Renal Artery Stenosis

Evaluations of secondary hypertension and laboratory data in the elderly population

Secondary hypertension in the elderly poses many challenges and requires a comprehensive diagnostic and management approach. This review explores the prevalence, diagnostic strategies, and treatment modalities for secondary hypertension in elderly patients, focusing on etiologies including primary aldosteronism, renal vascular disease, renal parenchymal disease, obstructive sleep apnea, thyroid disorders, Cushing's syndrome, pheochromocytomas and paragangliomas, and drug-induced hypertension. Key considerations include age-related changes in physiology and atypical presentations of underlying conditions necessitating thorough screening with a combination of clinical evaluation, laboratory tests, and imaging studies. Collaboration among healthcare providers is essential to ensure a timely diagnosis and personalized management tailored to the unique needs of elderly patients. Further research is needed to address knowledge gaps and optimize clinical strategies for managing secondary hypertension in this population.

Deep-learning-based sampling position selection on color Doppler sonography images during renal artery ultrasound scanning

Accurate selection of sampling positions is critical in renal artery ultrasound examinations, and the potential of utilizing deep learning (DL) for assisting in this selection has not been previously evaluated. This study aimed to evaluate the effectiveness of DL object detection technology applied to color Doppler sonography (CDS) images in assisting sampling position selection. A total of 2004 patients who underwent renal artery ultrasound examinations were included in the study. CDS images from these patients were categorized into four groups based on the scanning position: abdominal aorta (AO), normal renal artery (NRA), renal artery stenosis (RAS), and intrarenal interlobular artery (IRA). Seven object detection models, including three two-stage models (Faster R-CNN, Cascade R-CNN, and Double Head R-CNN) and four one-stage models (RetinaNet, YOLOv3, FoveaBox, and Deformable DETR), were trained to predict the sampling position, and their predictive accuracies were compared. The Double Head R-CNN model exhibited significantly higher average accuracies on both parameter optimization and validation datasets (89.3 ± 0.6% and 88.5 ± 0.3%, respectively) compared to other methods. On clinical validation data, the predictive accuracies of the Double Head R-CNN model for all four types of images were significantly higher than those of the other methods. The DL object detection model shows promise in assisting inexperienced physicians in improving the accuracy of sampling position selection during renal artery ultrasound examinations.

Carotid and Renal Vascular Disease

This article review covers carotid artery disease, abdominal aortic aneurysm, and atherosclerotic renal artery disease. It overviews each condition's clinical presentation, diagnosis, medical management, and interventional approach. Carotid artery disease is characterized by hemispheric and neuropsychological manifestations, which can help detect this condition. Screening for carotid artery stenosis is recommended in high-risk individuals and can be performed using different methods, with carotid duplex ultrasonography being the preferred option. Carotid endarterectomy and carotid artery stenting are indicated based on specific criteria and patient characteristics. An abdominal aortic aneurysm is often asymptomatic, but abdominal, back, or flank pain may sometimes be present. Ultrasonography is an effective method for screening and monitoring abdominal aortic aneurysms, with high sensitivity and specificity. Smoking cessation is a crucial intervention for preventing further enlargement of small aortic aneurysms. Repair of abdominal aortic aneurysm is recommended based on the aneurysm size, growth rate, and the presence of symptoms. Endovascular repair is preferred when suitable anatomy is present. Atherosclerotic renal artery disease is associated with resistant hypertension, renal failure, and occasionally pulmonary edema. Doppler ultrasonography is a valuable diagnostic tool for detecting it, while the renal resistive index provides additional insights into disease severity and treatment response. Revascularization is not routinely recommended for atherosclerotic renal artery disease, but it may be considered in specific cases, such as renal arterial fibromuscular dysplasia or unexplained congestive heart failure.

