Revascularization Of Renal Artery Stenosis Research Articles

Abstract P423: Blood Pressure and Renal Function Outcomes After Revascularization of Renal Artery Stenosis in Patients from 3 Different Clinical Settings

The effects of renal percutaneous transluminal angioplasty (rPTA) of renal artery stenosis (RAS) on BP and renal function are controversial. We aim to search for possible differences in these outcomes in different clinical settings. We conducted an observational analysis of effects of rPTA in patients with RAS diagnosed as a result of: screening patients with peripheral artery disease (Vascular Dpt.; G1, n = 20), patients with resistant hypertension or with clinical suspicion of RAS (Hypertension Unit; G2, n = 28) or kidney transplant patients with renal function impairment and/or elevation of BP (Transplantation Unit; G.3, n = 21). RAS is defined as a reduction of ≥70% of the renal artery lumen. Sixty-nine patients were examined (mean age 67±12yr, 64% male). Overall, mean±S.D. baseline SBP/DBP (mmHg) was 147.4±20.6 and 75.7±1.8, and the estimated glomerular filtration rate (eGFR) was 48.7±27.0 mL/min/1.73m 2 . G.1 exhibited a higher prevalence of smoking patients (90%) and patients with past major vascular events (100%), lower DBP (70.0±9.8 mmHg) and better renal function (eGFR: 62.5±23.2 mL/min/1.73m 2 ), compared to G.2 and G.3. Twelve months after rPTA, BP decreased only in patients in G.2 and G.3: variation of (Δ) SBP(mmHg): mean (95%CI)= -18.9 (-26.7 to -11.0) and -20.0 (-29.8 to -10.1), respectively; p<0.001 for both; ΔDBP (mmHg): mean (95%CI)= -6.6 (-10.7 to -2.4), p=0.003 and -6.3 (-11.7 to -0.8), p=0.027, respectively. Regarding renal function, it only improved in G.3: ΔeGFR (mL/min/1.73m 2 ): mean (95%CI)= 8.9 (1.5 to 16.4), p=0.022. ΔSBP was associated with baseline SBP (r= -0.709, p<0.001) and the origin group (Rho = -0.362, p = 0.003); ΔeGFR was associated with baseline eGFR (r= -0.508, p<0.001) and the origin group (Rho = 0.356, p = 0.004). Overall, median ΔSBP was -11 mmHg, and median ΔeGFR was +1.0 mL/min/1.73m 2 . An ANOVA analyzed factors associated with these changes. After adjusting for confounders, ΔSBP was dependent on baseline SBP and group of origin (both p<0.05; adjusted R 2 0.340). ΔeGFR was dependent on baseline eGFR and diabetes (both p<0.05; adjusted R 2 0.123). Blood pressure decreased in patients with suspected RAS because of resistant hypertension 12 months after rPTA. Both BP and renal function improved after rPTA in kidney transplant patients with diagnosis of RAS. Higher BP levels and lower eGFR correlated with better results. Patients with peripheral artery disease screened for RAS showed no change in BP or renal function after rPTA.

Renal denervation in secondary arterial hypertension therapy: clinical case

Introduction. Renovascular hypertension is one of the most severe types of hypertension in terms of the choice of treatment strategy. Recent studies have not provided a clear answer to the question of which treatment approach (conservative or surgical) is most appropriate for these patients.Brief description. The presented case describes a female patient with a longterm uncontrolled hypertension, whose examination revealed bilateral renal artery stenosis. Considering the debatable clinical effectiveness of revascularization of renal artery stenosis, the patient underwent distal renal artery denervation using multielectrode catheters. A decrease in blood pressure was shown. Follow-up of the patient demonstrated stable antihypertensive effect of the procedure, as well as its safety in case of impaired renal function.Discussion. This clinical demonstrates the third way in the treatment of patients with renal arteries stenosis and resistant hypertension — renal sympathetic denervation. This method requires a separate controlled study with individuals with renal dysfunction, including renovascular origin.

Concurrent Primary Aldosteronism and Renal Artery Stenosis: An Overlooked Condition Inducing Resistant Hypertension.

