Unilateral Renal Artery Stenosis Research Articles

Isolated Unilateral Renal Artery Stenosis in Young Female with Takayasu Arteritis: Case Report

Isolated Unilateral Renal Artery Stenosis in Young Female with Takayasu Arteritis: Case Report

The Metabolic Syndrome Does Not Affect Development of Collateral Circulation in the Poststenotic Swine Kidney

The collateral circulation is important in maintenance of blood supply to the ischemic kidney distal to renal artery stenosis (RAS). Obesity metabolic syndrome (MetS) preserves renal blood flow (RBF) in the stenotic kidney, but whether this is related to an increase of collateral vessel growth is unknown. We hypothesized that MetS increased collateral circulation around the renal artery. Twenty-one domestic pigs were randomly divided into unilateral RAS fed an atherogenic (high-fat/high-fructose, MetS-RAS) or standard diet, or controls (n = 7 each). RBF, glomerular filtration rate (GFR), and the peristenotic collateral circulation were assessed after 10 weeks using multidetector computed tomography (CT) and the intrarenal microcirculation by micro-CT. Vascular endothelial growth factor (VEGF) expression was studied in the renal artery wall, kidney, and perirenal fat. Renal fibrosis and stiffness were examined by trichrome and magnetic resonance elastography. Compared with controls, RBF and GFR were decreased in RAS, but not in MetS-RAS. MetS-RAS formed peristenotic collaterals to the same extent as RAS pigs but induced greater intrarenal microvascular loss, fibrosis, stiffness, and inflammation. MetS-RAS also attenuated VEGF expression in the renal tissue compared with RAS, despite increased expression in the perirenal fat. MetS does not interfere with collateral vessel formation in the stenotic kidney, possibly because decreased renal arterial VEGF expression offsets its upregulation in perirenal fat, arguing against a major contribution of the collateral circulation to preserve renal function in MetS-RAS. Furthermore, preserved renal function does not protect the poststenotic kidney from parenchymal injury.

Percutaneous renal artery stent implantation in the treatment of atherosclerotic renal artery stenosis.

We aimed to investigate the clinical curative effect of percutaneous renal artery stent implantation (PTRAS) in the treatment of atherosclerotic renal artery stenosis (ARAS), and to analyze the factors influencing the curative effect of PTRAS. A total of 230 patients with unilateral or bilateral renal artery stenosis were retrospectively analyzed. According to whether adverse cardiogenic or nephrogenic events occurred, 230 patients were divided into two groups to analyze the risk factors of adverse cardiogenic or nephrogenic events. The blood pressure of patients at each time-point after operation was decreased significantly compared with that before operation (P<0.01). The levels of serum creatinine (SCr) at 24 h and 36 months after PTRAS were slightly increased compared with that before operation (P>0.05). The estimated glomerular filtration rate (eGFR) at each time-point after operation was slightly decreased compared with that before operation, but the difference was not statistically significant (P>0.05). Renography showed that GFR on the side of stent implantation at 36 months after PTRAS had no significant change compared with that before operation (P>0.05), but GFR on the unaffected side without receiving PTRAS was significantly increased compared with that before operation (P=0.0014). During the 36-month follow-up, there were a total of 56 cases of adverse cardiogenic or nephrogenic events. Multivariate regression analysis results showed that adverse cardiogenic or nephrogenic events after PTRAS were obviously associated with age (≥65 years old), Charlson comorbidity index (CCI) score (≥2 points), diabetes mellitus, stroke and congestive heart failure (CHF) (P<0.05). In conclusion, PTRAS can effectively control the blood pressure and reduce the types of antihypertensive drugs used by patients with ARAS, but it has no definitely protective effect on renal function. Age (≥65 years old), CCI score (≥2 points), diabetes mellitus, stroke and CHF are risk factors leading to adverse cardiogenic or nephrogenic events after PTRAS.

