Sympatho-renal axis in chronic disease

The road to renal denervation for hypertension and beyond (HF): two decades of failed, succeeded, and to be determined

Activation of the sympathetic nervous system has been attributed to the development of hypertension. Two established approaches for treating hypertension are pharmacotherapy and lifestyle changes. With an improved understanding of renal nerve anatomy and physiology, renal denervation has been proposed as an alternative treatment for hypertension. Specifically, it has been shown that the interruption of sympathetic nerves connecting the kidney and the sympathetic nervous system can reduce blood pressure. Here, we present a review on how renal denervation can help hypertension patients, specifically focusing on our novel understanding of renal nerve anatomy, denervation technique, and subsequent clinical trials, and how it may be used to treat other cardiovascular diseases like heart failure.

Impact of renal denervation on cardiac remodeling in resistant hypertension: A meta-analysis

Twelve studies involving 433 patients were included. After RDN treatment, LVMI decreased by 13.08 g/m2 (95% confidence interval [CI]: -18.38, -7.78; p < .00001), PWTd decreased by 0.60 mm (95% CI: -0.87, -0.34; p < .00001), IVSTd decreased by 0.78 mm (95% CI: -1.06, -0.49; p < .00001), and LVEF increased by 1.80% (95% CI: 0.71, 2.90; p = .001). However, there were no statistically significant improvements in LVIDd (95% CI: -1.40, 0.24; p = .17) and diastolic function (E/A) (95% CI: -0.04, 0.14; p = .28). Drug treatment for resistant hypertension (RH) is challenging. Renal denervation (RDN) is one of the most promising treatments for RH. Although studies have shown RDN can control blood pressure, the impacts of RDN on cardiac remodeling and cardiac function are unclear. This meta-analysis evaluated the effect of RDN on cardiac structure and function in patients with RH. PubMed, Embase, and Cochrane were used to conduct a systematic search. The main inclusion criteria were studies on patients with RH who received RDN and reported the changes in echocardiographic parameters before and after RDN. Echocardiographic parameters included left ventricular mass index (LVMI), end-diastolic left ventricular internal dimension (LVIDd), left ventricular end-diastolic posterior wall thickness (PWTd), end-diastolic interventricular septum thickness (IVSTd), E/A, and left ventricular ejection fraction (LVEF). Data was analyzed using RevMan. Twelve studies involving 433 patients were included. After RDN treatment, LVMI decreased by 13.08g/m2 (95%confidence interval [CI]: -18.38, -7.78, p < .00001), PWTd decreased by 0.60mm (95% CI: -0.87, -0.34, p < 0.00001), IVSTd decreased by 0.78mm (95% CI: -1.06, -0.49, p < .00001), and LVEF increased by 1.80% (95% CI: 0.71, 2.90, p = .001). However, there were no statistically significant improvements in LVIDd (95% CI: -1.40, 0.24, p = .17) and diastolic function (E/A) (95% CI: -0.04, 0.14, p =.28). This meta-analysis finds that RDN can improve left ventricular hypertrophy and ejection fraction in patients with RH but has no significant effect on LVIDd and diastolic function. However, more studies are warranted due to the lack of a strict control group, a limited sample size, and research heterogeneity.

The role of renal denervation in cardiology and beyond: An updated comprehensive review and future directives

Renal denervation (RDN) is a minimally invasive intervention performed by denervation of the nervous fibers in the renal plexus, which decreases sympathetic activity. These sympathetic nerves influence various physiological functions that regulate blood pressure (BP), including intravascular volume, electrolyte composition, and vascular tone. Although proven effective in some trials, controversial trials, such as the Controlled Trial of Renal Denervation for Resistant Hypertension (SYMPLICITY-HTN3), have demonstrated contradictory results for the effectiveness of RDN in resistant hypertension (HTN). In the treatment of HTN, individuals with primary HTN are expected to experience greater benefits compared to those with secondary HTN due to the diverse underlying causes of secondary HTN. Beyond its application for HTN, RDN has also found utility in addressing cardiac arrhythmias, such as atrial fibrillation, and managing cases of heart failure. Non-cardiogenic applications of RDN include reducing the intensity of obstructive sleep apnea (OSA), overcoming insulin resistance, and in chronic kidney disease (CKD) patients. This article aims to provide a comprehensive review of RDN and its uses in cardiology and beyond, along with providing future directions and perspectives.

Neuromodulation Therapies in Heart Failure: A State-of-the-Art Review

Heart failure (HF) continues to impact the population globally with increasing prevalence. While the pathophysiology of HF is quite complex, the dysregulation of the autonomic nervous system, as evident in heightened sympathetic activity, serves as an attractive pathophysiological target for newer therapies and HF. The degree of neurohormonal activation has been found to correlate to the severity of symptoms, decline in functional capacity, and mortality. Neuromodulation of the autonomic nervous system aims to restore the balance between sympathetic nervous system and the parasympathetic nervous system. Given that autonomic dysregulation plays a major role in the development and progression of HF, restoring this balance may potentially have an impact on the core pathophysiological mechanisms and various HF syndromes. Autonomic modulation has been proposed as a potential therapeutic strategy aimed at reduction of systemic inflammation. Such therapies, complementary to drug and device-based therapies may lead to improved patient outcomes and reduce disease burden. Most professional societies currently do not provide a clear recommendation on the use of neuromodulation techniques in HF. These include direct and indirect vagal nerve stimulation, spinal cord stimulation, baroreflex activation therapy, carotid sinus stimulation, aortic arch stimulation, splanchnic nerve modulation, cardiopulmonary nerve stimulation, and renal sympathetic nerve denervation. In this review, we provide a comprehensive overview of neuromodulation in HF.

The denervation or activation of renal sympathetic nerve and renal blood flow

The denervation or activation of the sympathetic nerve in the kidney can affect renal hemodynamics. The sympathetic nervous system regulates the physiological functions of the kidneys. Stimulation of sympathetic efferent nerves affects various parameters related to renal hemodynamics, including sodium excretion, renin secretion, and renal blood flow (RBF). Hence, renal sympathetic fibers may also play an essential role in regulating systemic vascular resistance and controlling blood pressure. In the absence of renal nerves, the hemodynamics response to stimuli is negligible or absent. The effect of renal sympathetic denervation on RBF is dependent on several factors such as interspecies differences, the basic level of nerve activity in the vessels or local density of adrenergic receptor in the vascular bed. The role of renal denervation has been investigated therapeutically in hypertension and related disorders. Hence, the dynamic impact of renal nerves on RBF enables using RBF dynamic criteria as a marker for renal denervation therapy.

Effects of electroacupuncture at KI3 and ST36 on the hypothalamic paraventricular nucleus in a rat model of chronic glomerulonephritis

OBJECTIVE

The hypothalamic paraventricular nucleus (PVN) acts as a critical integrating center of endocrine/autonomic responses and regulates visceral functional activities. However, its involvement in electroacupuncture (EA) treatment of chronic glomerulonephritis (CGN) remains unclear.

METHODS

Over four experiments, we randomized 111 rats into: control, untreated model (CGN) or EA-treated model (CGN + EA) groups, a model group receiving EA after PVN damage (CGN + EA + Lesion) or untreated model groups injected with adeno-associated viral vectors encoding human M4 muscarinic receptor (CGN + hM4D) or enhanced green fluorescent protein (CGN + EGFP). CGN was modeled by intraperitoneal injection of bovine serum albumin for 2 weeks. Rats in the CGN + EA and CGN + EA + Lesion groups received EA at bilateral ST36 and KI3 for 14 days. Urine/serum samples were collected to evaluate inflammatory factors and changes in renal function.

