The prevalence of accessory renal arteries in sudanese population in Khartoum State: a cross-sectional CT study from 2017 to 2020

BACKGROUND

Renal artery variations are clinically significant due to their implications for surgical procedures and renal function. However, data on these variations in Sudanese populations are limited. This study aimed to determine the prevalence and characteristics of renal artery variations in a Sudanese population.

METHODS

A cross-sectional retrospective study was conducted in Khartoum state from October 2017 to October 2020. A total of 400 Sudanese participants who underwent abdominal CT scans were included. Data on demographic characteristics, kidney measurements, and renal vasculature were collected and analyzed using descriptive statistics and inferential tests.

RESULTS

The mean age of participants was 46.7 ± 18 years, with a nearly equal gender distribution. Overall, renal artery variations were present in 11% of participants, with accessory renal arteries observed in 6% of the study population. Among those with accessory vessels, 50% were on the right side, 29.2% on the left, and 20.8% bilateral, distributed across hilar 29.2%, lower polar 29.2%, and upper polar 41.7% regions. No significant associations were found between accessory renal arteries and age or gender (p-value > 0.05). However, participants with accessory renal arteries exhibited significantly narrower width 5.0 ± 1.4 than those with no with accessory renal arteries 5.8 ± 1.1 (p-value 0.002) Early dividing renal arteries were found in 5% of participants, with nearly half being bilateral. No significant associations were found between the presence of early dividing renal arteries and demographic or renal measurements (p-value > 0.05).

CONCLUSION

This study provides valuable insights into the prevalence and characteristics of renal artery variations in a Sudanese population. The findings contribute to our understanding of renal anatomy in this demographic and can inform clinical practice and surgical planning, particularly in renal transplantation and other renal procedures.

Renal cortex microperfusion evaluated by laser speckle contrast imaging in an ex vivo perfused kidney model-A proof-of-concept study

BACKGROUND

Validated quantitative biomarkers for assessment of renal graft function during normothermic machine perfusion (NMP) conditions are lacking. The aim of this project was to quantify cortex microperfusion during ex vivo kidney perfusion using laser speckle contrast imaging (LSCI), and to evaluate the sensitivity of LSCI when measuring different levels of renal perfusion. Furthermore, we aimed to introduce LSCI measurements during NMP in differentially damaged kidneys.

METHODS

Eleven porcine kidneys were nephrectomized and perfused ex vivo. Cortex microperfusion was simultaneously monitored using LSCI. First, a flow experiment examined the relationship between changes in delivered renal flow and corresponding changes in LSCI-derived cortex microperfusion. Second, renal cortical perfusion was reduced stepwise by introducing a microembolization model. Finally, LSCI was applied for measuring renal cortex microperfusion in kidneys exposed to minimal damage or 2 h warm ischemia (WI).

RESULTS

Cortex microperfusion was calculated from the LSCI-obtained data. The flow experiment resulted in relatively minor changes in cortex microperfusion compared to the pump-induced changes in total renal flow. Based on stepwise injections of microspheres, we observed different levels of cortex microperfusion that correlated with administrated microsphere dosages (r2 = 0.95-0.99). We found no difference in LSCI measured cortex microperfusion between the kidneys exposed to minimal damage (renal cortex blood flow index, rcBFI = 2090-2600) and 2 h WI (rcBFI = 2189-2540).

CONCLUSIONS

Based on this preliminary study, we demonstrated the feasibility of LSCI in quantifying cortex microperfusion during ex vivo perfusion. Furthermore, based on LSCI-measurements, cortical microperfusion was similar in kidneys exposed to minimal and 2 h WI.

Retrospective analysis of the perioperative outcome in living donor kidney transplantation with multiple renal arteries: does accessory vessel ligation affect the outcome?

PURPOSE

Accurate surgical reconstruction of arterial vascular supply is a crucial part of living kidney transplantation (LDKT). The presence of multiple renal arteries (MRA) in grafts can be challenging. In the present study, we investigated the impact of ligation versus anastomosis of small accessory graft arteries on the perioperative outcome.

METHODS

Clinical and radiological outcomes of 51 patients with MRA out of a total of 308 patients who underwent LDKT with MRA between 2011 and 2020 were stratified in two groups and analyzed. In group 1 (20 patients), ligation of accessory arteries (ARAs) and group 2 (31 patients) anastomosis of ARAs was performed.

RESULTS

Significant differences were observed in the anastomosis-, surgery-, and warm ischemia time (WIT) in favor of group 1. Students t-test showed comparable serum creatinine levels of 2.33 (± 1.75) to 1.68 (± 0.83) mg/dL in group 1 and 2.63 (± 2.47) to 1.50 (± 0.41) mg/dL in group 2, were seen from 1 week to 1 year after transplant. No increased rates of Delayed graft function (DGF), primary transplant dysfunction and transplant rejection were seen, but graft loss and revision rates were slightly higher when the ARAs were ligated. Analysis of Doppler sonography revealed that segmental perfusion deficits tend to regenerate during the clinical course.

CONCLUSION

Ligation of smaller accessory renal arteries may not affect the outcome of living kidney transplantation, except for a minor increase in the reoperation rate. Segmental perfusion deficits of the graft seem to regenerate in most cases as seen in Doppler sonography.

Changes in renal microcirculation in patients with nephrotic and nephritic syndrome: The role of resistive index

BACKGROUND

Renal Resistive Index (RRI) is an important and non-invasive parameter of renal damage and it is associated with abnormal microcirculation or to a parenchymal injury. The aim of our study was to compare the RRI in a cohort of patients with renal diseases categorized in three groups: nephrotic syndrome (NS), acute nephritic syndrome (ANS) and patients with urinary abnormalities (UA).

METHODS

Four hundred eighty-two patients with median age of 48 years (IQR 34-62) with indications for kidney disease were included in the study. Biochemical analyses, clinical assessment with detection of NS, ANS and UA and comorbidities were reported. Renal Doppler ultrasound with RRI was evaluated in all patients at the time of enrolment.

RESULTS

NS was present in 81 (16.8 %) patients while ANS in 81 (16.8 %) and UA in 228 (47.3 %) patients. Patients with ANS showed significant higher RRI compared to both patients with NS [0.71 (IQR 0.67-0.78) vs 0.68 (0.63-0.73), p < 0.001] and UA [0.71 (0.67-0.78) vs 0.65 (0.61-0.71), p < 0.001]; RRI was higher in NS patients than in patients with UA [0.68 (0.63-0.73) vs 0.65 (0.61-0.71), p < 0.001]. Patients with ANS had significantly lower median estimated glomerular filtration rate (eGFR) compared respectively to NS and UA patients [19.7 ml/min vs 54.8 ml/min and vs 72.3 ml/min, p < 0.001], while renal length was significantly higher in patients with NS compared to both patients with ANS and UA [111.88 mm vs 101.98 mm and vs 106.15, p < 0.001]. Patients with ANS had more frequently hematuria and RRI ≥ 0.70 (p < 0.001) compared to both patients with NS and patients with UA. The multiple regression analysis, weighted for age, showed that RRI inversely correlates with eGFR (β coefficient = -0.430, p < 0.001).

CONCLUSIONS

Higher and pathological RRI were found in ANS than NS and UA. Renal resistive index in ANS reflects changes in intrarenal perfusion and microvascular dysfunction related to disease characteristics.

Venous vascular reconstruction of a robotically procured right kidney with two renal veins transplanted into a pediatric recipient

BACKGROUND

Right versus left kidney donor nephrectomy remains a controversial topic in renal transplantation given the increased incidence of right kidney vascular anomalies and associated venous thrombosis. We present the case of a 3-year-old pediatric recipient with urethral atresia and end-stage kidney disease who received a robotically procured living donor right pelvic kidney with two short same-size renal veins and a short ureter.

METHODS

We utilized a completely deceased iliac vein system (common iliac vein with both external and internal veins) to extend the two renal veins. Due to the distance between both renal veins, the external iliac vein was anastomosed to the upper hilum renal vein, and the internal iliac vein was anastomosed to the lower hilum renal vein. The donor's short ureter was anastomosed to the recipient's ureter end-to-side.

RESULTS

The patient had immediate graft function and there were no post-operative complications. Renal ultrasound was unremarkable at 48 hours post-transplant. Serum creatinine was 0.5 mg/dL at 3 months post-transplant.

CONCLUSION

We demonstrate the successful transplantation of a robotically procured right pelvic donor kidney with two short renal veins using a deceased donor iliac vein system for venous reconstruction without increasing technical complications. This technique of venous reconstruction can be used in right kidneys with similar anatomical variations without affecting graft function.

Spontaneous renal tumour regression following an aortic dissection

Spontaneous tumour regression is a rare but well-documented phenomenon, especially for renal cell carcinomas. We describe the case of a 60-year-old male who presented with chest pain and shortness of breath. He was diagnosed with a large type A aortic dissection and an incidental right renal mass, highly suspicious of a renal cell carcinoma. Following repair of the dissection, subsequent imaging showed that the renal mass had largely resolved. Spontaneous tumour regression is commonly thought to occur through immunological mechanisms. A vascular cause of tumour regression through infarction is postulated in this case. Although angioembolisation is a well-recognised management option in the context of palliative treatment of symptomatic renal tumours, this case suggests an extended role for angioembolisation in the treatment of small renal masses.

