Renal Artery Flow Research Articles

Renal Artery Blood Flow and Surface Parenchymal Perfusion During Renal Artery Endoshunting in a Porcine Model

ObjectiveIschaemia and reperfusion can result in permanent tissue damage. During complex open abdominal aortic surgery, transient clamping of renovisceral arteries may be required to successfully complete the vascular repair. Endovascular shunting (endoshunting) presents an alternative technique for managing such temporary renovisceral ischaemia. This study aimed to investigate the performance of endoshunting to the renal circulation in a porcine model. MethodsThis study of five domestic pigs investigated arterial volume flow rates during endoshunting of a single renal artery and the associated impact on renal perfusion parameters (laser Doppler renal parenchymal perfusion, renal oxygen extraction, and selective urinary output). The study was performed in three steps: baseline registrations (30 minutes), endoshunting (120 minutes), and restitution (60 minutes). The right kidney was used as the experimental side and the left kidney as control. ResultsThe median arterial flow rate in the left control kidney remained constant throughout the experiment. On the right (endoshunted) side, the baseline median arterial flow rate was 267 (range, 160 – 404) mL/min. Following activation of the endoshunt, the median arterial volume flow dropped by 59% to 110 (range, 45 – 150) mL/min (p = .018). During endoshunting, the median kidney surface perfusion decreased to 42% of the baseline value. On the control side, a rise in the median parenchymal perfusion was observed after endoshunt activation, which was again normalised following restitution of native right renal artery flow. During endoshunting, the median regional urine production was 0.32 (range, 0.12 – 0.50) mL/hour but resumed after renal artery flow restitution. ConclusionOn average, the endoshunted kidneys showed a rapid restoration of blood flow, parenchymal perfusion, and urine production after 120 minutes of endoshunting. This suggests that endoshunting to the kidney using an endoshunt system might be a promising strategy to preserve renal function when a temporary interruption of native renal artery blood flow is needed during complex vascular surgical repairs involving the renal arteries.

De Novo Atherosclerotic Renal Artery Stenosis Covered Stent Treatment for Resistant Hypertension (ARTISAN) Results

BackgroundAtherosclerotic renal artery stenosis (ARAS) may provoke hypertension and/or impaired kidney function. Some patients develop uncontrolled hypertension and deteriorating kidney function despite optimal medical therapy. In these patients, endovascular treatment is an important therapeutic option. ARTISAN was a prospective, open-label, single-arm, multicenter clinical trial to evaluate the safety and effectiveness of the iCast RX covered stent both functionally for reestablishing renal artery flow, and clinically for controlling resistant hypertension. MethodsPatients considered for enrollment had average systolic blood pressure (SBP) ≥155 mm Hg despite taking 3 antihypertensive medications. Prior to enrollment and covered stent placement, angiographic confirmation of ARAS ≥80% with physiologic significance was required. Clinical assessments were performed at 30 days, 9 months, and annually through 36 months. Covered stent safety and efficacy were based on 9-month coprimary end points, including primary vessel patency and SBP improvement at 9 months. Secondary outcomes included target lesion revascularization, major adverse events, and secondary patency. ResultsSixty-eight of the planned 138 subjects were enrolled. Primary patency was seen in 94.3% of subject lesions; the mean SBP reduction was 15.7 mm Hg. The functional and clinical end points met prespecified performance goals of 70% primary patency (P < .0001) and ≥10 mm Hg SBP decrease (P = .0192), respectively, at 9 months. Six subjects (8.8%) experienced 7 major adverse events within 36 months. The clinically driven target lesion revascularization rate was 7.3% at 36 months. ConclusionsThe high primary patency and improvement in SBP, persisting through 36 months, suggest that the iCast RX covered stent is safe and effective for the treatment of appropriately selected patients with ARAS.

Hypogammaglobulinemia in a child with atypical hemolytic-uremic syndrome

We present a unique clinical case of an atypical hemolytic-uremic syndrome in a child. The mutation in exon 6 of the CD46 gene (chr1:207940532G&gt;C) leads to a homozygous or hemizygous missense substitution. An 8-year-old girl was urgently hospitalized with symptoms of hemorrhagic syndrome and acute kidney injury. The child from the second pregnancy with an aggravated obstetric anamnesis, the first operative labor at the 38th week, who has an aggravated genealogical anamnesis. Initially, the disease developed in the guise of gastroenterological pathology: the girl had dyspeptic disorders, most likely associated with pathology of carbohydrate metabolism, also frequent infectious diseases and a lag in physical development. From the age of 4 years, the girl suffered from persistent hypoalbuminemia, hypoproteinemia and hypogammaglobulinemia, requiring replacement therapy with intravenous immunoglobulins. She was repeatedly examined in gastroenterological departments in Yekaterinburg and Moscow in 2021-2023, but no data concerning protein-losing enteropathies or primary immunodeficiency was obtained. Also, the whole-exome sequencing with result validation hasn’t confirmed an inherited etiology of the presumed congenital immune error. However, a CD46 gene mutation, associated with the development of hemolytic-uremic syndrome in some publications, was identified in the study. The signs of thrombotic microangiopathy were preceded by fever of unspecified etiology: microangiopathic hemolysis, thrombocytopenia, hyperazotemia, C3 consumption, proteinuria, and macrohematuria; hypercholesterolemia, protein metabolism disorder, increased transaminases, ferritin were also noted. According to the ultrasound of the kidneys there were diffuse changes in the parenchyma, decreased velocity indices of blood flow in both renal arteries at all levels. Differential diagnosis was carried out with thrombotic thrombocytopenic purpura, autoimmune hemolytic anemia, antinuclear form of atypical hemolytic-uremic syndrome, viral and bacterial infections, systemic pathology, antiphospholipid syndrome, and hemoblastosis. The girl didn’t need a renal replacement therapy. When complement-blocking therapy with eculizumab was initiated on vital indications, the signs of the disease were gradually eliminated. The prolonged absence of nephropathy in the child may indicate the diversity of the CD46 gene’s functions and different phenotypic manifestation of its mutations. Analysis of literature sources and detection of CD46 “environment” genes (CYBA, LYST, ARPCIB) by full-exome sequencing suggest ambiguity and polymorphism of phenotypic manifestations of complement-mediated mutation.

