Early sympathetic activation in the initial clinical stages of chronic renal failure

Cardiovascular and Kidney Outcomes of Non-Diabetic CKD by Albuminuria Severity: Findings From the CRIC Study

RATIONALE & OBJECTIVE

The clinical trajectory of normoalbuminuric chronic kidney disease (CKD), particularly in the absence of diabetes, has not yet been well-studied. This study evaluated the association of kidney and cardiovascular outcomes with levels of albuminuria in a cohort of patients with non-diabetic CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,463 adults with non-diabetic CKD without known glomerulonephritis and diagnosed with hypertensive nephrosclerosis or unknown cause of CKD participating in the Chronic Renal Insufficiency Cohort (CRIC) Study.

EXPOSURE

Albuminuria stage at study entry.

OUTCOME

Primary outcome: Composite kidney (halving of eGFR, kidney transplantation, or dialysis), Secondary outcomes: (1) eGFR slope, (2) composite cardiovascular disease events (hospitalization for heart failure, myocardial infarction, stroke, or all-cause death), (3) all-cause death.

ANALYTICAL APPROACH

Linear mixed effects and Cox proportional hazards regression analyses.

RESULTS

Lower levels of albuminuria were associated with female sex and older age. For the primary outcome, compared with normoalbuminuria, those with moderate and severe albuminuria had higher rates of kidney outcomes (adjusted hazard ratio [aHR] 3.3, 95% CI 2.4-4.6; aHR 8.6, 95% CI 6.0-12.0) and cardiovascular outcomes (aHR 1.5, 95% CI 1.2-1.9; aHR 1.5, 95% CI 1.1-2.0). Those with normoalbuminuria (<30 mcg/mg; N=863) had a slower decline in eGFR (-0.46 mL/min/1.73m2/year), compared to those with moderate (30-300 mcg/mg, N=372; 1.41 mL/min/1.73m2/ year), or severe albuminuria (>300 mcg/mg, N=274; 2.63 mL/min/1.73m2/year). Kidney outcomes, in adjusted analyses, occurred, on average, sooner among those with moderate (8.6 years) and severe (7.3 years) albuminuria compared to those with normoalbuminuria (9.3 years), whereas the average times to cardiovascular outcomes were similar across albuminuria groups (8.2, 8.1, and 8.6 years, respectively).

LIMITATIONS

Self-report of CKD etiology without confirmatory kidney biopsies. Residual confounding.

CONCLUSIONS

Participants with normoalbuminuric non-diabetic CKD experienced substantially slower CKD progression but only modestly lower cardiovascular risk than those with high levels of albuminuria. These findings inform the design of future studies investigating interventions among individuals with lower levels of albuminuria.

The Clinical Significance and Application of Heart Rate Variability in Dialysis Patients: A Narrative Review

Autonomic nervous system (ANS) dysfunction is prevalent in end-stage kidney disease (ESKD) patients, carrying significant risks for morbidity and mortality. Heart rate variability (HRV) is a simple and non-invasive method to evaluate ANS functions and predict prognoses in specific patient populations. Since there is a lack of a clear understanding of the clinical significance of HRV in predicting prognoses in ESKD patients, an updated review on this topic is urgently warranted. The clinical significance of HRV in dialysis patients includes its associations with metabolic syndrome, nutritional status, intradialytic hypotension, vascular access failure, major adverse cardiovascular events, and mortality. These findings underscore the essential role of the autonomic reserve, which might denote the elevation of ANS activity as a response to external stimulus. Patients with a higher level of sympathetic activity at the resting stage, but who are unable to adequately elevate their sympathetic activity under stress might be susceptible to a worse outcome in critical circumstances. Further applications of HRV include HRV biofeedback, risk classification, and real-time HRV monitoring. Overall, HRV is an optimal tool for predicting prognoses in dialysis patients. Further study is encouraged in order to gain a clearer understanding of the clinical significance and application of HRV, and thereby enhance the care of ESKD patients.

Impact of Renal Denervation on Urinary Peptide-Based Biomarkers in Hypertension

BACKGROUND

Catheter-based renal denervation (RDN) reduces blood pressure in hypertension. Urinary peptides are associated with cardiovascular and renal disease and provide prognostic information. We aimed to investigate the effect of RDN on urinary peptide-based classifiers associated with chronic kidney and heart disease and to identify urinary peptides affected by RDN.

METHODS

This single-arm, single-center study included patients undergoing catheter-based RDN. Urine samples were collected before and 24 months after RDN and were analyzed using capillary electrophoresis coupled with mass spectrometry. Predefined urinary peptide-based classifiers for chronic kidney disease (CKD273), coronary artery disease (CAD238), and heart failure (HF1) were applied.

RESULTS

This study included 48 patients (33% female) with uncontrolled hypertension. At 24 months after RDN, systolic blood pressure (165±17 versus 148±20 mm Hg; P<0.0001), diastolic blood pressure (90±17 versus 81±13 mm Hg; P<0.0001), and mean arterial pressure (115±15 versus 103±13 mm Hg; P<0.0001) decreased significantly. A total of 103 urinary peptides from 37 different proteins, mostly collagens, altered following RDN. CAD238, a 238 coronary artery-specific polypeptide-based classifier, significantly improved following RDN (Cohen's d, -0.632; P=0.0001). The classification scores of HF1 (P=0.8295) and CKD273 (P=0.6293) did not change significantly.

CONCLUSIONS

RDN beneficially affected urinary peptides associated with coronary artery disease.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01888315.

Autonomic Modulation with Mindfulness-Based Stress Reduction in Chronic Kidney Disease: A Randomized Controlled Trial

Background

Chronic kidney disease (CKD) is characterized by overactivation of the sympathetic nervous system (SNS) that leads to increased cardiovascular disease risk. Despite the deleterious consequences of SNS overactivity, there are very few therapeutic options available to combat sympathetic overactivity.

Aim

To evaluate the effects of Mindfulness-Based Stress Reduction (MBSR) on SNS activity in CKD patients.

Method

Participants with CKD stages III-IV were randomized to an 8-week MBSR program or Health Education Program (HEP; a structurally parallel, active control group). Primary outcomes were direct intraneural measures of SNS activity directed to muscle (MSNA) via microneurography at rest and during stress maneuvers.

Results

28 participants (63 ±9 years; 86% males) completed the intervention with 16 in MBSR and 12 in HEP. There was a significant Group (MBSR vs. HEP) by Time (baseline vs. post-intervention) interaction in the change in MSNA reactivity to mental stress (p=0.026), with a significant reduction in the mean change in MSNA over 3 minutes of mental arithmetic at post-intervention (10.6 ± 7.1 to 5.0 ± 5.7 bursts/min, p<0.001), while no change was observed within the HEP group (p=0.773).

Conclusions

In this randomized controlled trial, patients with CKD had an amelioration of sympathetic reactivity during mental stress following 8-weeks of MBSR but not after HEP. Our findings demonstrate that mindfulness training is feasible and may have clinically beneficial effects on autonomic function in CKD.

Sympathetic overactivity, hypertension and cardiovascular disease: state of the art

Cardiovascular disease (CVD) remains the most prevalent cause of premature death worldwide. It had been suspected for decades that increased activity of the sympathetic nervous system (SNS) might play a pathogenetic role in the development and progression of hypertension, heart failure (HF) and CVD. The use of microneurographic techniques to directly assess the SNS has allowed this field to advance considerably in recent years. We now have compelling evidence for a key role of sympathetic overactivity in the pathogenesis and progression of hypertension and associated hypertension-mediated organ damage (such as endothelial dysfunction, arterial stiffness and left ventricular hypertrophy), HF (with or without reduced left ventricular ejection fraction). Sympathetic overactivity also drives increased cardiovascular risk in the settings of obesity, metabolic syndrome, chronic kidney disease and obstructive sleep apnoea, among other conditions. Thus, sympathetic overactivity is an important factor that drives patients through the CVD continuum, from the early appearance of cardiovascular risk factors, to impairments of the structure and function of components of the heart and arteries, to established CVD, and ultimately to a life-threatening cardiovascular event. A deeper understanding of the role of sympathetic overactivity in the pathogenesis of CVD and HF will support the optimization of therapeutic interventions for these conditions.

Renal Denervation in End-Stage Renal Disease: Current Evidence and Perspectives

In patients with end-stage renal disease (ESRD) undergoing haemodialysis, hypertension is of common detection and frequently inadequately controlled. Multiple pathophysiological mechanisms are involved in the development and progression of the ESRD-related high blood pressure state, which has been implicated in the increased cardiovascular risk reported in this hypertensive clinical phenotype. Renal sympathetic efferent and afferent nerves play a relevant role in the development and progression of elevated blood pressure values in patients with ESRD, often leading to resistant hypertension. Catheter-based bilateral renal nerves ablation has been shown to exert blood pressure lowering effects in resistant hypertensive patients with normal kidney function. Promising data on the procedure in ESRD patients with resistant hypertension have been reported in small scale pilot studies. Denervation of the native non-functioning kidney's neural excitatory influences on central sympathetic drive could reduce the elevated cardiovascular morbidity and mortality seen in ESRD patients. The present review article will focus on the promising results obtained with renal denervation in patients with ESRD, its mechanisms of action and future perspectives in these high risk patients.