Human Kidney Proximal Tubule-Microvascular Model Facilitates High-Throughput Analyses of Structural and Functional Effects of Ischemia-Reperfusion Injury

Kidney ischemia reperfusion injury (IRI) poses a major global healthcare burden, but effective treatments remain elusive. IRI involves a complex interplay of tissue-level structural and functional changes caused by interruptions in blood and filtrate flow and reduced oxygenation. Existing in vitro models poorly replicate the in vivo injury environment and lack means of monitoring tissue function during the injury process. Here, a high-throughput human primary kidney proximal tubule (PT)-microvascular model is described, which facilitates in-depth structural and rapid functional characterization of IRI-induced changes in the tissue barrier. The PREDICT96 (P96) microfluidic platform's user-controlled fluid flow can mimic the conditions of IR to induce pronounced changes in cell structure that resemble clinical and in vivo phenotypes. High-throughput trans-epi/endo-thelial electrical resistance (TEER) sensing is applied to non-invasively track functional changes in the PT-microvascular barrier during the two-stage injury process and over repeated episodes of injury. Notably, ischemia causes an initial increase in tissue TEER followed by a sudden increase in permeability upon reperfusion, and this biphasic response occurs only with the loss of both fluid flow and oxygenation. This study demonstrates the potential of the P96 kidney IRI model to enhance understanding of IRI and fuel therapeutic development.

A Retrospective Analysis of the 1-Year Graft Survival Rate in Indonesian Renal Transplant Recipients With Multiple Renal Arteries

BACKGROUND

Renal transplantation is the preferred treatment for end-stage renal disease because of its association with improved survival and quality of life. The debate over multiple renal arteries (MRA) vs a single renal artery regarding kidney function, posttransplant complications, and graft and patient survival remains ongoing. Our goal was to determine the 1-year graft survival rate among renal transplant recipients with MRA at Cipto Mangunkusumo Hospital in Jakarta.

METHODS

A retrospective study was conducted between January 2012 and December 2020, including all kidney transplant candidates with MRA. Data on graft survival, patient demographics, previous renal transplantation, duration of hemodialysis, and delayed graft function were collected and analyzed using SPSS 24. Kaplan-Meier plots and Cox regression analyses were used to determine risk factors for 1-year survival.

RESULTS

Among 752 renal transplant recipients, 104 cases had MRA. The majority were men (71.5%), and the median age of recipients was 47 years. One-year graft survival was observed in 96% of cases, whereas patient survival was 97.7%. No significant difference was found in graft survival based on the number of arteries (single renal artery vs MRA), length of hemodialysis, or previous renal transplantation. However, delayed graft function was significantly associated with graft survival.

CONCLUSION

This study highlights that 1-year graft survival in renal transplant recipients with MRA is not significantly affected by the length of hemodialysis before surgery or previous renal transplantation.

Doppler-based evaluation of intrarenal venous flow as a new tool to predict acute kidney injury: A systematic review and meta-analysis

Congestion is a common complication in the critical care setting, these patients are at increased risk of developing acute kidney injury (AKI). Congestive nephropathy (CN) has recently been described as a mechanism of worsening renal function, and evaluation of renal venous flow by pulsed Doppler (PD) is a useful tool to assess the presence of renal vein congestion. We comprehensively explore the ability of the PD in the evaluation of the intrarenal venous flow (IRVF) to predict the development of AKI in critically ill patients. We searched Pubmed-MEDLINE, Scopus, Embase, and Cochrane Library of Systematic Reviews (to 31th December 2021). We evaluated the association between Doppler-based Intrarenal venous flow demodulation and AKI. CN was defined as the presence of a pulsatile pattern (biphasic or monophasic) in the PD. A total of 4 articles (660 patients) were included in our systematic review, three of these in the metanalysis (413 patients): one study was excluded because its data were inadequate for pooling. Two studies originated in Europe and the other two in the United States. AKI occurrence ranged between 34 and 68%. Patients who developed AKI had a significant difference in PD pattern (continuous vs. pulsatile) in the IRVF (RR=0.46; 95% CI 0.28-0.76). Nevertheless, a large heterogeneity was observed among the studies (I2=68.7%; p=0.04). Albeit preliminary, these findings suggest that the presence of a pulsatile pattern in the PD of the IRVF may be involved in the development of AKI in the critically ill patient. The effect of alterations in the IRVF and renal function warrant further investigation.

High-Frame-Rate Volumetric Porcine Renal Vasculature Imaging

OBJECTIVE

The aim of this study was to assess the feasibility and imaging options of contrast-enhanced volumetric ultrasound kidney vasculature imaging in a porcine model using a prototype sparse spiral array.

METHODS

Transcutaneous freehand in vivo imaging of two healthy porcine kidneys was performed according to three protocols with different microbubble concentrations and transmission sequences. Combining high-frame-rate transmission sequences with our previously described spatial coherence beamformer, we determined the ability to produce detailed volumetric images of the vasculature. We also determined power, color and spectral Doppler, as well as super-resolved microvasculature in a volume. The results were compared against a clinical 2-D ultrasound machine.

RESULTS

Three-dimensional visualization of the kidney vasculature structure and blood flow was possible with our method. Good structural agreement was found between the visualized vasculature structure and the 2-D reference. Microvasculature patterns in the kidney cortex were visible with super-resolution processing. Blood flow velocity estimations were within a physiological range and pattern, also in agreement with the 2-D reference results.

CONCLUSION

Volumetric imaging of the kidney vasculature was possible using a prototype sparse spiral array. Reliable structural and temporal information could be extracted from these imaging results.

Holographic 3D renal segments reconstruction protects renal function by promote choice of selective renal artery clamping during robot-assisted partial nephrectomy

OBJECTIVE

To investigate the impact of selective artery clamping (SAC) and main artery clamping (MAC) during robot-assisted partial nephrectomy (RAPN) on renal function and the influence of holographic three-dimensional (3D) reconstruction of renal segments on the selection between SAC and MAC.

METHODS

This retrospective observational study included patients who underwent RAPN at First Hospital Affiliated to the Army Medical University between December 2016 and July 2022. According to the clamping methods, the patients were divided into the SAC group and the MAC group. The primary outcome was renal function.

RESULTS

A total of 422 patients (194 in the SAC group and 228 in the MAC group) were included. The RAPN procedures were all completed successfully. The patients in SAC group had less glomerular filtration rate (GFR) decline in the affected kidney (8.6 ± 7.0 ml/min vs. 18.7 ± 10.9 ml/min, P < 0.001) and minor estimated glomerular filtration rate (eGFR) decrease (4.3 ± 10.5 ml/min vs. 12.6 ± 12.1 ml/min, P < 0.001) than those in MAC group. Among 37 patients with baseline renal insufficiency, the GFR decline of the affected kidney in the SAC subgroup was significantly lower than in the MAC subgroup (5.5 ± 6.5 ml/min vs. 14.3 ± 9.2 ml/min, P = 0.002). The proportion of patients who underwent 3D reconstruction was significant higher in the SAC group than in the MAC group. (65.46% vs. 28.07%, P < 0.001).

CONCLUSION

The SAC technique during RAPN may serve as a protective measure for renal function, while the implementation of holographic 3D renal segment reconstruction technique may facilitate optimal selection of SAC.

Change in renal blood flow in response to intrarenal pressure alterations induced by ureteroscopy in an in-vivo porcine model

INTRODUCTION

High irrigation rates are commonly used during ureteroscopy and can increase intrarenal pressure (IRP) substantially. Concerns have been raised that elevated IRP may diminish renal blood flow (RBF) and perfusion of the kidney. Our objective was to investigate the real-time changes in RBF while increasing IRP during Ureteroscopy (URS) in an in-vivo porcine model.

METHODS

Four renal units in two porcine subjects were used in this study, three experimental units and one control. For the experimental units, RBF was measured by placing an ultrasonic flow cuff around the renal artery, while performing ureteroscopy in the same kidney using a prototype ureteroscope with a pressure sensor at its tip. Irrigation was cycled between two rates to achieve targeted IRPs of 30 mmHg and 100 mmHg. A control data set was obtained by placing the ultrasonic flow cuff on the contralateral renal artery while performing ipsilateral URS.

RESULTS

At high IRP, RBF was reduced in all three experimental trials by 10-20% but not in the control trial. The percentage change in RBF due to alteration in IRP was internally consistent in each porcine renal unit and independent of slower systemic variation in RBF encountered in both the experimental and control units.

CONCLUSION

RBF decreased 10-20% when IRP was increased from 30 to 100 mmHg during ureteroscopy in an in-vivo porcine model. While this reduction in RBF is unlikely to have an appreciable effect on tissue oxygenation, it may impact heat-sink capacity in vulnerable regions of the kidney.

Horseshoe kidney: Morphologic features, embryologic and genetic etiologies, and surgical implications

The horseshoe kidney (HSK) is the most common congenital abnormality of the upper urinary tract with an incidence of approximately 1 in 500 in the general population. Although individuals with HSK are often asymptomatic, they are at increased risk for neoplasms, infections, ureteropelvic obstruction secondary to lithiasis or vascular compression. Direct injury from trauma is increased in these individuals as is the risk of intraoperative complications secondary to damage involving the typically complex renal or adrenal vascular supply. We briefly review etiological factors including renal and urinary system embryology, genetic mutations, abnormalities related to faulty cell signaling, aberrant cell migration, and other possible causes including environmental exposures and trauma. In addition, we call attention to factors that might influence the success of surgical procedures in patients with HSK. We argue that an understanding of possible etiologies of the HSK and its different subtypes may be useful when planning surgical procedures or considering risk-benefit ratios associated with different surgical options. We briefly present the organization of a HSK in a 100-year-old male demonstrating an unusual vascular supply discovered during a dissection laboratory session in a medical school anatomy course. We describe the structure of the HSK, the position and relationships of the HSK to other structures within the abdomen, and the associated vascular relationships.