RESULTS

EA inhibited the release of interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-1β, and decreased urine protein (PRO), creatinine (Cre) and blood urea nitrogen (BUN) levels. PVN damage influenced the effect of EA on the levels of these parameters. EA appeared to inhibit the firing frequency and spectral energy of PVN neurons. In the viral vector experiment, levels of PRO, Cre, IL-6, IL-1β and TNF-α in the CGN group were increased in CGN versus control groups (p < 0.0001), decreased in CGN + hM4D versus CGN groups (p < 0.05) and did not differ between CGN + EGFP and control groups (p > 0.05).

CONCLUSION

Our findings indicate that EA at ST36 and KI3 improves CGN in this rat model by weakening the activity of PVN neurons, alleviating impairment of renal function impairment and restricting the release of inflammatory factors.

Autonomic nervous system and cardiac neuro-signaling pathway modulation in cardiovascular disorders and Alzheimer's disease

The heart is a functional syncytium controlled by a delicate and sophisticated balance ensured by the tight coordination of its several cell subpopulations. Accordingly, cardiomyocytes together with the surrounding microenvironment participate in the heart tissue homeostasis. In the right atrium, the sinoatrial nodal cells regulate the cardiac impulse propagation through cardiomyocytes, thus ensuring the maintenance of the electric network in the heart tissue. Notably, the central nervous system (CNS) modulates the cardiac rhythm through the two limbs of the autonomic nervous system (ANS): the parasympathetic and sympathetic compartments. The autonomic nervous system exerts non-voluntary effects on different peripheral organs. The main neuromodulator of the Sympathetic Nervous System (SNS) is norepinephrine, while the principal neurotransmitter of the Parasympathetic Nervous System (PNS) is acetylcholine. Through these two main neurohormones, the ANS can gradually regulate cardiac, vascular, visceral, and glandular functions by turning on one of its two branches (adrenergic and/or cholinergic), which exert opposite effects on targeted organs. Besides these neuromodulators, the cardiac nervous system is ruled by specific neuropeptides (neurotrophic factors) that help to preserve innervation homeostasis through the myocardial layers (from epicardium to endocardium). Interestingly, the dysregulation of this neuro-signaling pathway may expose the cardiac tissue to severe disorders of different etiology and nature. Specifically, a maladaptive remodeling of the cardiac nervous system may culminate in a progressive loss of neurotrophins, thus leading to severe myocardial denervation, as observed in different cardiometabolic and neurodegenerative diseases (myocardial infarction, heart failure, Alzheimer's disease). This review analyzes the current knowledge on the pathophysiological processes involved in cardiac nervous system impairment from the perspectives of both cardiac disorders and a widely diffused and devastating neurodegenerative disorder, Alzheimer's disease, proposing a relationship between neurodegeneration, loss of neurotrophic factors, and cardiac nervous system impairment. This overview is conducive to a more comprehensive understanding of the process of cardiac neuro-signaling dysfunction, while bringing to light potential therapeutic scenarios to correct or delay the adverse cardiovascular remodeling, thus improving the cardiac prognosis and quality of life in patients with heart or neurodegenerative disorders.

Pharmacotherapy for Essential Hypertension: A Brief Review

Hypertension is one of the leading causes of disability-adjusted life years and mortality, with approximately 15% prevalence worldwide. Most patients with hypertension from low- to high-income countries do not receive treatment. Among those who receive treatment, the majority remain undertreated and do not achieve their blood pressure goals. Therefore, new hypertension guidelines introduce more conscientious treatment strategies to maximize the probability of achieving the new strict blood pressure goals compared with the previous guidelines. Who should receive treatment for hypertension? Which antihypertensive medications have the strongest supporting data? Are generic and more affordable medications as effective as expensive brand medications? What are the different treatment strategies to maximize success in controlling blood pressure? Here, we briefly review pharmacotherapy for hypertension and provide answers to these questions as well as some other common questions regarding treatment of hypertension.

The sympathies of the body: functional organization and neuronal differentiation in the peripheral sympathetic nervous system

During the last 30 years, our understanding of the development and diversification of postganglionic sympathetic neurons has dramatically increased. In parallel, the list of target structures has been critically extended from the cardiovascular system and selected glandular structures to metabolically relevant tissues such as white and brown adipose tissue, lymphoid tissues, bone, and bone marrow. A critical question now emerges for the integration of the diverse sympathetic neuron classes into neural circuits specific for these different target tissues to achieve the homeostatic regulation of the physiological ends affected.

Improving Diuretic Response in Heart Failure by Implementing a Patient-Tailored Variability and Chronotherapy-Guided Algorithm

Heart failure is a major public health problem, which is associated with significant mortality, morbidity, and healthcare expenditures. A substantial amount of the morbidity is attributed to volume overload, for which loop diuretics are a mandatory treatment. However, the variability in response to diuretics and development of diuretic resistance adversely affect the clinical outcomes. Morevoer, there exists a marked intra- and inter-patient variability in response to diuretics that affects the clinical course and related adverse outcomes. In the present article, we review the mechanisms underlying the development of diuretic resistance. The role of the autonomic nervous system and chronobiology in the pathogenesis of congestive heart failure and response to therapy are also discussed. Establishing a novel model for overcoming diuretic resistance is presented based on a patient-tailored variability and chronotherapy-guided machine learning algorithm that comprises clinical, laboratory, and sensor-derived inputs, including inputs from pulmonary artery measurements. Inter- and intra-patient signatures of variabilities, alterations of biological clock, and autonomic nervous system responses are embedded into the algorithm; thus, it may enable a tailored dose regimen in a continuous manner that accommodates the highly dynamic complex system.

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.

The use of echocardiography as a health assessment tool in green sea turtles (Chelonia mydas)

There are limited techniques available to assess the health of sea turtles as physical examination has little correlation to clinical findings, and blood reference intervals are broad and provide limited prognostic significance. Advances in the portability of ultrasound machines allow echocardiography to be increasingly used in the health assessments of wild animals. This study performed blood analysis and echocardiograms on 11 green sea turtles upon admission to a rehabilitation clinic and six animals before release. Significant differences were seen between groups, with admission animals having significantly smaller diameters of the cavum arteriosum at systole and diastole, smaller E-waves and an increased fractional shortening. Pre-release animals displayed significant increases in the maximum blood velocities of both the pulmonary artery and the left aorta. Significant negative correlations were seen between fractional shortening and uric acid and between the velocity time integral of the pulmonary artery and urea. The pulmonary artery velocity time integral was also significantly correlated to the E wave. Furthermore, there was asynchrony between the cavum arteriosum and the cavum pulmonale and the detection of a parasitic granuloma in the ventricular outflow tract of one animal. Overall, the results suggest that cardiac function in stranded green sea turtles is significantly impaired and that echocardiography has applications in the health assessments of green sea turtles.

A drug-induced hypotensive challenge to verify catheter-based radiofrequency renal denervation in an obese hypertensive swine model

Objective

Sham-controlled trials provided proof-of-principle for the blood pressure-lowering effect of catheter-based renal denervation (RDN). However, indicators for the immediate assessment of treatment success are lacking. This study sought to investigate the impact of RDN on renal renin arteriovenous difference (renal renin AV-Δ) following a hypotensive challenge (HC).