Diagnostic Performance of Magnetic Resonance Angiography for Artery Stenosis After Kidney Transplant: A Systematic Review and Meta-Analysis

RATIONALE AND OBJECTIVES

Magnetic resonance angiography (MRA) is used to diagnose artery stenosis after kidney transplant. However, there is a lack of applicable consensus guidelines, and the diagnostic value of this technique is unclear. Therefore, the aim of the present study was to evaluate the diagnostic performance of MRA for the detection of artery stenosis after kidney transplant.

MATERIALS AND METHODS

We searched PubMed, Web of Science, Cochrane Library, and Embase from database inception to September 1, 2022. Two independent reviewers assessed the methodological quality of eligible studies using the quality assessment of diagnostic accuracy studies-2 tool. The diagnostic odds ratio, pooled sensitivity, and specificity values, positive likelihood ratios, and negative likelihood ratios were calculated to synthesize data with a bivariate random-effects model. Meta-regression analysis was performed in cases of high among-study heterogeneity.

RESULTS

Eleven studies were included in the meta-analysis. The area under the summary receiver operating characteristic curve was 0.96 (95% confidence interval [CI]: 0.94-0.98). The pooled sensitivity and specificity values for MRA in diagnosing artery stenosis after kidney transplant were 0.96 (95% CI: 0.76-0.99) and 0.93 (95% CI: 0.86-0.96), respectively.

CONCLUSION

MRA demonstrated high sensitivity and specificity for diagnosing artery stenosis after kidney transplant, suggesting that it may be used reliably in clinical practice. However, further large-scale studies are required to validate the present findings.

[Hypertension as a common element of renal transplantation with pressor kidney and posterior reversible encephalopathy syndrome]

Secondary arterial hypertension accounts for only 5-10% of cases of arterial hypertension, hence the importance of its clinical suspicion for diagnosis. One of the most common causes of secondary hypertension is renovascular hypertension, caused by renal hypoperfusion and activation of the renin-angiotensin-aldosterone system. In addition to arterial hypertension being one of the most prevalent cardiovascular risk factors in the population, its poor control can cause acute neurological disorders such as Posterior Reversible Leukoencephalopathy syndrome (PRES), being characteristic the appearance of visuals alterations. Next, we present the case of a kidney transplant patient with well-controlled arterial hypertension with worsening secondary to renal artery stenosis and development of PRES.

Ultrasonographic Assessment of Atherosclerotic Renal Artery Stenosis in Elderly Patients with Chronic Kidney Disease: An Italian Cohort Study

Although atherosclerotic renal artery stenosis (ARAS) is strictly associated with high cardiovascular risk and mortality, it often may remain unrecognized being clinically silent and frequently masked by co-morbidities especially in elderly patients with coexisting chronic kidney disease (CKD). The present observational study was conducted in elderly CKD-patients with atherosclerosis on other arterial beds. The aims were assessment of (1) ARAS prevalence; (2) best predictor(s) of ARAS, using duplex ultrasound; and (3) cardiovascular and renal outcomes at one-year follow-up. The cohort was represented by 607 consecutive in-patients. Inclusion criteria were age ≥65 years; CKD stages 2−5 not on dialysis; single or multiple atherosclerotic plaque on epiaortic vessels, abdominal aorta, aortic arch, coronary arteries, peripheral arteries that had been previously ascertained by one or more procedures. Duplex ultrasound was used to detect ARAS. Multiple regression analysis and ROS curve were performed to identify the predictors of ARAS. ARAS was found in 53 (44%) out of 120 patients who met the inclusion criteria. In univariate analysis, GFR (b = −0.021; p = 0.02); hemoglobin (b = −0.233; p = 0.02); BMI (b = 0.134; p = 0.036) and atherosclerosis of abdominal aorta and/or peripheral vessels (b = 1.025; p < 0.001) were associated with ARAS. In multivariable analysis, abdominal aorta and/or peripheral atherosclerosis was a significant (p = 0.002) predictor of ARAS. The area under the ROC curve was 0.655 (C.I. = 0.532−0.777; p = 0.019). ARAS is common in older CKD patients with extra-renal atherosclerosis, with the highest prevalence in those with aortic and peripheral atherosclerosis. ARAS may pass by unnoticed in everyday clinical practice.