Glomerular microcirculation: Implications for diabetes, preeclampsia, and kidney injury

This review outlines the features of tandem regulation of glomerular microcirculation by autoregulatory mechanisms and intraglomerular redistribution of blood flow. Multiple points of cooperation exist between autoregulatory and distributional mechanisms. Mutual interactions between myogenic and tubuloglomerular feedback (TGF) mechanisms regulating the inflow are briefly discussed. In addition to this, TGF operation involving purinergic, autocoid, and NO signaling affects, however, not only afferent arteriolar tone, but mesangial cell tone as well. The latter reversibly reconfigures the distribution of blood flow between the shorter and longer pathways in the glomerular tuft. I advance a hypothesis that blood flow in these pathways spontaneously alternates, and mesangial cell tonicity serves as a rheostatic shift between them. Furthermore, humoral messengers from macula densa cells, themselves dependent on myogenic mechanisms, fine-tune the secretion of renin and, subsequently, the local, intrarenal generation of angiotensin II, which, in turn, provides additional vasomotor signaling to glomerular capillaries through changing the tone of mesangial cells. This complex regulatory network may partially explain the phenomenon of renal functional reserve, as well as suggest implications for changes in renal function during pregnancy, early diabetes mellitus, and acute kidney injury.

Renal Artery Thrombosis After Laparoscopic Living-Donor Nephrectomy: A Case Report

Renal transplantation is the most successful treatment for end-stage renal disease, and the number of living-donor nephrectomies has been rising over the years due to the advantages it offers over deceased donors. Although this surgery is considered safe, it can be associated with complications amplified by the fact that it is performed on a healthy individual. Renal artery thrombosis is a rare disease that needs prompt diagnosis and treatment to avoid renal function deterioration, which becomes even more important in cases of solitary kidneys. We report the first case of renal artery thrombosis after laparoscopic living-donor nephrectomy treated with catheter-directed thrombolysis.

[Italian Society of Interventional Cardiology (GISE) and Italian Society of Arterial Hypertension (SIIA) Consensus document on the role of renal denervation in the management of the difficult to treat hypertension]

Arterial hypertension is the most prevalent cardiovascular risk factor worldwide. Despite the availability of many and effective antihypertensive medications, the prevalence of uncontrolled blood pressure (BP) remains high. As sympathetic hyperactivity has long been recognized as a major contributor to resistant hypertension, catheter-based renal denervation (RDN) has emerged as a new strategy to reduce BP. RDN aims to interrupt the activity of renal sympathetic nerves by applying radiofrequency (RF) energy, ultrasound (US) energy, or injection of alcohol in the perivascular space. The Symplicity HTN-3 trial, the largest sham-controlled trial using the first-generation RF-based RDN device, failed to significantly reduce BP. Since then, new devices and techniques have been developed and consequently many sham-controlled trials using second-generation RF or US-based RDN devices have demonstrated the BP lowering efficacy and safety of the procedure. A multidisciplinary team involving hypertension experts, interventionalists with expertise in renal interventions and anesthesiologists, plays a pivotal role from the selection of the patient candidate for the procedure to the post-procedural care. The aim of this consensus document is to summarize the current evidence about the use of RDN in difficult to treat hypertension and to propose a management strategy from the selection of the patient candidate for the procedure to the post-procedural care.

Controversies in Hypertension IV: Renal Denervation

Renal denervation is not a cure for hypertension. Although more recent sham-controlled trials were positive, a significant minority of patients in each trial were unresponsive. The optimal patient or patients need to be defined. Combined systolic/diastolic hypertension appears more responsive than isolated systolic hypertension. It remains uncertain whether patients with comorbidities associated with higher adrenergic tone should be targeted, including obesity, diabetes, sleep apnea, and chronic kidney disease. No biomarker can adequately predict response. A key to a successful response is the adequacy of denervation, which currently cannot be assessed in real time. It is uncertain what is the optimal denervation methodology: radiofrequency, ultrasound, or ethanol injection. Radiofrequency requires targeting the distal main renal artery plus major branches and accessory arteries. Although denervation appears to be safe, conclusive data on quality of life, improved target organ damage, and reduced cardiovascular events/mortality are required before denervation can be generally recommended.

Implications of Tumor Surgery in Horseshoe Kidneys: A Comparative Study of Outcomes and Surgical Practices

OBJECTIVE

To contrast surgical outcomes of Horseshoe Kidney (HSK) patients with localized renal masses suspected of cancer with nonfused nonectopic kidney patients, emphasizing safe surgical practices for HSKs.

METHODS

The study examined solid tumors from the Mayo Clinic Nephrectomy registry between 1971 and 2021. Each HSK case was matched to three non-HSK patients based on various factors. The outcomes measured included complications within 30days of surgery, change in estimated glomerular filtration rate, and overall, cancer-specific, and metastasis-free survival rates.

RESULTS

Thirty of the 34 HSKs had malignant tumors compared with 90 of the 102 patients in the nonfused nonectopic referent cohort. Accessory isthmus arteries were present in 93% of HSK cases, with 43% exhibiting multiple arteries and 7% with 6 or more arteries. Estimated blood loss and surgery duration were significantly higher in HSKs (900 vs 300 mL, P = .004; 246 vs 163 minutes, P < .001, respectively). The HSK group demonstrated an overall complication rate of 26% (vs 17% in referents, P = .2) and a median change in estimated glomerular filtration rate at 3months of - 8.5 (vs -8.1 in referents, P = .8). At 5-year follow-up, survival rates for HSK patients were 72%, 91%, and 69% for overall, cancer-specific, and metastasis-free survival, respectively. The corresponding rates were 79%, 86%, and 77%, respectively, for matched referent patients (P > .05).

CONCLUSION

HSK tumor management is technically challenging with higher blood loss; however, the data demonstrate comparable outcomes for patients with HSK tumors, including complications and survival, to those without HSKs in experienced centers.

Influence of arterial blood gases on the renal arterial resistive index in intensive care unit

BACKGROUND

Renal artery Doppler sonography with resistive index (RI) determination is a noninvasive, fast, and reliable diagnostic tool increasingly used in the intensive care unit (ICU) to predict and assess the reversibility of acute kidney injury (AKI). However, interpreting the RI can be challenging due to numerous influencing factors. While some studies have explored various confounding factors, arterial blood gases have received limited attention. Therefore, our study aims to evaluate the impact of arterial blood gases on the RI in the ICU setting.

METHODS

This prospective observational study enrolled ICU patients who required blood gas analysis and had not experienced significant hemodynamic changes recently. The RI was measured using standardized Doppler ultrasound within an hour of the arterial blood gases sampling and analysis.

RESULTS

A total of sixty-four patients were included in the analysis. Univariate analysis revealed a correlation between the RI and several variables, including PaCO2 (R = 0.270, p = 0.03), age (R = 0.574, p < 0.0001), diastolic arterial pressure (DAP) (R = - 0.368, p = 0.0028), and SaO2 (R = - 0.284, p = 0.0231). Multivariate analysis confirmed that age > 58 years and PaCO2 were significant factors influencing the RI, with respective odds ratios of 18.67 (p = 0.0003) and 1.132 (p = 0.0267).

CONCLUSION

The interpretation of renal arterial RI should take into account thresholds for PaCO2, age, and diastolic arterial pressure. Further studies are needed to develop a comprehensive scoring system that incorporates all these cofactors for a reliable analysis of RI levels. Trial registration This observational study, registered under number 70-0914, received approval from local Ethical Committee of Toulouse University Hospital.

Intra-renal Arteries in Nephrectomy from a Historical Aspect, a Quest Originated by Medical Illustrations to Reach Modern Angiography

The aim of the present paper is to contribute to the understanding of the history of the anatomical study of the intra-renal arteries. The vasculature and especially the intra-renal arteries of the kidneys are an intriguing field which was first studied through art and then perfected by medicine. Angiography and microsurgery have resulted in partial nephrectomy techniques for surviving kidneys with adequate functional results. Graves' categorization dating from 1954 opened the way for innovative approaches that have resulted in modern topographical anatomy. CONCLUSION: Our understanding of the anatomy of intra-renal arteries has played a significant role in surgical anatomy and internal medicine.

A novel functional role for the classic CNS neurotransmitters, GABA, glycine, and glutamate, in the kidney: potent and opposing regulators of the renal vasculature

The presence of a renal GABA/glutamate system has previously been described; however, its functional significance in the kidney remains undefined. We hypothesized, given its extensive presence in the kidney, that activation of this GABA/glutamate system would elicit a vasoactive response from the renal microvessels. The functional data here demonstrate, for the first time, that activation of endogenous GABA and glutamate receptors in the kidney significantly alters microvessel diameter with important implications for influencing renal blood flow. Renal blood flow is regulated in both the renal cortical and medullary microcirculatory beds via diverse signaling pathways. GABA- and glutamate-mediated effects on renal capillaries are strikingly similar to those central to the regulation of central nervous system capillaries, that is, exposing renal tissue to physiological concentrations of GABA, glutamate, and glycine led to alterations in the way that contractile cells, pericytes, and smooth muscle cells, regulate microvessel diameter in the kidney. Since dysregulated renal blood flow is linked to chronic renal disease, alterations in the renal GABA/glutamate system, possibly through prescription drugs, could significantly impact long-term kidney function.NEW & NOTEWORTHY Functional data here offer novel insight into the vasoactive activity of the renal GABA/glutamate system. These data show that activation of endogenous GABA and glutamate receptors in the kidney significantly alters microvessel diameter. Furthermore, the results show that these antiepileptic drugs are as potentially challenging to the kidney as nonsteroidal anti-inflammatory drugs.