The protective effect of bergamot polyphenolic fraction on reno-cardiac damage induced by DOCA-salt and unilateral renal artery ligation in rats

Abstract Funding Acknowledgements None. The complex pathological interactions between renal and cardiovascular systems represent a real global epidemic and renovascular hypertension remains among the most prevalent, but also potentially reversible, risk factor for numerous reno-cardiac diseases in humans and pets. Here, we investigated the anti-inflammatory and reno-cardiac protective effects of a polyphenol-rich fraction of citrus bergamot (BPF) in an experimental model of hypertension induced by unilateral renal artery ligation (RAL). Adult male Wistar rats underwent unilateral renal artery ligation and treatment with 20 mg/kg deoxycorticosterone acetate (DOCA), twice a week for a period of 4 weeks, and 1% sodium chloride water. A subgroup of hypertensive rats received 100 mg/kg/day of BPF for 28 days, by gavage. Another group of animals was treated with a sub-cutaneous injection of vehicle (CTRL). RAL DOCA-Salt rats showed a significant increase in mean arterial blood pressure (MAP; p&amp;lt;0.05 vs CTRL) which strongly increased the resistive index (RI; p&amp;lt;0.05 vs CTRL) of contralateral renal artery flow and kidney volume after 4 weeks (p&amp;lt;0.001 vs CTRL). Renal dysfunction also led to a dysfunction of cardiac tissue strain associated with overt dyssynchrony in cardiac wall motion, as shown by the increased time-to-peak (T2P; p&amp;lt;0.05) and the decreased whole peak capacity (Pk; p&amp;lt;0.01) in displacement and strain rate (p&amp;lt;0.05) in longitudinal motion. The hearts of RAL DOCA-Salt rats showed a larger time delay between the fastest and the lowest region (Maximum Opposite Wall Delay-MOWD) (p&amp;lt;0.05 in displacement and p&amp;lt;0.01 in strain rate vs CTRL). A significant increase in the levels of the circulating pro-inflammatory cytokines and chemokines (p&amp;lt;0.05 for IL-12(40), p&amp;lt;0.01 for GM-CSF, KC, IL-13, and TNF- α) and in the NGAL expression of the ligated kidney (p&amp;lt;0.001) was observed.This pathological condition was prevented by BPF treatment, by reducing the increase of blood pressure in RAL DOCA-Salt rats (p&amp;lt;0.05) and exerting a protective effect on the volume of the contralateral kidney (p&amp;lt;0.01). BPF ameliorates cardiac tissue strain dysfunction by increasing Pk in displacement (p&amp;lt;0.01) and reducing the T2P in strain rate motion (p&amp;lt;0.05). These effects significantly improve MOWD (p&amp;lt;0.05) preventing the overt dyssynchrony in cardiac wall motion. The reno-cardiac protective effect of BPF was associated with a significant reduction in serum level of the pro-inflammatory cytokines and chemokines (p&amp;lt;0.05 for KC and IL-12(40), p&amp;lt;0.01 for GM-CSF, IL-13, and TNF- α)restoring physiological levels of NGAL (p&amp;lt;0.05) protein of the tethered kidney. In conclusion, the present results show that BPF promotes an efficient renovascular protection preventing the progression of inflammation and reno-cardiac damage, suggesting the potential clinical and veterinary role of dietary supplementation with the polyphenol-rich fraction of citrus bergamot in counteracting hypertension-induced reno-cardiac syndrome.

#2115 Phase-contrast magnetic resonance imaging (PC-MRI) for quantification of volumetric flow in renal transplant arteries: an observational cohort study