The role of nitric oxide in renovascular hypertension: from the pathophysiology to the treatment

Renovascular hypertension is one of the most relevant causes of secondary hypertension, mostly caused by atherosclerotic renovascular stenosis or fibromuscular dysplasia. The increase in angiotensin II production, oxidative stress, and formation of peroxynitrite promotes the decrease in nitric oxide (NO) availability and the development of hypertension, renal and endothelial dysfunction, and cardiac and vascular remodeling. The NO produced by nitric oxide synthases (NOS) acts as a vasodilator; however, endothelial NOS uncoupling (eNOS) also contributes to NO reduced availability in renovascular hypertension. NO donors and NO-derived metabolites have been investigated in experimental renovascular hypertension and have shown promissory effects in attenuating blood pressure and organ damage in this condition. Therefore, understanding the role of decreased NO in the pathophysiology of renovascular hypertension promotes the study and development of NO donors and molecules that can be converted into NO (such as nitrate and nitrite), contributing for the treatment of this condition in the future.

Renal Artery Partial Occlusion After Aortic Dissection Is Associated With Impaired Renal Function in the Affected Kidney

BACKGROUND

The renal artery is often involved in aortic dissection, leading to kidney ischaemia and renal dysfunction. However, some patients with aortic dissection with combined renal artery involvement do not show clinical renal dysfunction. This study aimed to analyse the relationship between renal artery involvement and renal function.

METHODS

Data and images were collected from 79 patients (Group A), in Beijing Anzhen hospital between January 2015 and December 2017, who had type A aortic dissection, in order to analyse the relationship between renal artery involvement and serum creatinine. In order to further analyse the relationship between renal artery involvement and single kidney function, data from 27 patients (Group B) with aortic dissection from August 2018 to October 2018 were collected. Renal dynamic imaging was conducted, and clinical and image data were recorded.

RESULTS

Results showed that patients with one partially occluded renal artery had higher variance of serum creatinine after surgery compared with patients with one false-lumen renal artery (5.8±22.7 umol/L versus -18.7±22.7 umol/L; p=0.003). The glomerular filtration rate of a single kidney that had a partially occluded renal artery was lower than that of a single kidney with a normal renal artery (37.77±9.57 versus 42.73±10.54; p=0.04).

CONCLUSIONS

A partially occluded renal artery in aortic dissection was associated with impaired renal function after surgery, even though patients did not present high serum creatinine. More attention should be paid to those experiencing aortic dissection.

The Renal Vasculature: What the Radiologist Needs to Know

The physiologic role of the kidneys is dependent on the normal structure and functioning of the renal vasculature. Knowledge and understanding of the embryologic basis of the renal vasculature are necessary for the radiologist. Common anatomic variants involving the renal artery (supernumerary arteries and prehilar branching) and renal vein (supernumerary veins, delayed venous confluence, retroaortic or circumaortic vein) may affect procedures like renal transplantation, percutaneous biopsy, and aortic aneurysm repair. Venous compression syndromes (anterior and posterior nutcracker syndrome) can be symptomatic and can be diagnosed with a combination of radiologic features. Renal artery stenosis is commonly atherosclerotic and is diagnosed with Doppler US, CT angiography, or MR angiography. Fibromuscular dysplasia, the second most common cause of renal artery narrowing, has a characteristic string-of-beads appearance resulting from multifocal stenoses and dilatations. Manifestations of renal vasculitis differ depending on whether the affected vessels are large, medium, or small. Renal vascular injury is graded according to the American Association for the Surgery of Trauma (AAST) renal injury scale, which defines vascular injury and active bleeding in renal injuries. Both renal arteries and veins are affected by primary neoplasms or secondarily by neoplasms from adjacent structures. Differentiation between bland thrombus and tumor thrombus and the extent of involvement dictate management in malignancies, especially renal cell carcinoma. Aneurysms, pseudoaneurysms, arteriovenous malformations, and arteriovenous fistulas can affect renal vessels and can be diagnosed with specific imaging features. The radiologist has a critical role in identification of specific imaging characteristics and establishing the diagnosis in the varied pathologic conditions affecting the renal vasculature, which is critical for directing management. Thus, the renal vasculature should be an integral part of radiologists' checklist. ^©RSNA, 2021.