Endothelial mechanical stretch regulates the immunological synapse interface of renal endothelial cells in a sex-dependent manner

Increased mechanical endothelial cell stretch contributes to the development of numerous cardiovascular and renal pathologies. Recent studies have shone a light on the importance of sex-dependent inflammation in the pathogenesis of renal disease states. The endothelium plays an intimate and critical role in the orchestration of immune cell activation through upregulation of adhesion molecules and secretion of cytokines and chemokines. While endothelial cells are not recognized as professional antigen-presenting cells, in response to cytokine stimulation, endothelial cells can express both major histocompatibility complex (MHC) I and MHC II. MHCs are essential to forming a part of the immunological synapse interface during antigen presentation to adaptive immune cells. Whether MHC I and II are increased under increased mechanical stretch is unknown. Due to hypertension being multifactorial, we hypothesized that increased mechanical endothelial stretch promotes the regulation of MHCs and key costimulatory proteins on mouse renal endothelial cells (MRECs) in a stretch-dependent manner. MRECs derived from both sexes underwent 5%, 10%, or 15% uniaxial cyclical stretch, and immunological synapse interface proteins were determined by immunofluorescence microscopy, immunoblot analysis, and RNA sequencing. We found that increased endothelial mechanical stretch conditions promoted downregulation of MHC I in male MRECs but upregulation in female MRECs. Moreover, MHC II was upregulated by mechanical stretch in both male and female MRECs, whereas CD86 and CD70 were regulated in a sex-dependent manner. By bulk RNA sequencing, we found that increased mechanical endothelial cell stretch promoted differential gene expression of key antigen processing and presentation genes in female MRECs, demonstrating that females have upregulation of key antigen presentation pathways. Taken together, our data demonstrate that mechanical endothelial stretch regulates endothelial activation and immunological synapse interface formation in renal endothelial cells in a sex-dependent manner.NEW & NOTEWORTHY Endothelial cells contribute to the development of renal inflammation and have the unique ability to express antigen presentation proteins. Whether increased endothelial mechanical stretch regulates immunological synapse interface proteins remains unknown. We found that antigen presentation proteins and costimulatory proteins on renal endothelial cells are modulated by mechanical stretch in a sex-dependent manner. Our data provide novel insights into the sex-dependent ability of renal endothelial cells to present antigens in response to endothelial mechanical stimuli.

Radio frequency-based renal denervation: a story of simplicity?

Radio frequency-based renal denervation is a safe and effective way of lowering blood pressure, a common condition associated with high cardiovascular risk. Several catheters have been developed to administer energy to the renal arteries and their side branches, thereby modulating sympathetic renal activity. The Symplicity Flex™ and Symplicity Spyral™ are first- and second-generation devices, respectively, for radio frequency-based renal denervation. There is a continuous need to further improve and adjust interventional antihypertensive therapies. Several randomized controlled trials have been conducted to investigate the safety and efficacy of these catheters and most were able to show radio frequency-based renal denervation to be feasible, safe and effective in lowering blood pressure in hypertensive patients with and without concomitant antihypertensive medication. Herein, the authors discuss the pathophysiologic concepts of renal denervation and its procedural approaches, report catheter designs, summarize clinical trials outcomes and, finally, discuss real-world evidence.

Predicting renal function response to renal artery stenting

OBJECTIVE

The Cardiovascular Outcomes in Renal Atherosclerotic Lesions Trial found no benefit of renal artery stenting (RAS) over medical therapy, although it was underpowered to detect a benefit among patients with chronic kidney disease (CKD). A post hoc analysis demonstrated improved event-free survival after RAS for patients whose renal function improved by 20% or more. A significant obstacle to achieving this benefit is the inability to predict which patients' renal function will improve from RAS. The objectives of the current study were to identify predictors of renal function response to RAS.

METHODS

The Veteran Affairs Corporate Data Warehouse was queried for patients who underwent RAS between 2000 and 2021. The primary outcome was improvement in renal function (estimated glomerular filtration rate [eGFR]) after stenting. Patients were categorized as responders if the eGFR at 30 days or greater after stenting increased by 20% or more compared with before stenting. All others were nonresponders.

RESULTS

The study cohort included 695 patients with a median follow-up of 7.1 years (interquartile range, 3.7-11.6 years). Based on postoperative change in eGFR, 202 stented patients (29.1%) were responders, and the remainder (n = 493 [70.9%]) were nonresponders. Before RAS, responders had a significantly higher mean serum creatinine, lower mean eGFR, and higher rate of decline of preoperative GFR in the months before stenting. After stenting, responders had a 26.1% increase in eGFR, compared with before stenting (P < .0001), which remained stable during follow-up. In contrast, nonresponders had a progressive 5.5% decrease in eGFR after stenting. Logistic regression analysis identified three predictors of renal function response to stenting: (1) diabetes (odds ratio [OR], 0.64; 95% confidence interval [CI], 0.44-0.91; P = .013), (2) CKD stages 3b or 4 (OR, 1.80; 95% CI, 1.26-2.57; P = .001), and (3) rate of decline in preoperative eGFR per week before stenting (OR, 1.21; 95% CI, 1.05-1.39; P = .008). CKD stages 3b and 4 and the rate of decline in preoperative eGFR are positive predictors of renal function response to stenting, whereas diabetes is a negative predictor.

CONCLUSIONS

Based on our data, patients in CKD stages 3b and 4 (eGFR 15-44 mL/min/1.73 m2) are the only subgroups with a significant probability of improved renal function after RAS. The rate of decline of preoperative eGFR over the months before stenting is a powerful discriminator of patients who are most likely to benefit from RAS. Specifically, patients with a more rapid decrease in eGFR before stenting have a significantly greater probability of improved renal function with RAS. In contrast, diabetes is a negative predictor of improved renal function, so interventionalists should be circumspect about RAS in diabetic patients.

Impaired microvascular circulation in distant organs following renal ischemia

Mortality in acute kidney injury (AKI) patients remains very high, although very important advances in understanding the pathophysiology and in diagnosis and supportive care have been made. Most commonly, adverse outcomes are related to extra-renal organ dysfunction and failure. We and others have documented inflammation in remote organs as well as microvascular dysfunction in the kidney after renal ischemia. We hypothesized that abnormal microvascular flow in AKI extends to distant organs. To test this hypothesis, we employed intravital multiphoton fluorescence imaging in a well-characterized rat model of renal ischemia/reperfusion. Marked abnormalities in microvascular flow were seen in every organ evaluated, with decreases up to 46% observed 48 hours postischemia (as compared to sham surgery, p = 0.002). Decreased microvascular plasma flow was found in areas of erythrocyte aggregation and leukocyte adherence to endothelia. Intravital microscopy allowed the characterization of the erythrocyte formations as rouleaux that flowed as one-dimensional aggregates. Observed microvascular abnormalities were associated with significantly elevated fibrinogen levels. Plasma flow within capillaries as well as microthrombi, but not adherent leukocytes, were significantly improved by treatment with the platelet aggregation inhibitor dipyridamole. These microvascular defects may, in part, explain known distant organ dysfunction associated with renal ischemia. The results of these studies are relevant to human acute kidney injury.

Horseshoe Kidney: 500 Years From the First Report in the Literature

Horseshoe kidney or ren arcuatus is the most common renal fusion anomaly, with an incidence of 1:500 in the normal population and a male predominance of 2:1. In >90% of cases, the fusion occurs along the inferior pole. It may vary in location, orientation, and arterial and venous anatomy. In 1522, Berengario da Carpi described this renal malformation for the first time in his masterpiece "Isagogae breves" (Introduction to Anatomy). He reported the results of a postmortem examination in the public autopsy room of the University of Bologna, describing "kidneys that are continuous as if they were a kidney, with two emulsifying veins, two emulsifying arteries, two ureteral outlets." In 1564, Leonardo Botallo described and illustrated the features of this atypical anatomical representation, and later, in 1602, Leonard Doldius added further details by examining this anatomical feature during an autopsy. In 1761, Giovanni Battista Morgagni discussed this condition not only as a rare anatomical curiosity found only in necroscopy but also discussed its physiological aspect. In the nineteenth century, with the advent of renal surgery, the horseshoe kidney played a more important role in urological diagnosis and treatment, and its identification became more frequent. With the advent of pyelography, imaging reports of the horseshoe kidney allowed a more accurate representation of the anatomical variants, which was particularly useful in preoperative assessment and outcomes. Berengario da Carpi laid the foundation for a better knowledge of this anatomical anomaly. Five hundred years after the first report in the literature, relevant advances have been made in the management of complications associated with horseshoe kidney and in diagnosis, confirming the need to monitor individuals with this condition who are at higher risk of developing chronic kidney disease.