Abstract Background and Aims Impaired renal transplant blood flow, a manifestation of severe transplant renal artery stenosis (TRAS), can negatively impact transplant function and survival. Phase-contrast magnetic resonance imaging (PC-MRI) is a non-invasive method of quantifying blood flow volume. Recent work has demonstrated the utility of this technique in measuring native renal blood flow, whilst validating the use of flow measurements taken on the aorta above and below the origin of the renal arteries to calculate flow in the renal arteries [1]. As part of a quality improvement study incorporating PC-MRI into renal transplant assessment, this study set out to (a) establish the normal range for transplant renal blood flow volume and (b) assess whether PC-MRI improved screening for TRAS. Method Between January 2019 and February 2021, PC-MRI sequences were included in the protocols for all magnetic resonance angiograms (MRA) performed as part of clinically-indicated renal transplant assessment. As part of the MRA study, using a coronal localizer MR image, planes were prescribed on the external iliac artery (EIA) both proximal and distal to the transplant artery anastomosis site in a perpendicular orientation (Fig. 1A). Using CV142 software [2], arterial cross-sections were highlighted manually at the pre-determined planes (Fig. 1B) to generate flow curves that coincided with the cardiac cycle (Fig. 1C). Studies were excluded if: the EIA flow waveform was incongruous with the cardiac cycle, contemporaneous heart rate data was not recorded, or the calculated flow volume was a negative value. Results During the study period 392 transplant MRAs were performed, of which 218 were included in this analysis. Potential TRAS was identified in 49 (22.5%) studies, with 19 (8.7%) having this diagnosis confirmed by intra-arterial digital subtraction angiography (IADSA). In the 169 (77.5%) studies without evidence of TRAS, the mean flow in the proximal EIA was 0.90 L/min (95% CI 0.85-0.94 L/min) and in the distal EIA 0.47 L/min (95% CI 0.44-0.50 L/min). The difference between the two measurement points, that is the flow in the transplant renal artery, was 0.42 L/min (95% CI 0.39-0.45 L/min) (Fig. 2A). In the 19 studies with TRAS confirmed by IADSA, mean flow at the time of the initial MRA was 0.34 L/min (95% CI 0.25-0.43 L/min); there was no difference when compared with the group without evidence of TRAS on MRA (p = 0.09) (Fig. 2B). Of the patients who had potential TRAS identified on MRA, 30 patients proceeded to IADSA; there was no difference in PC-MRI flow volume in the 11 who had a diagnosis of TRAS refuted on IADSA and the 19 who had diagnosis of TRAS confirmed (p = 0.97). ROC curve analysis of PC-MRI arterial flow measurement as a diagnostic test for TRAS, whereby the positive group of 19 had IADSA confirmed TRAS, the negative group of 176 had either normal MRA artery appearances or normal IADSA, and the disease prevalence is 13.7% [3], shows AUC 0.62 (95% CI 0.55-0.69) P = 0.09, sensitivity 57.9 specificity 67.1 (Fig. 2C). Conclusion This is the largest study to incorporate functional PC-MRI sequences into MRA protocols for the assessment of people with any form of kidney disease. The results suggest that the blood flow volume in healthy transplant renal arteries lies between 0.39–0.45 L/min. In comparative analysis between patients with healthy transplant arteries and those with IADSA-confirmed TRAS, there was no difference in arterial flow volume, though the study was limited by the small population in the group with IADSA-confirmed TRAS. PC-MRI does not appear to improve the screening accuracy of MRA in identifying TRAS. However, there may be a future role for PC-MRI as part of multi-parametric MR protocols for comprehensive assessment of patients with kidney transplants.

The effect of baroreflex-induced sympathetic suppression on renal arterial impedance in rats

Objective: We examined the effect of baroreflex on renal arterial impedance (ZRA) to gain insights into renal hemodynamics and local autoregulation. Methods: This study involved male Wistar-Kyoto rats (n = 6). We measured renal arterial pressure (PRA) and renal arterial flow (FRA). For high-resolution renal arterial impedance (ZRA) over the frequency range of 0.1-70 Hz, random pacing was employed. We isolated the bilateral carotid sinus baroreceptor regions and utilized a servo pump to control carotid sinus pressure (CSP) either at 60 mmHg or 140 mmHg. We controlled mean arterial pressure (AP) at 100 mmHg (AP-fix) or allowed to vary in response to changes in CSP (AP-variable). A three‐element Windkessel (3-WK) model was used to quantify ZRA (R1: proximal resistance, R2: distal resistance, and C: renal compliance). Results: With AP-fix, an increase of CSP from 60 mmHg to 140 mmHg did not change mean PRA (99.85 ± 0.16 vs. 98.00 ± 1.22 mmHg, P = ns) or mean FRA (8.73 ± 0.41 vs. 8.10 ± 0.38 min/mL, Δ = −7%, P = ns). This rise of CSP did not significantly affect R1 (0.74 ± 0.11 vs. 0.61 ± 0.12 mmHg·min/mL, P = ns) or R2 (8.13 ± 1.08 vs. 8.79 ± 0.85 mmHg·min/mL, P = ns), but it did increase C by 20% (4.05 ± 0.47 vs. 4.88 ± 0.35 (×10−5) mL/mmHg, P &lt; 0.05). With AP-variable, elevating CSP from 60 mmHg to 140 mmHg significantly lowered mean PRA by 38% (105.42 ± 2.84 vs. 65.15 ± 4.87 mmHg, P &lt; 0.01), but did not change mean FRA (9.00 ± 0.48 vs. 7.92 ± 0.66 min/mL, Δ = −12%, P = ns). Changes in CSP did not affect R1 (0.77 ± 0.12 vs. 1.23 ± 0.24 mmHg·min/mL, P = ns), but they did reduce R2 by 41% (8.01 ± 1.08 vs. 4.76 ± 0.79 mmHg·min/mL, P &lt; 0.01) and increase C almost five-fold (3.79 ± 0.36 vs. 22.16 ± 6.91 (×10−5) mL/mmHg, P &lt; 0.05). Conclusion: The minor change in FRA (−12%) despite a 38% drop in PRA suggests the presence of local autoregulation to buffer changes in renal blood flow. The primary effect of renal hemodynamic regulation on ZRA was found in R2. When AP was allowed to vary in response to changes in CSP, increasing CSP, the baroreflex-induced sympathetic suppression decreased R2. However, when AP was held constant at 100 mmHg, the reduction in R2 was not observed, even with baroreflex activation resulting from changes in CSP. Hence, the local renal autoregulation may counteract the baroreflex, maintaining renal blood flow unchanged. Such a mechanism serves to protect the glomeruli from exogenously induced high mean AP. NTT Research, Inc. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Renal artery flow alterations in neonates with hypoxic ischemic encephalopathy.

