Causes and consequences of increased sympathetic activity in renal disease

The impact of chronic kidney disease on prognosis in acute stroke: unraveling the pathophysiology and clinical complexity for optimal management

BACKGROUND

Chronic kidney disease (CKD) significantly increases stroke risk and severity, posing challenges in both acute management and long-term outcomes. CKD contributes to cerebrovascular pathology through systemic inflammation, oxidative stress, endothelial dysfunction, vascular calcification, impaired cerebral autoregulation, and a prothrombotic state, all of which exacerbate stroke risk and outcomes.

METHODS

This review synthesizes evidence from peer-reviewed literature to elucidate the pathophysiological mechanisms linking CKD and stroke. It evaluates the efficacy and safety of acute reperfusion therapies-intravenous thrombolysis and endovascular thrombectomy-in CKD patients with acute ischemic stroke. Considerations, such as renal function, drug dosage adjustments, and the risk of contrast-induced nephropathy, are critically analyzed. Evidence-based recommendations and research priorities are drawn from an analysis of current practices and existing knowledge gaps.

RESULTS

CKD influences stroke outcomes through systemic and local pathophysiological changes, necessitating tailored therapeutic approaches. Reperfusion therapies are effective in CKD patients but require careful monitoring of renal function to mitigate risks, such as contrast-induced nephropathy and thrombolytic complications. The bidirectional relationship between stroke and CKD highlights the need for integrated management strategies to address both conditions. Early detection and optimized management of CKD significantly reduce stroke-related morbidity and mortality.

CONCLUSION

Optimizing stroke care in CKD patients requires a comprehensive understanding of their pathophysiology and clinical management challenges. This article provides evidence-based recommendations, emphasizing individualized treatment decisions and coordinated care. It underscores the importance of integrating renal considerations into stroke treatment protocols and highlights the need for future research to refine therapeutic strategies, address knowledge gaps, and consider tailored interventions to improve outcomes and quality of life for this high-risk population.

Quercetin supplementation prevents kidney damage and improves long-term prognosis in hypertensive patients

Quercetin has shown potential antihypertensive-like activities in several studies. The present study aimed to test the effect of quercetin supplementation on kidney damage and long-term prognosis in hypertensive patients. The data of enrolled hypertensive patients were acquired from the NHANES dataset. The flavanol intake data was extracted from the FNDDS flavonoid database. Information regarding mortality was extracted from the NCHS. A total of 5801 hypertensive patients were included in this study. Preliminary analysis found that the total flavanols intake dosage was the independent influence factor of the kidney damage prevalence in hypertension, and it was found that only the quercetin supplementation was the protective factor for kidney damage after stratification analysis. For every 10 mg/d increase in quercetin intake, the kidney damage prevalence decreased by 8% [OR = 0.92, 95% CI: 0.85-0.99, p = 0.032]. The comprehensive analysis results suggested that hypertensive patients in the quercetin-high group had a lower kidney damage prevalence and a higher survival probability than those in the quercetin-low group. The urine microalbumin of hypertensive patients in the quercetin-high group was significantly lower than that of hypertensive patients in the quercetin-low group. In addition, at a median follow-up time of 122 months, the mortality decreased by 9% [HR = 0.91, 95% CI: 0.84-0.99, p = 0.031] for every 10 mg/d increase in quercetin intake. The findings suggested that high quercetin intake was associated with low kidney damage prevalence and high survival probability. Based on the existing evidence, promoting quercetin supplementation as a supplementary treatment for hypertensive patients was warranted.

Association between blood pressure variability and risk of kidney function decline in hypertensive patients without chronic kidney disease: a post hoc analysis of Systolic Blood Pressure Intervention Trial study

BACKGROUND

Blood pressure variability (BPV) is a risk factor for poor kidney function independent of blood pressure (BP) in chronic kidney disease (CKD). Little is known about the association between kidney function decline and BPV in hypertensive patients without CKD.

METHODS

A post-hoc analysis of the Systolic Blood Pressure Intervention Trial (SPRINT) was performed. BPV was measured as standard deviation (SD) and average real variability (ARV). Cox proportional hazard models were employed to explore the relationship between BPV and incident CKD and albuminuria.

RESULTS

A total of 5700 patients were included, with a mean age of 66.4 years old. During a median of 3.29 years follow-up, 150 (2.6%) patients developed CKD and 222 (7.2%) patients developed albuminuria. Patients were divided into four groups according to the quartiles of BPV. Compared with SBPV Q1, the incidence of CKD was higher in SBPV Q2-Q4; hazard ratios and 95% confidence interval were 1.81 (1.07-3.04), 1.85 (1.10-3.12) and 1.90 (1.13-3.19), respectively. The association between incident CKD and albuminuria with DBPV was less significant than SBPV. Similar results were found when measuring BPV as ARV and SD. No interaction was detected in BP-lowering strategy and SBPV on incident CKD and albuminuria ( P  > 0.05).

CONCLUSION

This study found that BPV was a risk factor for incident CKD and albuminuria in patients without CKD, especially SBPV. Although intensive BP control increased the risk of CKD, the association between SBPV and kidney function decline did not differ between the two treatment groups.

REGISTRATION

URL: https://clinicaltrials.gov/ , Unique identifier: NCT01206062.

Renalase: a novel regulator of cardiometabolic and renal diseases

Renalase is a ~38 kDa flavin-adenine dinucleotide (FAD) domain-containing protein that can function as a cytokine and an anomerase. It is emerging as a novel regulator of cardiometabolic diseases. Expressed mainly in the kidneys, renalase has been reported to have a hypotensive effect and may control blood pressure through regulation of sympathetic tone. Furthermore, genetic variations in the renalase gene, such as a functional missense polymorphism (Glu37Asp), have implications in the cardiovascular and renal systems and can potentially increase the risk of cardiometabolic disorders. Research on the physiological functions and biochemical actions of renalase over the years has indicated a role for renalase as one of the key proteins involved in various disease states, such as diabetes, impaired lipid metabolism, and cancer. Recent studies have identified three transcription factors (viz., Sp1, STAT3, and ZBP89) as key positive regulators in modulating the expression of the human renalase gene. Moreover, renalase is under the post-transcriptional regulation of two microRNAs (viz., miR-29b, and miR-146a), which downregulate renalase expression. While renalase supplementation may be useful for treating hypertension, inhibition of renalase signaling may be beneficial to patients with cancerous tumors. However, more incisive investigations are required to unravel the potential therapeutic applications of renalase. Based on the literature pertaining to the function and physiology of renalase, this review attempts to consolidate and comprehend the role of renalase in regulating cardiometabolic and renal disorders.

Obesity-Related Glomerulopathy: From Mechanism to Therapeutic Target

Obesity-related glomerulopathy (ORG) is a secondary glomerular disease caused by obesity, with clinical manifestations such as proteinuria and glomerulomegaly. Currently, the high incidence of obesity brings a change in the spectrum of kidney diseases across the globe, including China. ORG has become another important secondary nephropathy leading to end-stage renal disease (ESRD), and its incidence has increased significantly. This trend is bound to bring about a serious socioeconomic burden. Therefore, it is urgent to study its pathogenesis and intervention measures. Currently, the occurrence and development mechanisms in ORG are complicated by many factors, which are still unclear. In the past 20 years, with the continuous intensive research on mechanisms such as hypoxia in the metabolic process, immune inflammation, and pyroptosis, there have been new advances in the mechanism of ORG, especially the important role of inflammation in podocyte injury and its impact on the progress of ORG. Here, we briefly review the possible pathogenic role of the inflammasome in the podocyte damage in ORG and summarize the possible therapeutical strategies targeting inflammasome.