Renal scattered tubular-like cells confer protective effects in the stenotic murine kidney mediated by release of extracellular vesicles

To test the hypothesis that intrinsic renal scattered tubular cells (STC-like cells) contribute to repairing injured tubular epithelial cells (TEC) by releasing extracellular vesicle (EV). EV released from primary cultured pig STC-like cells were confirmed by electron microscopy. Antimycin-A (AMA)-induced injured proximal TEC (PK1 cells) were co-cultured with STC-like cells, STC-like cells-derived EV, or EV-free conditioned-medium for 3 days. Cellular injury, oxidative stress and mitochondrial function were assessed. Transfer of mitochondria from STC-like cells to TEC was assessed using Mito-trackers, and their viability by mitochondrial membrane potential assays. STC-like cells-derived EV were intra-arterially injected into mice 2 weeks after induction of unilateral renal artery stenosis. Two weeks later, renal hemodynamics were studied using magnetic-resonance-imaging, and renal fibrosis assessed ex-vivo. Cultured STC-like cells released EV that were uptaken by TEC. A protective effect conferred by STC-like cells in AMA-induced TEC injury was partly mimicked by their EV. Furthermore, STC-like cells-EV carried and transferred mitochondrial material to injured TEC, which partly restored mitochondrial function. In vivo, STC-like cells-derived EV engrafted in the stenotic kidney, and improved its perfusion and oxygenation. STC-like cells-EV exert protective effects on injured tubular cells in vitro and in vivo, partly by transferring STC-like cells mitochondria, which remain at least partly functional in recipient TEC.

Hypertension with metabolic alkalosis

Severe hypertension in children is chiefly renal parenchymal or renovascular in origin. Renovascular hypertension is usually symptomatic and rarely presents with renal tubular dysfunction. We describe a 2-year-old child with polyuria, failure to thrive, hyponatremia, hypokalemia, metabolic alkalosis, hypercalciuria, low molecular weight proteinuria, and medullary nephrocalcinosis. Evaluation revealed severe hypertension and discrepant renal sizes. Doppler ultrasonography and digital subtraction angiography showed right main renal artery stenosis. Hypertension and electrolyte abnormalities abated following percutaneous angioplasty. Unilateral renal artery stenosis may manifest with symptoms of renal tubular dysfunction alone. Hypokalemia and metabolic alkalosis must prompt consideration of renovascular hypertension and monogenic causes. Angiography is essential for confirmation of renovascular hypertension and enables angioplasty, the mainstay of management.

A rapid T1 mapping method for assessment of murine kidney viability using dynamic manganese-enhanced magnetic resonance imaging.

Dynamic manganese-enhanced MRI (MEMRI) allows assessment of tissue viability by tracing manganese uptake. We aimed to develop a rapid T1 mapping method for dynamic MEMRI to facilitate assessments of murine kidney viability. A multi-slice saturation recovery fast spin echo (MSRFSE) was developed, validated, and subsequently applied in dynamic MEMRI at 16.4T on ischemic mouse kidneys after 4 weeks of unilateral renal artery stenosis (RAS). Baseline T1 values and post-contrast R1 (1/T1 ) changes were measured in cortex (CO), outer (OSOM), inner (ISOM) strips of outer medulla, and inner medulla (IM). Validation studies showed strong agreement between MSRFSE and an established saturation recovery Look-Locker method. Baseline T1 (s) increased in the stenotic kidney CO (2.10 [1.95-2.56] vs. 1.88 [1.81-2.00], P = 0.0317) and OSOM (2.17 [2.05-2.33] vs. 1.96 [1.87-2.00], P = 0.0075) but remained unchanged in ISOM and IM. This method allowed a temporal resolution of 1.43 min in dynamic MEMRI. Mn2+ uptake and retention decreased in stenotic kidneys, particularly in the OSOM (ΔR1 : 0.48 [0.38-0.56] vs. 0.64 [0.61-0.69] s-1 , P < 0.0001). Dynamic MEMRI by MSRFSE detected decreased cellular viability and discerned the regional responses to RAS. This technique may provide a valuable tool for noninvasive evaluation of renal viability. Magn Reson Med 80:190-199, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Measurement of Murine Single-Kidney Glomerular Filtration Rate Using Dynamic Contrast-Enhanced MRI.