Differences in peripheral microcirculatory blood flow regulation in chronic kidney disease based on wavelet analysis of resting near-infrared spectroscopy

Vascular impairment is closely related to increased mortality in chronic kidney disease (CKD). The objective of this study was to assess impairments in the regulation of peripheral microvascular perfusion in patients with CKD based on time-frequency spectral analysis of resting near-infrared spectroscopy (NIRS) signals. Total hemoglobin (tHb) concentration and tissue saturation index (TSI) signals were collected using NIRS for a continuous 5 mins at 10 Hz from the forearm of 55 participants (34 CKD including 5 with end-stage renal disease, and 21 age-matched control). Continuous wavelet transform-based spectral analysis was used to quantify the spectral amplitude within five pre-defined frequency intervals (I, 0.0095-0.021 Hz; II, 0.021-0.052 Hz; III, 0.052-0.145 Hz; IV, 0.145-0.6 Hz and V, 0.6-2.0 Hz), representing endothelial, neurogenic, myogenic, respiratory and heartbeat activity, respectively. CKD patients showed lower tHb average spectral amplitude within the neurogenic frequency interval compared with controls (p = 0.014), consistent with an increased sympathetic outflow observed in CKD. CKD patients also showed lower TSI average spectral amplitude within the endothelial frequency interval compared with controls (p = 0.046), consistent with a reduced endothelial function in CKD. These findings demonstrate the potential of wavelet analysis of NIRS to provide complementary information on peripheral microvascular regulation in CKD.

Renal Denervation in the Treatment of Resistant Hypertension and Difficult-to-Control Hypertension - Consensus Document of the Croatian Hypertension League - Croatian Society of Hypertension, Croatian Cardiac Society, Croatian Endovascular Initiative, Croatian Society for Diabetes and Metabolic Diseases, Croatian Renal Association, and Croatian Society of Family Physicians of the Croatian Medical Association

Renal denervation (RDN) as a method of treating arterial hypertension (AH) was introduced in Croatia in 2012. A multidisciplinary team and a network of hospitals that diagnose and treat patients with severe forms of AH were established, and a very strict diagnostic-treatment algorithm was prepared. At monthly meetings patients with truly resistant hypertension who were candidates for RDN were discussed. According to the 2021 ESH position statement and 2023 ESH guidelines, RDN is considered an alternative and additional, not a competitive method of treating patients with various forms of AH which must be performed by following a structured procedure and the patient's preference should be considered. In view of the changes in the global scientific community, the Croatian Hypertension League brings this consensus document on RDN conducted with radiofrequency-based catheter, the only currently available method in Croatia. In this document, exclusion and inclusion criteria are shown, as well as three groups of patients in whom RDN could be considered. The new diagnostic-treatment algorithm is prepared and follow-up procedure is explained. In Croatia, RDN is reimbursed by the national insurance company, thus pharmacoeconomic analyses is also shown. Criteria required by an individual centre to be approved of RDN are listed, and plans for prospective research on RDN in Croatia, including the Croatian registry for RDN, are discussed.

Does Renal Denervation a Reasonable Treatment Option in Hemodialysis-Dependent Patient with Resistant Hypertension? A Narrative Review

PURPOSE OF REVIEW

This narrative review aims to assess the pathophysiology, diagnosis, and treatment of resistant hypertension (RH) in end-stage kidney disease (ESKD) patients on dialysis, with a specific focus on the effect of renal denervation (RDN) on short-term and long-term blood pressure (BP) control. Additionally, we share our experience with the use of RDN in an amyloidotic patient undergoing hemodialysis with RH.

RECENT FINDINGS

High BP, an important modifiable cardiovascular risk factor, is often observed in patients in ESKD, despite the administration of multiple antihypertensive medications. However, in clinical practice, it remains challenging to identify RH patients on dialysis treatment because of the absence of specific definition for RH in this context. Moreover, the use of invasive approaches, such as RDN, to treat RH is limited by the exclusion of patients with reduced renal function (eGFR < 45 mL/min/1.73 m3) in the clinical trials. Nevertheless, recent studies have reported encouraging results regarding the effectiveness of RDN in stage 3 and 4 chronic kidney disease (CKD) and ESKD patients on dialysis, with reductions in BP of nearly up to 10 mmhg. Although multiple underlying pathophysiological mechanisms contribute to RH, the overactivation of the sympathetic nervous system in ESKD patients on dialysis plays a crucial role. The diagnosis of RH requires both confirmation of adherence to antihypertensive therapy and the presence of uncontrolled BP values by ambulatory BP monitoring or home BP monitoring. Treatment involves a combination of nonpharmacological approaches (such as dry weight reduction, sodium restriction, dialysate sodium concentration reduction, and exercise) and pharmacological treatments. A promising approach for managing of RH is based on catheter-based RDN, through radiofrequency, ultrasound, or alcohol infusion, directly targeting on sympathetic overactivity.

Association of cumulative resting heart rate exposure with rapid renal function decline: a prospective cohort study with 27,564 older adults

OBJECTIVE

To evaluate the prospective association between cumulative resting heart rate (cumRHR) and rapid renal function decline (RRFD) in a cohort of individuals aged 60 and older.

METHODS

In the Tianjin Chronic Kidney Disease Cohort Study, the individuals who underwent three consecutive physical examinations between 2014 and 2017, with estimated glomerular filtration rate (eGFR) greater than 60 mL/min per 1.73 m2 and aged 60 years or older were enrolled. A total of 27,564 patients were prospectively followed up from January 1, 2017 to December 31, 2020. The 3-year cumRHR was calculated. The primary outcome was RRFD, defined as an annualized decline in eGFR of 5 mL/min per 1.73 m2 or greater. Logistic and restricted spline regression models and subgroup analysis were used to investigate the association of cumRHR with RRFD after adjusting for all confounders.

RESULTS

During a median follow-up of 3.2 years, a total of 4,347 (15.77%) subjects developed RRFD. In fully-adjusted models, compared with the lowest quartile of cumRHR, the odds ratio (OR) for the highest was 1.44 (1.28-1.61), P < 0.001. Furthermore, each 1-standard deviation (27.97 beats/min per year) increment in cumRHR was associated with a 17% (P < 0.001) increased risk of RRFD, with a linear positive correlation (P for non-linear = 0.803). Participants with a 3-year cumRHR ≥ 207 (beats/min) * year (equivalent to ≥ 69 beats/min per year in 3 years) were found to be at a higher risk of RRFD.

CONCLUSIONS

The cumRHR is significantly associated with a higher risk of RRFD among older adults. These results might provide an effective goal for managing and delaying the decline of renal function in the older adults.

Cardiovascular complications in chronic kidney disease: a review from the European Renal and Cardiovascular Medicine Working Group of the European Renal Association

Chronic kidney disease (CKD) is classified into five stages with kidney failure being the most severe stage (stage G5). CKD conveys a high risk for coronary artery disease, heart failure, arrhythmias, and sudden cardiac death. Cardiovascular complications are the most common causes of death in patients with kidney failure (stage G5) who are maintained on regular dialysis treatment. Because of the high death rate attributable to cardiovascular (CV) disease, most patients with progressive CKD die before reaching kidney failure. Classical risk factors implicated in CV disease are involved in the early stages of CKD. In intermediate and late stages, non-traditional risk factors, including iso-osmotic and non-osmotic sodium retention, volume expansion, anaemia, inflammation, malnutrition, sympathetic overactivity, mineral bone disorders, accumulation of a class of endogenous compounds called 'uremic toxins', and a variety of hormonal disorders are the main factors that accelerate the progression of CV disease in these patients. Arterial disease in CKD patients is characterized by an almost unique propensity to calcification and vascular stiffness. Left ventricular hypertrophy, a major risk factor for heart failure, occurs early in CKD and reaches a prevalence of 70-80% in patients with kidney failure. Recent clinical trials have shown the potential benefits of hypoxia-inducible factor prolyl hydroxylase inhibitors, especially as an oral agent in CKD patients. Likewise, the value of proactively administered intravenous iron for safely treating anaemia in dialysis patients has been shown. Sodium/glucose cotransporter-2 inhibitors are now fully emerged as a class of drugs that substantially reduces the risk for CV complications in patients who are already being treated with adequate doses of inhibitors of the renin-angiotensin system. Concerted efforts are being made by major scientific societies to advance basic and clinical research on CV disease in patients with CKD, a research area that remains insufficiently explored.

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.

Short-term blood pressure variability as a potential therapeutic target for kidney disease

Short-term blood pressure variability (BPV) measured with ambulatory blood pressure (BP) monitoring has been demonstrated to be significant in predicting various clinical outcomes. Short-term BPV is distinguished from long-term BPV based on the time interval in which BP fluctuations are measured. Increased short-term BPV has been linked to detrimental effects on the microvascular structure and contributes to subclinical organ damage in the heart, blood vessels, and kidneys, regardless of the average 24-h BP levels. Short-term BPV can be defined by various measures, including calculated metrics (standard deviation, coefficient of variation, average real variability, weighted standard deviation, variability independent of the mean) or dipping patterns. Nevertheless, the additional role of short-term BPV beyond the predictive value of average 24-h BPs or established risk factors for cardiovascular disease and kidney disease remains unclear. In particular, longitudinal studies that evaluate the association between short-term BPV and kidney function impairment are limited and no conclusive data exist regarding which short-term BPV indicators most accurately reflect the prognosis of kidney disease. The issue of how to treat BPV in clinical practice is another concern that is frequently raised. This paper presents a review of the evidence for the prognostic role of short-term BPV in kidney outcomes. Additionally, this review discusses the remaining concerns about short-term BPV that need to be further investigated as an independent risk modifier.