High-throughput image analysis with deep learning captures heterogeneity and spatial relationships after kidney injury

Recovery from acute kidney injury can vary widely in patients and in animal models. Immunofluorescence staining can provide spatial information about heterogeneous injury responses, but often only a fraction of stained tissue is analyzed. Deep learning can expand analysis to larger areas and sample numbers by substituting for time-intensive manual or semi-automated quantification techniques. Here we report one approach to leverage deep learning tools to quantify heterogenous responses to kidney injury that can be deployed without specialized equipment or programming expertise. We first demonstrated that deep learning models generated from small training sets accurately identified a range of stains and structures with performance similar to that of trained human observers. We then showed this approach accurately tracks the evolution of folic acid induced kidney injury in mice and highlights spatially clustered tubules that fail to repair. We then demonstrated that this approach captures the variation in recovery across a robust sample of kidneys after ischemic injury. Finally, we showed markers of failed repair after ischemic injury were correlated both spatially within and between animals and that failed repair was inversely correlated with peritubular capillary density. Combined, we demonstrate the utility and versatility of our approach to capture spatially heterogenous responses to kidney injury.

Effects of Coriandrum sativum on distant organ inflammation and apoptosis due to liver ischemia/reperfusion injury

Liver ischemia/reperfusion (IR) often affects distant organs, such as small intestine, kidney, and lung. Coriandrum sativum (CS) has an antioxidant and anti-inflammatory effect on liver damage. The aim of this study was to investigate the anti-inflammatory and antiapoptotic effects of CS extract on small intestine, lung, and kidney after the liver IR injury. Small intestine, lung, and kidney tissues were evaluated and scored in terms of cell degeneration, inflammation, and congestion, as well as caspase-3 (Cas-3) and cluster of differentiation 31 (CD31) immunostainings were carried out. Renal enzymes, creatinine and urea levels were measured biochemically in serum. After IR, a decrease in villi size, diffuse degeneration, epithelial cell shedding and extensive congestion in the capillaries were observed. Meanwhile, the number of degenerated villi and congestion decreased in the IR+CS group. Due to IR, increased congestion was detected in the interalveolar septum of the lungs and in the capillaries between the kidney tubules. It was also observed that the positively stained cells with Cas-3 and CD31 were increased in the lung, kidney, and small intestine tissues of the IR group, and decreased in the IR+CS group. Kidney enzymes, urea and creatinine levels were significantly increased in the IR group and decreased in the IR+CS group. In conclusion, it was observed that liver IR caused changes in distant organs, especially in the small intestine, lung, and kidneys. Damaging effects of IR as well as apoptosis and inflammation were found to be decreased in the groups treated with CS.

Classifying Kidney Disease in a Vervet Model Using Spatially Encoded Contrast-Enhanced Ultrasound Perfusion Parameters

Early stages of diabetic kidney disease (DKD) are difficult to diagnose in patients with type 2 diabetes. This work was aimed at identifying contrast-enhanced ultrasound (CEUS) perfusion parameters, a microcirculatory biomarker indicative of early DKD progression. CEUS kidney flash-replenishment data were acquired in control, insulin resistant and diabetic vervet monkeys (N = 16). By use of a mono-exponential model, time-intensity curve parameters related to blood volume (A), velocity (β) and flow rate (perfusion index [PI]) were extracted from 10 concentric kidney layers to study spatial perfusion patterns that could serve as strong indicators of disease. Mean squared error (MSE) was used to assess model performance. Features calculated from the perfusion parameters were inputs for the linear regression models to determine which features could distinguish between cohorts. The mono-exponential model performed well, with average MSEs (±standard deviation) of 0.0254 (±0.0210), 0.0321 (±0.0242) and 0.0287 (±0.0130) for the control, insulin resistant and diabetic cohorts, respectively. Perfusion index features, with blood pressure, were the best classifiers between cohorts (p < 0.05). CEUS has the potential to detect early microvascular changes, providing insight into disease-related structural changes in the kidney. The sensitivity of this technique should be explored further by assessing various stages of DKD.

Sex and strain differences in renal hemodynamics in mice

The present study was to examine sex and strain differences in glomerular filtration rate (GFR) and renal blood flow (RBF) in C57BL6, 129/Sv, and C57BLKS/J mice, three commonly used mouse strains in renal research. GFR was measured by transdermal measurement of FITC-sinitrin clearance in conscious mice. RBF was measured by a flow probe placed in the renal artery under an anesthetic state. In C57BL6 mice, there were no sex differences in both GFR and RBF. In 129/Sv mice, females had significantly greater GFR than males at age of 24 weeks, but not at 8 weeks. However, males had higher RBF and lower renal vascular resistance (RVR). Similar to 129/Sv, female C57BLKS/J had significantly greater GFR at both 8 and 24 weeks, lower RBF, and higher RVR than males. Across strains, male 129/Sv had lower GFR and higher RBF than male C57BL6, but no significant difference in GFR and greater RBF than male C57BLKS/J. No significant difference in GFR or RBF was observed between C57BL6 and C57BLKS/J mice. Deletion of eNOS in C57BLKS/J mice reduced GFR in both sexes, but decreased RBF in males. Furthermore, there were no sex differences in the severity of renal injury in eNOS-/- dbdb mice. Taken together, our study suggests that sex differences in renal hemodynamics in mice are strain and age dependent. eNOS was not involved in the sex differences in GFR, but in RBF. Furthermore, the sexual dimorphism did not impact the severity of renal injury in diabetic nephropathy.

Translational value of preclinical models for renal denervation: a histological comparison of human versus porcine renal nerve anatomy

BACKGROUND

Preclinical models have provided key insights into the response of local tissues to radiofrequency (RF) renal denervation (RDN) that is unobtainable from human studies. However, the anatomic translatability of these models to the procedure in humans is incompletely understood.  Aims: We aimed to compare the renal arterial anatomy in normotensive pigs treated with RF-RDN to that of human cadavers to evaluate the suitability of normotensive pigs for determining the safety of RF-RDN.

METHODS

Histopathologic analyses were performed on RF-treated renal arteries in a porcine model and untreated control renal arteries. Similar analyses were performed on untreated renal arteries from human cadavers.  Results: In both human and porcine renal arteries, the median number of nerves was lower in the more distal sections (the numbers in the proximal, middle, distal, 1st bifurcation, and 2nd bifurcation sections were 65, 58, 47, 22.5, and 14.7 in humans, respectively, and 39, 26, 29, 16.5, and 9.3 in the porcine models, respectively). Renal nerves were common in the regions between arteries and adjacent veins, but only 3% and 13% of the renal nerves in humans and pigs, respectively, were located behind the renal vein. The semiquantitative score of RF-induced renal arterial nerve necrosis was significantly greater at 7 days than 28 days (0.98 vs 0.75; p=0.01), and injury to surrounding organs was rarely observed.

CONCLUSIONS

The distribution of nerve tissue and the relative distribution of extravascular anatomic structures along the renal artery was similar between humans and pigs, which validates the translational value of the normotensive porcine model for RDN.

Multiparametric renal magnetic resonance imaging: A reproducibility study in renal allografts with stable function

Monitoring renal allograft function after transplantation is key for the early detection of allograft impairment, which in turn can contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising noninvasive technique to assess and characterize renal physiopathology; however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period). The purposes of the current study were to evaluate the reproducibility of mpMRI in transplant patients and to characterize normal values of the measured parameters, and to estimate the labeling efficiency of Pseudo-Continuous Arterial Spin Labeling (PCASL) in the infrarenal aorta using numerical simulations considering experimental measurements of aortic blood flow profiles. The subjects were 20 transplant patients with stable kidney function, maintained over 1 year. The MRI protocol consisted of PCASL, intravoxel incoherent motion, and T1 inversion recovery. Phase contrast was used to measure aortic blood flow. Renal blood flow (RBF), diffusion coefficient (D), pseudo-diffusion coefficient (D*), flowing fraction ( f ), and T1 maps were calculated and mean values were measured in the cortex and medulla. The labeling efficiency of PCASL was estimated from simulation of Bloch equations. Reproducibility was assessed with the within-subject coefficient of variation, intraclass correlation coefficient, and Bland-Altman analysis. Correlations were evaluated using the Pearson correlation coefficient. The significance level was p less than 0.05. Cortical reproducibility was very good for T1, D, and RBF, moderate for f , and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f (r = 0.66), RBF and eGFR (r = 0.64), and D* and eGFR (r = -0.57) were found. Normal values of the measured parameters employing the mpMRI protocol in kidney transplant patients with stable function were characterized and the results showed good reproducibility of the techniques.

Renal Ischemia Tolerance Mediated by eIF5A Hypusination Inhibition Is Regulated by a Specific Modulation of the Endoplasmic Reticulum Stress

Through kidney transplantation, ischemia/reperfusion is known to induce tissular injury due to cell energy shortage, oxidative stress, and endoplasmic reticulum (ER) stress. ER stress stems from an accumulation of unfolded or misfolded proteins in the lumen of ER, resulting in the unfolded protein response (UPR). Adaptive UPR pathways can either restore protein homeostasis or can turn into a stress pathway leading to apoptosis. We have demonstrated that N1-guanyl-1,7-diamineoheptane (GC7), a specific inhibitor of eukaryotic Initiation Factor 5A (eIF5A) hypusination, confers an ischemic protection of kidney cells by tuning their metabolism and decreasing oxidative stress, but its role on ER stress was unknown. To explore this, we used kidney cells pretreated with GC7 and submitted to either warm or cold anoxia. GC7 pretreatment promoted cell survival in an anoxic environment concomitantly to an increase in xbp1 splicing and BiP level while eiF2α phosphorylation and ATF6 nuclear level decreased. These demonstrated a specific modulation of UPR pathways. Interestingly, the pharmacological inhibition of xbp1 splicing reversed the protective effect of GC7 against anoxia. Our results demonstrated that eIF5A hypusination inhibition modulates distinctive UPR pathways, a crucial mechanism for the protection against anoxia/reoxygenation.