Noise-Induced Vascular Dysfunction, Oxidative Stress, and Inflammation Are Improved by Pharmacological Modulation of the NRF2/HO-1 Axis

Vascular oxidative stress, inflammation, and subsequent endothelial dysfunction are consequences of traditional cardiovascular risk factors, all of which contribute to cardiovascular disease. Environmental stressors, such as traffic noise and air pollution, may also facilitate the development and progression of cardiovascular and metabolic diseases. In our previous studies, we investigated the influence of aircraft noise exposure on molecular mechanisms, identifying oxidative stress and inflammation as central players in mediating vascular function. The present study investigates the role of heme oxygenase-1 (HO-1) as an antioxidant response preventing vascular consequences following exposure to aircraft noise. C57BL/6J mice were treated with the HO-1 inducer hemin (25 mg/kg i.p.) or the NRF2 activator dimethyl fumarate (DMF, 20 mg/kg p.o.). During therapy, the animals were exposed to noise at a maximum sound pressure level of 85 dB(A) and a mean sound pressure level of 72 dB(A). Our data showed a marked protective effect of both treatments on animals exposed to noise for 4 days by normalization of arterial hypertension and vascular dysfunction in the noise-exposed groups. We observed a partial normalization of noise-triggered oxidative stress and inflammation by hemin and DMF therapy, which was associated with HO-1 induction. The present study identifies possible new targets for the mitigation of the adverse health effects caused by environmental noise exposure. Since natural dietary constituents can achieve HO-1 and NRF2 induction, these pathways represent promising targets for preventive measures.

Capillary Rarefaction in Obesity and Metabolic Diseases-Organ-Specificity and Possible Mechanisms

Obesity and its comorbidities like diabetes, hypertension and other cardiovascular disorders are the leading causes of death and disability worldwide. Metabolic diseases cause vascular dysfunction and loss of capillaries termed capillary rarefaction. Interestingly, obesity seems to affect capillary beds in an organ-specific manner, causing morphological and functional changes in some tissues but not in others. Accordingly, treatment strategies targeting capillary rarefaction result in distinct outcomes depending on the organ. In recent years, organ-specific vasculature and endothelial heterogeneity have been in the spotlight in the field of vascular biology since specialized vascular systems have been shown to contribute to organ function by secreting varying autocrine and paracrine factors and by providing niches for stem cells. This review summarizes the recent literature covering studies on organ-specific capillary rarefaction observed in obesity and metabolic diseases and explores the underlying mechanisms, with multiple modes of action proposed. It also provides a glimpse of the reported therapeutic perspectives targeting capillary rarefaction. Further studies should address the reasons for such organ-specificity of capillary rarefaction, investigate strategies for its prevention and reversibility and examine potential signaling pathways that can be exploited to target it.

Sympathetic Hyperactivity—A Hidden Enemy in Chronic Kidney Disease Patients

Chronic kidney disease is often characterized by the presence of sympathetic hyperactivity. The aim of this brief review is to summarize available knowledge on the pathogenesis of sympathetic hyperactivity and to discuss its clinical relevance, the consequences of this knowledge for the choice of treatment, and the yet unresolved issues.

The effect of osteopathic manual therapy with breathing retraining on cardiac autonomic measures and breathing symptoms scores: A randomised wait-list controlled trial

BACKGROUND

Breathing retraining and manual therapy (MT), delivered independently or together, influence autonomic activity, and improve symptoms in patients with chronic conditions. This study evaluated the effects of breathing retraining and osteopathic MT on cardiac autonomic measures and breathing symptoms during spontaneous breathing in healthy active adults.

METHODS

Participants (n = 18) received breathing retraining and four, weekly manual therapy sessions, randomised to start immediately, or after 6-week delay. Heart-rate (HR) variability was assessed as a 7-day average of waking 6-min electrocardiograms, using time (logarithm of root-mean-square of successive differences; LnRMSSD) and frequency domain (logarithm of high-frequency; LnHF) measures. Recordings were taken before, one week following intervention or delay, and then following the later intervention for those with delayed starts. Changes were compared between those who received and had yet to receive the intervention, and before and after treatment for the whole cohort.

RESULTS

Following the intervention, HR-variability measures increased 4% overall (Effect Sizes: 1.0-1.1) for the whole cohort. Between-group analyses showed that the immediate-start group increased more than the delayed start group: LnRMSSD 0.27 (0.02-0.52; 95%CI) ln.ms, and LnHF 0.41 (-0.01-0.84) ln.ms² for immediate start; compared with LnRMSSD -0.09 (-0.29-0.11) ln.ms, and LnHF -0.19 (-0.59-0.22) ln.ms² (P = 0.02-0.03 for interaction) for delayed start. Resting HR decreased following intervention in the whole cohort (Effect Size -0.8; P = 0.02).

CONCLUSION

A 6-week osteopathic treatment consisting of breathing retraining and MT is beneficial in raising HR-variability compared to no treatment, and may induce favourable (parasympathetic over sympathetic) autonomic modulation.

TRIAL REGISTRATION

ACTRN12614001119684.

Range of adiposity and cardiorenal syndrome

Obesity and obesity-related co-morbidities, diabetes mellitus, and hypertension are among the fastest-growing risk factors of heart failure and kidney disease worldwide. Obesity, which is not a unitary concept, or a static process, ranges from alterations in distribution to the amount of adiposity. Visceral adiposity, which includes intraabdominal visceral fat mass and ectopic fat deposition such as hepatic, cardiac, or renal, was robustly associated with a greater risk for cardiorenal morbidity than subcutaneous adiposity. In addition, morbid obesity has also demonstrated a negative effect on cardiac and renal functioning. The mechanisms by which adipose tissue is linked with the cardiorenal syndrome (CRS) are hemodynamic and mechanical changes, as well neurohumoral pathways such as insulin resistance, endothelial dysfunction, nitric oxide bioavailability, renin-angiotensin-aldosterone, oxidative stress, sympathetic nervous systems, natriuretic peptides, adipokines and inflammation. Adiposity and other associated co-morbidities induce adverse cardiac remodeling and interstitial fibrosis. Heart failure with preserved ejection fraction has been associated with obesity-related functional and structural abnormalities. Obesity might also impair kidney function through hyperfiltration, increased glomerular capillary wall tension, and podocyte dysfunction, which leads to tubulointerstitial fibrosis and loss of nephrons and, finally, chronic kidney disease. The development of new treatments with renal and cardiac effects in the context of type 2 diabetes, which improves mortality outcome, has highlighted the importance of CRS and its prevalence. Increased body fat triggers cellular, neuro-humoral and metabolic pathways, which create a phenotype of the CRS with specific cellular and biochemical biomarkers. Obesity has become a single cardiorenal umbrella or type of cardiorenal metabolic syndrome. This review article provides a clinical overview of the available data on the relationship between a range of adiposity and CRS, the support for obesity as a single cardiorenal umbrella, and the most relevant studies on the recent therapeutic approaches.

Baseline High Blood Pressure is Associated with Clinico-Pathologic Findings and Later Renal Progression in Chronic Glomerulonephritis

Background

Several factors had been suggested to contribute to the development of hypertension in chronic glomerulonephritis (GN). This study was conducted to find the association of baseline blood pressure (BP) with pathophysiologic findings and later renal progression in chronic GN.

Methods

Clinico-pathological findings including serum creatinine (Cr), proteinuria, pathological findings, and urinary Na excretion were analyzed in a total of 233 patients with IgA nephropathy from The Kyung-Hee Cohort of GN. Glomerular surface area (GSA) was measured by imaging analysis and urine angiotensinogen (AGT) concentrations by human ELISA kits.

