 months (P = .10). Sixty-seven percent of treated patients had improvement (>10% increase in GFR) or stabilization of renal function. A rapid decline in GFR before intervention was correlated with improvement after PTA/S. Responders after PTA/S had a 27% decrease in GFR before intervention (44 +/- 13 mL . min(-1) . 1.73 m(-2) to 32 +/- 13 mL . min(-1) . 1.73 m(-2); P < .001) with a negative to positive slope change in GFR values. Ten patients underwent reintervention for in-stent restenosis. Cases without improvement in GFR after PTA/S were associated with eventual dialysis need (P = .01; mean follow-up, 19 months). Survival at 3 years was 76%, and dialysis-free survival was 63% as estimated by Kaplan-Meier analyses.

CONCLUSIONS

Renal artery stenoses causing renal dysfunction can be safely treated via endovascular means. Rapidly decreasing renal function is associated with the response to renal artery angioplasty/stenting and helps identify patients for renal salvage.