To develop and validate a method for measuring murine single-kidney glomerular filtration rate (GFR) using dynamic contrast-enhanced MRI (DCE-MRI). This prospective study was approved by the Institutional Animal Care and Use Committee. A fast longitudinal relaxation time (T1 ) measurement method was implemented to capture gadolinium dynamics (1 s/scan), and a modified two-compartment model was developed to quantify GFR as well as renal perfusion using 16.4T MRI in mice 2 weeks after unilateral renal artery stenosis (RAS, n = 6) or sham (n = 8) surgeries. This approach was validated by comparing model-derived GFR and perfusion to those obtained by fluorescein isothiocyanante (FITC)-inulin clearance and arterial spin labeling (ASL), respectively, using the Pearson's and Spearman's rank correlations and Bland-Altman analysis. The compartmental model provided a good fitting to measured gadolinium dynamics in both normal and RAS kidneys. The proposed DCE-MRI method offered assessment of single-kidney GFR and perfusion, comparable to the FITC-inulin clearance (Pearson's correlation coefficient r = 0.95 and Spearman's correlation coefficient ρ = 0.94, P < 0.0001, and mean difference -7.0 ± 11.0 μL/min) and ASL (r = 0.92 and ρ = 0.84, P < 0.0001, and mean difference 4.4 ± 66.1 mL/100 g/min) methods. The proposed DCE-MRI method may be useful for reliable noninvasive measurements of single-kidney GFR and perfusion in mice. Magn Reson Med 79:2935-2943, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Abstract P225: Non-invasive Measurement of Renal Blood Flow (RBF) in Different Rat Models by Magnetic Resonance Imaging (MRI)

Quantitative measure of RBF provides important information regarding renal physiology and pathology, in different animal’s models. Arterial Spin Labelling-MRI (ASL-MRI) is a non-invasive method to measure blood flow without exogenous contrast media, using arterial water protons labeled by radiofrequency as an endogenous tracer. However, the low signal/noise radio, and the motion artifacts are a challenge for the acquisition of RBF in small animals. Our objective is evaluated the feasibility and reproducibility of the RBF measure by ASL-MRI in different hypertensive rats models. ASL-MRI images were obtained in Sprague-Dawley (SD) rats (200-300g) under inhalation anesthesia using a 7 Tesla Varian MRI system with a spin echo imaging sequence. After 4 days the MRI studies was repeated to evaluate reproducibility, using paired sample T-test and the test-retest reliability (TR) equation. RBF was also measured in in Dahl SS rats on regular chow and spontaneous hypertensive rats (SHR). Additionally we measure the RBF in a set of animals under unilateral nephrectomy (UNx) and renal arterial stenosis (RS) before and after the surgery. Table 1 shows the mean cortical RBF in different rat strains and models. Re-test analysis showed no relevant differences, being the means of differences 9.4±35 ml/min/100g tissue (p=0.58) in SD rats. The TR was 92.4±6%. UNx increase the RBF in 69.1% in comparison with sham group. (p&lt;0.01). After the RS the blood pressure increased and the RBF decrease 56% (p&lt;0.01) in comparison with sham group. ASL-MRI performed with navigator correction and respiratory gating is a feasible and reproducible non-invasive method to measure RBF in several rat models.

Split renal function in patients with unilateral atherosclerotic renal artery stenosis—effect of renal angioplasty

ObjectiveTo evaluate the effect of percutaneous transluminal renal angioplasty (PTRA) on split renal function (SRF) in patients with unilateral atherosclerotic renal artery stenosis (ARAS).MethodsWe performed a retrospective analysis of all consecutively examined patients at our centre with significant ARAS undergoing PTRA during 2002–07. A significant ARAS was defined as a lesion with a trans-stenotic mean arterial pressure gradient of at least 10 mmHg or a diameter stenosis >50% on angiography. Ambulatory (24 h) systolic and diastolic blood pressure (ASBP and ADBP, respectively) and calculated SRF using 99mTc-DTPA renal scintigraphy were evaluated before (baseline) and 4 weeks after PTRA.ResultsASBP and ADBP were significantly lower 4 weeks after PTRA compared with baseline levels. Although total estimated glomerular filtration rate (eGFR; four-variable Modification of Diet in Renal Disease equation) had not changed by PTRA, analysis of SRF showed significantly increased eGFR in stenotic kidneys and a comparable reduction in eGFR in non-stenotic kidneys 4 weeks after PTRA.ConclusionsIn patients with unilateral ARAS, PTRA significantly improved eGFR in stenotic kidneys and decreased filtration in contralateral, non-stenotic kidneys. These potentially beneficial effects may not be apparent when total renal function remains stable. The clinical significance of these findings needs to be evaluated further.