Results

Systolic BP was ≥130mmHg in 124 patients (53%). Systolic BP was negatively correlated with follow-up eGFR (r=−0.32, p<0.0001) and positively serum uric acid concentrations, while it had no significant relationships with initial serum Cr and eGFR. As compared with patients with systolic BP<130 mmHg, those with ≥130 mmHg were older and showed higher serum Cr, proteinuria, 24 hr urinary Na excretion, mean GSA, and T-I fibrosis, lower follow-up eGFR, and steeper decline in slope of eGFR. The results in patients with normal serum Cr concentrations were comparable to those in whole group. Systolic BP was positively correlated with age, baseline and follow-up proteinuria, serum uric acid concentrations and IgM deposit and negatively with follow-up eGFR. In subgroup analysis, systolic BP was also positively correlated with mean GSA and urinary AGT concentrations.

Conclusion

This study showed that baseline systolic BP is related to urinary Na excretion, glomerulomegaly, T-I fibrosis and later renal progression in patients with IgA nephropathy.

Neural control of cardiovascular function in black adults: implications for racial differences in autonomic regulation

Black adults are at increased risk for developing hypertension and cardiovascular and chronic kidney disease and have greater associated morbidity/mortality than white adults who are otherwise demographically similar. Despite the key role of the autonomic nervous system in the regulation of cardiovascular function, the mechanistic contributions of sympathetic nerves to racial differences in cardiovascular dysfunction and disease remain poorly understood. In this review, we present an update and synthesis of current understanding regarding the roles of autonomic neural mechanisms in normal and pathophysiological cardiovascular control in black and white adults. At rest, many hemodynamic and autonomic variables, including blood pressure, cardiac output, and sympathetic nerve activity, are similar in healthy black and white adults. However, resting sympathetic vascular transduction and carotid baroreflex responses are altered in ways that tend to promote increased vasoconstriction and higher blood pressure, even in healthy, normotensive black adults. Acute sympathoexcitatory maneuvers, including exercise and cold pressor test, often result in augmented sympathetic and hemodynamic responses in healthy black adults. Clinically, although mechanistic evidence is scarce in this area, existing data support the idea that excessive sympathetic activation and/or transduction into peripheral vasoconstriction contribute importantly to the pathophysiology of hypertension and chronic kidney disease in black compared with white adults. Important areas for future work include more detailed study of sympathetic and hemodynamic reactivity to exercise and other stressors in male and female black adults and, particularly, sympathetic control of renal function, an important area of clinical concern in black patients.

Association Between Systolic and Diastolic Blood Pressure Variability and the Risk of End-Stage Renal Disease

Recent data suggest that visit-to-visit variability of blood pressure (BP) is associated with cardiovascular events. We evaluated the role of BP variability as a determinant of end-stage renal disease (ESRD). Using nationally representative data from the Korean National Health Insurance System, 8 199 089 subjects had been enrolled during 2009 to 2010 who were free of ESRD and underwent ≥3 health examinations during 2005 to 2010 were followed to the end of 2017. BP variability was measured using the coefficient of variation, SD, and variability independent of the mean. The primary outcome was the development of ESRD, defined as a combination of the relevant disease code and the initiation of renal replacement therapy. The χ² test, t test, and log-rank test were used in the statistical analysis. There were 16 567 cases of ESRD during a median follow-up of 7.89±0.88 years. The highest quartile of systolic or diastolic BP showed a higher incident rate of ESRD compared with the other 3 quartiles. It was augmented in patients with the highest quartile of both systolic and diastolic BP variabilities. Among patients with the highest quartile of systolic and diastolic BP variabilities, the uncontrolled hypertension group (>140/90 mm Hg) taking antihypertensive medication showed the highest incidence rate of ESRD. These results were consistent when modeling variability of BP using coefficient of variation, SD, and variability independent of the mean and in various sensitivity analyses. Systolic and diastolic BP variabilities were independently associated with an increased incidence of ESRD, and it was augmented when both variabilities were present together.

The Effects of Breviscapine Injection on Hypertension in Hypertension-Induced Renal Damage Patients: A Systematic Review and a Meta-Analysis

Background: Breviscapine (Dengzhanhua) injection has been wildly used in clinical treatment for cerebral infarction, cardiovascular disease, diabetic nephropathy, renal impairment of essential hypertension and stroke in China. Breviscapine injection and antihypertensive drugs combination therapy is supposed to be beneficial for hypertension-induced renal damage patients.

Objectives: To evaluate the beneficial and adverse effects of breviscapine injection on hypertension in hypertension-induced renal damage patients, an extensive meta-analysis was performed.

Methods: We searched PubMed, the Cochrane Library, Embase, CNKI, Sino Med, VIP, and Wanfang Data for relevant literature. The timeframe of retrieval was set from the founding date of each database to September 28, 2018.

Results: Fourteen papers were included in this study. The quality of all the studies included was determined to be low. All studies were conducted with Chinese populations. Meta-analysis showed that, compared with single-use antihypertensive drugs, using breviscapine injection in combination with antihypertensive drugs to treat hypertension in hypertension-induced renal damage patients can reduce 24-h urinary total protein (24 h UTP) [WMD = −0.04, 95% CI (−0.05, −0.02), P ≤ 0.001], but does not lower systolic blood pressure (SBP) [WMD = −1.02, 95% CI (−2.88, 0.84), P = 0.281] or diastolic blood pressure (DBP) [WMD = −0.21, 95% CI (−1.71, 1.29), P = 0.786] more effectively. There was also no statistically significant difference in adverse events between experimental groups and control groups.

Conclusion: Breviscapine injection, in combination with antihypertensive drugs, appears to be more effective in improving the 24 h UTP, but overall have no effect on improving the blood pressure in hypertension-induced renal damage patients. Moderate dose of breviscapine injection (10 ml) may have effects on reducing blood pressure in hypertension-induced renal damage patients but high doses of breviscapine injection (20 ml) may increase blood pressure by subgroup analysis. However, the evidence of methodological quality and sample sizes is weak, and thus, further standardized research is required.

Combined Therapy of Hypertensive Nephropathy with Breviscapine Injection and Antihypertensive Drugs: A Systematic Review and a Meta-Analysis

Objective

To evaluate the beneficial and adverse effects of breviscapine injection in combination with antihypertensive drugs for treating hypertensive nephropathy in clinical practice.

Methods

We searched PubMed, the Cochrane Library, Embase, CNKI, Sino Med, VIP, and Wanfang Data for relevant literature. The timeframe of retrieval was set from the founding date of each database to September 28, 2018.

Results

Fourteen papers were included in this study. The quality of all the studies included was determined to be low. All studies were conducted with Chinese populations. Meta-analysis showed that, compared with single-use antihypertensive drugs, using breviscapine injection in combination with antihypertensive drugs to treat hypertensive nephropathy can reduce serum creatinine (Scr) [WMD = –35.16, 95% CI(–50.01, –20.31), P ≤ 0.001], blood urea nitrogen (BUN) [WMD = –2.00, 95% CI(–3.07, –0.94), P ≤ 0.001], 24-hour urinary total protein (24 h UTP) [WMD = –0.04, 95% CI(–0.05, –0.02), P ≤ 0.001], and the beta-2-microglobulin (B2M) [WMD = –0.09, 95% CI(–0.11, –0.07), P ≤ 0.001], improve creatinine clearance rate (Ccr) [WMD = 7.84, 95% CI(5.20, 10.49), P ≤ 0.001], and increase the clinical efficacy [RR = 1.27, 95% CI(1.05, 1.53), P = 0.014], but does not lower systolic blood pressure (SBP) [WMD = –1.02, 95% CI(–2.88, 0.84), P = 0.281]. There was no significant difference in adverse events between experimental groups and control groups.