Methods

Twelve hypertensive Ossabaw swine underwent either combined surgical and chemical (n = 3) or catheter-based RDN (n = 9). A telemetry monitor was implanted to acquire hemodynamic data continuously. Before and after RDN, a sodium nitroprusside-induced HC was performed. Renal renin AV-Δ was calculated as the difference of plasma renin concentrations drawn from the renal artery and vein.

Results

In total, complete renal renin AV data were obtained in eight animals at baseline and six animals at baseline and 3 months of follow-up. Baseline renal renin AV-Δ correlated inversely with change in 24-h minimum systolic (− 0.764, p = 0.02), diastolic (r = − 0.679, p = 0.04), and mean (r = − 0.663, p = 0.05) blood pressure. In the animals with complete renin secretion data at baseline and follow-up, the HC increased renal renin AV-Δ at baseline, while this effect was attenuated following RDN (0.55 ± 0.34 pg/ml versus − 0.10 ± 0.16 pg/ml, p = 0.003). Renin urinary excretion remained unchanged throughout the study (baseline 0.286 ± 0.187 pg/ml versus termination 0.305 ± 0.072 pg/ml, p = 0.789).

Conclusion

Renin secretion induced by HC was attenuated following RDN and may serve as an indicator for patient selection and guide successful RDN procedures.

Prediction and measurement of diuretic responsiveness after oral administration of furosemide to healthy dogs and dogs with congestive heart failure

Background

In human patients, cumulative urine volume (uVol) and urine sodium (uNa) can be predicted using spot urine samples and these quantitative measures help detect low diuretic responsiveness (LDR).

Hypothesis/objectives

Formulas using spot urine samples predict cumulative uVol and uNa output after oral administration of furosemide to dogs.

Animals

Eight healthy dogs, 6 dogs with congestive heart failure (CHF).

Methods

Prospective interventional study. Spot urine samples at 180 and 270 minutes after furosemide (3 mg/kg PO) were used to predict cumulative uVol and uNa output over 7 hours. Differentiation of dogs fulfilling predefined criteria for LDR was examined using receiver operating characteristic (ROC) curves.

Results

Predicted uNa output at 180 minutes (r_s = 0.763, [95% confidence interval [CI], 0.375‐0.923], P = .002) and 270 minutes (r = 0.816, [95% CI, 0.503‐0.940], P < .001) was highly correlated to 7‐hour uNa output. Predicted uVol at 180 minutes (r = 0.598, [95% CI, 0.098‐0.857], P = .02) and 270 minutes (r = 0.791, [95% CI, 0.450‐0.931], P < .001) was moderately correlated to 7‐hour uVol. Predicted uNa using 180‐minute (area under the curve [AUC], 0.933 [95% CI, 0.804‐1.000]) and 270‐minute (AUC, 0.911 [95% CI, 0.756‐1.000]) samples identified dogs with LDR (n = 5) with high accuracy.

Conclusions and Clinical Importance

Urinary Na excretion and uVol are complementary but distinct aspects of diuretic responsiveness in dogs. Quantification of diuretic responsiveness in the clinical setting opens new diagnostic, treatment, and monitoring strategies.

Renal Denervation to Treat Heart Failure

Heart failure (HF) is a global pandemic with a poor prognosis after hospitalization. Despite HF syndrome complexities, evidence of significant sympathetic overactivity in the manifestation and progression of HF is universally accepted. Confirmation of this dogma is observed in guideline-directed use of neurohormonal pharmacotherapies as a standard of care in HF. Despite reductions in morbidity and mortality, a growing patient population is resistant to these medications, while off-target side effects lead to dismal patient adherence to lifelong drug regimens. Novel therapeutic strategies, devoid of these limitations, are necessary to attenuate the progression of HF pathophysiology while continuing to reduce morbidity and mortality. Renal denervation is an endovascular procedure, whereby the ablation of renal nerves results in reduced renal afferent and efferent sympathetic nerve activity in the kidney and globally. In this review, we discuss the current state of preclinical and clinical research related to renal sympathetic denervation to treat HF.

Open-loop analysis on sympathetically mediated arterial pressure and urine output responses in rats: effect of renal denervation

Primary acute sympathetic activation (PASA) can increase arterial pressure (AP). Under this situation, the kidneys may receive mutually opposing influences from sympathetic activation: a direct anti-diuretic effect via the renal innervation and pressure diuresis. We examined whether PASA would reduce urine output regardless of the AP elevation. We also examined the impact of renal denervation (RDN) on urine output during PASA. The experiment was performed on rats 3 to 9 days after unilateral RDN (n = 10). Under anesthesia, systemic sympathetic nerve activity (SNA) was varied over a wide range via the carotid sinus baroreflex. The slope of urine flow versus SNA was positive (0.252 ± 0.052 μL·min-1·kg-1· %-1) on the intact side, and it was greater on the denervated side (0.331 ± 0.069 μL·min-1·kg-1· %-1, P < 0.05). In conclusion, urine output change was an effect of elevated AP during PASA. Nevertheless, RDN was able to augment pressure diuresis during PASA.

Increased Intra-Abdominal Pressure During Laparoscopic Pneumoperitoneum Enhances Albuminuria via Renal Venous Congestion, Illustrating Pathophysiological Aspects of High Output Preeclampsia

Intra-abdominal hypertension (IAH) causes severe organ dysfunction. Our aim is to evaluate the effect of increased intra-abdominal pressure (IAP) on renal function, hypothesizing that venous congestion may increase proteinuria and fluid retention without endothelial dysfunction. Three urine samples were collected from 32 non-pregnant women undergoing laparoscopic-assisted vaginal hysterectomy (LAVH) and from 10 controls placed in Trendelenburg position for 60 min. Urine sampling was done before (PRE), during or immediately after (PER), and two hours after (POST) the procedure. Urinary albumin, protein and creatinine concentrations were measured in each sample, and ratios were calculated and compared within and between groups. During LAVH, the albumin/creatinine ratio (ACR) increased and persisted POST-procedure, which was not observed in controls. A positive correlation existed between the LAVH duration and the relative change in both ACR and protein/creatinine ratio (PCR) PER- and POST-procedure. Iatrogenic IAH increases urinary ACR and PCR in non-pregnant women via a process of venous congestion. This mechanism might explain the presentation of one specific subtype of late-onset preeclampsia, where no drop of maternal cardiac output is observed.

Precise characterization of urinary tract innervation using three-dimensional reconstruction: A contemporary review

A precise understanding of the autonomic innervation of the urinary tract is crucial to successful management of urologic disease given the important role that neurophysiology plays in genitourinary pathology. Recent studies using a combination of contemporary histopathology and imaging technologies have furthered our understanding of the spatial nerve distribution in the kidneys, ureters, and bladder. The findings of these recent studies may have important clinical applications in expanding our knowledge of the etiology and treatment of disease processes affecting the urinary tract. In this narrative review, our goal is to provide an overview of the autonomic innervation of the urinary tract. Specifically, we aim to provide a three-dimensional gender-specific description of renal, ureteral and vesical innervation. We also highlight some possible opportunities for clinical and investigational application of this new knowledge.