To explore the clinical features of coexisting primary aldosteronism (PA) and renal artery stenosis (RAS), we retrospectively analyzed records from 71 patients with PA with RAS and a control group of 121 patients with PA without RAS. Aldosterone-to-renin concentration ratio tests and computerized tomography (CT) scanning of the adrenal and renal arteries were routinely conducted to screen for PA and RAS. Color Doppler flow and/or magnetic resonance imaging were used as substitute testing of patients for whom CT was contraindicated. Standard percutaneous renal arteriography (PTRA) was considered for patients with RAS exceeding 70% based on non-invasive tests and for those without PTRA contraindications. The patients with PA with RAS were further divided into severe (RAS>70%) and moderate (50% < RAS <70%) RAS groups. The prevalence of RAS among PA patients was 6.9% (71/1,033), including 3.2% (33/1,033) with severe RAS. Compared with the PA without RAS group, the severe RAS group showed higher levels of systolic blood pressure (SBP) (171.82 ± 18.24 vs. 154.11 ± 18.96 mmHg; P < 0.001) and diastolic BP(DBP) (110.76 ± 15.90 vs. 91.73 ± 12.85 mmHg; P < 0.001) and prevalence of resistant hypertension (RH) (90.9 vs. 66.9%; P = 0.008), whereas the moderate RAS group merely showed higher DBP (98.63 ± 14.90 vs. 91.73 ± 12.85 mmHg; P = 0.006). The direct renin concentrations (DRCs) (5.37 ± 3.94 vs. 3.71 ± 2.10 μU/mL; P < 0.001) and false-negative rate (33.8 vs. 3.3%; P < 0.01) of PA screening tests were significantly higher in the PA with RAS group than in the control group, but only in severe RAS group, in subgroup analysis. Among patients who underwent successful treatment for severe RAS, mean DRC decreased from 11.22 ± 9.10 to 3.24 ± 2.69 μIU/mL (P < 0.001). Overall, the prevalence of RH decreased from 81.7 to 2.8% (P < 0.001) when both PA and RAS were treated with standard methods. PA with concurrent severe RAS is a condition that induces RH. PA can be easily missed in patients with coexisting RAS. RAS patients with RH after successful revascularization for RAS should be evaluated for coexisting PA.

Efficiency of Percutaneous Stent Angioplasty in Renal Artery Stenosis - 15 Years of Experience at a Single Center.

To determine the therapeutic efficiency of percutaneous revascularization in renal artery stenosis (RAS), as well as the role of comprehensive factors such as patient selection and degree of artery stenosis, on clinical outcome. 101 patients with hemodynamically relevant RAS underwent percutaneous angioplasty (PTA). 65.7 % were male (mean age: 64 years; range: 18-84). The clinical data was retrospectively analyzed. The serum creatinine (Cr), glomerular filtration rate (GFR), and blood pressure (BP) levels pre- and postprocedural, between 6 months and 1year, were retrospectively collected and statistically analyzed. Follow-up data was available in 34 (33.7 %) and 28patients (27.7 %) for Cr and MAP, respectively. A significant drop in mean arterial pressure (MAP) was observed on follow-up (mean -5.27 mmHg). Higher baseline Cr and MAP values showed a more pronounced drop in the follow-up (Cr: p0.002; difference to baseline -0.25 mg/dL, 95 %CI:-0.36, -0.07 and BP p < 0.001; diff. to baseline -0.72 mmHg; 95 %CI: -1.4, -0.40). There was no association between comorbidities, gender, and degree of stenosis with renal and BP outcome. No significant improvement in renal function was observed on follow-up (mean Cr drop: -0.015 mg/dL). The age group 51-60 years showed a significant improvement in BP (p 0.030; diff. to baseline -19.2 mmHg; 95 %CI: -34, -4.3). There was a slight reduction in antihypertensive medication following angioplasty (0.2 fewer). Minor complications were recorded in five procedures (4.9 %). Percutaneous renal artery revascularization in the presence of atherosclerotic RAS is a safe procedure associated with a significant drop in post-procedural BP. No significant improvement in renal function was observed. Further prospective studies focused on patient selection are necessary. · Percutaneous stent angioplasty in renal artery stenosis is associated with a significant improvement in post-procedural blood pressure control.. · There is no improvement in renal function after percutaneous stent angioplasty for renal artery stenosis (RAS).. · Percutaneous stent angioplasty is a safe procedure.. · Guerreiro H, Avanesov M, Dinnies S et al. Efficiency of Percutaneous Stent Angioplasty in Renal Artery Stenosis - 15Years of Experience at a Single Center. Fortschr Röntgenstr 2021; 193: 298 - 304.