Conclusion

Breviscapine injection in combination with antihypertensive drugs can improve clinical efficacy and Ccr and reduce Scr, BUN, 24 h UTP, and B2M in patients with hypertensive nephropathy. The present meta-analysis indicated that breviscapine injection can serve as a renal protective effect to patients with hypertensive nephropathy. However, the evidence of methodological quality and sample sizes is weak, and thus, further standardized research is required.

Sympathetic overactivity in dialysis patients-Underappreciated and clinically consequential

Cardiovascular morbidity and mortality remain frustratingly common in dialysis patients. A dearth of established evidence-based treatment calls for alternative therapeutic avenues to be embraced. Sympathetic hyperactivity, predominantly due to afferent nerve signaling from the diseased native kidneys, has been established to be prognostic in the dialysis population for over 15 years. Despite this, tangible therapeutic interventions have, to date, been unsuccessful and the outlook for patients remains poor. This narrative review summarizes established experimental and clinical data, highlighting recent developments, and proposes why interventions to ameliorate sympathetic hyperactivity may well be beneficial for this high-risk population.

Hypertensive emergencies in diabetic patients from predominantly African American urban communities

Aim: The aim of this study was to identify risk factors for hypertensive emergencies in diabetic patients presenting with severely elevated blood pressure. Methods: Using electronic medical records, this study identified diabetic patients with hypertensive crisis who presented to the emergency department of Newark Beth Israel Medical Center, Newark, NJ from June 2013 to May 2016. Diabetic patients with hypertensive emergencies were compared with non-diabetic patients based on important demographic and clinical characteristics. Results: Patients with diabetes accounted for 52.27% of all hypertensive emergencies during the study period. There were 264 diabetic patients with hypertensive emergencies and 519 diabetic patients with hypertensive urgencies. The majority of patients were African Americans (88.6%). The odds of hypertensive emergencies were strikingly higher in diabetic patients with hyperlipidemia (OR 1.66, 95% CI 1.23-2.24), coronary artery disease (OR 2.95, 95% CI 2.15-4.05), congestive heart failure (OR 6.28, 95% CI 4.49-8.80), renal insufficiency (OR 2.84, 95% CI 2.10-3.86) and low hemoglobin (OR 0.9, 95% CI 0.84-0.97). Acute or worsening heart failure was the most frequent acute target organ injury (49.6%) followed by non-ST elevation myocardial infarction (41.7%). Diabetic and non-diabetic patients had similar rates of target organ injuries. Conclusion: The development of hypertensive emergencies in patients with diabetes was not because of diabetes per se but because of coexisting highly elevated blood pressure. Tight blood pressure control may decrease the risk of hypertensive emergencies in this patient population.

Endovascular Baroreflex Amplification for Resistant Hypertension

Purpose of review

Most hypertension devices have been designed to interrupt or modify the sympathetic nervous system, which seems to be unbalanced in hypertension. Carotid baroreceptors play a pivotal role in maintaining adrenergic balance via a direct feedback interface and would be an exceptional target for intervention. The purpose of this review is to define the role of the baroreceptor in hypertension, to examine device-based therapies targeting the baroreflex and to explore future promises of endovascular baroreflex amplification (EBA).

Recent findings

In the last two decades, two therapeutic strategies targeting the carotid baroreceptor have evolved: baroreflex activation therapy (BAT) and EBA. Both therapies enhance baroreceptor activity, either directly by electrical stimulation or indirectly by changing the geometric shape of the carotid sinus and increasing pulsatile wall strain.

Summary

By showing a significant, sympathetic inhibition-mediated effect on blood pressure, BAT has laid the foundation for baroreflex-targeting therapies for resistant hypertension. EBA is a less invasive therapy with promising first-in-man study results. Ongoing randomized sham-controlled trials are needed to better understand efficacy, durability, and long-term safety and define phenotypes that may most benefit from this treatment.

Electronic supplementary material

The online version of this article (10.1007/s11906-018-0840-8) contains supplementary material, which is available to authorized users.

Heart Rate Variability and Its Relation to Chronic Kidney Disease: Results From the PREVEND Study

OBJECTIVE

In the general population, reduced heart rate variability (HRV) has been associated with cardiovascular disease. However, its relation to chronic kidney disease (CKD) is debated. We therefore investigated the relation between low HRV and renal outcomes.

METHODS

In the population-based Prevention of REnal and Vascular ENdstage Disease study, renal outcomes (CKD, estimated glomerular filtration rate [eGFR], urinary albumin) were measured at baseline and three consecutive examinations. HRV measures (among which SDNN [standard deviation of normal-to-normal RR intervals]) were calculated from time series of beat-to-beat pulse wave recordings at baseline. The lowest (risk) quartile was compared with the upper three quartiles combined, in multivariable survival and linear mixed-effects analyses.

RESULTS

In 4605 participants (49% males, age range = 33-80, 0.6% blacks), we observed 341 new participants of CKD during a median follow-up duration of 7.4 years. Low SDNN was associated with higher incidence of CKD (crude HR = 1.66, 95% CI = 1.30 to 2.12, p < .001), but this association was no longer significant after adjustment for age, sex, and cardiovascular risk factors (adjusted HR = 1.13, 95% CI = 0.86 to 1.48, p = .40, similar for other HRV measures). No associations between SDNN and eGFR trajectories were found in the total sample. However, in a subgroup of participants with baseline CKD (n = 939), we found a significant association of low SDNN (but not other HRV measures) with lower baseline eGFR, even after multivariable adjustment (adjusted βlevel difference = -3.73 ml/min/1.73 m, 95% CI = -6.70 to -0.75, p = .014), but not with steeper eGFR decline.

CONCLUSIONS

These results suggest that reduced HRV may be a complication of CKD rather than a causal factor.

Multimodality Imaging in Patients with Secondary Hypertension: With a Focus on Appropriate Imaging Approaches Depending on the Etiologies

Although the causes of hypertension are usually unknown, about 10% of the cases occur secondary to specific etiologies, which are often treatable. Common categories of secondary hypertension include renal parenchymal disease, renovascular stenosis, vascular and endocrinologic disorders. For diseases involving the renal parenchyma and adrenal glands, ultrasonography (US), computed tomography (CT) or magnetic resonance (MR) imaging is recommended. For renovascular stenosis and vascular disorders, Doppler US, conventional or noninvasive (CT or MR) angiography is an appropriate modality. Nuclear imaging can be useful in the differential diagnosis of endocrine causes. Radiologists should understand the role of each imaging modality and its typical findings in various causes of secondary hypertension. This article focuses on appropriate imaging approaches in accordance with the categorized etiologies leading to hypertension.

Synergistical action of the β2 adrenoceptor and fatty acid binding protein 2 polymorphisms on the loss of glomerular filtration rate in Chinese patients with type 2 diabetic nephropathy

PURPOSE

Since altered sympathetic nerve activity and insulin resistance are implicated in the pathogenesis of type 2 diabetic nephropathy, we investigated the effect of polymorphic Arg16Gly and Gln27Glu in the β2 adrenoceptor gene and Ala54Thr in the fatty acid binding protein 2 gene on the estimated glomerular filtration rate (eGFR) in Chinese patients with the above disease.

METHODS

A total of 552 diabetic subjects recruited from annual health examinations were studied. The eGFR was calculated from the Modification of Diet in Renal Disease equation for the Chinese. Plasma norepinephrine level and genotype were determined by high-performance liquid chromatography-tandem mass spectrometry and TaqMan method, respectively. Holter-derived heart rate viability (HRV) and the MRI-generated renal apparent diffusion coefficient (ADC) were evaluated.