To compare kidney blood flow and kidney function tests in infants with hypoxic ischemic encephalopathy (HIE), and the effects of therapeutic hypothermia (TH) during the first 7days of life. Fifty-nine infants with HIE were prospectively evaluated. Infants with moderate-severe HIE who required TH were classified as group 1 (n = 36), infants with mild HIE were classified as group 2 (n = 23), and healthy infants were classified as group 3 (n = 60). Kidney function tests were evaluated on the sixth hour, third and seventh days of life in Group 1 and Group 2, and on the sixth hour and third day of life in group 3. Renal artery (RA) Doppler ultrasonography (dUS) was performed in all infants on the first, third, and seventh days of life. Systolic and end diastolic blood flow in RA tended to increase and RA resistive index (RI) tended to decrease with time in group 1 (p = 0.0001). While end diastolic blood flow rates in RA on the third day were similar in patients with severe HIE and mild HIE, it was lower in patients with mild-moderate-severe HIE than healthy newborns. On the seventh day, all three groups had similar values (p > 0.05). Serum blood urea nitrogen (BUN), creatinine, uric acid, and cystatin C levels gradually decreased and glomerular filtration rate (GFR) gradually increased during TH in group 1 (p = 0.0001). Serum creatinine levels gradually decreased while GFR gradually increased during the study period in group 2. Therapeutic hypothermia seems to help restore renal blood flow and kidney functions during the neonatal adaptive period with its neuroprotective properties.

Comparative evaluation of fetal renal artery hemodynamics in normohydramnios, idiopathic oligohydramnios and polyhydramnios in third trimester pregnancy

AbstractObjectiveTo compare the renal artery (RA) flow indices (RI and PI) among normohydramnios, idiopathic oligohydramnios, and polyhydramnios and determine applicability of fetal RA Doppler indices in predicting the pregnancy outcome.MethodsTotal 106 3rd trimester pregnant patients were divided into cases and controls based on amniotic fluid index. Routine antenatal and color Doppler (including kidneys) ultrasound was performed for all patients in this study. The postnatal follow‐up was done, and the pregnancies having poor outcomes in terms of NICU admissions were assessed.ResultsStatistically significant differences were noted when comparing RI and PI values of normohydramnios (0.91 ± 0.04 and 2.38 ± 0.21, respectively) with oligohydramnios (1.02 ± 0.07 and 2.99 ± 0.38, respectively) and polyhydramnios (0.90 ± 0.12 and 2.7 ± 0.84, respectively) independently (p value &lt; 0.05). Our study demonstrated an increase in NICU admissions in the fetus having raised values of RI and PI.ConclusionFetal RA RI and PI can be used as an antenatal predictor for the pregnancy outcome associated with idiopathic oligohydramnios; however, fetal RA PI was found to be a better predictor for the pregnancy outcome than fetal RA RI value in our study.

Assessment of renal sympathetic control using invasive pressure and flow velocity measurements in humans.

Renal sympathetic innervation is important in the control of renal and systemic hemodynamics and is a target for pharmacological and catheter-based therapies. The effect of a physiological sympathetic stimulus using static handgrip exercise on renal hemodynamics and intraglomerular pressure in humans is unknown. We recorded renal arterial pressure and flow velocity in patients with a clinical indication for coronary or peripheral angiography using a sensor-equipped guidewire during baseline, handgrip, rest, and hyperemia following intrarenal dopamine (30 μg/kg). Changes in perfusion pressure were expressed as the change in mean arterial pressure, and changes in flow were expressed as a percentage with respect to baseline. Intraglomerular pressure was estimated using a Windkessel model. A total of 18 patients (61% male and 39% female) with a median age of 57 yr (range: 27-85 yr) with successful measurements were included. During static handgrip, renal arterial pressure increased by 15.2 mmHg (range: 4.2-53.0 mmHg), whereas flow decreased by 11.2%, but with a large variation between individuals (range: -13.4 to 49.8). Intraglomerular pressure increased by 4.2 mmHg (range: -3.9 to 22.1 mmHg). Flow velocity under resting conditions remained stable, with a median of 100.6% (range: 82.3%-114.6%) compared with baseline. During hyperemia, maximal flow was 180% (range: 111%-281%), whereas intraglomerular pressure decreased by 9.6 mmHg (interquartile range: 4.8 to 13.9 mmHg). Changes in renal pressure and flow during handgrip exercise were significantly correlated (ρ = -0.68, P = 0.002). Measurement of renal arterial pressure and flow velocity during handgrip exercise allows the identification of patients with higher and lower sympathetic control of renal perfusion. This suggests that hemodynamic measurements may be useful to assess the response to therapeutic interventions aimed at altering renal sympathetic control.NEW & NOTEWORTHY Renal sympathetic innervation is important in the homeostasis of systemic and renal hemodynamics. We showed that renal arterial pressure significantly increased and that flow decreased during static handgrip exercise using direct renal arterial pressure and flow measurements in humans, but with a large difference between individuals. These findings may be useful for future studies aimed to assess the effect of interventions that influence renal sympathetic control.

Fetal Renal Artery Doppler in Cases of Isolated Oligohydramnios: Can it Predict Adverse Neonatal Outcome?

Aims and Objectives: This study compares the fetal renal artery flow velocity waveforms of pregnancies complicated by oligohydramnios with normal pregnancies and to detect any statistically significant difference between the two Groups and to further determine the relationship of these findings with neonatal outcome. Method: All pregnant women in IIIrd trimester with gestational age between 32 weeks to 36 weeks with isolated oligohydramnios were included as cases (Group-A). Normal IIIrd trimester pregnancies (Group-B) with gestational age between 32 weeks to 36 weeks served as controls between the study period of Jan 2018 to Dec 2019. Results: The mean umbilical artery pulsatility index (PI; mean ± SD) in patients of Group-A was 1.0730 ± 0.0637 and that of patients in Group-B was 1.0012 ± 0.1400 with P = 0.0023. The mean umbilical artery S/D ratio (mean ± SD) in patients of Group-A, was 2.9120 ± 0.2476 and that of patients in Group-B was 2.5135 ± 0.2751 with P &lt; 0.0001. The mean renal artery PI (mean ± SD) in patients of Group-A was 2.5863 ± 0.2608 and that of patients in Group-B was 2.4737 ± 0.2648 with P = 0.0240. The mean birth weight and Apgar Score were also found to be statistically significant between the two Groups. Conclusion: The distribution of mean renal artery PI and umbilical artery PI, in oligohydramnios cases, was higher in comparison to normal cases. As the Neonatal intensive care unit (NICU) admission was higher in the oligohydramnios group with abnormal renal artery doppler indices, our recommendation is that abnormal fetal renal artery Doppler indices are an indication for early referral to tertiary care setup, as the majority of these neonates will require NICU care postdelivery.