Magnetization Transfer Imaging Predicts Porcine Kidney Recovery After Revascularization of Renal Artery Stenosis.

Stenotic kidney (STK) and contralateral kidney magnetization transfer ratios (MTRs; Mt/M0) were measured at 3.0-T magnetic resonance imaging, at offset frequencies of 600 and 1000 Hz, before and 1 month post-PTRA in 7 RVD pigs. Stenotic kidney MTR was correlated to renal perfusion, renal blood flow (RBF), and glomerular filtration rate (GFR), determined using multidetector computed tomography and with ex vivo renal fibrosis (trichrome staining). Untreated RVD (n = 6) and normal pigs (n = 7) served as controls. Renovascular disease induced hypertension and renal dysfunction. Blood pressure and renal perfusion were unchanged post-PTRA, but GFR and RBF increased. Baseline cortical STK-MTR predicted post-PTRA renal perfusion and RBF, and MTR changes associated inversely with changes in perfusion and normalized GFR. Stenotic kidney MTR at 600 Hz showed closer association with renal parameters, but both frequencies predicted post-PTRA cortical fibrosis. Renal STK-MTR, particularly at 600 Hz offset, is sensitive to hemodynamic changes after PTRA in swine RVD and capable of noninvasively predicting post-PTRA kidney perfusion, RBF, and fibrosis. Therefore, STK-MTR may be a valuable tool to predict renal hemodynamic and functional recovery, as well as residual kidney fibrosis after revascularization in RVD.

Clinical characteristics of concurrent primary aldosteronism and renal artery stenosis: A retrospective case–control study

ABSTRACT Background: Rare cases of concurrent primary aldosteronism (PA) and renal artery stenosis (RAS) have been reported. Methods: In this retrospective case–control study, we selected a cohort of 10 PA with RAS patients and a control group of 20 PA without RAS patients from January 1, 2006, to January 1, 2016. Results: All patients presented with refractory hypertension, and a nonstatistically significant trend toward lower mean serum potassium was seen in the PA with RAS group (p =.07). PA with RAS patients had lower mean orthostatic aldosterone-to-renin ratios (38.4 ± 41.4 ng dL−1/ng mL−1 h−1 vs. 87.4.4 ± 38.4 ng dL−1/ng mL−1 h−1, respectively; p < .01) and a higher false-negative rate (50% vs. 15%, respectively; p < .05) compared with controls. All misdiagnosed patients had the diagnosis of PA confirmed when we revaluated the repeated screening and confirmative tests because of residual hypertension or hypokalemia after successful revascularization of renal artery stenosis. Conclusions: PA is easily missed in patients with RAS because of the high false-negative rate for screening tests. RAS patients with residual hypertension after successful renal angioplasty should be monitored for coexisting PA. Reevaluation of screening and confirmatory tests is helpful in establishing the correct diagnoses.

A case report of successfully treated nephrotic syndrome after renal angioplasty

BackgroundThe standard treatment of renovascular hypertension accompanying renal artery stenosis (RAS) consists of angioplasty and administration of antihypertensive medication. Although nephrotic syndrome (NS) has been reported to be associated with RAS, the development of NS after revascularization of RAS is extremely rare.Case presentationA 48-year-old man presented with uncontrolled hypertension and azotemia. The right kidney was atrophic, and RAS of the left kidney was suspected based on a post-captopril DTPA scan. His blood pressure stabilized after renal angioplasty; however, he complained of edema after 1 week. NS developed and was diagnosed as focal segmental glomerulosclerosis (FSGS) based on renal biopsy. He received an angiotensin receptor blocker. Proteinuria resolved after 1 year.ConclusionsFSGS rarely develops after angioplasty of renal artery stenosis. This is the first report of successful treatment of this condition using an angiotensin receptor blocker during 1-year follow-up.