RESULTS

The Gly16Gly and Thr54Thr homozygotes had significantly higher microalbuminuria and lower eGFR against other genotypes in their individual polymorphism. Besides, the Gly16Gly variant exhibited markedly elevated norepinephrine level, whereas indicative of insulin resistance was increased in the Thr54Thr one. Multiple linear regression analysis further confirmed the independent genetic effect on the eGFR. Moreover, multifactor dimensionality reduction method detected a gene-gene synergistic action that subjects with the Gly16Gly/Thr54Thr genotype were exposed to higher risk of eGFR loss. Finally, these findings were accompanied by lower HRV and ADC, indicating sympathetically mediated hemodynamic changes.

CONCLUSIONS

By uncovering the genetic component of the coherent interplay between the elevated sympathetic nerve activity and metabolic disorders, our observations might promote the development of novel personalized prevention and management strategies against the diabetic nephropathy, especially in the genetically susceptible individuals.

Differential gene and lncRNA expression in the lower thoracic spinal cord following ischemia/reperfusion-induced acute kidney injury in rats

We used high-throughput RNA sequencing to analyze differential gene and lncRNA expression patterns in the lower thoracic spinal cord during ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) in rats. We observed that of 32662 mRNAs, 4296 out were differentially expressed in the T8-12 segments of the spinal cord upon I/R-induced AKI. Among these, 62 were upregulated and 34 were downregulated in response to I/R (FDR < 0.05, |log₂FC| > 1). Further, 52 differentially expressed lncRNAs (35 upregulated and 17 downregulated) were identified among 3849 lncRNA transcripts. The differentially expressed mRNAs were annotated as “biological process,” “cellular components” and “molecular functions” through gene ontology enrichment analysis. KEGG pathway enrichment analysis showed that cell cycle and renin-angiotensin pathways were upregulated in response to I/R, while protein digestion and absorption, hedgehog, neurotrophin, MAPK, and PI3K-Akt signaling were downregulated. The RNA-seq data was validated by qRT-PCR and western blot analyses of select mRNAs and lncRNAs. We observed that Bax, Caspase-3 and phospho-AKT were upregulated and Bcl-2 was downregulated in the spinal cord in response to renal injury. We also found negative correlations between three lncRNAs (TCONS_00042175, TCONS_00058568 and TCONS_00047728) and the degree of renal injury. These findings provide evidence for differential expression of lncRNAs and mRNAs in the lower thoracic spinal cord following I/R-induced AKI in rats and suggest potential clinical applicability.

Hyponatremia is Associated with Fluid Imbalance and Adverse Renal Outcome in Chronic Kidney Disease Patients Treated with Diuretics

Chronic kidney disease (CKD) is frequently complicated with hyponatremia, probably because of fluid overload or diuretic usage. Hyponatremia in CKD population is associated with increased mortality, but the effect on renal outcome was unknown. We investigated whether hyponatremia is associated with fluid status and is a prognostic indicator for adverse outcomes in a CKD cohort of 4,766 patients with 1,009 diuretic users. We found that diuretic users had worse clinical outcomes compared with diuretic non-users. Hyponatremia (serum sodium <135 mEq/L) was associated with excessive volume and volume depletion, measured as total body water by bioimpedance analysis, in diuretic users, but not in diuretic non-users. Furthermore, in Cox survival analysis, hyponatremia was associated with an increased risk for renal replacement therapy (hazard ratio, 1.45; 95% CI, 1.13-1.85, P < 0.05) in diuretic users, but not in diuretic non-users (P for interaction <0.05); restricted cubic spline model also showed a similar result. Hyponatremia was not associated with all-cause mortality or cardiovascular event whereas hypernatremia (serum sodium >141 mEq/L) was associated with an increased risk for all-cause mortality. Thus, hyponatremia is an indicator of fluid imbalance and also a prognostic factor for renal replacement therapy in CKD patients treated with diuretics.

Role of the Renal Microcirculation in Progression of Chronic Kidney Injury in Obesity

BACKGROUND

Obesity is largely responsible for the growing incidence and prevalence of diabetes, cardiovascular and renal diseases. Current strategies to prevent and treat obesity and its consequences have been insufficient to reverse the ongoing trends. Lifestyle modification or pharmacological therapies often produce modest weight loss which is not sustained and recurrence of obesity is frequently observed, leading to progression of target organ damage in many obese subjects. Therefore, research efforts have focused not only on the factors that regulate energy balance, but also on understanding mechanisms of target organ injury in obesity. Summary and Key Message: Microvascular (MV) disease plays a pivotal role in progressive kidney injury from different etiologies such as hypertension, diabetes, and atherosclerosis, which are all important consequences of chronic obesity. The MV networks are anatomical units that are closely adapted to specific functions of nutrition and removal of waste in every organ. Damage of the small vessels in several tissues and organs has been reported in obesity and may increase cardio-renal risk. However, the mechanisms by which obesity and its attendant cardiovascular and metabolic consequences interact to cause renal MV injury and chronic kidney disease are still unclear, although substantial progress has been made in recent years. This review addresses potential mechanisms and consequences of obesity-induced renal MV injury as well as current treatments that may provide protection of the renal microcirculation and slow progressive kidney injury in obesity.

Increased Blood Pressure Variability Prior to Chronic Kidney Disease Exacerbates Renal Dysfunction in Rats

Increased blood pressure variability (BPV), which can be experimentally induced by sinoaortic denervation (SAD), has emerged as a new marker of the prognosis of cardiovascular and renal outcomes. Considering that increased BPV can lead to organ-damage, the goal of the present study was to evaluate the effects of SAD on renal function in an experimental model of chronic kidney disease (CKD). SAD was performed in male Wistar rats 2 weeks before 5/6 nephrectomy and the animals were evaluated 4 weeks after the induction of CKD. Our data demonstrated that BPV was increased in SAD and CKD animals and that the combination of both conditions (SAD+CKD) exacerbated BPV. The baroreflex sensitivity index was diminished in the SAD and CKD groups; this reduction was more pronounced when SAD and CKD were performed together. 5/6 nephrectomy led to hypertension, which was higher in SAD+CKD animals. Regarding renal function, the combination of SAD and CKD resulted in reduced renal plasma and blood flow, increased renal vascular resistance and augmented uraemia when compared to CKD animals. Glomerular filtration rate and BPV were negatively correlated in SAD, CKD, and SAD+CKD animals. Moreover, SAD+CKD animals presented a higher level of glomerulosclerosis when compared to all other groups. Cardiac and renal hypertrophy, as well as oxidative stress, was also further increased when SAD and CKD were combined. These results show that SAD prior to 5/6 nephrectomy exacerbates renal dysfunction, suggesting that previous augmented BPV should be considered as an important factor to the progression of renal diseases.