Phenotypic diversity and metabolic specialization of renal endothelial cells

Complex multicellular life in mammals relies on functional cooperation of different organs for the survival of the whole organism. The kidneys play a critical part in this process through the maintenance of fluid volume and composition homeostasis, which enables other organs to fulfil their tasks. The renal endothelium exhibits phenotypic and molecular traits that distinguish it from endothelia of other organs. Moreover, the adult kidney vasculature comprises diverse populations of mostly quiescent, but not metabolically inactive, endothelial cells (ECs) that reside within the kidney glomeruli, cortex and medulla. Each of these populations supports specific functions, for example, in the filtration of blood plasma, the reabsorption and secretion of water and solutes, and the concentration of urine. Transcriptional profiling of these diverse EC populations suggests they have adapted to local microenvironmental conditions (hypoxia, shear stress, hyperosmolarity), enabling them to support kidney functions. Exposure of ECs to microenvironment-derived angiogenic factors affects their metabolism, and sustains kidney development and homeostasis, whereas EC-derived angiocrine factors preserve distinct microenvironment niches. In the context of kidney disease, renal ECs show alteration in their metabolism and phenotype in response to pathological changes in the local microenvironment, further promoting kidney dysfunction. Understanding the diversity and specialization of kidney ECs could provide new avenues for the treatment of kidney diseases and kidney regeneration.

Renal Artery Stenosis As Etiology of Recurrent Flash Pulmonary Edema and Role of Imaging in Timely Diagnosis and Management

Renal hypoperfusion from renal artery stenosis (RAS) activates the renin-angiotensin system, which in turn causes volume overload and hypertension. Atherosclerosis and fibromuscular dysplasia are the most common causes of renal artery stenosis. Recurrent flash pulmonary edema, also known as Pickering syndrome, is commonly associated with bilateral renal artery stenosis. There should be a high index of clinical suspicion for renal artery stenosis in the setting of recurrent flash pulmonary edema and severe hypertension in patients with atherosclerotic disease. Duplex ultrasonography is commonly recommended as the best initial test for the detection of renal artery stenosis. Computed tomography (CT) angiography (CTA) or magnetic resonance (MR) angiography (MRA) are useful diagnostic imaging studies for the detection of renal artery stenosis in patients where duplex ultrasonography is difficult. If duplex ultrasound, CTA, and MRA are indeterminate or pose a risk of significant renal impairment, renal angiography is useful for a definitive diagnosis of RAS. The focus of medical management for RAS relies on controlling renovascular hypertension and aggressive lifestyle modification with control of atherosclerotic disease risk factors. The restoration of renal artery patency by revascularization in the setting of RAS due to atherosclerosis may help in the management of hypertension and minimize renal dysfunction.

Treatment with Mesenchymal Stem Cells Improves Renovascular Hypertension and Preserves the Ability of the Contralateral Kidney to Excrete Sodium

BACKGROUND

Mesenchymal stem cells (MSC) improve renal function and renovascular hypertension in the 2-kidney 1-clip model (2K-1C). While MSC play an immunomodulatory role, induce neoangiogenesis, and reduce fibrosis, they do not correct sodium loss by the contra-lateral kidney.