The role of different Doppler parameters in predicting adverse neonatal outcomes in fetuses with late-onset fetal growth restriction.

The aim of this study is to clarify the role of different Doppler parameters such as umbilicocerebral ratio (UCR), cerebroplacentouterine ratio (CPUR), aortic isthmus, renal artery, and umbilical vein flow Doppler in predicting adverse neonatal outcomes in fetuses with late -onset fetal growth restriction. The study included all patients diagnosed with fetal growth restriction at 32-39 weeks' gestation between 01/02/2020 and 01/02/2022 and treated at the Department of Obstetrics and Gynecology, Inonu University School of Medicine. Patients included in the study had a median gestational week at delivery of 37 (minimum 33+0-maximum 39+0), median CPR of 1.42 (minimum-maximum 0.43-3.57), and median UCR of 0.7 (minimum-maximum 0.28-2.3). Receiver operating characteristic analysis was performed to determine the performance of the measured obstetric Doppler parameters in predicting the development of adverse neonatal outcomes. Umbilical venous blood flow showed the best performance in predicting adverse neonatal outcomes [area under the curve 0.952, 95% confidence interval (CI) 0.902-0.981, p<0.001]. Multivariate logistic regression analysis showed that fetuses with abnormal CPUR had a 4.5-fold (95% CI 0.084-0.583, p=0.02) increased risk of adverse neonatal outcome, whereas fetuses with abnormal umbilical venous flow had a 1.07-fold (95% CI 0.903-0.968, p<0.001) increased risk of adverse neonatal outcome. The results of this study demonstrate that the use of UCR, CPUR, umbilical venous flow, and aortic isthmus PI Doppler parameters along with umbilical artery PI and CPR are effective in predicting adverse neonatal outcomes in fetuses with late -onset fetal growth restriction.

The effects of excess salt intake on the kidney metabolism in normal Sprague Dawley rats.

Introduction: This study aimed to determine the effects of a high salt diet upon the metabolism of O 2 and substances in the kidney in normal Sprague Dawley (SD) rats. Methods were developed enabling the intermittent collection of renal arteriovenous (A-Vr) blood and urine samples and to measure renal blood flow (RBF) and arterial pressure (BP) in conscious freely moving rats with GFR determined in a separate group of conscious rats. Other groups were studied to obtain cortical (Cx) and outer medullary (OM) tissue samples for associated transcriptomic and metabolomic profiles. Methods: SD rats were instrumented with a renal arterial ultrasonic flow probe, a femoral arterial and renal venous catheters, and RBF and BP measured continuously (24/7). Arterial (A) and renal venous (Vr) blood and urine were collected repeatedly before and 7, 14, and 21 days after increasing the salt diet from 0.4% (LS) to 4% (HS) NaCl. GFR was measured in age-matched rats and used as control shams for normalization. Blood O 2 content was determined by radiometry. A global metabolomic analysis was performed on plasma and Cx and OM tissue samples at JAX laboratories (Thermo Q-Exactive Orbitrap coupled to Vanquich UPLC system) and together with mRNAseq analysis for Cx and OM by Novogene Inc. Results: BP increased less than 5 mmHg by day 3 of the HS diet while RBF rose nearly 20% (P&lt;0.05) and both were sustained at this level throughout the study. O 2 delivery, O 2 consumption (VO 2 ) and O 2 extraction rose over the 21 days of the HS diet (P&lt;0.05). Total GFR increased from 0.64 to 0.83 mL/min/100 g bw (P&lt;0.05) at HS 7 and remained elevated at HS 21. Whole kidney Na + reabsorption and kidney VO 2 were highly correlated positively (r=0.99). A sparse partial least squares discriminant analysis (sPLS-DA) of metabolomics for each of the 4 modes (C18 +/- and HILIC +/-) revealed clear distinctions between LS, HS14, and HS21 within Cx and OM. The mRNAseq tissue analysis found that the HS diet resulted in reduced expression of genes related to the TCA cycle and metabolism of amino acids and fatty acids. This was consistent with the metabolomic data showing a reduction of tissue citrate and succinate levels. In contrast, glycolysis-related genes including hexokinase, pyruvate kinase and lactate dehydrogenase were upregulated in the Cx tissue by HS. Minimal changes in metabolic pathways were observed in the OM tissue. A-Vr x RBF enabled metabolomic flux determination which showed the release of glucose on LS fed rats which was not evident with the HS diet. Uptake of citrate which was seen on LS was less evident on HS but there was a clear tendency observed for increased release of lactate, pyruvate, and α-ketoglutarate. Conclusions: Normal SD rats fed a HS underwent changes of RBF, O 2 extraction and utilization of metabolic substrates, most notably transitioning ATP production predominantly driven from TCA cycle to non-TCA cycle pathways which we are currently exploring more deeply. HL-116264, HL-151587 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Multiparametric magnetic resonance imaging: A robust tool to test pathogenesis and pathophysiology behind nephropathy in humans.