Brain natriuretic peptide as a potential novel marker of salt-sensitivity in chronic kidney disease patients without cardiac dysfunction

Although the renin-angiotensin system (RAS) is counter-balanced by a salt-sensitive mechanism in the hypertensive state, both are reported to be up-regulated in chronic kidney disease (CKD) patients. We conducted this study to evaluate the associations among the RAS, renal function, hypertension, and atherosclerosis, as well as to identify markers for salt-sensitivity. A total of 213 pre-dialysis CKD patients with preserved cardiac function (EF >50 %) were enrolled. Their renal and cardiac biochemical markers and plasma renin activity (PRA) were measured, and echocardiography and carotid artery ultrasound were performed. Their salt intake was estimated by the NaCl excretion from a 24-h collected urine sample. The PRA was higher in patients with hypertension (p = 0.018), and had a significant negative correlation with the eGFR (r = -0.23, p = 0.0067). Importantly, the PRA had a strong negative correlation with the brain natriuretic peptide (BNP) level (r = -0.28, p = 0.017) regardless of whether the patients were being treated with RAS inhibitors. The BNP level was related to the renal functions (eGFR: p = 0.001, ACR: p = 0.009). There was a significant positive correlation between the BNP level and carotid intima-media thickness (p < 0.001). A multivariate analysis revealed that older age and an excess of NaCl excretion were independent predictors of BNP elevation (p = 0.02 and 0.003, respectively). Our analysis revealed details of the counterbalance between BNP and PRA, as well as identifying that excess salt intake is a predictor of BNP elevation. These results indicate that the BNP could be a possible valuable marker for salt sensitivity, and that high salt sensitivity could facilitate atherosclerosis in CKD patients.

Chronic Kidney Disease As a Potential Indication for Renal Denervation

Renal denervation is being used as a blood pressure lowering therapy for patients with apparent treatment resistant hypertension. However, this population does not represent a distinct disease condition in which benefit is predictable. In fact, the wide range in effectiveness of renal denervation could be a consequence of this heterogeneous pathogenesis of hypertension. Since renal denervation aims at disrupting sympathetic nerves surrounding the renal arteries, it seems obvious to focus on patients with increased afferent and/or efferent renal sympathetic nerve activity. In this review will be argued, from both a pathophysiological and a clinical point of view, that chronic kidney disease is particularly suited to renal denervation.

The blood pressure-lowering effect of renal denervation is inversely related to kidney function

OBJECTIVES

In renal denervation (RDN), a wide range in the blood pressure (BP)-lowering effect has been reported. On the basis of the current knowledge of pathophysiology, we hypothesized that the BP-lowering effect of RDN would be inversely related to kidney function. Second, we investigated whether direct and indirect variables of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) would be related as well.

METHODS

Sixty-seven patients from a prospective cohort of patients treated with RDN with completed 6 months follow-up were included. Data collected during routine standardized work-up before RDN were used: 24-h urine excretion of creatinine, albumin, sodium and catecholamines, plasma creatinine, renin activity and aldosterone, ambulatory BP-monitoring and a captopril challenge test. When considered well tolerated, antihypertensive drugs were stopped before these investigations.

RESULTS

The BP-lowering was inversely related to estimated glomerular filtration rate (eGFR) in patients who stopped antihypertensive drugs prior to testing (ß: 0.46, P = 0.013). There was a positive relation between SBP at baseline and the BP-lowering effect of RDN (ß:-0.55 mmHg per mmHg, P < 0.001). Parameters related to the rennin-angiotensin system (aldosterone, captopril test) and the sympathetic nervous system (dipping pattern and catecholamines in urine) positively related to the BP-lowering effect of RDN.

CONCLUSION

The present explorative study shows an inverse relation between the BP-lowering effect of RDN and eGFR. Second, we found relations between variables of the RAAS and SNS with the BP-lowering effect of RDN. The data complement current concepts on pathophysiology of sympathetic hyperactivity and hypertension and may give some insight in the wide range of the effect of RDN.

Hypertension in Chronic Glomerulonephritis

Chronic glomerulonephritis (GN), which includes focal segmental glomerulosclerosis and proliferative forms of GN such as IgA nephropathy, increases the risk of hypertension. Hypertension in chronic GN is primarily volume dependent, and this increase in blood volume is not related to the deterioration of renal function. Patients with chronic GN become salt sensitive as renal damage including arteriolosclerosis progresses and the consequent renal ischemia causes the stimulation of the intrarenal renin-angiotensin-aldosterone system(RAAS). Overactivity of the sympathetic nervous system also contributes to hypertension in chronic GN. According to the KDIGO guideline, the available evidence indicates that the target BP should be ≤140mmHg systolic and ≤90mmHg diastolic in chronic kidney disease patients without albuminuria. In most patients with an albumin excretion rate of ≥30mg/24 h (i.e., those with both micro-and macroalbuminuria), a lower target of ≤130mmHg systolic and ≤80mmHg diastolic is suggested. The use of agents that block the RAAS system is recommended or suggested in all patients with an albumin excretion rate of ≥30mg/ 24 h. The combination of a RAAS blockade with a calcium channel blocker and a diuretic may be effective in attaining the target BP, and in reducing the amount of urinary protein excretion in patients with chronic GN.

Technical aspects of renal denervation in end-stage renal disease patients with challenging anatomy

We describe our preliminary experience with percutaneous renal denervation in end-stage renal disease patients with resistant hypertension and challenging anatomy, in terms of the feasibility, safety, and efficacy of this procedure. Four patients with end-stage renal disease patients with resistant hypertension (mean hemodialysis time, 2.3 years) who had been taking at least four antihypertensive medications underwent percutaneous renal denervation. Renal artery eligibility included the absence of prior renal artery interventions, vessel stenosis <70%, or extended calcifications (more than 30% of the vessel circumference). No cut off values of vessel diameter were used. All patients were successfully treated with no intra- or postprocedural complications, and all showed 24-hour ambulatory blood pressure reduction at the 12-month follow-up. Percutaneous renal denervation is a feasible approach for end-stage renal disease patients with resistant hypertension with encouraging short-term preliminary results in terms of procedural efficacy and safety.

Heart Rate Variability Correlates to Functional Aerobic Impairment in Hemodialysis Patients

Background

Autonomic dysfunction (AD) is highly prevalent in hemodialysis (HD) patients and has been implicated in their increased risk of cardiovascular mortality.

Objective

To correlate heart rate variability (HRV) during exercise treadmill test (ETT) with the values obtained when measuring functional aerobic impairment (FAI) in HD patients and controls.

Methods

Cross-sectional study involving HD patients and a control group. Clinical examination, blood sampling, transthoracic echocardiogram, 24-hour Holter, and ETT were performed. A symptom-limited ramp treadmill protocol with active recovery was employed. Heart rate variability was evaluated in time domain at exercise and recovery periods.

Results

Forty-one HD patients and 41 controls concluded the study. HD patients had higher FAI and lower HRV than controls (p<0.001 for both). A correlation was found between exercise HRV (SDNN) and FAI in both groups. This association was independent of age, sex, smoking, body mass index, diabetes, and clonidine or beta-blocker use, but not of hemoglobin levels.

Conclusion

No association was found between FAI and HRV on 24-hour Holter or at the recovery period of ETT. Of note, exercise HRV was inversely correlated with FAI in HD patients and controls.

Detection of autonomic dysfunction in hemodialysis patients using the exercise treadmill test: the role of the chronotropic index, heart rate recovery, and R-R variability

OBJECTIVE

To evaluate the ability of different parameters of exercise treadmill test to detect autonomic dysfunction in hemodialysis patients.

METHODS

Cross-sectional study involving hemodialysis patients and a control group. Clinical examination, blood sampling, echocardiogram, 24-hour Holter, and exercise treadmill test were performed. A ramp treadmill protocol symptom-limited with active recovery was employed.

RESULTS

Forty-one hemodialysis patients and 41 controls concluded the study. There was significant difference between hemodialysis patients and controls in autonomic function parameters in 24h-Holter and exercise treadmill test. Probability of having autonomic dysfunction in hemodialysis patients compared to controls was 29.7 at the exercise treadmill test and 13.0 in the 24-hour Holter. Chronotropic index, heart rate recovery at the 1st min, and SDNN at exercise were used to develop an autonomic dysfunction score to grade autonomic dysfunction, in which, 83% of hemodialysis patients reached a scoring ≥2 in contrast to 20% of controls. Hemodialysis was independently associated with either altered chronotropic index or autonomic dysfunction scoring ≥2 in every tested model (OR=50.1, P=0.003; and OR=270.9, P=0.002, respectively, model 5).