Contrast-enhanced ultrasound in evaluating the severity of acute kidney injury: An animal experimental study

PURPOSE

Early assessment of the severity of acute kidney injury (AKI) is critical to the prognosis of patients. Renal microcirculation hemodynamic changes and inflammatory response are the essential links of AKI induced by ischemia-reperfusion injury (IRI). This study aims to explore the value of contrast-enhanced ultrasound (CEUS) based on vascular cell adhesion molecule-1 (VCAM-1) targeted microbubbles (TM) in evaluating the renal microcirculation hemodynamics and inflammatory response of different severity of AKI.

METHODS

Eighteen male C57BL/6J mice were randomly divided into three groups (n = 6): sham operation (sham) group, mild IRI-AKI (m-AKI) group, and severe IRI-AKI (s-AKI) group. CEUS based on VCAM-1 TM was used to evaluate renal microcirculation perfusion and inflammatory response. Pearson's correlation was used to analyze the correlation between ultrasonic variables and pro-inflammatory factors.

RESULTS

Compared with the sham group, AUC in m-AKI and s-AKI groups was significantly decreased, and s-AKI group was lower than m-AKI group (P < 0.05). NID of m-AKI and s-AKI groups was significantly higher than that of the sham group, and s-AKI group was higher than that of m-AKI group (P < 0.05). There was a linear positive correlation between NID and VCAM-1 protein expression (r = 0.7384, P < 0.05). NID and AUC were correlated with TNF-α and IL-6 levels (P < 0.05). Compared with early AKI biomarkers, CEUS based on VCAM-1 TM has higher sensitivity in evaluating the severity of AKI.

CONCLUSIONS

CEUS based on VCAM-1 TM can evaluate renal microcirculation perfusion and inflammatory response in mild and severe AKI, which may provide helpful information for assessing the severity of AKI.

End-diastolic velocity mediates the relationship between renal resistive index and the risk of death

OBJECTIVE

Renal resistive index predicts the risk of death in many populations but the mechanism linking renal resistive index and death remains elusive. Renal resistive index is derived from end-diastolic velocity (EDV) and peak systolic velocity (PSV). However, the predictive value of EDV or PSV considered alone is unknown.

METHODS

We conducted a retrospective analysis of 2362 consecutive patients who received a kidney transplant from 1985 to 2017. EDV and PSV were measured at 3 months after transplantation, renal resistive index was calculated, and the risk of death was assessed [median follow-up: 6.25 years (0.25-29.15); total observation period: 13 201 patient-years].

RESULTS

Doppler indices were available in 1721 of 2362 (78.9%) patients (exclusions: 113 who died or returned to dialysis before, 427 with no Doppler studies, 27 with renal artery stenosis, 74 missing values). Among them, 279 (16.4%) had diabetes before transplantation. Mean age was 51.5 ± 14.7, 1097 (63.7%) were male. During follow-up, 217 of 1721 (12.6%) patients died. Renal resistive index and EDV shared many determinants (notably systolic, diastolic and pulse pressure, recipient age and diabetes) unlike renal resistive index and PSV. EDV used as a binary [lowest tertile vs. higher values: (hazard ratio: 2.57 (1.96-3.36), P  < 0.001)] and as a continuous (the lower EDV, the greater the risk of death) variable was significantly associated with the risk of death. This finding was confirmed in multivariable analyses. Prediction of similar magnitude was found for renal resistive index. No association was found between PSV used as a binary or a continuous variable and the risk of death.

CONCLUSION

Low EDV explains high renal resistive index, and the mechanism-linking renal resistive index to the risk of death is through low EDV.

VEGFR2 insufficiency enhances phosphotoxicity and undermines Klotho's protection against peritubular capillary rarefaction and kidney fibrosis

Vascular endothelial growth factor (VEGF) and its cognate receptor (VEGFR2) system are crucial for cell functions associated with angiogenesis and vasculogenesis. Klotho contributes to vascular health maintenance in the kidney and other organs in mammals, but it is unknown whether renoprotection by Klotho is dependent on VEGF/VEGFR2 signaling. We used heterozygous VEGFR2-haploinsufficient (VEGFR2+/-) mice resulting from heterozygous knockin of green fluorescent protein in the locus of fetal liver kinase 1 encoding VEGFR2 to test the interplay of Klotho, phosphate, and VEGFR2 in kidney function, the vasculature, and fibrosis. VEGFR2+/- mice displayed downregulated VEGF/VEGFR2 signaling in the kidney, lower density of peritubular capillaries, and accelerated kidney fibrosis, all of which were also found in the homozygous Klotho hypomorphic mice. High dietary phosphate induced higher plasma phosphate, greater peritubular capillary rarefaction, and more kidney fibrosis in VEGFR2+/- mice compared with wild-type mice. Genetic overexpression of Klotho significantly attenuated the elevated plasma phosphate, kidney dysfunction, peritubular capillary rarefaction, and kidney fibrosis induced by a high-phosphate diet in wild-type mice but only modestly ameliorated these changes in the VEGFR2+/- background. In cultured endothelial cells, VEGFR2 inhibition reduced free VEGFR2 but enhanced its costaining of an endothelial marker (CD31) and exacerbated phosphotoxicity. Klotho protein maintained VEGFR2 expression and attenuated high phosphate-induced cell injury, which was reduced by VEGFR2 inhibition. In conclusion, normal VEGFR2 function is required for vascular integrity and for Klotho to exert vascular protective and antifibrotic actions in the kidney partially through the regulation of VEGFR2 function.NEW & NOTEWORTHY This research paper studied the interplay of vascular endothelial growth factor receptor type 2 (VEGFR2), high dietary phosphate, and Klotho, an antiaging protein, in peritubular structure and kidney fibrosis. Klotho protein was shown to maintain VEGFR2 expression in the kidney and reduce high phosphate-induced cell injury. However, Klotho cytoprotection was attenuated by VEGFR2 inhibition. Thus, normal VEGFR2 function is required for vascular integrity and Klotho to exert vascular protective and antifibrotic actions in the kidney.

Application of ultrasound microbubble contrast to evaluate the effect of sitaxentan on renal microvascular perfusion in beagles undergoing cardiopulmonary bypass

BACKGROUND & OBJECTIVE

We aimed to evaluate the effect of sitaxentan on renal microvascular perfusion via application of ultrasound microbubble contrast.

METHODS

Male beagles were randomly divided into: Sham, cardiopulmonary bypass (CPB) and sitaxentan-infused (Sit) groups (n = 6). The ascending slope rate (ASR), area under the curve (AUC), derived peak intensity, and time to peak (TTP) were obtained via ultrasound microbubble contrast before CPB (T1), after 1 h CPB (T2), at end of CPB (T3), and 2 h after CPB (T4).

RESULTS

Compared with the Sham group, the CPB group had lower ASR of the renal cortex and medulla at T2 - 4, higher AUC and TTP at T3 - 4, and lower derived peak intensity at T4. The ASR at T2 - 4 in the Sit group was lower, TTP was higher at T2 - 4, and AUC was higher at T3 - 4 (P < 0.05). Compared with the CPB group, the Sit group had higher ASR of the renal cortex and medulla at T3 - 4 and AUC and TTP at T3 - 4 (P < 0.05). Compared with that at T1, the ASR of the renal cortex and medulla at T2 - 4 in the CPB group was lower, and AUC and TTP were higher at T3 - 4. The ASR of the renal cortex and medulla at T2 - 4 in the Sit group was lower, TTP was higher at T2 - 4, and AUC was higher at T4 (P < 0.05).

CONCLUSIONS

Ultrasound microbubble contrast could be effectively used to evaluate renal microvascular perfusion peri-CPB in beagles, which was prone to decrease and could be improved via pretreatment with sitaxentan.

Long-term follow-up of patients undergoing renal sympathetic denervation

OBJECTIVES

Renal denervation (RDN) proved to significantly lower blood pressure (BP) at 2-6 months in patients on and off antihypertensive drugs. Given a lack of longer-term follow-up data, our aim was to assess the safety and efficacy of RDN up to five years taking into account antihypertensive drug regimen changes over time.

METHODS

In the present single-center study, patients underwent RDN for (therapy resistant) hypertension. Patients underwent protocolized yearly follow-up out to five years. Data were collected on 24-h ambulatory BP and office BP monitoring, renal function, antihypertensive drug regimen, and safety events, including non-invasive renal artery imaging at 6/12 months. Efficacy analyses were performed using linear mixed-effects models.

RESULTS

Seventy-two patients with mean age 63.3 ± 9.5 (SD) years (51% female) were included. Median follow-up time was 3.5 years and Clark's Completeness Index was 72%. Baseline ambulatory daytime BP was 146.1/83.7 ± 17.4/12.2 mmHg under a mean number of 4.9 ± 2.7 defined daily doses (DDD). At five years, ambulatory daytime systolic BP as calculated from the mixed model was 120.8 (95% CI 114.2-127.5) mmHg and diastolic BP was 73.3 (95% CI 69.4-77.3) mmHg, implying a reduction of -20.9/-8.3 mmHg as compared to baseline estimates (p < 0.0001). The number of DDDs remained stable over time (p = 0.87). No procedure-related major adverse events resulting in long-term consequences were observed.