Can the pre-dialysis period in stage IV chronic kidney disease be prolonged?

Analysed herein are the results of treating a total of 29 patients presenting with stage IV chronic kidney disease (CKD) induced by ischaemic nephropathy. All patients had renal artery stenosis more than 80%, decreased glomerular filtration rate (GFR) below 30 ml/min/1.73m2 and were regarded by the nephrologists as potential candidates for programmed haemodialysis. After preparation aimed at preventing contrast-induced nephropathy all patients underwent stenting of the stenosed renal arteries. In the early postoperative period, 21 patients were found to have stabilization of the GFR with a tendency to increase. One woman developed acute renal failure requiring renal replacement therapy by means of haemodialysis. During the follow-up period from 1 to 5 years, 26 patients showed no progression of azotemia. CKD changed to stage III in 15 patients (p<0.005). Twenty-three (84%) patients during the follow-up period developed no new cardiovascular events. Hence, performing renal revascularization for renal artery stenosis >80% revealed in patients with stage IV CKD promotes prolongation of the dialysis-free period.

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 ACCmax ≤ 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.

Multimarker assessment for the prediction of renal function improvement after percutaneous revascularization for renal artery stenosis.

Identifying patients likely to have improved renal function after percutaneous transluminal renal angioplasty and stenting (PTRA) for renal artery stenosis (RAS) is challenging. The purpose of this study was to use a comprehensive multimarker assessment to identify those patients who would benefit most from correction of RAS. In 127 patients with RAS and decreased renal function and/or hypertension referred for PTRA, quantification of hemodynamic cardiac stress using B-type natriuretic peptide (BNP), renal function using estimated glomerular filtration rate (eGFR), parenchymal renal damage using resistance index (RI), and systemic inflammation using C-reactive protein (CRP) were performed before intervention. Predefined renal function improvement (increase in eGFR ≥10%) at 6 months occurred in 37% of patients. Prognostic accuracy as quantified by the area under the receiver-operating characteristics curve for the ability of BNP, eGFR, RI and CRP to predict renal function improvement were 0.59 (95% CI, 0.48-0.70), 0.71 (95% CI, 0.61-0.81), 0.52 (95% CI, 0.41-0.65), and 0.56 (95% CI, 0.44-0.68), respectively. None of the possible combinations increased the accuracy provided by eGFR (lower eGFR indicated a higher likelihood for eGFR improvement after PTRA, P=ns for all). In the subgroup of 56 patients with pre-interventional eGFR <60 mL/min/1.73 m(2), similar findings were obtained. Quantification of renal function, but not any other pathophysiologic signal, provides at least moderate accuracy in the identification of patients with RAS in whom PTRA will improve renal function.

Renal Artery Stenosis - are there Patients who Benefit from Intervention?

Atherosclerotic renal artery stenosis (ARAS) is one of the most relevant long-term complications of atherosclerotic disease. It is associated both with hypertension and increased renal and cardiovascular risk and overall mortality. Diagnostic modalities include non-invasive duplex ultrasound, dynamic magnetic resonance angiography (MRA) and computer tomography angiography (CTA) and are confirmed by using invasive renal angiography. Percutaneous revascularization of renal artery stenosis has been studied in various clinical trials. With regard to hypertension, several case series could show a clinical response to revascularization. However, the majority of randomized clinical trials could not confirm the correlation between intervention and the improvement of hypertension, kidney function, cardiovascular events, and mortality. Based on this predication the crucial tool in the treatment of ARAS is an optimal medical therapy, including statins, antihypertensive agents and platelet inhibition. Today the core point is to select subgroups and appropriate indications for better outcomes and avoiding unnecessary procedures very carefully. Therefore in patients with typical manifestations of ARAS including resistant or malignant hypertension, progressive decline of renal function, flash pulmonary edema or angina, renal artery intervention remains a sensible therapeutic option - after hemodynamic testing prior to revascularization. In the future further trials targeting patients who fulfill rational selection criteria need to be undertaken to confirm the efficacy of revascularization.