Cardiorenal Syndrome and Heart Failure-Challenges and Opportunities

Cardiorenal syndromes (CRS) describe concomitant bidirectional dysfunction of the heart and kidneys in which 1 organ initiates, perpetuates, and/or accelerates decline of the other. CRS are common in heart failure and universally portend worsened prognosis. Despite this heavy disease burden, the appropriate diagnosis and classification of CRS remains problematic. In addition to the hemodynamic drivers of decreased renal perfusion and increased renal vein pressure, induction of the renin-angiotensin-aldosterone system, stimulation of the sympathetic nervous system, disruption of balance between nitric oxide and reactive oxygen species, and inflammation are implicated in the pathogenesis of CRS. Medical therapy of heart failure including renin-angiotensin-aldosterone system inhibition and β-adrenergic blockade can blunt these deleterious processes. Renovascular disease can accelerate the progression of CRS. Volume overload and diuretic resistance are common and complicate the management of CRS. In heart failure and CRS being treated with diuretics, worsening creatinine is not associated with worsened outcome if clinical decongestion is achieved. Adjunctive therapy is often required in the management of volume overload in CRS, but evidence for these therapies is limited. Anemia and iron deficiency are importantly associated with CRS and might amplify decline of cardiac and renal function. End-stage cardiac and/or renal disease represents an especially poor prognosis with limited therapeutic options. Overall, worsening renal function is associated with significantly increased mortality. Despite progress in the area of CRS, there are still multiple pathophysiological and clinical aspects of CRS that need further research to eventually develop effective therapeutic options.

The regulation effect of WNT-RAS signaling in hypothalamic paraventricular nucleus on renal fibrosis

Background

Abnormal activation of wnt/β-catenin signaling and renin-angiotensin system is known to play a vital role in the development and progression of CKD. We hypothesized that abnormal expression of central wnt/β-catenin signaling and renin-angiotensin system (WNT-RAS signaling) was tightly involved in CKD.

Methods

We established sham-operated and 5/6 nephrectomized (5/6 NX) rat model and blocked the central wnt signaling by intracerebroventricular injection of adeno-associated virus vector which can overexpress target gene DKK1. The central and renal expression level of wnt/β-catenin signaling and RAS and renal injury were assessed.

Results

The expression levels of the main wnt/β-catenin signaling components in both brain and kidney of 5/6NX rats, such as wnt3a and active-β-catenin, were elevated obviously and the up-regulation were inhibited by central blockade of the wnt signaling. Furthermore, the expression of the major components of RAS in both brain and kidney in 5/6NX rats, such as angiotensinogen (AGT), angiotensin converting enzyme (ACE-1), angiotensin II AT1-receptor (AT1R), was significantly up-regulated and the up-regulated expression was inhibited by central blockade of the wnt singling. Notably, central blockade of the wnt signaling improved renal function as indicated by decreased serum creatinine and 24 h urinary protein, and attenuated interstitial fibrosis as indicated by reduced Sirius red staining and expression of Fibronectin, Collagen-I and α-SMA.

Conclusion

These data suggest that the central WNT-RAS signaling plays a significant role in the development and progression of CKD.

Acute changes in morphology and renal vascular relaxation function after renal denervation using temperature-controlled radiofrequency catheter

BACKGROUND

Resistant hypertension and renal sympathetic hyperactivity are closely linked, and catheter-based renal denervation (RDN) is regarded as a new treatment strategy. However, the acute changes in vascular morphology and relaxation function have yet to be evaluated, and these may be important for the efficacy and safety of the procedure. In this study, we explored these questions by conventional temperature-controlled cardiac radiofrequency catheter-based RDN in a pig model.

METHODS

Six mini-pigs were randomly divided into the renal denervation (RDN) group (n = 3) and the Sham-RDN group (n = 3). Animals in the RDN group underwent unilateral radiofrequency ablation, and those in the Sham-RDN group underwent the same procedure except for the ablation. The pigs were examined by angiography pre- and post-RDN and were euthanized immediately thereafter. Renal arteries were processed for histological and molecular biology analyses as well as for in vitro vascular tension testing.

RESULTS

Compared with the Sham-RDN group, the RDN caused vascular intima and media injury, renal nerve vacuolization, mild collagen fiber hyperplasia and elastic fiber cleavage (all p < 0.05). The RDN group also significantly exhibited nitric oxide synthase pathway inhibition and decreased endothelium-independent vascular relaxation function Compared to the Sham-RDN group (all p < 0.05).

CONCLUSIONS

In this porcine model, renal artery denervation led to vascular wall injury and endothelial dysfunction in the acute phase, which negatively affected vascular relaxation function. Thus, this process may be detrimental to the prognosis and progress of hypertension patients.

Sympathoadrenergic suppression improves heart function by upregulating the ratio of sRAGE/RAGE in hypertension with metabolic syndrome

Receptors-for-Advanced-Glycation-End-products (RAGE) activate pro-inflammatory programs mediated by carboxymethyllysine (CML) and high-mobility-group-box1 protein (HMGB1). The soluble isoform sRAGE neutralizes RAGE-ligands preventing cardiovascular complications in conditions associated with increased sympathetic activation like hypertension and diabetes. The effects of sympathetic modulation on RAGE/sRAGE-balance and end-organ damage in metabolic syndrome on top of hypertension remains unknown. We hypothesized that increased sympathoadrenergic activity might lead to an unfavourable RAGE/sRAGE regulation. Renal denervation (RDN) was used to modulate sympathetic activation in obese spontaneously hypertensive rats (SHRobRDN) versus sham-operated obese spontaneously hypertensive rats (SHRob), their hypertensive lean controls (SHR) and non-hypertensive controls. Cardiac fibrosis was assessed by histological analysis and sRAGE/RAGE and ligand levels by Western blotting. Levels of CML and HMGB1 were highest in SHRob and were significantly lowered by RDN in serum (-44% and -45%) and myocardium (-25% and -52%). Myocardial RAGE was increased in SHR (+72% versus controls) and in SHRob (+68% versus SHR) while sRAGE decreased (-50% in SHR versus controls and -51% in SHRob versus SHR). RDN reduced myocardial RAGE expression. (-20%) and increased sRAGE levels in heart (+80%) and serum (+180%) versus sham-operated SHRob. Myocardial fibrosis correlated inversely with myocardial sRAGE content (r = -0.79; p = .004; n = 10). Myocardial sRAGE shedding active A-Disintegrin-And-Metalloprotease-10 (ADAM-10) was decreased in SHR (-33% versus controls) and in SHRob (-54% versus SHR), and was restored after RDN (+129% versus SHRob). Serum ADAM-10 activity was also decreased in SHRob (-66% versus SHR) and restored after RDN (+150% versus SHRob). In vitro, isoproterenol induced a ß1-adrenergic receptor mediated increase of RAGE expression in splenocytes (+200%) and decreased sRAGE secretion of splenocytes and cardiac fibroblasts (-50% and -49%) by ß2-adrenergic receptor stimulation mediated suppression of ADAM-10 activity. In conclusion, sympathetic activity affects sRAGE/RAGE-balance, which can be suppressed through sympathetic modulation by RDN, preventing RAGE-induced cardiac damage in hypertension with metabolic syndrome.

Selective vs. Global Renal Denervation: a Case for Less Is More

PURPOSE OF REVIEW

Review the renal nerve anatomy and physiology basics and explore the concept of global vs. selective renal denervation (RDN) to uncover some of the fundamental limitations of non-targeted renal nerve ablation and the potential superiority of selective RDN.