Neurocirculatory regulation and adaptations to exercise in chronic kidney disease

Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated blood pressure reactivity during exercise. Classic mechanisms of exercise intolerance in CKD have been extensively described previously and include uremic myopathy, chronic inflammation, malnutrition, and anemia. We contend that these classic mechanisms only partially explain the exercise intolerance experienced in CKD and that alterations in cardiovascular and autonomic regulation also play a key contributing role. The purpose of this review is to examine the physiological factors that contribute to neurocirculatory dysregulation during exercise and discuss the adaptations that result from regular exercise training in CKD. Key neurocirculatory mechanisms contributing to exercise intolerance in CKD include augmentation of the exercise pressor reflex, aberrations in neurocirculatory control, and increased neurovascular transduction. In addition, we highlight how some contributing factors may be improved through exercise training, with a specific focus on the sympathetic nervous system. Important areas for future work include understanding how the exercise prescription may best be optimized in CKD and how the beneficial effects of exercise training may extend to the brain.

A prospective exploratory study to assess echocardiographic changes in patients with supratentorial tumors - Effect of craniotomy and tumor decompression

Background

Functional changes in the myocardium secondary to increased intracranial pressure (ICP) are studied sparingly. Direct echocardiographic changes in patients with supratentorial tumors have not been documented. The primary aim was to assess and compare the transthoracic echocardiography changes in patients with supratentorial tumors presenting with and without raised intracranial pressure for neurosurgery.

Methods

Patients were divided into two groups based on preoperative radiological and clinical evidence of midline shift of <6 mm without features of raised ICP (Group 1) or greater than 6mm with features of raised ICP (Group 2). Hemodynamic, echocardiographic, and optic nerve sheath diameter (ONSD) parameters were obtained during the preoperative period and 48 h after the surgery.

Results

Ninety patients were assessed, 88 were included for analysis. Two were excluded based on a poor echocardiographic window (1) and change in the operative plan (1). Demographic variables were comparable. About 27% of the patients in Group 2 had ejection fraction <55% and 21.2% had diastolic dysfunction in Group 2 in the preoperative period. There was a decrease in the number of patients with a left ventricular (LV) function <55% from 27% before surgery to 19% in the postoperative period in group 2. About 5.8% patients with moderate LV dysfunction in the preoperative period had normal LV function postoperatively. We found a positive correlation between ONSD parameters and radiological findings of raised intracranial pressure.

Conclusion

The study demonstrated that in patients with supratentorial tumors with ICP, cardiac dysfunction might be present in the preoperative period.

Exercise modulates sympathetic and vascular function in chronic kidney disease

BACKGROUNDChronic kidney disease (CKD) is characterized by chronic overactivation of the sympathetic nervous system (SNS), which increases the risk of cardiovascular (CV) disease and mortality. SNS overactivity increases CV risk by multiple mechanisms, including vascular stiffness. We tested the hypothesis that aerobic exercise training would reduce resting SNS activity and vascular stiffness in patients with CKD.METHODSIn this randomized controlled trial, sedentary older adults with CKD underwent 12 weeks of exercise (cycling, n = 32) or stretching (an active control group, n = 26). Exercise and stretching interventions were performed 20-45 minutes/session at 3 days/week and were matched for duration. Primary endpoints include resting muscle sympathetic nerve activity (MSNA) via microneurography, arterial stiffness by central pulse wave velocity (PWV), and aortic wave reflection by augmentation index (AIx).RESULTSThere was a significant group × time interaction in MSNA and AIx with no change in the exercise group but with an increase in the stretching group after 12 weeks. The magnitude of change in MSNA was inversely associated with baseline MSNA in the exercise group. There was no change in PWV in either group over the study period.CONCLUSIONOur data demonstrate that 12 weeks of cycling exercise has beneficial neurovascular effects in patients with CKD. Specifically, exercise training safely and effectively ameliorated the increase in MSNA and AIx observed over time in the control group. This sympathoinhibitory effect of exercise training showed greater magnitude in patients with CKD with higher resting MSNA.TRIAL REGISTRATIONClinicalTrials.gov, NCT02947750.FUNDINGNIH R01HL135183; NIH R61AT10457; NIH NCATS KL2TR002381; and NIH T32 DK00756; NIH F32HL147547; and VA Merit I01CX001065.

Nutritional Biomarkers and Heart Rate Variability in Patients with Subacute Stroke

Malnutrition and autonomic dysfunction are associated with poor outcomes, mortality, and psychological problems after stroke. Relevant laboratory biomarkers include serum albumin, prealbumin, and transferrin. Heart rate variability (HRV), a noninvasive measurement, can objectively measure autonomic nervous system (ANS) function. The relationship between HRV and nutritional biomarkers in stroke patients has not been studied. This study aimed to examine the relationship between nutritional biomarkers and HRV parameters in stroke patients. We retrospectively recruited 426 patients with subacute stroke who were examined for nutritional biomarkers, such as serum albumin, prealbumin, and transferrin, and underwent 24 h ambulatory Holter electrocardiography. Patients were divided into groups according to their nutritional biomarker status. Differences in HRV parameters between nutritional biomarker-deficient and normal groups were assessed. Pearson's correlation and multiple regression analyses were used to verify the relationship between HRV parameters and nutritional biomarkers. HRV parameters were significantly lower in the nutritional biomarker-deficient groups. In addition, there was a significant association between HRV parameters and nutritional biomarkers. Serum albumin, prealbumin, and transferrin levels were associated with ANS function, as measured by HRV, and their deficiency may be a predictive factor for the severity of ANS dysfunction in stroke patients.

Hypertension management in patients with cardiovascular comorbidities

Arterial hypertension is a leading cause of death globally. Due to ageing, the rising incidence of obesity, and socioeconomic and environmental changes, its incidence increases worldwide. Hypertension commonly coexists with Type 2 diabetes, obesity, dyslipidaemia, sedentary lifestyle, and smoking leading to risk amplification. Blood pressure lowering by lifestyle modifications and antihypertensive drugs reduce cardiovascular (CV) morbidity and mortality. Guidelines recommend dual- and triple-combination therapies using renin–angiotensin system blockers, calcium channel blockers, and/or a diuretic. Comorbidities often complicate management. New drugs such as angiotensin receptor-neprilysin inhibitors, sodium–glucose cotransporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, and non-steroidal mineralocorticoid receptor antagonists improve CV and renal outcomes. Catheter-based renal denervation could offer an alternative treatment option in comorbid hypertension associated with increased sympathetic nerve activity. This review summarises the latest clinical evidence for managing hypertension with CV comorbidities.

Ticagrelor-Aspirin Versus Clopidogrel-Aspirin Among CYP2C19 Loss-of-Function Carriers With Minor Stroke or Transient Ischemic Attack in Relation to Renal Function: A Post Hoc Analysis of the CHANCE-2 Trial

BACKGROUND

Evidence on the risk-benefit ratio of dual antiplatelet therapies among patients with stroke and impaired renal function is limited and inconsistent.

OBJECTIVE

To investigate the effect of renal function on the efficacy and safety of ticagrelor-aspirin versus clopidogrel-aspirin treatment.

DESIGN

Post hoc analysis of a multicenter, randomized, double-blind, placebo-controlled trial. (ClinicalTrials.gov: NCT04078737).

SETTING

202 centers in China.

PATIENTS

CYP2C19 loss-of-function allele carriers with minor stroke or transient ischemic attack.

INTERVENTION

Ticagrelor-aspirin and clopidogrel-aspirin.

MEASUREMENTS

Renal function was evaluated by estimated glomerular filtration rate (eGFR) levels. The primary efficacy and safety outcomes were recurrent stroke and severe or moderate bleeding within 90 days, respectively.

RESULTS

Among 6378 patients, 4050 (63.5%) had normal (eGFR ≥90 mL/min/1.73 m²), 2010 (31.5%) had mildly decreased (eGFR 60 to 89 mL/min/1.73 m²), and 318 (5.0%) had moderately to severely decreased (eGFR <60 mL/min/1.73 m²) renal function. The corresponding differences in recurrent stroke between ticagrelor-aspirin and clopidogrel-aspirin for normal, mildly decreased, and moderately to severely decreased renal function was -2.8 percentage points (95% CI, -4.4 to -1.3 percentage points) (hazard ratio [HR], 0.63 [CI, 0.49 to 0.81]), -0.2 percentage point (CI, -2.4 to 2.0 percentage points) (HR, 0.98 [CI, 0.69 to 1.39]), and 3.7 percentage points (CI, -2.3 to 10.1 percentage points) (HR, 1.31 [CI, 0.48 to 3.55]), respectively. Rates of severe or moderate bleeding did not substantially differ by treatment assignments across eGFR categories.