Pickering Syndrome precipitated by Angiotensin Converting Enzyme Inhibitor

Pickering syndrome is an under recognised cardio-renal syndrome where life threatening flash pulmonary edema develops in the setting of diastolic dysfunction of the heart. Renal artery stenosis induced activation of sympathetic nervous system and renin-angiotensin-aldosterone system result in fluid retention; such fluid retention in the setting of diastolic dysfunction results in flash pulmonary edema. Most patients who present with pickering syndrome have normal coronary circulation and left ventricular systolic function. We here present a case of pickering syndrome that was precipitated by initiation of angiotensin converting enzyme inhibitor therapy in a patient with undiagnosed unilateral renal artery stenosis. The incidence of flash pulmonary edema decreases on revascularization of renal artery stenosis. Underlying renal artery stenosis should be suspected in a patient with recurrent flash pulmonary edema as such patients merit from revascularization of renal artery stenosis. To the best of our knowledge we are the first to report angiotensin converting enzyme inhibitors as a precipitator of pickering syndrome.

1D.07

Objective: The benefit of revascularization for renal artery stenosis is currently unclear. A number of prospective, randomised studies showed no advantage of interventional revascularization (PTA) over medical therapy apart from a reduction in the number of antihypertensive drugs. A predictor of a more positive response to interventional treatment is urgently needed. We have shown that patients with a high resistive index (RI, > 80) by Doppler ultrasonography have inferior outcome after interventional revascularization for renal artery stenosis. We here obtained long-term follow up data from the original study collective and compared this to a matched group of recent patients with high resistive index which did not undergo revascularization but had improved medical therapy.Design and method: We measured the renal RI with Doppler ultrasonography in segmental arteries of both kidneys. 131 patients underwent renal angioplasty, 35 of these had renal RI values > 80. A further group of 31 patients with RI > 80 and renal artery stenosis > 65% did not undergo angioplasty. The combined endpoint was > 50 percent decrease in eGFR, end stage renal failure, or death. Mean (± SD) follow-up was 8.8 ± 4 years. Results: In patients with high RI (> 80), a decrease in renal function occurred in 74% patients after PTA and 77% without PTA compared to 19% of those with PTA and low RI. 71% and 52% of patients, compared to 17%, required dialysis, and 89% and 48% compared to 31% died (p<0.001 high RI compared to low RI). A total of 94% and 90% with high RI reached the combined endpoint as compared to 39% of those with low RI (multivariate relative risk 16, CI 3.7 to 68; P < 0.001 high RI vs low RI). Conclusions: Patients with renal artery stenosis and a high renal resistive index do not benefit from angioplasty in long-term follow up for renal and patient survival. Patients with high resistive index continue to suffer a poor prognosis even under improved medical therapy.

Renal artery stenosis: Up-date on diagnosis and treatment

Significant renal artery stenosis (RAS) can cause or result in deterioration of arterial hypertension and may promote the development of renal insufficiency. The activation of the renin-angiotensin-aldosterone system results in structural heart disease and may impact patient survival. Technical improvements of diagnostic and interventional endovascular tools have led to a more widespread use of endoluminal renal artery revascularization and extension of the indications for this type of therapy during the past two decades. Whereas balloon angioplasty is still the method of choice for the treatment of fibromuscular dysplasia, stent implantation is indicated in ostial atherosclerotic RAS. However, none of the so far published or presented randomized controlled trials could prove a beneficial outcome of RAS revascularization compared to medical management. As a result of these negative trials including the largest published trial to date, the ASTRAL trial, referrals to endovascular renal artery revascularization have declined and, moreover, reimbursement of these procedures has become a matter of debate. Crucial for a clinical benefit following revascularization of RAS is proper patient selection, revascularization being only indicated after proof of hemodynamic relevance of RAS. This article summarizes the appropriate diagnostic work-up of patients with suspected RAS, discusses the limitations of the results published so far and their impact on the indication for RAS revascularization.