Chronic kidney disease (CKD) is a major population disease. In diabetes as well as hypertension, kidney disease is one of the most serious complications. Recent research has demonstrated that chronic hypoxia is a key actor in the pathogenesis of CKD. In this review, we focus on how functional magnetic resonance imaging (fMRI) techniques can shed light on pathogenetic mechanisms and monitor new treatments aimed at preventing or ameliorating the disease. Multiparametric MRI techniques can measure changes in renal artery flow, tissue perfusion, and oxygenation repetitively over short time periods, enabling high time resolution. Furthermore, renal fibrosis can be quantified noninvasively by MRI diffusion tensor imaging, and techniques are upcoming to measure renal oxygen consumption. These techniques are all radiation and contrast-free. We briefly present data, demonstrating that fMRI techniques can play a major role in future research in CKD, and possibly also in daily clinical practice.

Atnalı böbrekte nutcracker sendromu beklenen bir vasküler anomali midir?

Purpose: Horseshoe kidney is the most common fusion anomaly that congenital systemic and urological anomalies accompany most of the patients. In this study, we aimed to investigate its association with vascular anomalies and especially nutcracker syndrome along with accompanying urological and other systemic anomalies in children with horseshoe kidney. &#x0D; Materials and methods: Twenty-six patients are diagnosed with horseshoe kidney in our clinic and 22 healthy children of the same age and sex were included in the study. All children were prospectively evaluated using Doppler ultrasonography in terms of renal artery and renal vein flow velocities, lumen diameters and vascular anomalies and presence of nutcracker syndrome. &#x0D; Results: Urological anomaly was found in 50% of the children with horseshoe kidneys, and systemic anomaly in 44% of them. In Doppler ultrasonographic evaluations performed on patients to detect vascular pathologies and nutcracker syndrome; findings of nutcracker syndrome were present in 2 patients in the horseshoe kidney group, while they were detected incidentally in 1 patient in the control group. An accessory renal artery originating from the left common iliac artery was found in a case with horseshoe kidney, and a circumaortic left renal vein in one case. &#x0D; Conclusions: In our study in which we investigated nutcracker syndrome based on the presence of vascular anomalies accompanying horseshoe kidneys in children, nutcracker syndrome findings were found in similar numbers in both groups. However, we think that these children should be followed for a long time in terms of vascular pathologies (aneurysm, rupture) and malignancies that may occur in adulthood, as well as congenital vascular anomalies.

A comparison between the superb microvascular imaging technique and conventional Doppler ultrasound in evaluating chronic allograft damage in renal transplant recipients

The present study comparatively evaluates the performance of conventional Doppler ultrasound and superb microvascular imaging (SMI) in delineating the cortical microvessels of the transplanted kidney and compares the chronic allograft damage index (CADI) based on the examination of biopsy specimens with Doppler ultrasound and SMI findings. Sixty-eight renal transplant recipients underwent kidney biopsy with the pre-diagnosis of rejection before undergoing renal Doppler ultrasound examination between January 2020 and October 2020. The distance between the kidney capsule and the vascular structure closest to the kidney capsule was measured at the level of the lower pole in the transplanted kidney using color Doppler ultrasound (CDUS), power Doppler ultrasound (PDUS), and the SMI technique. The kidney size, resistive index at the level of the arcuate artery in the lower pole of the kidney, and renal artery flow rates were also measured. The mean distance between the kidney capsule and the vessel was 2.44 ± 2.0 mm on CDUS, 1.34 ± 1.2 mm on PDUS, 0.99 ± 1.8 mm using the color SMI (cSMI) technique, and 0.86 ± 1.8 mm using the monochrome SMI (mSMI) technique. The study found that the SMI technique was superior to CDUS and PDUS in delineating the cortical microvasculature of the kidney. Both Doppler ultrasound examinations and the SMI technique proved effective in predicting the CADI (P = 0.006 for CDUS, P = 0.002 for PDUS, P = 0.018 for cSMI, and P = 0.027 for mSMI). Among conventional Doppler ultrasound examinations and the SMI technique, PDUS had the highest sensitivity, and cSMI had the highest specificity in differentiating high and low CADI values. Both the cSMI and mSMI techniques had similar sensitivity values, whereas only cSMI exhibited high specificity. CDUS had the lowest specificity value (P = 0.003 for CDUS, P = 0.002 for PDUS, P = 0.005 for cSMI, and P = 0.004 for mSMI). The present study is the first in the literature to demonstrate the utility of the distance between the kidney capsule and the vessels in predicting the CADI score and to compare the Doppler ultrasound examinations and SMI technique in doing so.

A dumbbell rescue stent graft facilitates clamp-free repair of aortic injury in a porcine model