RECENT FINDINGS

Recent trials testing the efficacy of RDN showed mixed results. Initial investigations targeted global RDN as a therapeutic goal. The repeat observation of heterogeneous response to RDN including non-responders with lack of a BP reduction, or even more unsettling, BP elevations after RDN has raised concern for the detrimental effects of unselective global RDN. Subsequent studies have suggested the presence of a heterogeneous fiber population and the potential utility of renal nerve stimulation to identify sympatho-stimulatory fibers or "hot spots." The recognition that RDN can produce heterogeneous afferent sympathetic effects both change therapeutic goals and revitalize the potential of therapeutic RDN to provide significant clinical benefits. Renal nerve stimulation has emerged as potential tool to identify sympatho-stimulatory fibers, avoid sympatho-inhibitory fibers, and thus guide selective RDN.

Anatomical and procedural determinants of ambulatory blood pressure lowering following catheter-based renal denervation using radiofrequency

BACKGROUND/PURPOSE

Catheter-based renal sympathetic denervation (RDN) has been introduced to lower blood pressure (BP) and sympathetic activity in patients with uncontrolled hypertension with at best equivocal results. It has been postulated that anatomic and procedural elements introduce unaccounted variability and yet little is known of the impact of renal anatomy and procedural parameters on BP response to RDN.

METHODS/MATERIALS

Anatomical parameters such as length and diameter were analyzed by quantitative vascular analysis and the prevalence of accessory renal arteries and renal artery disease were documented in 150 patients with resistant hypertension undergoing bilateral RDN using a mono-electrode radiofrequency catheter (Symplicity Flex, Medtronic).

RESULTS

Accessory renal arteries and renal artery disease were present in 56 (37%) and 14 patients (9%), respectively. At 6-months, 24 h-ambulatory BP was reduced by 11/6 mm Hg (p < 0.001 for both). Change of systolic blood pressure (SBP) was not related to the presence of accessory renal arteries (p = 0.543) or renal artery disease (p = 0.598). Patients with at least one main renal artery diameter ≤ 4 mm had a more pronounced reduction of 24 h-ambulatory SBP compared to patients where both arteries were >4 mm (-19 vs. -10 mmHg; p = 0.038). Neither the length of the renal artery nor the number of RF ablations influenced 24 h-ambulatory BP reduction at 6 months.

CONCLUSIONS

24 h-ambulatory BP lowering was most pronounced in patients with smaller renal artery diameter but not related to renal artery length, accessory arteries or renal artery disease. Further, there was no dose-response relationship observed with increasing number of ablations.

CONDENSED ABSTRACT

Because little is known of the impact of renal anatomy and procedural parameters on blood pressure (BP) response to renal denervation (RDN), anatomical and procedural data were analyzed in 150 patients undergoing bilateral RDN. BP lowering was most pronounced in patients with smaller renal artery diameter but not related to renal artery length, the presence of renal artery disease or accessory renal arteries. Further, there was no dose-response relationship observed with increasing number of ablations.

A multinational clinical approach to assessing the effectiveness of catheter-based ultrasound renal denervation: The RADIANCE-HTN and REQUIRE clinical study designs

Catheter-based renal denervation is a new approach to treat hypertension via modulation of the renal sympathetic nerves. Although nonrandomized and small, open-label randomized studies resulted in significant reductions in office blood pressure 6months after renal denervation with monopolar radiofrequency catheters, the first prospective, randomized, sham-controlled study (Symplicity HTN-3) failed to meet its blood pressure efficacy end point. New clinical trials with new catheters have since been designed to address the limitations of earlier studies. Accordingly, the RADIANCE-HTN and REQUIRE studies are multicenter, blinded, randomized, sham-controlled trials designed to assess the blood pressure-lowering efficacy of the ultrasound-based renal denervation system (Paradise) in patients with established hypertension either on or off antihypertensive medications, is designed to evaluate patients in 2 cohorts-SOLO and TRIO, in the United States and Europe. The SOLO cohort includes patients with essential hypertension, at low cardiovascular risk, and either controlled on 1 to 2 antihypertensive medications or uncontrolled on 0 to 2 antihypertensive medications. Patients undergo a 4-week medication washout period before randomization to renal denervation (treatment) or renal angiogram (sham). The TRIO cohort includes patients with hypertension resistant to at least 3 antihypertensive drugs including a diuretic. Patients will be stabilized on a single-pill, triple-antihypertensive-drug combination for 4weeks before randomization to treatment or sham. Reduction in daytime ambulatory systolic blood pressure (primary end point) will be assessed at 2months in both cohorts. A predefined medication escalation protocol, as needed for blood pressure control, is implemented between 2 and 6months in both cohorts by a study staff member blinded to the randomization process. At 6months, daytime ambulatory blood pressure and antihypertensive treatment score will be assessed. REQUIRE is designed to evaluate patients with resistant hypertension on standard of care medication in Japan and Korea. Reduction in 24-hour ambulatory systolic blood pressure will be assessed at 3months (primary end point). Both studies are enrolling patients, and their results are expected in 2018.

High screen failure rate in patients with resistant hypertension: Findings from SYMPLICITY HTN-3

BACKGROUND

The SYMPLICITY HTN-3 trial, which randomized subjects to renal denervation (RDN) or sham control, was designed to evaluate the efficacy and safety of RDN for the treatment of resistant hypertension. Outcomes were previously reported. This retrospective analysis evaluated reasons for screen failure (SF) for randomization in the trial.

METHODS

SYMPLICITY HTN-3 enrolled subjects with office systolic blood pressure (SBP) ≥160 mmHg on stable and maximal doses of ≥3 antihypertensive medication classes. Blood pressure was measured during screening visit (SV) 1 and SV2 a minimum of 2 weeks later to ensure resistant hypertension and to exclude white-coat hypertension. We analyzed baseline characteristics and reasons for SF at each SV and changes in BP between SVs.

RESULTS

Among 1,415 patients screened, 880 (62%) did not meet criteria for randomization. Compared with randomized patients, those in the SF cohort were more likely to be older (58.7 vs. 57.4 years, P=.029), current smokers (14.5% vs. 10.7%, P=.041), and prescribed fewer antihypertensive medications (4.7 vs. 5.1, P<.001). The predominant reason for SF at SV2 was office SBP <160 mmHg despite office SBP ≥160 mmHg at SV1.

CONCLUSION

Screening patients with resistant hypertension on maximal doses of ≥3 antihypertensive drugs led to a high SF rate. Screen failures were most common at SV1 and were due to failing the office SBP entry criteria. Not meeting ambulatory SBP criteria at SV2 was a secondary reason for SF, often due to white-coat hypertension; thus, 24-hour ambulatory monitoring is important to validate resistant hypertension.

Renal artery denervation for treatment of patients with self-reported obstructive sleep apnea and resistant hypertension: results from the Global SYMPLICITY Registry

BACKGROUND

Sleep-disordered breathing, predominantly obstructive sleep apnea (OSA), is highly prevalent in patients with hypertension. OSA may underlie the progression to resistant hypertension, partly due to increased activation of the sympathetic nervous system. This analysis of patients with and without OSA evaluated the blood pressure (BP)-lowering effect of sympathetic modulation by renal denervation (RDN) in a real-world setting.

METHODS

The Global SYMPLICITY Registry (NCT01534299) is a prospective, open-label, multicenter registry conducted worldwide to evaluate the safety and effectiveness of RDN in patients with uncontrolled hypertension. Office and 24-h ambulatory BP were reported for all patients, based on the presence of OSA.