Prediction and assessment of responses to renal artery revascularization with dynamic contrast-enhanced magnetic resonance imaging: a pilot study

The aim of this study was to assess the potential of dynamic contrast-enhanced (DCE) MRI to predict and evaluate functional outcomes after renal artery revascularization for renal artery stenosis (RAS). The single-kidney glomerular filtration rate (SK-GFR) was measured in 15 patients with atherosclerotic RAS with DCE-MRI and radioisotopes at baseline and 4 mo after revascularization. DCE-MRI also produced measurements of blood flow, blood volume, extraction fraction, tubular transit time, and functional volume. Stented kidneys (n = 22) were divided into three response groups on the basis of the changes in radioisotope SK-GFR: improved (n = 5), stable (n = 13), and deteriorated (n = 4). A good agreement was found between SK-GFR values from DCE-MRI and radioisotopes (correlation coefficient: 0.91). Before intervention, kidneys that improved had lower extraction fraction, higher blood volume, longer tubular transit time, and lower SK-GFR. After intervention, improved kidneys had increased functional volume, and deteriorated kidneys had reduced functional volume and extraction fraction. Revascularization improved blood flow and blood volume in all groups. This pilot study led to the hypothesis that well-vascularized kidneys with reduced extraction fractions are most likely to benefit from revascularization. More generally, DCE-MRI has the potential to replace radioisotope measurement of SK-GFR and may improve patient management by providing additional information on tissue perfusion.

Changes in Glomerular Filtration Rate After Renal Revascularization Correlate With Microvascular Hemodynamics and Inflammation in Swine Renal Artery Stenosis

The selection of patients with renal artery stenosis (RAS) likely to improve glomerular filtration rate (GFR) after percutaneous transluminal renal angioplasty is difficult. We examined basal hemodynamic and inflammatory factors linked to improved stenotic kidney (STK) function after percutaneous transluminal renal angioplasty in swine RAS. Fifteen pigs after 6 weeks of hemodynamically significant RAS were studied before and 4 weeks after technically successful percutaneous transluminal renal angioplasty+stenting. STK and contralateral kidney hemodynamics and function were evaluated by multidetector computed-tomography before and after acetylcholine challenge. Single-kidney deoxyhemoglobin (R2*, reciprocal to blood relaxation) and energy-dependent tubular function were assessed using blood-oxygen-level-dependent magnetic resonance imaging before and after furosemide. Baseline renal vein and inferior vena cava levels of inflammatory markers were measured and their gradient and net release calculated. Baseline parameters were compared with normal (n=7) and sham-RAS (n=7) pigs and correlated with the change in STK-GFR after revascularization (ΔGFR). Four weeks after percutaneous transluminal, renal angioplasty blood pressure was normalized in all animals, but STK-GFR improved in 10 of 15 (ΔGFR =+22.0±8.5 mL/min). ΔGFR correlated inversely with basal STK-GFR, renal release of inflammatory markers, and medullary R2* response to furosemide, but directly with GFR response to acetylcholine. Basal contralateral kidney GFR correlated directly with ΔGFR. Low basal STK-GFR with preserved response to acetylcholine may predict benefit from revascularization in RAS, whereas renal inflammation and robust STK-R2* responses to furosemide (possibly reflecting avid tubular oxygen consumption) are associated with less favorable outcomes. These tools may be useful for identification of patients likely to improve renal function after revascularization.

The effect of revascularization of renal artery stenosis on renal perfusion in patients with atherosclerotic renovascular disease

Only a small fraction of patients with atherosclerotic renovascular disease (ARVD) treated with revascularization have improved renal function after the procedure. It has been suggested that this may be due to effects of renal microvascular disease. Our aim was to measure the effect of renal artery stenosis (RAS) revascularization on renal perfusion in patients with renovascular disease. Seventeen renovascular disease patients were treated by dilatation of unilateral (N = 8) or bilateral (N = 9) RAS (N = 23 kidneys), mainly because of uncontrolled or refractory hypertension. The patients were studied before and after (103 ± 29 days) the procedure. Renal perfusion was measured using quantitative positron emission tomography (PET) perfusion imaging. Although renal perfusion correlated inversely with the degree of RAS in patients with renovascular disease, it did not change after revascularization. Our data support the notion of former clinical trials that angiographic severity of RAS does not determine the response to revascularization. Quantitative PET perfusion imaging is a promising tool to noninvasively measure renal perfusion for the assessment of physiological impact of RAS.

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.

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.

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.