Descendo-bifemoral bypass grafting and renal artery revascularization to treat complex obliterative arteriopathy.

Our goal was to describe a new standardized approach in patients with extensive obliterative arteriopathy aimed at distal revascularization and surgical kidney recruitment via descendo-bifemoral bypass grafting and renal artery revascularization. Three patients with Leriche's syndrome and either a compromised single kidney or unilateral significant renal artery stenosis were treated with a standardized surgical approach, restoration of distal perfusion via descendo-bifemoral bypass with synchronous ( n = 2) left-sided renal artery revascularization or metachronous ( n = 1) right-sided renal artery revascularization. The intended surgical aim was achieved successfully in all 3 cases. All patients showed a decline in serum creatinine levels. One patient who needed substitution therapy was free from dialysis 3 months after surgery. Additionally, blood pressure management was substantially reduced because uncontrolled peak systolic episodes were no longer observed and pharmacotherapeutic agents could be partially withdrawn. Distal revascularization and surgical kidney recruitment via descendo-bifemoral bypass and renal artery revascularization is a promising option to treat complex obliterative arteriopathy.

Hyponatremic hypertensive syndrome - a retrospective cohort study.

AIMTo ascertain the frequency of hyponatremic hypertensive syndrome (HHS) in a cohort of children with hypertensive emergency in a tertiary pediatric hospital.METHODSA retrospective review was undertaken among children with hypertensive emergency admitted in our tertiary children hospital between June 2014 and December 2015 with an aim to identify any children with HHS. Three children with HHS were identified during this period.RESULTSThe 3 patients with HHS presented with hypertensive emergency. They were initially managed with Labetalol infusion and thereafter switched to oral anti-hypertensives (combination of Nifedipine sustained release, Hydralazine and Beta Blocker). All 3 were diagnosed to have unilateral renal artery stenosis. One child was lost to follow up, whereas the other 2 underwent renal angioplasty which was followed with normalization of blood pressure.CONCLUSIONDespite activation of renin angiotensin axis secondary to renal artery stenosis, these groups of children have significant hyponatremia. Renal re-vascularisation produces excellent results in most of them.

Autonomic remodeling may be responsible for decreased incidence of aortic dissection in STZ-induced diabetic rats via down-regulation of matrix metalloprotease 2.

BackgroundEpidemiological studies reported that diabetic patients had a lower incidence of aortic dissection (AD), but the definite mechanism is unknown. We aim to investigate the possible protective effect of diabetes mellitus (DM) on AD formation with an emphasis on autonomic remodeling.MethodsStreptozotocin (STZ) intraperitoneal injection was applied to induce diabetes, unilateral renal artery stenosis (URAS) together with β-amino propionitrile (BAPN) oral treatment was used to induce AD. Sixty SD rats were equally and randomly divided into four groups (normal group, DM group, URAS + BAPN oral treatment group, DM + URAS + BAPN oral treatment group). Rats were fed for 6 weeks, the number of AD was recorded and remained rats were sacrificed. Thoracic aorta were harvested, morphological changes were assessed. Expression of tyrosine hydroxylase (TH), choline acetylase (ChAT), matrix metalloprotease 2 (MMP2) and matrix metalloprotease 9 (MMP9) were evaluated.ResultsA total of 7 AD was noted in S + B group, DM rats did not develop AD. Diabetic rats had a lower incidence of AD (P < 0.01). In dissected aorta, collagen deposition increased while elastic fiber became fragmented. These pathological changes diminished in diabetic rats. Diabetic rats had a lower expression of ChAT (P < 0.01). URAS + BAPN treatment elevated expression of TH in normal rat and ChAT in diabetic rats (P < 0.001). Expression of MMP2 and MMP9 elevated in all the rats after URAS + BAPN, but the elevation range of MMP2 in diabetic rats was smaller (P < 0.001).ConclusionsSTZ-induced diabetic rats have a lower incidence of AD after URAS and BAPN treatment, this protective effect could be possibly attributed to autonomic innervation modification and possible related down-regulation of MMP2.

Non-invasive imaging cannot replace formal angiography in the diagnosis of renovascular hypertension.