RESULTS

Among 1868 patients, self-reported OSA occurred in 205 patients, who were more likely to be men (76 vs 57%, P < 0.001), have a higher BMI (34 ± 6 vs 30 ± 5 kg/m, P < 0.001), chronic kidney disease (30 vs 21%, P = 0.003), left ventricular hypertrophy (25 vs 15%, P < 0.001), and type 2 diabetes (50 vs 36%, P < 0.001). Among OSA patients, the baseline office SBP (166 ± 26 mmHg) was reduced by 14.0 ± 25.3 mmHg at 6 months (P < 0.001). Ambulatory 24-h SBP was reduced by 4.9 ± 18.0 mmHg (n = 115, P = 0.005) from 155 ± 19 mmHg at baseline. The 6-month change in SBP from baseline was not statistically different between OSA and non-OSA patients. BP reduction after RDN was also similar in OSA patients already treated with and not treated with continuous positive airway pressure.

CONCLUSION

RDN resulted in significant BP reductions at 6 months in hypertensive patients with and without OSA, and regardless of continuous positive airway pressure usage in OSA patients.

Renal sympathetic denervation for treatment of patients with heart failure: summary of the available evidence

Heart failure syndrome results from compensatory mechanisms that operate to restore - back to normal - the systemic perfusion pressure. Sympathetic overactivity plays a pivotal role in heart failure; norepinephrine contributes to maintenance of the systemic blood pressure and increasing preload. Cardiac norepinephrine spillover increases in patients with heart failure; norepinephrine exerts direct toxicity on cardiac myocytes resulting in a decrease of synthetic activity and/or viability. Importantly, cardiac norepinephrine spillover is a powerful predictor of mortality in patients with moderate to severe HF. This provided the rationale for trials that demonstrated survival benefit associated with the use of beta adrenergic blockers in heart failure with reduced ejection fraction. Nevertheless, the MOXCON trial demonstrated that rapid uptitration of moxonidine (inhibitor of central sympathetic outflow) in patients with heart failure was associated with excess mortality and morbidity, despite reduction of plasma norepinephrine. Interestingly, renal norepinephrine spillover was the only independent predictor of adverse outcome in patients with heart failure, in multivariable analysis. Recently, renal sympathetic denervation has emerged as a novel approach for control of blood pressure in patients with treatment-resistant hypertension. This article summarizes the available evidence for the effect of renal sympathetic denervation in the setting of heart failure. Key messages Experimental studies supported a beneficial effect of renal sympathetic denervation in heart failure with reduced ejection fraction. Clinical studies demonstrated improvement of symptoms, and left ventricular function. In heart failure and preserved ejection fraction, renal sympathetic denervation is associated with improvement of surrogate endpoints.

Improvement of Myocardial Function Following Catheter-Based Renal Denervation in Heart Failure

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A porcine model of heart failure was induced by myocardial infarction followed by rapid ventricular pacing for 4 weeks.

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Catheter-based renal denervation was performed using an expandable basket with 4 electrodes to deliver radiofrequency energy. Histological examination showed significant denervation of the renal arteries after the procedure.

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Compared with the control group, animals that received renal denervation showed significant improvement of cardiac function as determined by LV ejection fraction, maximum rate of LV pressure rise normalized to instantaneous developed pressure, and reduction of myocardial and renal norepinephrine gradient at 10 weeks after procedure.

Renal denervation (RD) is a potential novel nonpharmacological therapy for heart failure (HF). We performed bilateral catheter-based RD in 10 adult pigs and compared them with 10 control subjects after induction of HF to investigate the long-term beneficial effects of RD on left ventricular (LV) function and regional norepinephrine gradient after conventional HF pharmacological therapy. Compared with control subjects, animals treated with RD demonstrated an improvement in LV function and reduction of norepinephrine gradients over the myocardium and kidney at 10-week follow-up. Our results demonstrated that effective bilateral RD decrease regional norepinephrine gradients and improve LV contractile function compared with medical therapy alone.

Improvement in health-related quality of life after renal sympathetic denervation in real-world hypertensive patients: 12-month outcomes in the Global SYMPLICITY Registry

Renal denervation has been shown to reduce blood pressure in patients with uncontrolled hypertension, but less is known about its impact on quality of life. This analysis evaluated 12-month blood pressure and quality of life outcomes in 934 patients from the Global SYMPLICITY Registry who completed the EuroQoL five-dimensions three-level questionnaire (EQ-5D-3L). At baseline, 32% of patients reported anxiety/depression and 48% reported pain/discomfort. At 12 months (n=496), office and 24-hour ambulatory systolic blood pressure were reduced by 13.9±26.6 and 7.7±19.3 mm Hg, respectively, and 8% (P<.001) more patients reported no problems in anxiety/depression. Furthermore, numerically more patients reported no problems in pain/discomfort (4%, P=.08). Perceived health-related quality of life (visual analog scale) improved from baseline to 12 months (68±18 vs 73±17, P<.001), and the improvement was largest among patients with severe anxiety/depression at baseline (50±24 vs 64±22, P=.005 [n=32]). In this analysis, renal denervation was associated with a significant improvement in health-related quality of life, particularly anxiety/depression.

Effects of renal sympathetic denervation on blood pressure, sleep apnoea severity and metabolic indices: a prospective cohort study

BACKGROUND

Catheter-based renal sympathetic denervation (RSD) significantly reduces blood pressure in patients with resistant hypertension, who commonly have obstructive sleep apnoea (OSA). These patients are considered particularly responsive to the antihypertensive effects of RSD, but additional benefits of metabolic control on sleep apnoea severity have not been thoroughly investigated.

METHODS

The effect of RSD was evaluated prospectively in a cohort of patients with OSA (apnoea-hypopnea index (AHI) ≥15 events per hour and an Epworth Sleepiness Scale (ESS) score ≤9) and treatment resistant hypertension. Changes in blood pressure, polysomnographic parameters and metabolic indices were evaluated at baseline and six months post procedure.

RESULTS

At baseline, mean office blood pressure was 166.3/92.8 (14.5/11.7) mmHg and mean ambulatory blood pressure was 154.0/87.3 (11.9/8.5) mmHg. At six months post RSD, mean office blood pressure reduced by 6.6/6.5 (1.9/2.0) mmHg (p < 0.05) and mean ambulatory blood pressure reduced by 8.3/6.2 (2.3/2.0) (p < 0.05). The mean AHI at baseline was 21.3 events/h and 20.5 events/h at six months post RSD, with a mean reduction of 0.9 events/h (95% CI -0.7-1.6, p = 0.39). Glucose at two hours/2 h following tolerance testing reduced by 1.14 mmol/L (95% CI 0.22-2.06, p = 0.03) but changes in other metabolic indices were not statistically significant.

CONCLUSION

In patients with resistant hypertension and OSA, RSD resulted in modest improvements in blood pressure control, but no significant changes in sleep apnoea severity. Our study showed small increments in glucose tolerance but no significant changes in other markers of carbohydrate or lipid metabolism.