ObjectiveNoncompressible torso hemorrhage is a high-mortality injury. We previously reported improved outcomes with a retrievable rescue stent graft to temporize aortic hemorrhage in a porcine model while maintaining distal perfusion. A limitation was that the original cylindrical stent graft design prohibited simultaneous vascular repair, given the concern for suture ensnarement of the temporary stent. We hypothesized that a modified, dumbbell-shaped design would preserve distal perfusion and also offer a bloodless plane in the midsection, facilitating repair with the stent graft in place and improve the postrepair hemodynamics. MethodsIn an Institutional Animal Care and Use Committee-approved terminal porcine model, a custom retrievable dumbbell-shaped rescue stent graft (dRS) was fashioned from laser-cut nitinol and polytetrafluoroethylene covering and compared with aortic cross-clamping. Under anesthesia, the descending thoracic aorta was injured and then repaired with cross-clamping (n = 6) or dRS (n = 6). Angiography was performed in both groups. Operations were divided into phases: (1) baseline, (2) thoracic injury with either cross-clamp or dRS deployed, and (3) recovery, after which the clamp or dRS were removed. Target blood loss was 22% to simulate class II or III hemorrhagic shock. Shed blood was recovered with a Cell Saver and reinfused for resuscitation. Renal artery flow rates were recorded at baseline and during the repair phase and reported as a percentage of cardiac output. Phenylephrine pressor requirements were recorded. ResultsIn contrast with cross-clamped animals, dRS animals demonstrated both operative hemostasis and preserved flow beyond the dRS angiographically. Recovery phase mean arterial pressure, cardiac output, and right ventricular end-diastolic volume were significantly higher in dRS animals (P = .033, P = .015, and P = .012, respectively). Whereas distal femoral blood pressures were absent during cross-clamping, among the dRS animals, the carotid and femoral MAPs were not significantly different during the injury phase (P = .504). Cross-clamped animals demonstrated nearly absent renal artery flow, in contrast with dRS animals, which exhibited preserved perfusion (P<.0001). Femoral oxygen levels (partial pressure of oxygen) among a subset of animals further confirmed greater distal oxygenation during dRS deployment compared with cross-clamping (P = .006). After aortic repair and clamp or stent removal, cross-clamped animals demonstrated more significant hypotension, as demonstrated by increased pressor requirements over stented animals (P = .035). ConclusionsCompared with aortic cross-clamping, the dRS model demonstrated superior distal perfusion, while also facilitating simultaneous hemorrhage control and aortic repair. This study demonstrates a promising alternative to aortic cross-clamping to decrease distal ischemia and avoid the unfavorable hemodynamics that accompany clamp reperfusion. Future studies will assess differences in ischemic injury and physiological outcomes. Clinical RelevanceNoncompressible aortic hemorrhage remains a high-mortality injury, and current damage control options are limited by ischemic complications. We have previously reported a retrievable stent graft to allow rapid hemorrhage control, preserved distal perfusion, and removal at the primary repair. The prior cylindrical stent graft was limited by the inability to suture the aorta over the stent graft owing to risk of ensnarement. This large animal study explored a dumbbell retrievable stent with a bloodless plane to allow suture placement with the stent in place. This approach improved distal perfusion and hemodynamics over clamp repair and heralds the potential for aortic repair while avoiding complications.

Assessment of the re-entry tear index as a prognostic indicator for renal perfusion improvement after thoracic endovascular aortic repair in patients with acute and subacute Stanford type b aortic dissection with renal artery involvement.

Aortic dissection is the most common acute aortic syndrome, and renal artery is the most common involved artery. The size and location of the re-entry tear directly affect the blood flow enhancement of the false lumen branch artery after surgery. In this study, the morphology and hemodynamics of the re-entry tear were comprehensively analyzed, and the location and size of the re-entry tear were quantitatively evaluated to calculate the re-entry tear index (RTI). This study aimed to assess the predictive capability of a comprehensive quantitative RTI for improvement in renal perfusion following thoracic endovascular aortic repair (TEVAR) in cases of acute and subacute Stanford type B aortic dissection with renal artery involvement. In this prospective cohort study, 137 patients diagnosed with acute or subacute type B aortic dissection with concomitant renal artery involvement who underwent TEVAR at Anzhen Hospital in Beijing from October 2017 to November 2021 were enrolled. Renal blood flow was estimated quantitatively with ultrasound. Based on the ultrasound findings of renal artery flow, the patients were classified into two groups: group A [postoperative volume flow (VolFlow) reduced compared to preoperative VolFlow] and group B (postoperative VolFlow increased compared to preoperative VolFlow). All re-entry tears present in the aortic trunk according to reconstructed computed tomography angiography (CTA) obtained preoperatively were included in the analysis. The general information of patients, whether the involved renal artery arose partially or wholly from the false lumen, the proximal diameter and length of the covered stent, the diameter of primary entry tear, the RTI, etc. were analyzed. Univariate and multivariate logistic regression analyses were executed to assess the risk factors associated with increased renal arterial blood flow subsequent to TEVAR. Additionally, receiver operating characteristic (ROC) curve analysis was used to ascertain the optimal cutoff value and predictive efficacy of the RTI. A total of 137 patients, comprising of 32 with acute and 105 with subacute type B aortic dissection accompanied by renal artery involvement, underwent TEVAR. Among these patients, 44 (32.1%) were assigned to group A and 93 (67.9%) to group B. Renal blood flow exhibited an increase in 67.9% of the patients after TEVAR. The results of multivariate analysis indicated that the RTI is an independent risk factor for postoperative renal perfusion improvement [odds ratio =17.66; 95% confidence interval (CI): 2.13-78.55; P=0.020]. The optimal cutoff value for RTI, determined to be 0.033, demonstrated the ability to identify renal perfusion improvement in patients without hypertension with a sensitivity of 53.7% and a specificity of 68.9%. In patients with concomitant hypertension, RTI exhibited a sensitivity of 96.6% and a specificity of 60.0%, with an area under the ROC curve (AUC) of 0.792 (95% CI: 0.643-0.941; P=0.021) for identifying renal perfusion improvement. RTI demonstrated a favorable predictive value for improving renal malperfusion following TEVAR in cases of aortic dissection with renal artery involvement.