CONCLUSIONS

The BP-lowering effect of RDN was safely maintained at least five years post-procedure as reflected by a significant decrease in ambulatory daytime BP in the absence of escalating antihypertensive drug therapy over time.

Long-term outcomes after catheter-based renal artery denervation for resistant hypertension: final follow-up of the randomised SYMPLICITY HTN-3 Trial

BACKGROUND

The SYMPLICITY HTN-3 (Renal Denervation in Patients With Uncontrolled Hypertension) trial showed the safety but not efficacy of the Symplicity system (Medtronic, Santa Rosa, CA, USA) at 6 months follow-up in patients with treatment-resistant hypertension. This final report presents the 36-month follow-up results.

METHODS

SYMPLICITY HTN-3 was a single-blind, multicentre, sham-controlled, randomised clinical trial, done in 88 centres in the USA. Adults aged 18-80 years, with treatment-resistant hypertension on stable, maximally tolerated doses of three or more drugs including a diuretic, who had a seated office systolic blood pressure of 160 mm Hg or more and 24 h ambulatory systolic blood pressure of 135 mm Hg or more were randomly assigned (2:1) to receive renal artery denervation using the single electrode (Flex) catheter or a sham control. The original primary endpoint was the change in office systolic blood pressure from baseline to 6 months for the renal artery denervation group compared with the sham control group. Patients were unmasked after the primary endpoint assessment at 6 months, at which point eligible patients in the sham control group who met the inclusion criteria (office blood pressure ≥160 mm Hg, 24 h ambulatory systolic blood pressure ≥135 mm Hg, and still prescribed three or more antihypertensive medications) could cross over to receive renal artery denervation. Changes in blood pressure up to 36 months were analysed in patients in the original renal artery denervation group and sham control group, including those who underwent renal artery denervation after 6 months (crossover group) and those who did not (non-crossover group). For comparisons between the renal artery denervation and sham control groups, follow-up blood pressure values were imputed for patients in the crossover group using their most recent pre-crossover masked blood pressure value. We report long-term blood pressure changes in renal artery denervation and sham control groups, and investigate blood pressure control in both groups using time in therapeutic blood pressure range analysis. The primary safety endpoint was the incidence of all-cause mortality, end stage renal disease, significant embolic event, renal artery perforation or dissection requiring intervention, vascular complications, hospitalisation for hypertensive crisis unrelated to non-adherence to medications, or new renal artery stenosis of more than 70% within 6 months. The trial is registered with ClinicalTrials.gov, NCT01418261.

FINDINGS

From Sep 29, 2011, to May 6, 2013, 1442 patients were screened, of whom 535 (37%; 210 [39%] women and 325 [61%] men; mean age 57·9 years [SD 10·7]) were randomly assigned: 364 (68%) patients received renal artery denervation (mean age 57·9 years [10·4]) and 171 (32%) received the sham control (mean age 56·2 years [11·2]). 36-month follow-up data were available for 219 patients (original renal artery denervation group), 63 patients (crossover group), and 33 patients (non-crossover group). At 36 months, the change in office systolic blood pressure was -26·4 mm Hg (SD 25·9) in the renal artery denervation group and -5·7 mm Hg (24·4) in the sham control group (adjusted treatment difference -22·1 mm Hg [95% CI -27·2 to -17·0]; p≤0·0001). The change in 24 h ambulatory systolic blood pressure at 36 months was -15·6 mm Hg (SD 20·8) in the renal artery denervation group and -0·3 mm Hg (15·1) in the sham control group (adjusted treatment difference -16·5 mm Hg [95% CI -20·5 to -12·5]; p≤0·0001). Without imputation, the renal artery denervation group spent a significantly longer time in therapeutic blood pressure range (ie, better blood pressure control) than patients in the sham control group (18% [SD 25·0] for the renal artery denervation group vs 9% [SD 18·8] for the sham control group; p≤0·0001) despite a similar medication burden, with consistent and significant results with imputation. Rates of adverse events were similar across treatment groups, with no evidence of late-emerging complications from renal artery denervation. The rate of the composite safety endpoint to 48 months, including all-cause death, new-onset end-stage renal disease, significant embolic event resulting in end-organ damage, vascular complication, renal artery re-intervention, and hypertensive emergency was 15% (54 of 352 patients) for the renal artery denervation group, 14% (13 of 96 patients) for the crossover group, and 14% (10 of 69 patients) for the non-crossover group.

INTERPRETATION

This final report of the SYMPLICITY HTN-3 trial adds to the totality of evidence supporting the safety of renal artery denervation to 36 months after the procedure. From 12 months to 36 months after the procedure, patients who were originally randomly assigned to receive renal artery denervation had larger reductions in blood pressure and better blood pressure control compared with patients who received sham control.

FUNDING

Medtronic.

Case Report: Horseshoe Kidney Transplantation Using Split Technique

With the increasing demand for donor organs and its limited availability, kidneys with atypical anatomy are being used more and more. The experience with transplanting horseshoe kidneys is limited. Understanding variations in uretero-pelvic anatomy and aberrant vascular anatomy is of paramount importance for the utilization of horse-shoe kidneys for transplantation. We describe our experience in procuring a horse-shoe kidney from a deceased donor, splitting the kidney and transplantation into 2 recipients.

Changes in residual kidney Pulsatility Index following living donor nephrectomy

OBJECTIVE

Nephrectomy in kidney transplant donors provokes a compensatory hyperfiltration process of the residual kidney, characterized by changes in renal vascular hemodynamics. This research aimed to determine the short-term difference in the pulsatility index (PI) of kidney transplant donors' residual kidney before and after nephrectomy.

METHODS

This is a prospective historical study using secondary data from kidney transplant living donors who have undergone nephrectomy at a tertiary referral hospital in Jakarta, Indonesia, from March 2019 to January 2020. PI of renal, segmental, interlobar, and arcuate arteries of the residual kidneys were measured in the preoperative and day-1, day-7, day-30 postoperative period. The pre- and postoperative PI values were statistically analyzed to examine differences between the groups.

RESULTS

PI of 40 residual kidneys were obtained. There were no significant mean PI changes in the arteries except for the middle interlobar artery (p = 0.049), which showed no significant difference after post hoc analysis.

CONCLUSIONS

There is no significant short-term difference in PI of the residual kidney before and after kidney transplant donor nephrectomy.

ADVANCES IN KNOWLEDGE

Short-term postoperative PI of the residual kidney arteries may not be suitable as a predictor for chronic kidney disease in kidney transplant donors. Other quantitative Doppler ultrasound parameters must be considered.

Triple V-plasty: Novel Renovascular Reconstruction Technique in Live-Donor Transplantation

INTRODUCTION

Donor renovascular anomalies, including multiplicity, length and caliber of blood vessels, could hinder renal transplantation, especially from live-donors. However, meticulous back-bench vascular reconstruction ascertaining orientation and patency of individual vessels can be effective in utilization of renal grafts with multiple renal arteries, helping to expand the pool of live-donors.

SURGICAL TECHNIQUE

Sequential v-plasty of individual donor renal arteries using fine, non-absorbable, monofilament (7-0 or 8-0 Prolene) suture in an uninterrupted fashion enables creation of a single, wide ostium for anastomosis with the target, inflow recipient (usually external or common iliac) artery. Additionally, entwined donor hilar renovasculature may necessitate incisional separation and re-anastomosis of a bifid vein for proper renovascular orientation following graft implantation in the recipient.

CONCLUSION

Application of never-before described ex vivo renovascular reconstruction led to live-donor renal transplantation between two pairs of donor-recipient through the National Kidney Registry with successful long-term outcomes.

Kidney Angiotensin in Cardiovascular Disease: Formation and Drug Targeting

The concept of local formation of angiotensin II in the kidney has changed over the last 10-15 years. Local synthesis of angiotensinogen in the proximal tubule has been proposed, combined with prorenin synthesis in the collecting duct. Binding of prorenin via the so-called (pro)renin receptor has been introduced, as well as megalin-mediated uptake of filtered plasma-derived renin-angiotensin system (RAS) components. Moreover, angiotensin metabolites other than angiotensin II [notably angiotensin-(1-7)] exist, and angiotensins exert their effects via three different receptors, of which angiotensin II type 2 and Mas receptors are considered renoprotective, possibly in a sex-specific manner, whereas angiotensin II type 1 (AT1) receptors are believed to be deleterious. Additionally, internalized angiotensin II may stimulate intracellular receptors. Angiotensin-converting enzyme 2 (ACE2) not only generates angiotensin-(1-7) but also acts as coronavirus receptor. Multiple, if not all, cardiovascular diseases involve the kidney RAS, with renal AT1 receptors often being claimed to exert a crucial role. Urinary RAS component levels, depending on filtration, reabsorption, and local release, are believed to reflect renal RAS activity. Finally, both existing drugs (RAS inhibitors, cyclooxygenase inhibitors) and novel drugs (angiotensin receptor/neprilysin inhibitors, sodium-glucose cotransporter-2 inhibitors, soluble ACE2) affect renal angiotensin formation, thereby displaying cardiovascular efficacy. Particular in the case of the latter three, an important question is to what degree they induce renoprotection (e.g., in a renal RAS-dependent manner). This review provides a unifying view, explaining not only how kidney angiotensin formation occurs and how it is affected by drugs but also why drugs are renoprotective when altering the renal RAS. SIGNIFICANCE STATEMENT: Angiotensin formation in the kidney is widely accepted but little understood, and multiple, often contrasting concepts have been put forward over the last two decades. This paper offers a unifying view, simultaneously explaining how existing and novel drugs exert renoprotection by interfering with kidney angiotensin formation.