LIMITATION

Renal function was only evaluated by using eGFR, and the proportion of patients with severely decreased renal function was low.

CONCLUSION

Patients with normal, rather than impaired, renal function received greater benefit from ticagrelor-aspirin versus clopidogrel-aspirin.

PRIMARY FUNDING SOURCE

Ministry of Science and Technology of the People's Republic of China.

Elevated heart rate as sympathetic biomarker in human obesity

BACKGROUND AND AIM

The present study was aimed at determining whether and to what extent a specific heart rate (HR) cutoff value allows to identify in obeses a more pronounced level of adrenergic overdrive.

METHODS AND RESULTS

In 86 obese subjects aged 44.7 ± 0.9 (mean ± SEM) years and in 45 heathy lean controls of similar age we evaluated muscle sympathetic nerve traffic (MSNA, microneurography) and venous plasma norepinephrine (NE, HPLC assay), subdividing the subjects in 3 different groups according to their resting clinic and 24-h HR values (<70, 70-79 and 80-89 beats/minute). MSNA and plasma NE values detected in the three obese groups were almost superimposable each other, no significant difference between groups being observed. A similar behavior was observed when HR values were assessed during the 24-h Holter monitoring. In the group as a whole no significant relationship was detected between MSNA, plasma NE and clinic HR, this being the case also when 24-h HR replaced clinic HR in the correlation analysis. In contrast lean controls displayed a progressive significant increase in MSNA values form the group with clinic (and 24 Holter) values below 70 beats/minute to the ones with HR values between 70 and 79 and above 80 beats/minute.

CONCLUSIONS

In the obese state measurement of resting HR may allow to provide some general information on the functional status of the adrenergic cardiovascular drive. When the information required, however, are more subtle the sensitivity of the approach appears to be reduced and HR cannot be regarded as a faithful sympathetic biomarker.

Physiological Mechanisms of Hypertension and Cardiovascular Disease in End-Stage Kidney Disease

PURPOSE OF REVIEW

In this article, we summarize recent advances in understanding hypertension and cardiovascular disease in patients with end-stage kidney disease.

RECENT FINDINGS

Factors such as anemia, valvular and vascular calcification, vasoconstrictors, uremic toxins, hypoglycemia, carbamylated proteins, oxidative stress, and inflammation have all been associated with the progression of cardiovascular disease in end-stage kidney disease but the causality of these mechanisms has not been proven. The high risk of cardiovascular mortality has not improved as in the general population despite many advancements in cardiovascular care over the last two decades. Mechanisms that increase hypertension risk in these patients are centered on the control of extracellular fluid volume; however, over-correction of volume with dialysis can increase risks of intradialytic hypotension and death in these patients. This review presents both recent and classic work that increases our understanding of hypertension and cardiovascular disease in end-stage kidney disease.

Renal denervation in the antihypertensive arsenal - knowns and known unknowns

Even though it has been more than a decade since renal denervation (RDN) was first used to treat hypertension and an intense effort on researching this therapy has been made, it is still not clear how RDN fits into the antihypertensive arsenal. There is no question that RDN lowers blood pressure (BP), it does so to an extent at best corresponding to one antihypertensive drug. The procedure has an excellent safety record. However, it remains clinically impossible to predict whose BP responds to RDN and whose does not. Long-term efficacy data on BP reduction are still unconvincing despite the recent results in the SPYRAL HTN-ON MED trial; experimental studies indicate that reinnervation is occurring after RDN. Although BP is an acceptable surrogate endpoint, there is complete lack of outcome data with RDN. Clear indications for RDN are lacking although patients with resistant hypertension, those with documented increase in activity of the sympathetic system and perhaps those who desire to take fewest medication may be considered.

Insight on Efficacy of Renal Artery Denervation for Refractory Hypertension with Chronic Kidney Diseases: A Long-Term Follow-Up of 24-Hour Ambulatory Blood Pressure

Aims

To explore the long-term efficacy and safety of renal denervation in patients with RHT and CKD, a post hoc analysis of eGFR subgroups was completed.

Methods

Fifty-four patients with refractory hypertension with chronic kidney disease were treated with RDN and enrolled in the study. Patients were divided into three groups according to eGFR: eGFR 46–90 ml/min group, eGFR 15–45 ml/min group, and eGFR <15 ml/min group. The planned follow-up period was 48 months to assess 24 h ambulatory blood pressure, renal function, type of antihypertensive medication, and RDN complications.

Results

The ablation sites of the GFR 46–90 ml/min group and GFR 15–45 ml/min group were 32.57 ± 2.99 and 29.53 ± 5.47, respectively. No complications occurred in the GFR 46–90 ml/min group. The GFR<15 ml/min group was treated with 27.07 ± 5.59  ablation. Renal artery dissection occurred in each group of GFR 15–45 ml/min and GFR <15 ml/min. And renal stent implantation artery was performed on these two patients. No severe renal artery stenosis occurred. There were no significant differences in Scr and eGFR between the three groups at each follow-up point. Compared with baseline, SBP was significantly of each group decreased to varying degrees at each follow-up time point. SBP decreased most in the GFR 46–90 ml/min group. Compared with baseline, the type of antihypertensive drugs used in the GFR46-90 ml/min group decreased significantly except for 36 and 48 months. At 48 months' postadmission, there was a significant decrease in the type of antihypertensive medication used in the GFR15-45 ml/min group, and there was no significant decrease in the type of antihypertensive medication used in the GFR<15 ml/min group.

Conclusions

RDN can safely reduce SBP in CKD patients combined with RHT for 48 months, with the most pronounced reduction in the GFR15-45 ml/min group. The variety of antihypertensive drugs was significantly reduced after RDN. This was particularly evident in patients with GFR 15–45 ml/min.

Sympathetic activation in heart failure

Sympathetic activation has been long appreciated exclusively as a fundamental compensatory mechanism of the failing heart and, thus, welcome and to be supported. In the initial clinical phases of heart failure (HF), the sympathetic nervous system overdrive plays a compensatory function aimed at maintaining an adequate cardiac output despite the inotropic dysfunction affecting the myocardium. However, when the sympathetic reflex response is exaggerated it triggers a sequence of unfavourable remodelling processes causing a further contractile deterioration that unleashes major adverse cardiovascular consequences, favouring the HF progression and the occurrence of fatal events. Eventually, the sympathetic nervous system in HF was demonstrated to be a ‘lethality factor’ and thus became a prominent therapeutic target. The existence of an effective highly specialized intracardiac neuronal network immediately rules out the old concept that sympathetic activation in HF is merely the consequence of a drop in cardiac output. When a cardiac damage occurs, such as myocardial ischaemia or a primary myocardial disorder, the adaptive capability of the system may be overcame, leading to excessive sympatho-excitation coupled with attenuation till to abolishment of central parasympathetic drive. Myocardial infarction causes, within a very short time, both a functional and anatomical remodelling with a diffuse up-regulation of nerve growth factor (NGF). The subsequent nerve sprouting signal, facilitated by a rise in the levels of NGF in the left stellate ganglion and in the serum, triggers an increase in cardiac nerve density in both peri-infarct and non-infarcted areas. Finally, NFG production decreases over time, supposedly as an adaptative response to the prolonged exposure to sympathetic overactivity, leading in the end to a reduction in sympathetic nerve density. Accordingly, NGF levels were markedly reduced in patients with severe congestive heart failure. The kidney is the other key player of the sympathetic response to HF as it indeed reacts to under-perfusion and to loop diuretics to preserve filtration at the cost of many pathological consequences on its physiology. This vicious loop ultimately participates to the chronic and disruptive sympathetic overdrive.

In conclusion, sympathetic activation is the natural physiological consequence to life stressors but also to any condition that may harm our body. It is the first system of reaction to any potential life-threatening event. However, in any aspect of life over reaction is never effective but, in many instances, is, actually, life threatening. One for all is the case of ischaemia-related ventricular fibrillation which is, strongly facilitated by sympathetic hyperactivity. The take home message? When, in a condition of harm, everybody is yelling failure is just around the corner.

Sympathetic activation and heart rate thresholds for cardiovascular risk in chronic kidney disease

AIM

The current study was designed at assessing whether the sympathetic cardiovascular drive (SNS) is differently activated in chronic kidney disease (CKD) patients displaying less or more elevated resting heart rate (HR) values. It was also designed at determining at which HR cutoff value the SNS displays a greater activation.

METHODS

In 95 CKD middle-age patients we evaluated muscle sympathetic nerve activity (MSNA, microneurography) and venous plasma norepinephrine (HPLC assay), subdividing the patients in different groups according to their resting clinic and 24-h HR.

RESULTS

In CKD progressively greater values of clinic or 24-h HR were associated with a progressive increase in both MSNA and norepinephrine. HR cutoff values indicated by large-scale clinical trials for determining cardiorenal risk, that is more than 80 bpm, were associated with MSNA values significantly greater than the ones detected in patients with lower HR, this being the case also for norepinephrine. Both MSNA and norepinephrine were significantly related to clinic ( r  = 0.47, P  < 0.0001 and r  = 0.26, P  < 0.0001, respectively) and 24-h ( r  = 0.42, P  < 0.0001 and r  = 0.27, P  < 0.0001, respectively) HR. MSNA, norepinephrine, but not HR, were significantly and inversely related to estimated glomerular filtration rate (eGFR) values ( r  = -0.47, r  = -0.23, P  < 0.0001 and P  < 0.02, respectively).