Renovascular disease (RVD) is found in about 10% of secondary childhood hypertension. Digital subtraction angiography (DSA) is the gold standard to diagnose RVD. Non-invasive imaging methods like Doppler ultrasound (US), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are increasingly used. Our aim was to evaluate the role and accuracy of US, MRA, and CTA compared to DSA in diagnosing RVD in children. A retrospective review of 127 children with suspected renovascular hypertension was performed in children referred to Great Ormond Street Hospital between 2006 and 2014 due to clinical suspicion of renovascular hypertension and/or findings on US and/or MRA or CTA. Ninety-nine of 127 children (78%) were diagnosed with renovascular disease and 80 were treated with percutaneous transluminal angioplasty during the same procedure. The median age at presentation was 5.6 (range, 2.5-10.6) years. Thirty-six children had unilateral renal artery stenosis in major extraparenchymal vessels, 47 bilateral stenosis and 16 intrarenal small vessel disease. US had a sensitivity of 63% and specificity of 95%. MRA and CTA were performed in 39 and 34 children, respectively. CTA sensitivity was slightly higher than that of MRA, 88 vs. 80%, and specificity 81 vs. 63%. The sensitivity of MRA and CTA is still too low to reliably rule out renovascular disease in children with a strong suspicion of this diagnosis. DSA remains the gold standard to diagnose renovascular hypertension and is recommended when clinical and laboratory criteria are highly suggestive of renovascular disease even with normal radiological investigations from non-invasive methods.

Noninvasive Assessment of Renal Fibrosis with Magnetization Transfer MR Imaging: Validation and Evaluation in Murine Renal Artery Stenosis

Purpose To test the utility of magnetization transfer imaging in detecting and monitoring the progression of renal fibrosis in mice with unilateral renal artery stenosis. Materials and Methods This prospective study was approved by the Institutional Animal Care and Use Committee. Renal artery stenosis surgery (n = 10) or sham surgery (n = 5) was performed, and the stenotic and contralateral kidneys were studied longitudinally in vivo at baseline and 2, 4, and 6 weeks after surgery. After a 16.4-T magnetic resonance imaging examination, magnetization transfer ratio was measured as an index of fibrosis (guided by parameters selected in preliminary phantom studies). In addition, renal volume, perfusion, blood flow, and oxygenation were assessed. Fibrosis was subsequently measured ex vivo by means of histologic analysis and hydroxyproline assay. The Wilcoxon rank sum or signed rank test was used for statistical comparisons between or within groups, and Pearson and Spearman rank correlation was used to compare fibrosis measured in vivo and ex vivo. Results In the stenotic kidney, the median magnetization transfer ratio showed progressive increases from baseline to 6 weeks after surgery (increases of 13.7% [P = .0006] and 21.3% [P = .0005] in cortex and medulla, respectively), which were accompanied by a progressive loss in renal volume, perfusion, blood flow, and oxygenation. The 6-week magnetization transfer ratio map showed good correlation with fibrosis measured ex vivo (Pearson r = 0.9038 and Spearman ρ = 0.8107 [P = .0002 vs trichrome staining]; r = 0.9540 and ρ = 0.8821 [P < .0001 vs Sirius red staining]; and r = 0.8429 and ρ = 0.7607 [P = .001 vs hydroxyproline assay]). Conclusion Magnetization transfer imaging was used successfully to measure and longitudinally monitor the progression of renal fibrosis in mice with unilateral renal artery stenosis. © RSNA, 2016 Online supplemental material is available for this article.