Effects of renal sympathetic denervation on cardiac systolic function after myocardial infarction in rats

This study investigated the therapeutic effects of renal denervation on cardiac systolic function after myocardial infarction (MI) in rats and the mechanism involved. Fifty male SD rats were randomly assigned to the sham group (n = 15), the MI group (n = 20), and the MI plus renal denervation group (n = 15). MI was established through thoracotomic ligation of the anterior descending artery. Renal denervation was achieved by laparotomic stripping of the renal arterial adventitial sympathetic nerve, approximately 3 mm from the abdominal aorta. Left ventricular function and hemodynamics were measured several weeks following MI. The left ventricular systolic function of the MI group was significantly reduced and the systolic blood pressure (SBP) remarkably declined. In rats with MI treated with renal denervation, the left ventricular ejection fraction (EF), fractional shortening (FS) and SBP markedly improved compared with the MI group. However, heart rate and fibrosis decreased significantly. These findings suggest that renal denervation has therapeutic effects on post-MI cardiac dysfunction. These effects are associated with increased left ventricular ejection fraction (LVEF) and SBP, as well as reduced heart rate and fibrosis. This may represent a new approach to the treatment of post-MI remodeling and subsequent heart failure.

Renal sympathetic denervation for treatment of patients with atrial fibrillation: Reappraisal of the available evidence

Afferent renal sympathetic nerve signaling regulates central sympathetic outflow. In this regard, renal sympathetic denervation has emerged as a novel interventional strategy for treatment of patients with resistant hypertension. Despite the disappointing results of the Simplicity HTN-3 randomized controlled trial, promoters of renal denervation argue that the negative results were due to ineffective denervation technique and poor patient selection. Yet, long-term "pathologic" increase of efferent sympathetic nerve activity is observed in many chronic disease states characterized by sympathetic overactivity, such as arrhythmia, heart failure, insulin resistance, and chronic kidney disease. In this review, we highlight the contemporary evidence on the safety/efficacy of renal denervation in the treatment of patients with atrial fibrillation.

Renal Denervation Suppresses the Inducibility of Atrial Fibrillation in a Rabbit Model for Atrial Fibrosis

Renal denervation (RD) was reported to reduce the susceptibility of atrial fibrillation (AF), but the underlying mechanism has not been well understood. This study was performed to investigate the effect of RD on the inducibility of AF in a rabbit model for atrial fibrosis and to explore the potential mechanisms. Thirty-five rabbits were randomly assigned into sham-operated group (n = 12), abdominal aortic constriction (AAC) group (n = 12) and AAC with RD (AAC-RD) group (n = 11). The incidence of AF induced by burst pacing in atriums was determined. Blood was collected to measure the levels of rennin, angiotensin II and aldosterone. Atrial samples were preserved to evaluate protein and gene expression of collagen, connective tissue growth factor (CTGF) and transforming growth factor-β1 (TGF-β1). Our data suggested cardiac structure remodeling and atrial fibrosis were successfully induced by AAC. Compared with the AAC group, the AAC-RD rabbits had smaller ascending aortic diameter and left ventricular end-systolic diameter. For burst pacing at the left atrium (LA), AF was induced in two of the 12 rabbits in the sham-operated group, 10 of the 12 rabbits in the AAC group, and 2 of the 11 rabbits in the AAC-RD group, with great difference among the three groups (P = 0.001). The percentage of LA burst stimulations with induced AF achieved 47.2% in the AAC group, which was higher than those in both the AAC-RD (12.1%) and the Sham-operated (5.6%) groups. Significantly increasing intercellular space in the AAC group (P<0.001) compared with the sham-operated rabbits. RD clearly decreased the volume fraction of collagen in LA and right atrium compared with that of the AAC group (P< 0.01). AAC-induced elevation of collagen I, CTGF and TGF-β1 was suppressed by RD. In conclusion, RD suppressed the inducibility of AF in a rabbit model for pressure associated atrial fibrosis, potentially by modulating renin-angiotensin-aldosterone system and decreasing pro-fibrotic factors.

Central Sympathetic Inhibition: a Neglected Approach for Treatment of Cardiac Arrhythmias?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Overactivation of the sympathetic nervous system (SNS) plays an important role in the pathogenesis of comorbidities related to AF such as hypertension, congestive heart failure, obesity, insulin resistance, and obstructive sleep apnea. Methods that reduce sympathetic drive, such as centrally acting sympatho-inhibitory agents, have been shown to reduce the incidence of spontaneous or induced atrial arrhythmias, suggesting that neuromodulation may be helpful in controlling AF. Moxonidine acts centrally to reduce activity of the SNS, and clinical trials indicate that this is associated with a decreased AF burden in hypertensive patients with paroxysmal AF and reduced post-ablation recurrence of AF in patients with hypertension who underwent pulmonary vein isolation (PVI). Furthermore, device-based approaches to reduce sympathetic drive, such as renal denervation, have yielded promising results in the prevention and treatment of cardiac arrhythmias. In light of these recent findings, targeting elevated sympathetic drive with either pharmacological or device-based approaches has become a focus of clinical research. Here, we review the data currently available to explore the potential utility of sympatho-inhibitory therapies in the prevention and treatment of cardiac arrhythmias.

Effects of serelaxin in acute heart failure patients with renal impairment: results from RELAX-AHF

BACKGROUND

Serelaxin showed beneficial effects on clinical outcome and trajectories of renal markers in patients with acute heart failure. We aimed to study the interaction between renal function and the treatment effect of serelaxin.

METHODS

In the current post hoc analysis of the RELAX-AHF trial, we included all patients with available estimated glomerular filtration rate (eGFR) at baseline (n = 1132). Renal impairment was defined as an eGFR <60 ml/min/1.73 m(2) estimated by creatinine.

RESULTS

817 (72.2 %) patients had a baseline eGFR <60 ml/min/1.73 m(2). In placebo-treated patients, baseline renal impairment was related to a higher 180 day cardiovascular (HR 3.12, 95 % CI 1.33-7.30) and all-cause mortality (HR 2.81, 95 % CI 1.34-5.89). However, in serelaxin-treated patients, the risk of cardiovascular and all-cause mortality was less pronounced (HR 1.19, 95 % CI 0.54 -2.64; p for interaction = 0.106, and HR 1.15 95 % CI 0.56-2.34 respectively; p for interaction = 0.088). In patients with renal impairment, treatment with serelaxin resulted in a more pronounced all-cause mortality reduction (HR 0.53, 95 % CI 0.34-0.83), compared with patients without renal impairment (HR 1.30, 95 % CI 0.51-3.29).

CONCLUSION

Renal dysfunction was associated with higher cardiovascular and all-cause mortality in placebo-treated patients, but not in serelaxin-treated patients. The observed reduction in (cardiovascular) mortality in RELAX-AHF was more pronounced in patients with renal dysfunction. These observations need to be confirmed in the ongoing RELAX-AHF-2 trial.

Renal denervation therapy for hypertension: pathways for moving development forward

This scientific statement provides a summary of presentations and discussions at a cardiovascular Think Tank co-sponsored by the American Society of Hypertension (ASH), the United States Food and Drug Administration (FDA), and the National Heart, Lung, and Blood Institute (NHLBI) held in North Bethesda, Maryland, on June 26, 2014. Studies of device therapies for the treatment of hypertension are requested by regulators to evaluate their safety and efficacy during their development programs. Think Tank participants thought that important considerations in undertaking such studies were: (1) Preclinical assessment: how likely it is that both efficacy and safety data indicating benefit in humans will be obtained, and/or whether a plausible mechanism of action for efficacy can be identified; (2) Early human trial(s): the ability to determine that the device has an acceptable benefit-to-risk balance for its use in the intended patient population and without the influence of drug therapy during a short-term follow-up period; and (3) Pivotal Phase III trial(s): the ability to prove the effectiveness of the device in a broad population in which the trial can be made as non-confounded as possible while still allowing for the determination for benefits when added to antihypertensive therapies.