CONCLUSION

In CKD both clinic and 24-h HR values greater than 80 bpm are associated with an enhanced sympathetic activation, which parallelles for magnitude the HR elevations. The sensitivity of HR as sympathetic marker is limited; however, no significant relationship being detected between HR and eGFR or left ventricular mass index.

Association Between Systolic Blood Pressure Variability and Major Adverse Cardiovascular Events in Korean Patients With Chronic Kidney Disease: Findings From KNOW-CKD

Background Whether visit-to-visit systolic blood pressure (SBP) variability can predict major adverse cardiovascular events (MACE) in patients with chronic kidney disease is unclear. Methods and Results We investigated the relationship between SDs of visit-to-visit SBP variability during the first year of enrollment and MACE among 1575 participants from KNOW-CKD (Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease). Participants were categorized into 3 groups according to tertiles of visit-to-visit SBP variability (SD). The study end point was MACE, defined as a composite of nonfatal myocardial infarction, unstable angina, revascularization, nonfatal stroke, hospitalization for heart failure, or cardiac death. During 6748 patient-years of follow-up (median, 4.2 years), MACE occurred in 64 participants (4.1%). Compared with the lowest tertile of visit-to-visit SBP variability (SD), the hazard ratios (HRs) for the middle and the highest tertile were 1.64 (95% CI, 0.80-3.36) and 2.23 (95% CI, 1.12-4.44), respectively, in a multivariable cause-specific hazard model. In addition, the HR associated with each 5-mm Hg increase in visit-to-visit SBP variability (SD) was 1.21 (95% CI, 1.01-1.45). This association was consistent in sensitivity analyses with 2 additional definitions of SBP variability determined by the coefficient of variation and variation independent of the mean. The corresponding HRs for the middle and highest tertiles were 2.11 (95% CI, 1.03-4.35) and 2.28 (95% CI, 1.12-4.63), respectively, in the analysis with the coefficient of variation and 1.76 (95% CI, 0.87-3.57) and 2.04 (95% CI, 1.03-4.03), respectively, with the variation independent of the mean. Conclusions Higher visit-to-visit SBP variability is associated with an increased risk of MACE in patients with chronic kidney disease. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01630486.

Renal Denervation Prevents Atrial Arrhythmogenic Substrate Development in CKD

BACKGROUND

In patients with chronic kidney disease (CKD), atrial fibrillation (AF) is highly prevalent and represents a major risk factor for stroke and death. CKD is associated with atrial proarrhythmic remodeling and activation of the sympathetic nervous system. Whether reduction of the sympathetic nerve activity by renal denervation (RDN) inhibits AF vulnerability in CKD is unknown.

METHODS

Left atrial (LA) fibrosis was analyzed in samples from patients with AF and concomitant CKD (estimated GFR, <60 mL/min per 1.73 m²) using picrosirius red and compared with AF patients without CKD and patients with sinus rhythm with and without CKD. In a translational approach, male Sprague Dawley rats were fed with 0.25% adenine (AD)-containing chow for 16 weeks to induce CKD. At week 5, AD-fed rats underwent RDN or sham operation (AD). Rats on normal chow served as control. After 16 weeks, cardiac function and AF susceptibility were assessed by echocardiography, radiotelemetry, electrophysiological mapping, and burst stimulation, respectively. LA tissue was histologically analyzed for sympathetic innervation using tyrosine hydroxylase staining, and LA fibrosis was determined using picrosirius red.

RESULTS

Sirius red staining demonstrated significantly increased LA fibrosis in patients with AF+CKD compared with AF without CKD or sinus rhythm. In rats, AD demonstrated LA structural changes with enhanced sympathetic innervation compared with control. In AD, LA enlargement was associated with prolonged duration of induced AF episodes, impaired LA conduction latency, and increased absolute conduction inhomogeneity. RDN treatment improved LA remodeling and reduced LA diameter compared with sham-operated AD. Furthermore, RDN decreased AF susceptibility and ameliorated LA conduction latency and absolute conduction inhomogeneity, independent of blood pressure reduction and renal function.

CONCLUSIONS

In an experimental rat model of CKD, RDN inhibited progression of atrial structural and electrophysiological remodeling. Therefore, RDN represents a potential therapeutic tool to reduce the risk of AF in CKD, independent of changes in renal function and blood pressure.

Renal Deafferentation Prevents Progression of Hypertension and Changes to Sympathetic Reflexes in a Rabbit Model of Chronic Kidney Disease

[Figure: see text].

Renal denervation in patients with versus without chronic kidney disease: results from the global SYMPLICITY Registry with follow-up data of 3 years

BACKGROUND

Activity of the sympathetic nervous system is increased in patients with hypertension and chronic kidney disease (CKD). Here we compare short- and long-term blood pressure (BP) lowering effects of renal denervation (RDN) between hypertensive patients with or without CKD in the Global SYMPLICITY Registry.

METHODS

Office and 24-hour ambulatory BP (ABP) were assessed at pre-specified time-points after RDN. The presence of CKD was defined according to estimated glomerular filtration rate (eGFR), and enrolled patients were stratified based on the presence (N = 475, eGFR < 60 ml/min/1.73m2) or absence (N = 1505, eGFR ≥ 60ml/min/1.73m2) of CKD.

RESULTS

Patients with CKD were older (p < 0.001) and were prescribed more antihypertensive medications (p < 0.001). eGFR-decline/year was not significantly different between groups after the first year. Office and 24-hour ABP were significantly reduced from baseline at all timepoints after RDN in both groups (all p < 0.001). After adjusting for baseline data, patients without CKD had a greater reduction in office systolic BP (-17.3 ± 28.3 vs. -11.7 ± 29.9 mmHg, p = 0.009), but not diastolic BP at 36 months compared to those with CKD. Similar BP and eGFR-results were found when the analysis was limited to patients with both baseline and 36-month BP data available. There was no difference in the safety profile of the RDN-procedure between groups.

CONCLUSIONS

After adjusting for baseline data, 24-hour systolic and diastolic ABP reduction was similar in patients with and without CKD after RDN, whereas office systolic but not diastolic BP was reduced less in patients with CKD. We conclude that RDN emerged as an effective antihypertensive treatment option in CKD patients.

Dysbiosis-Related Advanced Glycation Endproducts and Trimethylamine N-Oxide in Chronic Kidney Disease

Chronic kidney disease (CKD) is a public health concern that affects approximately 10% of the global population. CKD is associated with poor outcomes due to high frequencies of comorbidities such as heart failure and cardiovascular disease. Uremic toxins are compounds that are usually filtered and excreted by the kidneys. With the decline of renal function, uremic toxins are accumulated in the systemic circulation and tissues, which hastens the progression of CKD and concomitant comorbidities. Gut microbial dysbiosis, defined as an imbalance of the gut microbial community, is one of the comorbidities of CKD. Meanwhile, gut dysbiosis plays a pathological role in accelerating CKD progression through the production of further uremic toxins in the gastrointestinal tracts. Therefore, the gut-kidney axis has been attracting attention in recent years as a potential therapeutic target for stopping CKD. Trimethylamine N-oxide (TMAO) generated by gut microbiota is linked to the progression of cardiovascular disease and CKD. Also, advanced glycation endproducts (AGEs) not only promote CKD but also cause gut dysbiosis with disruption of the intestinal barrier. This review summarizes the underlying mechanism for how gut microbial dysbiosis promotes kidney injury and highlights the wide-ranging interventions to counter dysbiosis for CKD patients from the view of uremic toxins such as TMAO and AGEs.

Effects of renal sympathetic denervation on the course of congestive heart failure combined with chronic kidney disease: Insight from studies with fawn-hooded hypertensive rats with volume overload induced using aorto-caval fistula

Background: The coincidence of congestive heart failure (CHF) and chronic kidney disease (CKD) results in poor survival rate. The aim of the study was to examine if renal denervation (RDN) would improve the survival rate in CHF induced by creation of aorto-caval fistula (ACF).Methods: Fawn-hooded hypertensive rats (FHH), a genetic model of spontaneous hypertension associated with CKD development, were used. Fawn-hooded low-pressure rats (FHL), without CKD, served as controls. RDN was performed 4 weeks after creation of ACF and the follow-up period was 10 weeks.Results: We found that intact (non-denervated) ACF FHH exhibited survival rate of 58.8% (20 out of 34 rats), significantly lower than in intact ACF FHL (81.3%, 26/32 rats). In intact ACF FHL albuminuria remained stable throughout the study, whereas in ACF FHH it increased significantly, up to a level 40-fold higher than the basal values. ACF FHL did not show increases in renal glomerular and tubulointerstitial injury as compared with FHL, while ACF FHH exhibited marked increases in kidney injury as compared with FHH. RDN did not improve the survival rate in either ACF FHL or ACF FHH and did not alter the course of albuminuria in ACF FHL. RDN attenuated the albuminuria, but did not reduce the kidney injury in ACF FHH.Conclusions: Our present results support the notion that even modest CKD increases CHF-related mortality. RDN did not attenuate CHF-dependent mortality in ACF FHH, it delayed the progressive rise in albuminuria, but it did not reduce the degree of kidney injury.