BR 05-2 ANGIOPLASTY OF ATHEROSCLEROTIC RENAL ARTERY STENOSIS

Abstract Atherosclerotic renal artery stenosis is an increasingly recognized medical problem especially in elderly patients. It commonly occurs with systemic manifestations including hypertension (HTN), chronic kidney disease (CKD) or atherosclerotic diseases including coronary or peripheral artery disease. Significant renal artery stenosis may result in HTN, ischemic nephropathy, however it is still in debate about the benefit of revascularization. Although several randomized controlled trials including Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) and Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) study has failed to reveal a significant benefit of angioplasty, angioplasty with medical therapy is increasingly accepted in some patients with certain clinical conditions.For determining appropriate candidates for renal artery angioplasty, anatomical evaluation of renal artery stenosis and atherosclerotic change of abdominal aorta should be preferentially undergone. Angiographic stenosis more than 50% with physiologic significance, or ≥70% stenosis is considered significant. Translesional pressure gradient with or without hyperemia should be routinely assessed in intermediate stenosis (50-70%). Intravascular ultrasound assessment may be used to evaluate luminologic severity or characteristics.Global renal ischemia caused by renal artery stenosis should be an appropriate indication of revascularization, however unilateral and solitary ischemia would be considerable. Patients with cardiac disturbance syndrome or pulmonary edema relevant to renal artery stenosis can be managed with renal artery angioplasty. Several prospective randomized trials have failed to show a significant difference in blood pressure (BP) response after revascularization or medical treatment, nevertheless resistant HTN with global renal ischemia would be a proper indication of revascularization. Both patient groups with revascularization and medication alone in CORAL showed similar BP response about 15 mmHg. Such BP responders with optimal medication may be not appropriate candidates for revascularization for controlling BP. Patients with reduced renal function and global renal ischemia may be also good candidates for renal artery stenting. However, evidences to support revascularization in unilateral renal artery stenosis are limited. Revascularization would be considered if renal artery stenosis is relevant to hemodynamic significance. Although revascularization with stenting have been commonly used for patients with renal artery stenosis, previous results are inconclusive and lacking to support comprehensive indications of current clinical application. Selection of candidates who benefits with angioplasty should be carefully conducted with sufficient diagnostic evaluation.

Bilateral Renal Artery Stenosis With a Pheochromocytoma

Renal artery stenosis (RAS) is a common cause of secondary hypertension. Pheochromocytomas have been associated with hypertension in 0.1% of the population. Pheochromocytoma is a well-documented co-morbid condition of unilateral RAS. Bilateral RAS with a pheochromocytoma is extremely rare with only one documented case in the literature. We present the second documented case of bilateral RAS with a pheochromocytoma. The coexistence of these pathologies makes diagnosis challenging. Proper diagnosis of the etiology of hypertension is essential given the pre-surgical treatment required for neuroendocrine tumors. J Endocrinol Metab. 2016;6(3):95-96 doi: http://dx.doi.org/10.14740/jem335w

Ultrasonographic Tissue Characterization of Kidneys in Patients with Unilateral Renal Artery Stenosis

Introduction Ultrasound tissue characterization (USTC) has been applied to B-mode images of normal, young and transplanted kidneys, carotid, and peripheral atherosclerosis and venous thrombosis. We analyzed USTC from both kidneys of patients with severe unilateral renal artery stenosis. Seven women and 11 men, 79 ± 9 standard deviation (range = 57–96) years of age, were included. Severe, unilateral, renal artery stenosis was based on renal artery peak-systolic velocity (PSV) &gt; 200 cm/sec and/or renal-aortic PSV ratio &gt; 3.5. This sample population, selected sequentially by date of ultrasonographic examinations requested, was heterogeneous: kidney lengths and resistivity indices varied from 6.7 to 13.4 cm and 0.45 to 0.85. Methods USTC was applied to images selected for kidney length measurements. Pixel brightness in the 0–255 range was rescaled to zero for black and 200 for fascia brightness. Gray-scale medians (GSM) of entire kidneys were estimated for statistical comparisons between: (a) kidneys ipsilateral to stenosis (KIS), (b) kidneys contralateral to stenosis (KCS), and (c) normal, young kidneys (KN), previously published GSM = 37 ± 6 (27–48). Results Two distinct KCS subgroups were identified: (1) near-normal GSM &lt; 54 (KCSN, n = 10, 56%); and (2) elevated GSM &gt; 60 (KCSH, n = 8, 44%). Subgroup increasing GSM order was (1) KN, (2) KCSN (47 ± 7, &gt; KN, p &lt; 0.002), (3) KIS-CN (59 ± 20, &gt;KCSN, p &lt; 0.003), (4) KIS-CH (73 ± 20, &gt; KCSN, p &lt; 0.007), and (5) KCSH (78 ± 17, &gt;KIS-CN, p &lt; 0.05). GSM was independent of kidney length or resistivity index, with Pearson correlation coefficients &lt; 0.5 for either KIS or KCS, respectively. Conclusions Tissue echogenicity, represented by GSM, was an independent variable characterizing effects of unilateral renal artery stenosis on the ipsilateral or on both kidneys.

Effects of Restoration of Blood Flow on the Development of Aortic Atherosclerosis in ApoE-/- Mice With Unilateral Renal Artery Stenosis.