Controversies Surrounding Renal Denervation: Lessons Learned From Real-World Experience in Two United Kingdom Centers

Renal denervation (RDN) is a therapy that targets treatment-resistant hypertension (TRH). The Renal Denervation in Patients With Uncontrolled Hypertension (Symplicity) HTN-1 and Symplicity HTN-2 trials reported response rates of >80%; however, sham-controlled Symplicity HTN-3 failed to reach its primary blood pressure (BP) outcome. The authors address the current controversies surrounding RDN, illustrated with real-world data from two centers in the United Kingdom. In this cohort, 52% of patients responded to RDN, with a 13±32 mm Hg reduction in office systolic BP (SBP) at 6 months (n=29, P=.03). Baseline office SBP and number of ablations correlated with office SBP reduction (R=-0.47, P=.01; R=-0.56, P=.002). RDN appears to be an effective treatment for some patients with TRH; however, individual responses are highly variable. Selecting patients for RDN is challenging, with only 10% (33 of 321) of the screened patients eligible for the study. Medication alterations and nonadherence confound outcomes. Adequate ablation is critical and should impact future catheter design/training. Markers of procedural success and improved patient selection parameters remain key research aims.

Blood pressure and the capacity-load model in 8-year-old children from Nepal: Testing the contributions of kidney size and intergenerational effects

Objectives

Growth patterns in early life are increasingly linked with subsequent cardio-metabolic risk, but the underlying mechanisms require elucidation. We have developed a theoretical model of blood pressure, treating it as a function of homeostatic metabolic capacity, and antagonistic metabolic load. We sought to differentiate prenatal and postnatal components of metabolic capacity, and to identify intergenerational contributions to offspring capacity and load.

Methods

We followed up at 8 years a cohort of children originally recruited into a randomized trial of maternal micronutrient supplementation in pregnancy. Maternal anthropometry was measured at recruitment. Offspring anthropometry was measured at birth, 2 years and 8 years. Offspring blood pressure, kidney size, and body composition were measured at 8 years. Regression analysis was used to investigate potential associations of maternal phenotype, birth phenotype, and current body composition with kidney size and blood pressure.

Results

Blood pressure was positively associated with body fat, but negatively associated with birth weight and relative leg length. Kidney size was positively associated with birth weight but not with relative leg length. Adjusting for adiposity, blood pressure was independently negatively associated with birth weight, relative leg length, and kidney length. Maternal height and BMI predicted offspring size at birth and at 8 years, but not blood pressure.

Conclusions

Our data provide support for the capacity-load model of blood pressure in Nepalese children. Fetal and postnatal growth and kidney dimensions all contribute to metabolic capacity. Maternal phenotype contributed to offspring capacity and load, but these associations did not propagate to blood pressure.

Effects of catheter-based renal denervation on cardiac sympathetic activity and innervation in patients with resistant hypertension

OBJECTIVES

To investigate, whether renal denervation (RDN) has a direct effect on cardiac sympathetic activity and innervation density.

BACKGROUND

RDN demonstrated its efficacy not only in reducing blood pressure (BP) in certain patients, but also in decreasing cardiac hypertrophy and arrhythmias. These pleiotropic effects occur partly independent from the observed BP reduction.

METHODS

Eleven patients with resistant hypertension (mean office systolic BP 180 ± 18 mmHg, mean antihypertensive medications 6.0 ± 1.5) underwent I-123-mIBG scintigraphy to exclude pheochromocytoma. We measured cardiac sympathetic innervation and activity before and 9 months after RDN. Cardiac sympathetic innervation was assessed by heart to mediastinum ratio (H/M) and sympathetic activity by wash out ratio (WOR). Effects on office BP, 24 h ambulatory BP monitoring, were documented.

RESULTS

Office systolic BP and mean ambulatory systolic BP were significantly reduced from 180 to 141 mmHg (p = 0.006) and from 149 to 129 mmHg (p = 0.014), respectively. Cardiac innervation remained unchanged before and after RDN (H/M 2.5 ± 0.5 versus 2.6 ± 0.4, p = 0.285). Cardiac sympathetic activity was significantly reduced by 67 % (WOR decreased from 24.1 ± 12.7 to 7.9 ± 25.3 %, p = 0.047). Both, responders and non-responders experienced a reduction of cardiac sympathetic activity.

CONCLUSION

RDN significantly reduced cardiac sympathetic activity thereby demonstrating a direct effect on the heart. These changes occurred independently from BP effects and provide a pathophysiological basis for studies, investigating the potential effect of RDN on arrhythmias and heart failure.

Chronic Stress Facilitates the Development of Deep Venous Thrombosis

The increasing pressure of modern social life intensifies the impact of stress on the development of cardiovascular diseases, which include deep venous thrombosis (DVT). Renal sympathetic denervation has been applied as one of the clinical approaches for the treatment of drug-resistant hypertension. In addition, the close relationship between oxidative stress and cardiovascular diseases has been well documented. The present study is designed to explore the mechanism by which the renal sympathetic nerve system and the oxidative stress affect the blood coagulation system in the development of DVT. Chronic foot shock model in rats was applied to mimic a state of physiological stress similar to humans. Our results showed that chronic foot shock procedure could promote DVT which may be through the activation of platelets aggregation. The aggravation of DVT and activation of platelets were alleviated by renal sympathetic denervation or antioxidant (Tempol) treatment. Concurrently, the denervation treatment could also reduce the levels of circulating oxidation factors in rats. These results demonstrate that both the renal sympathetic nerve system and the oxidative stress contribute to the development of DVT in response to chronic stress, which may provide novel strategy for treatment of clinic DVT patients.

Neural regulation of the kidney function in rats with cisplatin induced renal failure

Aim: Chronic kidney disease (CKD) is often associated with a disturbed cardiovascular homeostasis. This investigation explored the role of the renal innervation in mediating deranged baroreflex control of renal sympathetic nerve activity (RSNA) and renal excretory function in cisplatin-induced renal failure.

Methods: Rats were either intact or bilaterally renally denervated 4 days prior to receiving cisplatin (5 mg/kg i.p.) and entered a chronic metabolic study for 8 days. At day 8, other groups of rats were prepared for acute measurement of RSNA or renal function with either intact or denervated kidneys.

Results: Following the cisplatin challenge, creatinine clearance was 50% lower while fractional sodium excretion and renal cortical and medullary TGF-β1 concentrations were 3–4 fold higher in both intact and renally denervated rats compared to control rats. In cisplatin-treated rats, the maximal gain of the high-pressure baroreflex curve was only 20% that of control rats, but following renal denervation not different from that of renally denervated control rats. Volume expansion reduced RSNA by 50% in control and in cisplatin-treated rats but only following bilateral renal denervation. The volume expansion mediated natriuresis/diuresis was absent in the cisplatin-treated rats but was normalized following renal denervation.

Conclusions: Cisplatin-induced renal injury impaired renal function and caused a sympatho-excitation with blunting of high and low pressure baroreflex regulation of RSNA, which was dependent on the renal innervation. It is suggested that in man with CKD there is a dysregulation of the neural control of the kidney mediated by its sensory innervation.