COVID-19 in Chronic Kidney Disease: The Impact of Old and Novel Cardiovascular Risk Factors

Cardiovascular disease is a frequent complication and the most common cause of death in patients with CKD. Despite landmark medical advancements, mortality due to cardiovascular disease is still 20 times higher in CKD patients than in the general population, which is mainly due to the high prevalence of risk factors in this group. Indeed, in addition to traditional cardiovascular risk factors, CKD patients are exposed to nontraditional ones, which include metabolic, hormonal, and inflammatory alterations. The global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has brought novel challenges for both cardiologists and nephrologists alike. Emerging evidence indicates that coronavirus disease 2019 (COVID-19) increases the risk of cardiovascular events and that several aspects of the disease may synergize with pre-existing cardiovascular risk factors in CKD patients. A better understanding of these mechanisms is pivotal for the prevention and treatment of cardiovascular events in this context, and we believe that additional clinical and experimental studies are needed to improve cardiovascular outcomes in CKD patients with COVID-19. In this review, we provide a summary of traditional and nontraditional cardiovascular risk factors in CKD patients, discussing their interaction with SARS-CoV-2 infection and focusing on CO-VID-19-related cardiovascular complications that may severely affect short- and long-term outcomes in this high-risk population.

The cholinergic anti-inflammatory pathway in chronic kidney disease-review and vagus nerve stimulation clinical pilot study

Inflammation and autonomic dysfunction are common findings in chronic and end-stage kidney disease and contribute to a markedly increased risk of mortality in this patient population. The cholinergic anti-inflammatory pathway (CAP) is a vagal neuro-immune circuit that upholds the homoeostatic balance of inflammatory activity in response to cell injury and pathogens. CAP models have been examined in preclinical studies to investigate its significance in a range of clinical inflammatory conditions and diseases. More recently, cervical vagus nerve stimulation (VNS) implants have been shown to be of potential benefit for patients with chronic autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease. We have previously shown that dialysis patients have a functional CAP ex vivo. Here we review the field and the potential role of the CAP in acute kidney injury and chronic kidney disease (CKD) as well as in hypertension. We also present a VNS pilot study in haemodialysis patients. Controlling inflammation by neuroimmune modulation may lead to new therapeutic modalities for improved treatment, outcome, prognosis and quality of life for patients with CKD.

Dietary salt modifies the blood pressure response to renin-angiotensin inhibition in experimental chronic kidney disease

Chronic kidney disease contributes to hypertension, but the mechanisms are incompletely understood. To address this, we applied the 5/6th nephrectomy rat model to characterize hypertension and the response to dietary salt and renin-angiotensin inhibition. 5/6th nephrectomy caused low-renin, salt-sensitive hypertension with hyperkalemia and unsuppressed aldosterone. Compared with sham rats, 5/6th nephrectomized rats had lower Na⁺/H⁺ exchanger isoform 3, Na⁺-K⁺-2Cl^- cotransporter, Na⁺-Cl^- cotransporter, α-epithelial Na⁺ channel (ENaC), and Kir4.1 levels but higher serum and glucocorticoid-regulated kinase 1, prostasin, γ-ENaC, and Kir5.1 levels. These differences correlated with plasma renin, aldosterone, and/or K⁺. On a normal-salt diet, adrenalectomy (0 ± 9 mmHg) and spironolactone (-11 ± 10 mmHg) prevented a progressive rise in blood pressure (10 ± 8 mmHg), and this was enhanced in combination with losartan (-41 ± 12 and -43 ± 9 mmHg). A high-salt diet caused skin Na⁺ and water accumulation and aggravated hypertension that could only be attenuated by spironolactone (-16 ± 7 mmHg) and in which the additive effect of losartan was lost. Spironolactone also increased natriuresis, reduced skin water accumulation, and restored vasorelaxation. In summary, in the 5/6th nephrectomy rat chronic kidney disease model, salt-sensitive hypertension develops with a selective increase in γ-ENaC and despite appropriate transporter adaptations to low renin and hyperkalemia. With a normal-salt diet, hypertension in 5/6th nephrectomy depends on angiotensin II and aldosterone, whereas a high-salt diet causes more severe hypertension mediated through the mineralocorticoid receptor.NEW & NOTEWORTHY Chronic kidney disease (CKD) causes salt-sensitive hypertension, but the interactions between dietary salt and the renin-angiotensin system are incompletely understood. In rats with CKD on a normal-salt diet targeting aldosterone, the mineralocorticoid receptor (MR) and especially angiotensin II reduced blood pressure. On a high-salt diet, however, only MR blockade attenuated hypertension. These results reiterate the importance of dietary salt restriction to maintain renin-angiotensin system inhibitor efficacy and specify the MR as a target in CKD.

Autonomic Cardiovascular Alterations in Chronic Kidney Disease: Effects of Dialysis, Kidney Transplantation, and Renal Denervation

PURPOSE OF REVIEW

To review the results of studies of the effects of dialysis and kidney transplantation on the autonomic nervous system alterations that occur in chronic kidney disease.

RECENT FINDINGS

Vagal control of the heart mediated by arterial baroreceptors is altered early in the course of the renal disease. Sympathetic activation occurs, with increases in resting heart rate, venous plasma norepinephrine levels, muscle sympathetic nerve traffic, and other indirect indices of adrenergic drive. The magnitude of the changes reflects the clinical severity of the kidney disease. Both the sympathetic and parasympathetic alterations have a reflex origin, depending on the impairment in baroreflex and cardiopulmonary reflex control of the cardiovascular system. These alterations are partially reversed during acute hemodialysis, but the responses are variable depending on the specific type of dialytic treatment that is employed. Renal transplantation improves reflex cardiovascular control, resulting in sympathoinhibition following renal transplantation if the native kidneys are removed. Sympathoinhibitory effects have been also reported in renal failure patients after bilateral renal denervation. Assessment of autonomic nervous system responses to dialysis and renal transplantation provides information of clinical interest, given the evidence that autonomic alterations are involved in the development and progression of cardiovascular complications, as well as in the prognosis of chronic kidney disease.

Interventions and Manipulations of Interoception

Interoceptive pathways may be manipulated at various levels to develop interventions to improve symptoms in a range of disorders. Primarily through the lens of the respiratory system, we outline various pathways that can be manipulated at neural, behavioral, and psychological levels to change the representation of and attention to interoceptive signals, which can alter interconnected physiological systems and improve functioning and adaptive behavior. Interventions can alter interoception via neuromodulation of the vagus nerve, slow breathing to change respiratory rate and depth, or awareness processes such as mindfulness-based interventions. Aspects of this framework may be applied to other physiological systems and future research may integrate interventions across multiple levels of manipulation or bodily systems.

Sympathetic hyperactivity in patients with hypertension: pathogenesis and treatment. Part I

The article is devoted to the influence of sympathetic  nervous system (SNS) on the cardiovascular  system.  Influence of SNS activity on the blood pressure  level and the pathogenesis of hypertension  development, as well as the effect of SNS on many biochemical and metabolic parameters playing a key role in the development  of metabolic syndrome and hypertension  are considered. Possible mechanisms  of action of various methods that reduce  the SNS activity, restore  the function of autonomic nervous system  and normalize the cardiovascular system and blood pressure  are considered.

Limited reliability of heart rate as a sympathetic marker in chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is characterized by a pronounced sympathetic overactivity as documented by the marked increase in muscle sympathetic nerve traffic (MSNA) and in plasma norepinephrine reported in this condition. Whether and to what extent in CKD heart rate (HR) reflects the adrenergic overdrive remains undefined. It is also undefined the relative validity of the different adrenergic markers in reflecting renal dysfunction.

MATERIALS AND METHODS

In 82 CKD patients, aged 58.4 ± 1.1 years (mean ± SEM), we measured resting clinic blood pressure, HR (EKG), venous NE (HPLC) and MSNA (microneurography). The same measurements were made in 24 age-matched healthy controls.

RESULTS

HR was significantly greater in CKD than in controls (74.0 ± 1.1 versus 68.2 ± 1.8 bpm, P < 0.02) and significantly directly related to the elevated plasma norepinephrine and MSNA values (r = 0.22 and 0.39, P < 0.05 and <0.0003, respectively). Both MSNA and plasma norepinephrine were significantly and inversely related to the estimated glomerular filtration rate. The correlation did not achieve statistical significance for HR. Similar results were obtained examining the relationships with left ventricular mass index.

CONCLUSION

Our data show that in CKD not only peripheral but also cardiac sympathetic drive is markedly enhanced and HR can be regarded as a marker of the adrenergic overdrive characterizing this condition. The reliability of HR as sympathetic marker appears to be limited, however, this variable being unable to closely reflect, at variance from MSNA and plasma norepinephrine, the interindividual differences in renal dysfunction and the accompanying structural cardiovascular alterations.