Assessment of renal microcirculation in biopsy-proven tubulointerstitial nephritis in patients with and without glomerular disease: the role of resistive index

BACKGROUND

Renal resistive index (RRI) measured by Doppler sonography is a marker of microvascular status and it is associated with changes in renal function. Aim of the study was to assess RRI in biopsy-proven tubulointerstitial nephritis (TIN) in patients with and without glomerular disease.

METHODS

132 consecutive patients underwent to native renal biopsy with diagnosis of isolated TIN or in association with glomerulonephritis. Estimated glomerular filtration rate (eGFR), 24-hour urinary protein excretion and renal ecocolorDoppler ultrasonography with RRI assessment were performed at time of enrollment.

RESULTS

Patients with isolated-TIN had significantly higher RRI than both patients with non-immunoglobulin A glomerulonephritis (non-IgA-TIN) [0.73 (0.68-0.77) vs 0.64 (0.60-0.67), p < 0.001] and patients with IgA nephropathy (IgAN) [0.73 (0.68-0.77) vs 0.66 (0.60-0.71), p < 0.01]. Patients with isolated-TIN had mainly RRI ≥ 0.70 (n = 15, 65.2%) with the respect to patients with non-IgA-TIN (n = 7, 12.3%) and patients with IgAN (n = 17, 32.7%). A negative linear correlation was found between RRI and hemoglobin (r = 0.233, p < 0.01) and between RRI and eGFR (r = 0.537, p < 0.001).

CONCLUSION

Tubulointerstitial damage is the most accurate histological lesion that correlates with eGFR and renal impairment. RRI can be a useful parameter to detect tubulointerstitial lesions.

Perfusion Analysis of Kidney Injury in Rats With Cirrhosis Induced by Common Bile Duct Ligation Using Arterial Spin Labeling MRI

BACKGROUND

Arterial spin labeling (ASL) has been proven to be effective in ischemia-induced acute kidney injury (AKI); however, validation of ASL magnetic resonance imaging (MRI) is limited in AKI in the presence of cirrhosis.

PURPOSE

To investigate the feasibility of ASL in revealing renal blood flow (RBF) changes in kidney injury in the presence of cirrhosis and to assess its value in the early diagnosis of disease.

STUDY TYPE

Longitudinal.

ANIMAL MODEL

Rats were randomized into baseline group (N = 3), sham surgery group (N = 18), and common bile duct ligation (BDL) group (N = 48). All groups were divided into six subgroups based on different sacrificed time points.

FIELD STRENGTH/SEQUENCE

3 T scanner, prototypic pulsed ASL sequence using flow-sensitive alternating inversion recovery preparation, half-Fourier acquisition single-shot turbo spin echo sequence.

ASSESSMENT

RBF measurement was performed by ASL. Hematoxylin-eosin (HE) score, Hypoxia-inducible factor-1alpha (HIF-1α) score, peritubular capillar (PTC) density, alanine aminotransferase, aspartate aminotransferase, serum total bilirubin, total bile acids, serum creatinine (Scr), and blood urea nitrogen (BUN) were harvested.

STATISTICAL TESTS

Analysis of variance, Pearson's correlation coefficient, and receiver operating characteristic curves were performed. P < 0.05 was considered statistically significant.

RESULTS

RBF, HE score, HIF-1α score, and PTC density after BDL were significantly different from baseline. RBF was highly correlated with HE score, HIF-1α score, and PTC density (r = -0.7598, r = -0.7434, r = 0.6406, respectively). RBF and Scr began to differ significantly from baseline at day 3 and 7 after intervention, respectively. The areas under the curves of RBF, Scr, and BUN for distinguishing non-AKI from AKI in cirrhosis were 1.00, 0.888, and 0.911, while those for distinguishing mild from severe kidney injury were 0.961, 0.830, and 0.857, respectively.

DATA CONCLUSION

ASL allows the longitudinal assessment of the degree of AKI induced by cholestatic cirrhosis in rats and can serve as a noninvasive marker for the early and accurate diagnosis of AKI.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

The potential protective effects of estradiol and 2-methoxyestradiol in ischemia reperfusion-induced kidney injury in ovariectomized female rats

AIMS

Investigating the impact of 17β estradiol (E2) and its endogenous non-hormonal metabolite 2-methoxyestradiol (2ME) on renal ischemia-reperfusion (RIR) induced kidney injury in ovariectomized (OVX) rats and the role of catechol-O-methyltransferase (COMT) in their effects.

MAIN METHODS

Eighty female rats were allocated into eight groups. Control group, Sham group, OVX group, OVX and RIR group, OVX + RIR + E2 group, OVX + RIR + 2ME group, OVX + RIR + E2 + Entacapone group and OVX + RIR + 2ME + Entacapone group, respectively. Twenty-four hours post RIR, creatinine (Cr) and blood urea nitrogen (BUN) were determined in serum, while malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), Glutathione (GSH), myeloperoxidase (MPO), as well as the expressions of COMT, hypoxia inducible factor-1α (HIF-1α) and tyrosine hydroxylase (TH) were assessed in the kidney tissues.

KEY FINDINGS

Serum Cr, BUN, MPO, as well as HIF-1α and TH expressions were significantly higher with concomitant decrease in COMT expression, SOD and CAT activities and GSH content observed in OVX and RIR group compared to sham group. E2 and 2ME treatment significantly ameliorated all parameters measured in OVX and RIR rats. On the other hand, Entacapone significantly decreased the effect of E2, with no effect on 2ME treatment.

SIGNIFICANCE

E2 ameliorates RIR-induced kidney injury and this effect is mediated, at least in part, via its COMT-mediated conversion to 2ME. Thus, 2ME by the virtue of its pleiotropic pharmacological effects can be used as a safe and effective treatment of RIR injury.

Renal denervation in resistant hypertension: a review of clinical trials and future perspectives

A previous report using the National Health and Nutrition Examination Survey demonstrated an increase in the prevalence of resistant hypertension, which does not respond to traditional therapy and medication. Studies using various animal hypertensive models have demonstrated significant blood pressure (BP) reduction following renal artery denervation (RDN). Catheter-based RDN became available in clinical trials as a possible treatment option for resistant hypertension. Although first clinical trials of RDN have demonstrated the efficacy and safety of this treatment mortality for lowering BP in patients with resistant hypertension, the role of RDN has been questioned since the results of the Symplicity HTN-3 trial. Considering the ethnic differences demonstrated in the Symplicity HTN-Japan and Global Symplicity registry, by contrast, RDN might be an effective for resistant hypertension in Asian population. Here, we discuss RDN applications and technology, the old and new clinical evidence of RDN, patients' selection of RDN responder, and optimization of RDN procedure in this review. The available evidence demonstrates that RDN could be effective in carefully selected patients with resistant hypertension, paving the way for future research in this area.

Hydroxyl Ethyl Starch (HES) Preserves Intrarenal Microcirculatory Perfusion Shown by Contrast-Enhanced Ultrasound (Ceus), and Renal Function in a Severe Hemodilution Model in Pigs

ABSTRACT

Acute normovolemic hemodilution (ANH) is associated with low oxygen carrying capacity of blood and purposed to cause renal injury in perioperative setting. It is best accomplished in a perioperative setting by a colloid such as hydroxyl ethyl starch (HES) due its capacity to fill the vascular compartment and maintain colloidal pressure. However, alterations of intra renal microvascular perfusion, flow and its effects on renal function and damage during ANH has not been sufficiently clarified. Based on the extensive use of HES in the perioperative setting we tested the hypothesis that the use of HES during ANH is able to perfuse the kidney microcirculation adequately without causing renal dysfunction and injury in pigs. Hemodilution (n = 8) was performed by stepwise replacing blood with HES to hematocrit (Hct) levels of 20% (T1), 15% (T2), and 10% (T3). Seven control animals were investigated. Systemic and renal hemodynamics were monitored. Renal microcirculatory perfusion was visualized and quantified using contrast-enhanced ultrasound (CEUS) and laser speckle imaging (LSI). In addition, sublingual microcirculation was measured by handheld vital microscopy (HVM). Intrarenal mean transit time of ultrasound contrast agent (IRMTT-CEUS) was reduced in the renal cortex at Hct 10% in comparison to control at T3 (1.4 ± 0.6 vs. 2.2 ± 0.7 seconds, respectively, P < 0.05). Although renal function was preserved, the serum neutrophil gelatinase-associated lipocalin (NGAL) levels was higher at Hct 10% (0.033 ± 0.004 pg/μg protein) in comparison to control at T3 (0.021 ± 0.002 pg/μg protein. A mild correlation between CO and IRMTT (renal RBC velocity) (r -0.53; P = 0.001) and CO and NGAL levels (r 0.66; P = 0.001) was also found. Our results show that HES induced ANH is associated with a preserved intra renal blood volume, perfusion, and function in the clinical range of Hct (<15%). However, at severely low Hct (10%) ANH was associated with renal injury as indicated by increased NGAL levels. Changes in renal microcirculatory flow (CEUS and LSI) followed those seen in the sublingual microcirculation measured with HVM.