CONCLUSION

The exercise treadmill test was feasible and useful to diagnose of the autonomic dysfunction in hemodialysis patients. Chronotropic index and autonomic dysfunction scoring ≥2 were the most effective parameters to differentiate between hemodialysis patients and controls suggesting that these variables portrays the best ability to detect autonomic dysfunction in this setting.

Cardiac autonomic dysfunction is associated with high-risk albumin-to-creatinine ratio in young adolescents with type 1 diabetes in AdDIT (adolescent type 1 diabetes cardio-renal interventional trial)

OBJECTIVE

This study examined the association between cardiac autonomic dysfunction and high albumin-to-creatinine ratio (ACR) in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Adolescents recruited as part of a multicenter screening study (n = 445, 49% female, aged 10-17 years, mean duration 6.9 years; mean HbA1c 8.4%, 68 mmol/mol) underwent a 10-min continuous electrocardiogram recording for heart rate variability analysis. Time-domain heart rate variability measures included baseline heart rate, SD of the R-R interval (SDNN), and root mean squared difference of successive R-R intervals (RMSSD). Spectral analysis included sympathetic (low-frequency) and parasympathetic (high-frequency) components. Standardized ACR were calculated from six early morning urine collections using an established algorithm, reflecting age, sex, and duration, and stratified into ACR tertiles, where the upper tertile reflects higher nephropathy risk.

RESULTS

The upper-tertile ACR group had a faster heart rate (76 vs. 73 bpm; P < 0.01) and less heart rate variability (SDNN 68 vs. 76 ms, P = 0.02; RMSSD 63 vs. 71 ms, P = 0.04). HbA1c was 8.5% (69 mmol/mmol) in the upper tertile vs. 8.3% (67 mmol/mol) in the lower tertiles (P = 0.07). In multivariable analysis, upper-tertile ACR was associated with faster heart rate (β = 2.5, 95% CI 0.2-4.8, P = 0.03) and lower RMSSD (β = -9.5, 95% CI -18.2 to -0.8, P = 0.03), independent of age and HbA1c.

CONCLUSIONS

Adolescents at potentially higher risk for nephropathy show an adverse cardiac autonomic profile, indicating sympathetic overdrive, compared with the lower-risk group. Longitudinal follow-up of this cohort will further characterize the relationship between autonomic and renal dysfunction and the effect of interventions in this population.

The effect of abnormal birth history on ambulatory blood pressure and disease progression in children with chronic kidney disease

OBJECTIVE

To examine the associations between abnormal birth history (birth weight <2500 g, gestational age <36 weeks, or small for gestational age), blood pressure (BP), and renal function among 332 participants (97 with abnormal and 235 with normal birth history) in the Chronic Kidney Disease in Children Study, a cohort of children with chronic kidney disease (CKD).

STUDY DESIGN

Casual and 24-hour ambulatory BP were obtained. Glomerular filtration rate (GFR) was determined by iohexol disappearance. Confounders (birth and maternal characteristics, socioeconomic status) were used to generate predicted probabilities of abnormal birth history for propensity score matching. Weighted linear and logistic regression models with adjustment for quintiles of propensity scores and CKD diagnosis were used to assess the impact of birth history on BP and GFR.

RESULTS

Age at enrollment, percent with glomerular disease, and baseline GFR were similar between the groups. Those with abnormal birth history were more likely to be female, of Black race or Hispanic ethnicity, to have low household income, or part of a multiple birth. Unadjusted BP measurements, baseline GFR, and change in GFR did not differ significantly between the groups; no differences were seen after adjusting for confounders by propensity score matching.

CONCLUSIONS

Abnormal birth history does not appear to have exerted a significant influence on BP or GFR in this cohort of children with CKD. The absence of an observed association is likely secondary to the dominant effects of underlying CKD and its treatment.

Heart rate and blood pressure variability in children with chronic kidney disease: a report from the CKiD study

BACKGROUND

Autonomic nervous system dysfunction and sympathetic nervous system over-activity play important roles in the development of hypertension associated with chronic kidney disease (CKD). In adults, increased blood pressure variability (BPV) appears to be directly related to sympathetic over-activity with increased risk of end-organ damage and cardiovascular events. Decreased heart rate variability (HRV) has been observed in adults with CKD, and is an independent predictor of mortality.

METHODS

The purpose of this study was to evaluate BPV and HRV in pediatric patients enrolled in the Chronic Kidney Disease in Children Study. Ambulatory blood pressure monitoring data were available for analysis of 215 person-visits from 144 children that were not receiving antihypertensive medications.

RESULTS

BPV and HRV were determined by standard deviation and coefficient of variation for heart rate and systolic and diastolic blood pressure for each patient averaged for wake/sleep periods during 24-h monitoring. Uniformly lower values were displayed during sleep versus wake periods: BPV was 20 % lower during sleep (p < 0.001) and HRV was 30 % lower during sleep (p < 0.001). A significant increase in systolic BPV was observed in hypertensive children compared to children with normal blood pressure (6.9 %, p = 0.009). Increased diastolic BPV was detected among hypertensive children during sleep period compared to children with normal blood pressure (11.5 %, p = 0.008). There was a significant decrease in HRV in hypertensive compared to normotensive children (-8.2 %, p = 0.006).

CONCLUSIONS

These findings are similar to those in adult patients and may underscore childhood origin and natural progression of adverse cardiovascular outcomes in adults with CKD.

Cardiac autonomic neuropathy predicts renal function decline in patients with type 2 diabetes: a cohort study

AIMS/HYPOTHESIS

The aim of this work was to assess the impact of cardiac autonomic neuropathy (CAN) on the development and progression of chronic kidney disease (CKD) in patients with type 2 diabetes.

METHODS

We conducted a cohort study in adults with type 2 diabetes. Patients with end-stage renal disease were excluded. CKD was defined as the presence of albuminuria (albumin/creatinine ratio GFR > 3.4 mg/mmol) or an estimated (eGFR) < 60 ml min(-1) 1.73 m(-2). CKD progression was based on repeated eGFR measurements and/or the development of albuminuria. CAN was assessed using heart rate variability.

RESULTS

Two hundred and four patients were included in the analysis. At baseline, the prevalence of CKD and CAN was 40% and 42%, respectively. Patients with CAN had lower eGFR and higher prevalence of albuminuria and CKD. Spectral analysis variables were independently associated with eGFR, albuminuria and CKD at baseline. After a follow-up of 2.5 years, eGFR declined to a greater extent in patients with CAN than in those without CAN (-9.0 ± 17.8% vs -3.3 ± 10.3%, p = 0.009). After adjustment for baseline eGFR and baseline differences, CAN remained an independent predictor of eGFR decline over the follow-up period (β = -3.5, p = 0.03). Spectral analysis variables were also independent predictors of eGFR decline.

CONCLUSIONS/INTERPRETATION

CAN was independently associated with CKD, albuminuria and eGFR in patients with type 2 diabetes. In addition, CAN was an independent predictor of the decline in eGFR over the follow-up period. CAN could be used to identify patients with type 2 diabetes who are at increased risk of rapid decline in eGFR, so that preventative therapies might be intensified.