Abstract 10045: Higher Renal Vascular Resistance is Associated With Greater Body Mass Index in Children

Background: Obesity is associated with increased risk for cardiovascular and renal diseases, however, there has been little focus on renal vascular function. The purpose of this study is to assess renal vascular flow regulation and investigate their relation to cardiovascular risk factors in obese children. Methods: Noninvasive ultrasonographic measurements were made in 108 overweight/obese children aged 7 to 13 years (body mass index 18 to 33kg/m 2 ). Using color Doppler sonography, peak systolic (PSV), end-diastolic (EDV), and average peak flow (APV) velocities of renal artery were measured. Pulsatility index as a parameter of vascular resistance was calculated. Pulsatility index was defined as (PSV-EDV)/APV. Quantitative B-mode ultrasound scans were used to measure intima-media thickness and diameters of the common carotid artery. Plasma lipid concentrations, uric acid, homeostasis model assessment of insulin resistance, and high sensitivity C-reactive protein were assessed in the obese children. Results: Compared with overweight children with body mass index &lt;25 kg/m 2 , pulsatility index in obese children with body mass index≥25 kg/m 2 was significantly higher (1.24 ±0.13 vs. 1.13 ±0.14 cm/sec, p &lt; 0.01), because APV and EDV were significantly lower (35 ±3 vs. 38 ±7 cm/sec and 21± 3 vs. 25 ±5 cm/sec, p &lt;0.05, respectively), although PSV was not significantly different. Pulsatility index correlated significantly with body mass index (r =0.58, p &lt; 0.01), insulin (r = 0.24, p &lt; 0.05), homeostasis model assessment of insulin resistance (r =0.25, p &lt; 0.01), triglycerides (r = 0.26, p &lt; 0.01), uric acid (r = 0.22, p &lt; 0.05), systolic blood pressure (r = 0.31, p &lt; 0.01), and carotid intima-media thickness (r = 0.36, p&lt;0.01). Renal blood flow velocities did not correlate with high sensitivity C-reactive protein. Conclusions: The present study indicates that obesity can adversely affect renal vascular flow and resistance in children. Obesity-related insulin resistance may be a main risk factor for renal vascular flow changes. Obesity not only is a risk factor for later cardiovascular disease, but also is associated with significant impairment of renal arterial flow dynamics.

Endovascular Perfusion Augmentation After Resuscitative Endovascular Balloon Occlusion of the Aorta Improves Renal Perfusion and Decreases Vasopressors

IntroductionResuscitative endovascular balloon occlusion of the aorta (REBOA) causes a severe ischemia-reperfusion injury. Endovascular Perfusion Augmentation for Critical Care (EPACC) has emerged as a hemodynamic/mechanical adjunct to vasopressors and crystalloid for the treatment of post-REBOA ischemia-reperfusion injury. The objective of the study is to examine the impact of EPACC as a tool for a wean from complete REBOA compared to standard resuscitation techniques. MethodsNine swine underwent anesthesia and then a controlled 30% blood volume hemorrhage with 30 min of supraceliac total aortic occlusion to create an ischemia-reperfusion injury. Animals were randomized to standardized critical care (SCC) or 90 min of EPACC followed by SCC. The critical care phase lasted 270 min after injury. Hemodynamic markers and laboratory values of ischemia were recorded. ResultsDuring the first 90 min the intervention phase SCC spent 60% (54%-73%) and EPACC spent 91% (88%-92%) of the time avoiding proximal hypotension (<60 mm Hg), P = 0.03. There was also a statistically significant decrease in cumulative norepinephrine dose at the end of the experiment between SCC (80.89 mcg/kg) versus EPACC (22.03 mcg/kg), P = 0.03. Renal artery flow during EPACC was similar compared to SCC during EPACC, P = 0.19. But during the last hour of the experiment (after removal of aortic balloon) the renal artery flow in EPACC (2.9 mL/kg/min) was statistically significantly increased compared to SCC (1.57 mL/min/kg), P = 0.03. There was a statistically significant decrease in terminal creatinine in the EPACC (1.7 mg/dL) compared to SCC (2.1 mg/dL), P = 0.03. ConclusionsThe 90 min of EPACC as a weaning adjunct in the setting of a severe ischemia-reperfusion injury after complete supraceliac REBOA provides improved renal flow with improvement in terminal creatinine compared to SCC with stabilized proximal hemodynamics and decreased vasopressor dose.

231-LB: GLP-1 Promotes Cortical and Medullary Perfusion in Human Kidney and Maintains Tissue Oxygenation during Na Loading

Purpose: GLP-1 receptor agonism has shown beneficial cardiovascular effects which could include the kidneys. In the human kidney, the high GLP-1 extraction and its natriuretic effect depend on the GLP-1 receptor and is accompanied by suppression of angiotensin II, independent of changes in renal plasma flow. Preclinical data showed that angiotensin II constricts the vasa recta and lowers medullary perfusion. The current randomized, controlled study was designed to test the hypothesis that GLP-1 increases renal medullary perfusion in healthy humans. Methods: Healthy male participants (n=10, 27 ± 4 years) ingested a fixed sodium intake for 4 days and were examined twice during a 1-hour infusion of either GLP-1 (1.5 pmol/kg/min) or placebo together with infusion of 0.9% NaCl (750 mL/h) . Interleaved measurements of renal artery flow, oxygenation (R2*) , and perfusion were acquired in the renal cortex and medulla during infusions, using magnetic resonance imaging. Results: GLP-1 infusion increased medullary perfusion (32 ± 7%, p&amp;lt;0.001) and cortical perfusion (13 ± 4%, p&amp;lt;0.001) compared to placebo. Here, NaCl infusion decreased medullary perfusion (-5 ± 2%, p=0.007) while cortical perfusion remained unchanged. R2* values increased by 3 ± 2% (p=0.025) in the medulla and 4 ± 1% (p=0.008) in the cortex during placebo, indicative of decreased oxygenation but remained unchanged during GLP-1. Renal arterial blood flow was not altered significantly by either intervention. Conclusions: GLP-1 increases predominantly medullary but also cortical perfusion in healthy human kidneys and maintains oxygenation during NaCl-loading. In perspective, GLP-1 may exert protective effects against renal hypoperfusion and ischemia. Disclosure B. Haddock: n/a. B. L. Jensen: None. A. Asmar: None.