Microvascular changes at different stages of chronic kidney disease

Patients with progressing chronic kidney disease (CKD) are more likely to experience cardio‐ and cerebrovascular events than progressing to end‐stage renal disease. The authors explored whether retinal microvascular calibers differed with the degree of renal impairment and between the standard and extended optic disk and may serve as a simple additional tool for risk stratification in this highly vulnerable patient cohort. The authors analyzed central retinal arteriolar and venular equivalent calibers (CRAE, CRVE) at different retinal zones (zone B&C) using digital retinal imaging in hypertensive patients with stage 2 (n = 66) or stage 3 CKD (n = 30). Results were adjusted for age, sex, HbA1c, and 24‐hour diastolic blood pressure. Mean eGFR was 77.7 ± 8.9 and 48.8 ± 7.9 ml/min/1.73 m² for stage 2 and 3 CKD, respectively. CRAE and CRVE in zones B and C were significantly lower in patients with stage 3 CKD compared to patients with stage 2 CKD (CRAE‐B:141.1 ± 21.4 vs. 130.5 ± 18.9 µm, p = .030; CRAE‐C:137.4 ± 19.4 vs 129.2 ± 18.2 µm, p = .049; CRVE‐B:220.8 ± 33.0 vs. 206.0 ± 28.4 µm, p = .004; and CRVE‐C:215.9 ± 33.0 vs. 201.2 ± 25.1µm, p = .003). In patients with stage 2 CKD, CRAE‐B was higher than CRAE‐C (141.1 ± 21.4 vs. 137.4 ± 19.4µm, p < .001). In contrast, such a difference was not found in patients with stage 3 CKD. CRAE of both retinal zones correlated with eGFR for the entire cohort. In patients with stage 3 CKD, retinal narrowing is more pronounced compared to patients with stage 2 CKD. Whether the novel observation of difference in arteriolar caliber between zones B and C in stage 2 CKD could serve as an early marker of CKD progression warrants further investigation.

Increased vascular α1-adrenergic receptor sensitivity in older adults with posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is an independent risk factor for the development of hypertension and cardiovascular disease. Patients with PTSD have heightened blood pressure and sympathetic nervous system reactivity; however, it is unclear if patients with PTSD have exaggerated vasoconstriction in response to sympathetic nerve activation that could also contribute to increased blood pressure reactivity. Therefore, we hypothesized that patients with PTSD have increased sensitivity of vascular α₁-adrenergic receptors (α1ARs), the major mediators of vasoconstriction in response to release of norepinephrine at sympathetic nerve terminals. To assess vascular α1AR sensitivity, we measured the degree of venoconstriction in a dorsal hand vein in response to exponentially increasing doses of the selective α1AR agonist, phenylephrine (PE), in 9 patients with PTSD (age = 59 ± 2 yr) and 10 age-matched controls (age = 60 ± 1 yr). Individual dose-response curves were generated to determine the dose of PE that induces 50% of maximal venoconstriction (i.e., PE ED₅₀) reflective of vascular α1AR sensitivity. In support of our hypothesis, PE ED₅₀ values were lower in PTSD compared with controls (245 ± 54 ng/min vs. 1,995 ± 459 ng/min, P = 0.012), indicating increased vascular α₁AR sensitivity in PTSD. The PTSD group also had an increase in slope of rise in venoconstriction, indicative of an altered venoconstrictive reactivity to PE compared with controls (19.8% ± 1.2% vs. 15.1% ± 1.2%, P = 0.009). Heightened vascular α₁AR sensitivity in PTSD may contribute to augmented vasoconstriction and blood pressure reactivity to sympathoexcitation and to increased cardiovascular disease risk in this patient population.

Role of comorbidities in heart failure prognosis Part 2: Chronic kidney disease, elevated serum uric acid

Despite improvements in pharmacotherapy, morbidity and mortality rates in community-based populations with chronic heart failure still remain high. The increase in medical complexity among patients with heart failure may be reflected by an increase in concomitant non-cardiovascular comorbidities, which are recognized as independent prognostic factors in this population. Heart failure and chronic kidney disease share many risk factors, and often coexist. The presence of kidney failure is associated with incremented risk of cardiovascular and non-cardiovascular mortality in heart failure patients. Chronic kidney disease is also linked with underutilization of evidence-based heart failure therapy that may reduce morbidity and mortality. More targeted therapies would be important to improve the prognosis of patients with these diseases. In recent years, serum uric acid as a determinant of cardiovascular risk has gained interest. Epidemiological, experimental and clinical data show that patients with hyperuricaemia are at increased risk of cardiac, renal and vascular damage and cardiovascular events. Moreover, elevated serum uric acid predicts worse outcome in both acute and chronic heart failure. While studies have raised the possibility of preventing heart failure through the use of uric acid lowering agents, the literature is still inconclusive on whether the reduction in uric acid will result in a measurable clinical benefit. Available evidences suggest that chronic kidney disease and elevated uric acid could worsen heart failure patients' prognosis. The aim of this review is to analyse a possible utilization of these comorbidities in risk stratification and as a therapeutic target to get a prognostic improvement in heart failure patients.

Coronary flow velocity reserve and inflammatory markers in living kidney donors

BACKGROUND

Coronary microvascular dysfunction is prevalent in chronic kidney disease (CKD), and may contribute to the development of myocardial dysfunction in CKD. Coronary flow velocity reserve (CFVR) is a marker of coronary microvascular function and falls with increasing CKD stage. Living kidney donors have renal function consistent with early stage CKD and concern has been raised about their cardiovascular risk. No studies to date have investigated the presence of coronary microvascular dysfunction in living kidney donors.

METHODS

25 healthy controls and 23 living kidney donors were recruited and underwent assessment with transthoracic echocardiography, Doppler CFVR, myocardial contrast echocardiography and serum multiplex immunoassay panels.

RESULTS

Doppler CFVR was significantly reduced in living kidney donors compared to controls (mean CFVR 3.4 ± 0.7 vs 3.8 ± 0.6, mean difference 0.4 95% confidence interval 0.03-0.8, p =.036). Quantitative myocardial contrast echocardiography showed a trend towards reduced coronary flow reserve in living kidney donors. Compared to controls, living kidney donors had higher serum high sensitivity C reactive peptide (hsCRP) and lower levels of uromodulin.

CONCLUSIONS

This is the first study of CFVR in living kidney donors. We have shown that the modest drop in estimated glomerular filtration rate in living kidney donors is associated with lower values of Doppler CFVR compared to controls, suggesting that isolated reductions in renal function may lead to altered microvascular function. The increase in hsCRP and reduction in uromodulin suggests that chronic subclinical inflammation may contribute to altered microvascular function in this population.

Renal denervation: where do we stand and what is the relevance to the nephrologist?

Catheter-based renal denervation to reduce high blood pressure (BP) has received well-deserved attention after a recent series of sham-controlled trials reported significant antihypertensive efficacy and very favourable tolerability and safety of the intervention. This emerging treatment option is of high relevance to nephrologists. Patients with chronic kidney disease (CKD) are at elevated risk of cardiovascular adverse events and often present with hypertension, which is very difficult to control with medication. Renal denervation promises a new tool to reduce BP and to prevent loss of renal function in this population. The current review considers the role of the kidney and neurohormonal activation in the development of hypertension and the rationale for renal denervation. The current state of the evidence for the effectiveness and tolerability of the procedure is considered from the nephrologists’ perspective, with a focus on the potential future role of renal denervation in the management of CKD patients with hypertension.

Sympathetic Overactivation in Patients With Essential Hypertension and Hepatic Iron Overload

Iron overload has been recently shown to be associated with a hyperadrenergic state in genetic hemochromatosis. Whether this is also the case in essential hypertension, characterized by sympathetic activation and frequently by body iron overload, is unknown. In 17 healthy normotensive controls (age 52.3±3.2 years, mean±SE), in 21 age-matched patients with hypertension with iron overload (HT+), defined by serum ferritin levels, and in 28 hypertensives without this condition, we measured efferent postganglionic muscle sympathetic nerve traffic (microneurography), heart rate and blood pressure variability (power spectral analysis), serum ferritin, and metabolic variables. Muscle sympathetic nerve traffic was significantly (P<0.02 at least) greater in HT+ than in patients with hypertension without iron overload and normotensive subjects both when expressed as bursts incidence over time (41.8±1.4 versus 31.5±1.4 and 23.6±0.9 bursts/min) and as bursts corrected for heart rate (55.3±1.8 versus 42.3±1.2 and 31.7±1.2 bursts/100 heartbeats). In HT+, low-frequency systolic blood pressure variability was significantly reduced. In HT+, but not in the other 2 groups, muscle sympathetic nerve traffic was significantly related to serum ferritin (r=0.51,P<0.03), transferrin saturation (r=0.47,P<0.03), and hepatic iron load (r=0.76,P<0.0001, magnetic resonance imaging), as well as to homeostatic model assessment index values (r=0.46,P<0.05). These data provide the first evidence that in HT+ elevated serum ferritin is associated with a hyperadrenergic state of greater magnitude than the one seen in patients with hypertension without iron overload. They also show that the potentiation of the sympathetic activation detected in HT+ is related to elevated serum ferritin and to the associated metabolic alterations, possibly participating in the increased cardiovascular risk characterizing iron overload.