Cardiac autonomic neuropathy in patients with diabetes mellitus

Cardiac autonomic neuropathy (CAN) is an often overlooked and common complication of diabetes mellitus. CAN is associated with increased cardiovascular morbidity and mortality. The pathogenesis of CAN is complex and involves a cascade of pathways activated by hyperglycaemia resulting in neuronal ischaemia and cellular death. In addition, autoimmune and genetic factors are involved in the development of CAN. CAN might be subclinical for several years until the patient develops resting tachycardia, exercise intolerance, postural hypotension, cardiac dysfunction and diabetic cardiomyopathy. During its sub-clinical phase, heart rate variability that is influenced by the balance between parasympathetic and sympathetic tones can help in detecting CAN before the disease is symptomatic. Newer imaging techniques (such as scintigraphy) have allowed earlier detection of CAN in the pre-clinical phase and allowed better assessment of the sympathetic nervous system. One of the main difficulties in CAN research is the lack of a universally accepted definition of CAN; however, the Toronto Consensus Panel on Diabetic Neuropathy has recently issued guidance for the diagnosis and staging of CAN, and also proposed screening for CAN in patients with diabetes mellitus. A major challenge, however, is the lack of specific treatment to slow the progression or prevent the development of CAN. Lifestyle changes, improved metabolic control might prevent or slow the progression of CAN. Reversal will require combination of these treatments with new targeted therapeutic approaches. The aim of this article is to review the latest evidence regarding the epidemiology, pathogenesis, manifestations, diagnosis and treatment for CAN.

Cardiorenal syndrome--current understanding and future perspectives

Combined cardiac and renal dysfunction has gained considerable attention. Hypotheses about its pathogenesis have been formulated, albeit based on a relatively small body of experimental studies, and a clinical classification system has been proposed. Cardiorenal syndrome, as presently defined, comprises a heterogeneous group of acute and chronic clinical conditions, in which the failure of one organ (heart or kidney) initiates or aggravates failure of the other. This conceptual framework, however, has two major drawbacks: the first is that, despite worldwide interest, universally accepted definitions of cardiorenal syndrome are lacking and characterization of heart and kidney failure is not uniform. This lack of consistency hampers experimental studies on mechanisms of the disease. The second is that, although progress has been made in developing hypotheses for the pathogenesis of cardiorenal syndrome, these initiatives are at an impasse. No hierarchy has been identified in the myriad of haemodynamic and non-haemodynamic factors mediating cardiorenal syndrome. This Review discusses current understanding of cardiorenal syndrome and provides a roadmap for further studies in this field. Ultimately, discussion of the definition and characterization issues and of the lack of organization among pathogenetic factors is hoped to contribute to further advancement of this complex field.

Obesity-related glomerulopathy and the nephron complement

Obesity-related glomerulopathy (ORG) is a secondary form of glomerular disease that can occur in individuals with obesity. However, the absolute risk for an obese individual to develop progressive renal deterioration is low. Therefore, obesity alone appears to be insufficient to develop such severe renal injury, and there are likely other factors that contribute to the development of this entity. The glomerular hyperfiltration found in patients with ORG has been postulated to lead to structural abnormalities in glomeruli, such as glomerulomegaly and focal segmental glomerular sclerosis, in a manner analogous to that described in patients with reduced renal mass. In fact, recent studies suggest that a reduction in nephron mass is implicated in patients with ORG and synergistically contributes to the development of this renal complication together with obesity-induced changes in renal hemodynamics.

Blood pressure-renal blood flow relationships in conscious angiotensin II- and phenylephrine-infused rats

Chronic ANG II infusion in rodents is widely used as an experimental model of hypertension, yet very limited data are available describing the resulting blood pressure-renal blood flow (BP-RBF) relationships in conscious rats. Accordingly, male Sprague-Dawley rats (n = 19) were instrumented for chronic measurements of BP (radiotelemetry) and RBF (Transonic Systems, Ithaca, NY). One week later, two or three separate 2-h recordings of BP and RBF were obtained in conscious rats at 24-h intervals, in addition to separate 24-h BP recordings. Rats were then administered either ANG II (n = 11, 125 ng·kg(-1)·min(-1)) or phenylephrine (PE; n = 8, 50 mg·kg(-1)·day(-1)) as a control, ANG II-independent, pressor agent. Three days later the BP-RBF and 24-h BP recordings were repeated over several days. Despite similar increases in BP, PE led to significantly greater BP lability at the heart beat and very low frequency bandwidths. Conversely, ANG II, but not PE, caused significant renal vasoconstriction (a 62% increase in renal vascular resistance and a 21% decrease in RBF) and increased variability in BP-RBF relationships. Transfer function analysis of BP (input) and RBF (output) were consistent with a significant potentiation of the renal myogenic mechanism during ANG II administration, likely contributing, in part, to the exaggerated reductions in RBF during periods of BP elevations. We conclude that relatively equipressor doses of ANG II and PE lead to greatly different ambient BP profiles and effects on the renal vasculature when assessed in conscious rats. These data may have important implications regarding the pathogenesis of hypertension-induced injury in these models of hypertension.

Effectiveness of renal denervation therapy for resistant hypertension: a systematic review and meta-analysis

OBJECTIVES

This study sought to determine the current effectiveness and safety of sympathetic renal denervation (RDN) for resistant hypertension.

BACKGROUND

RDN is a novel approach that has been evaluated in multiple small studies.

METHODS

We performed a systematic review and meta-analysis of published studies evaluating the effect of RDN in patients with resistant hypertension. Studies were stratified according to controlled versus uncontrolled design and analyzed using random-effects meta-analysis models.

RESULTS

We identified 2 randomized controlled trials, 1 observational study with a control group, and 9 observational studies without a control group. In controlled studies, there was a reduction in mean systolic and diastolic blood pressure (BP) at 6 months of -28.9 mm Hg (95% confidence interval [CI]: -37.2 to -20.6 mm Hg) and -11.0 mm Hg (95% CI: -16.4 to -5.7 mm Hg), respectively, compared with medically treated patients (for both, p < 0.0001). In uncontrolled studies, there was a reduction in mean systolic and diastolic BP at 6 months of -25.0 mm Hg (95% CI: -29.9 to -20.1 mm Hg) and -10.0 mm Hg (95% CI: -12.5 to -7.5 mm Hg), respectively, compared with pre-RDN values (for both, p < 0.00001). There was no difference in the effect of RDN according to the 5 catheters employed. Reported procedural complications included 1 renal artery dissection and 4 femoral pseudoaneurysms.

CONCLUSIONS

RDN resulted in a substantial reduction in mean BP at 6 months in patients with resistant hypertension. The decrease in BP was similar irrespective of study design and type of catheter employed. Large randomized controlled trials with long-term follow-up are needed to confirm the sustained efficacy and safety of RDN.

Renin-angiotensin system, hypertension, and chronic kidney disease: pharmacogenetic implications

About 80% of CKD (chronic kidney disease) patients are hypertensive, and kidney function and blood pressure are clearly related to both physiologic and pathologic conditions in a "vicious cycle". In this pathologic scenario, there is a renin-angiotensin system (RAS) hyperactivity associated to progression of renal damage. Current guidelines indicate as the first choice of antihypertensive intervention, the pharmacologic blockade of the RAS. Nonetheless, both response to treatment and renal protection have considerable inter-individual variability. The main aims of this review are to describe the genetic characteristics of RAS components and to identify the possible pharmacogenetic implications for RAS-blocker drugs in the hypertension-CKD scenario. To date, RAS polymorphisms have not been consistently associated to antihypertensive response and studies focusing on CKD are scarce. Nonetheless, pharmacogenetic studies for the RAS-blocker drugs could still be further explored, especially with new generation tools and focusing not only on the antihypertensive response, but also on renal protection as well.