BackgroundChronic unilateral renal artery stenosis (RAS) causes accelerated atherosclerosis in apolipoprotein E–deficient (ApoE−/−) mice, but effects of restoration of renal blood flow on aortic atherosclerosis are unknown.Methods and ResultsMale ApoE−/− mice underwent sham surgery (n=16) or had partial ligation of the right renal artery (n=41) with the ligature being removed 4 days later (D4LR; n=6), 8 days later (D8LR; n=11), or left in place for 90 days (chronic RAS; n=24). Ligature removal at 4 or 8 days resulted in improved renal blood flow, decreased plasma angiotensin II levels, a return of systolic blood pressure to baseline, and increased plasma levels of neutrophil gelatinase associated lipocalin. Chronic RAS resulted in increased lipid staining in the aortic arch (33.2% [24.4, 47.5] vs 11.6% [6.1, 14.2]; P<0.05) and descending thoracic aorta (10.2% [6.4, 25.9] vs 4.9% [2.8, 7.8]; P<0.05), compared to sham surgery. There was an increased amount of aortic arch lipid staining in the D8LR group (22.7% [22.1, 32.7]), compared to sham‐surgery, but less than observed with chronic RAS. Lipid staining in the aortic arch was not increased in the D4LR group, and lipid staining in the descending aorta was not increased in either the D8LR or D4LR groups. There was less macrophage expression in infrarenal aortic atheroma in the D4LR and D8LR groups compared to the chronic RAS group.ConclusionsRestoration of renal blood flow at either 4 or 8 days after unilateral RAS had a beneficial effect on systolic blood pressure, aortic lipid deposition, and atheroma inflammation.

Duplex derived intrarenal resistance index correlates with invasive pressure gradient measurements in detecting relevant unilateral renal artery stenosis.

The purpose of this study was to assess the correlation between the transstenotic pressure gradient as determined by a pressure wire and the decrease in the intrarenal resistance index (RI) > 0.05 measured by duplex ultrasound in significant unilateral renal artery stenosis (RAS). Intravascular ultrasound (IVUS) was correlated to the angiographic degree of RAS. In 17 patients, transstenotic pressure gradient measurements, IVUS and RI measurements were obtained before and after stenting. After stenting, graded stenosis was created by progressive balloon catheter inflation. Stenosis severity was expressed as the ratio of the distal pressure (Pd) corrected for aortic pressure (Pa). The balloon inflation pressure was adjusted to create a stenosis with Pd/Pa ratio 1.0 to 0.7. In parallel, RI measurements were performed in the affected kidney and compared to the contralateral kidney for the calculation of the side-difference in RI. IVUS was performed to correlate the cross-sectional degree of stenosis with quantitative angiography (QA). In 60 out 68 measurements, the RI difference (decline > 0.05) correlated with a Pd/Pa ratio < 0.9; this correlation was significant by linear regression analysis (p < 0.001). The preinterventional mean degree of stenosis was 63.4 % + 16.1 (24.6 - 84.6 %) as assessed by QA and 76.7 % + 13.2 % (47 - 92 %) as assessed by IVUS, showing a significant correlation (p < 0.035). In unilateral RAS, a drop in RI > 0.05 as compared to the unaffected kidney correlates to an invasively measured Pd/Pa ratio < 0.9, which is regarded as a significant pressure gradient associated with increased renin production, which promotes renovascular hypertension. QA underestimates RAS severity as compared to IVUS.

Improvement of Renovascular Malignant Hypertension after Angioplasty

Malignant hypertension in young female with disparity in kidney size raise the attention toward non-essential renovascular hypertension. In this case we describe a young female suffered severe hypertension associated with deterioration of kidney function and disparity in kidney size by ultrasound. Hemodialysis was started because of electrolytes imbalance and fluid overload which is unusual with unilateral renal artery stenosis. Management by traditional antihypertensive medication was with limited benefit and patient condition required intensive care monitoring. Balloon dilatation angioplasty with stent insertion in the left renal artery was performed, blood pressure started to respond to anti-hypertensive medications but she became anuric. Daily hemodialysis session was done, after few days her condition started to improve and serum creatinine returned to normal base 1.1 mg/dl without dialysis support. The patient presentation was not classic toward either unilateral renal artery stenosis or reno-parenchymal disease.