Contribution of the Renal Nerves to Hypertension in a Rabbit Model of Chronic Kidney Disease

Overactivity of the sympathetic nervous system and high blood pressure are implicated in the development and progression of chronic kidney disease (CKD) and independently predict cardiovascular events in end-stage renal disease. To assess the role of renal nerves, we determined whether renal denervation (RDN) altered the hypertension and sympathoexcitation associated with a rabbit model of CKD. The model involves glomerular layer lesioning and uninephrectomy, resulting in renal function reduced by one-third and diuresis. After 3-week CKD, blood pressure was 13±2 mm Hg higher than at baseline (P<0.001), and compared with sham control rabbits, renal sympathetic nerve activity was 1.2±0.5 normalized units greater (P=0.01). The depressor response to ganglion blockade was also +8.0±3 mm Hg greater, but total norepinephrine spillover was 8.7±3.7 ng/min lower (bothP<0.05). RDN CKD rabbits only increased blood pressure by 8.0±1.5 mm Hg. Renal sympathetic activity, the response to ganglion blockade and diuresis were similar to sham denervated rabbits (non-CKD). CKD rabbits had intact renal sympathetic baroreflex gain and range, as well as normal sympathetic responses to airjet stress. However, hypoxia-induced sympathoexcitation was reduced by −9±0.4 normalized units. RDN did not alter the sympathetic response to hypoxia or airjet stress. CKD increased oxidative stress markers Nox5 and MCP-1 (monocyte chemoattractant protein-1) in the kidney, but RDN had no effect on these measures. Thus, RDN is an effective treatment for hypertension in this model of CKD without further impairing renal function or altering the normal sympathetic reflex responses to various environmental stimuli.

Haemodialysis and peritoneal dialysis patients have severely impaired post-occlusive skin forearm vasodilatory response assessed with laser speckle contrast imaging

Background

Endothelial dysfunction is associated with cardiovascular events and mortality in various disease states, including end-stage renal disease (ESRD). Novel technological approaches have emerged for real-time assessment of endothelial reactivity. This study examined skin microcirculation using laser speckle contrast imaging (LSCI) before and after arterial occlusion in ESRD patients undergoing haemodialysis (HD) or peritoneal dialysis (PD).

Methods

The 38 HD patients were matched in a 1:1 ratio with 38 PD patients (for age, sex and dialysis vintage) and 38 controls (for age and sex). Skin microvascular reactivity parameters assessed with LSCI included baseline perfusion, occlusion perfusion and peak perfusion during post-occlusive reactive hyperaemia (PORH); time to peak perfusion; proportional change from baseline to peak perfusion; baseline and peak cutaneous vascular conductance (CVC); proportional change from baseline to peak CVC and amplitude of the PORH response (i.e. the difference between peak and baseline CVC).

Results

Baseline perfusion [HD: 46.97 ± 14.6; PD: 49.32 ± 18.07; controls: 42.02 ± 11.94 laser specle perfusion units (LSPU), P = 0.097] and peak post-occlusion perfusion (104.77 ± 28.68 versus 109.04 ± 40.77 versus 116.96 ± 30.96 LSPU, P = 0.238) did not differ significantly between groups. However, the post-occlusive vascular response was completely different since the proportional increase from baseline to peak perfusion (HD: 133 ± 66; PD: 149 ± 125; controls: 187 ± 61%, P = 0.001) was significantly lower in ESRD patients and time to peak response was lower in HD but similar in PD patients compared with controls (HD: 7.24 ± 6.99; PD: 10.68 ± 9.45; controls: 11.11 ± 5.1 s, Kruskal–Wallis P = 0.003; pairwise comparisons: HD versus controls, P = 0.002; HD versus PD, P = 0.154; PD versus controls, P = 0.406). ESRD patients also had lower levels of peak CVC, indicating the maximum capillary recruitment (HD: 1.05 ± 0.3; PD: 1.07 ± 0.44; controls: 1.57 ± 0.52 LSPU/mmHg, P < 0.001), lower proportional increase of CVC at peak (P < 0.001) and lower amplitude of the PORH response, a measure of the difference between baseline and maximum capillary recruitment (P = 0.001).

Conclusions

Using this novel non-invasive technology, endothelial post-occlusive forearm skin vasodilatory response was found to be similar between HD and PD patients and significantly impaired compared with controls. Future studies are needed to assess the prognostic implications of this microcirculatory functional defect.

Effects of renal denervation on kidney function and long-term outcomes: 3-year follow-up from the Global SYMPLICITY Registry

Aims

Several studies and registries have demonstrated sustained reductions in blood pressure (BP) after renal denervation (RDN). The long-term safety and efficacy after RDN in real-world patients with uncontrolled hypertension, however, remains unknown. The objective of this study was to assess the long-term safety and efficacy of RDN, including its effects on renal function.

Methods and results

The Global SYMPLICITY Registry is a prospective, open-label registry conducted at 196 active sites worldwide in hypertensive patients receiving RDN treatment. Among 2237 patients enrolled and treated with the SYMPLICITY Flex catheter, 1742 were eligible for follow-up at 3 years. Baseline office and 24-h ambulatory systolic BP (SBP) were 166 ± 25 and 154 ± 18 mmHg, respectively. SBP reduction after RDN was sustained over 3 years, including decreases in both office (−16.5 ± 28.6 mmHg, P < 0.001) and 24-h ambulatory SBP (−8.0 ± 20.0 mmHg; P < 0.001). Twenty-one percent of patients had a baseline estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m². Between baseline and 3 years, renal function declined by 7.1 mL/min/1.73 m² in patients without chronic kidney disease (CKD; eGFR ≥60 mL/min/1.73 m²; baseline eGFR 87 ± 17 mL/min/1.73 m²) and by 3.7 mL/min/1.73 m² in patients with CKD (eGFR <60 mL/min/1.73 m²; baseline eGFR 47 ± 11 mL/min/1.73 m²). No long-term safety concerns were observed following the RDN procedure.

Conclusion

Long-term data from the Global SYMPLICITY Registry representing the largest available cohort of hypertensive patients receiving RDN in a real-world clinical setting demonstrate both the safety and efficacy of the procedure with significant and sustained office and ambulatory BP reductions out to 3 years.

Renal 123I-MIBG Uptake before and after Live-Donor Kidney Transplantation

Increased sympathetic activity is suggested to be part of the pathogenesis in several diseases. Methods to evaluate sympathetic activity and renal nervous denervation procedural success are lacking. Scintigraphy using the norepinephrine analog Iodine-123 Metaiodobenzylguanidine (123I-MIBG) might provide information on renal sympathetic nervous activity. Renal transplantation induces complete denervation of the kidney and as such represents an ideal model to evaluate the renal 123I-MIBG scintigraphy method. The aim of this study was to evaluate whether renal 123I-MIBG scintigraphy can detect changes in renal sympathetic nervous activity following renal transplantation. Renal 123I-MIBG scintigraphy was performed in eleven renal transplant recipients at 1, 3, and 6 months following transplantation and in their respective living donors prior to their kidney donation. Relative uptake as well as washout was obtained. In transplanted patients, the relative 4 h uptake of 123I-MIBG, as measured by the kidney/background ratio, was 2.7 (0.4) (mean (SD)), 2.7 (0.5), and 2.5 (0.4) at 1, 3, and 6 months post-transplantation, respectively, as compared with the 4.0 (0.4) value in the donor kidney before donor nephrectomy (p < 0.01). There was no significant change in washout-rate between pre-transplantation and any of the follow-up time points. Living donor kidney transplantation was at 6 months post transplantation, associated with an almost 40% reduction in the relative 4 h 123I-MIBG uptake of the kidney. Further studies will help to fully establish its implications as a marker of renal innervation or denervation.

Sympathetic nerve traffic overactivity in chronic kidney disease: a systematic review and meta-analysis

BACKGROUND

Studies based on microneurographic sympathetic nerve activity (MSNA) recordings have shown that the sympathetic system is overactivated in chronic kidney disease (CKD) patients but the relationship between MSNA and renal function and other risk factors has not been systematically reviewed in this population.

DESIGN AND MEASUREMENTS

This meta-analysis compares MSNA in cardiovascular complications-free CKD patients (n = 638) and healthy individuals (n = 372) and assesses the relationship of MSNA with the eGFR, age, BMI and hemodynamic variables.

RESULTS

In a global analysis, MSNA was higher in CKD patients than in healthy control individuals (P < 0.001). The difference in MSNA between patients and healthy individuals was more marked in end-stage kidney diseases patients than in stage 3A 3B CKD patients (P < 0.001). In an analysis combining patients and healthy individuals, MSNA rose gradually across progressively lower eGFR categories (P < 0.01). In separate meta-regression analyses in CKD patients and in healthy individuals, MSNA associated directly with age (CKD: r = 0.57, P = 0.022; healthy individuals: r = 0.71, P = 0.031) and with the BMI (r = 0.75, P = 0.001 and r = 0.93, P = 0.003). In both groups, MSNA correlated with heart rate (r = 0.77, P = 0.02 and r = 0.66, P = 0.01) but was unrelated to plasma norepinephrine.

CONCLUSION

Independently of comorbidities, MSNA is markedly increased in CKD patients as compared with healthy individuals and it is related to renal function, age, the BMI and heart rate. Sympathetic activation intensifies as CKD progresses toward kidney failure and such an intensification is paralleled by a progressive rise in heart rate but it is not reflected by plasma norepinephrine.