OBJECTIVES

We investigated the tubular function of both stenotic and contralateral kidneys and the effect of MSC treatment by evaluating diuresis, natriuresis, and the expression of the main water and sodium transporters.

METHOD

Adult Wistar rats were allocated into four groups: control (CT), CT+MSC, 2K-1C, and 2K-1C+MSC. MSC (2 × 105) were infused through the tail vein 3 and 5 weeks after clipping. Systolic blood pressure (SBP) was monitored weekly by plethysmography. Six weeks after clipping, 24-hour urine and blood samples were collected for biochemical analysis. Gene expression of the Na/H exchanger-3, epithelial sodium channel, Na/K-ATPase, Na/K/2Cl cotransporter, and aquaporins 1 and 2 (AQP1 and AQP2) were analyzed by RT-PCR. Intrarenal distribution of AQP1 and AQP2 was analyzed by immunohistochemistry.

RESULTS

In hypertensive 2K-1C animals, MSC prevented additional increases in BP. AQP1, but not AQP2, was suppressed in the contralateral kidney, resulting in significant increase in urinary flow rate and sodium excretion. Gene expressions of sodium transporters were similar in both kidneys, suggesting that the high perfusing pressure in the contralateral kidney was responsible for increased natriuresis. Contralateral hypertensive kidney showed signs of renal deterioration with lower GFR in spite of normal RPF levels.

CONCLUSIONS

MSC treatment improved renal function and enhanced the ability of the contralateral kidney to excrete sodium through a tubular independent mechanism contributing to reduce SBP.

Diagnostic modalities in peripheral artery disease

Peripheral artery disease (PAD) affects approximately one in five persons older than 70 years of age and it is often present in patients with concomitant vascular disease in different body territories (e.g. coronary artery disease). Diagnosis at an early stage is important in order to achieve improvement in patient's symptoms and prognosis. Remarkable improvements in the field of noninvasive and invasive imaging techniques have led to an advanced level the management of patients with PAD. Throughout this review article, the clinically available diagnostic modalities in PAD are presented. Strong and weaker points are stressed out in a manner that elucidates that no perfect diagnostic method exists. Based on the patient's individual profile, as well as on certain aspects of the disease (e.g. morphology of carotid plaque lesions) the attending physician will ultimately decide which diagnostic path will lead to a prompt and correct diagnosis of PAD with the minimum amount of exams and risk for the patient.

[A high level of high-density lipoprotein cholesterol is a protective factor against transplant renal artery stenosis]

OBJECTIVE

To investigate the factors associated with the occurrence of transplant renal artery stenosis (TRAS).

METHODS

A retrospective analysis was conducted in 26 recipients who developed TRAS and 40 concurrent renal recipients without TRAS. We also conducted a nested case-control study in 14 patients with TRAS (TRAS-SD group) and another 14 non-TRAS recipients who received the allograft from the same donor (non-TRAS-SD group).

RESULTS

Compared with those in the concurrent recipients without TRAS, acute rejection (AR) occurred at a significantly higher incidence (P=0.004) and the warm ischemia time (WIT) was significantly longer (P=0.015) and the level of high?density lipoprotein cholesterol (HDL--C) significantly lower (P=0.009) in the recipients with TRAS. Logistic regression analysis suggested that AR (P=0.007) and prolonged WIT (P=0.046) were risk factors of TRAS while HDL-C (P=0.022) was the protective factor against TRAS. In recent years early diagnosis of TRAS had been made in increasing cases, the interval from transplantation to TRAS diagnosis became shortened steadily, and the recipients tended to have higher estimated glomerular filtration rate at the time of TRAS diagnosis.

CONCLUSION

Apart from the surgical technique, AR and prolonged WIT are also risk factors of TRAS while a high HDL-C level is the protective factor against TRAS. The improvement of the diagnostic accuracy by ultrasound is the primary factor contributing to the increased rate of early TRAS diagnosis in recent years.