Renal Denervation Prevents Heart Failure Progression Via Inhibition of the Renin-Angiotensin System

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.

The pig as an optimal animal model for cardiovascular research

Cardiovascular disease is a worldwide health problem and a leading cause of morbidity and mortality. Preclinical cardiovascular research using animals is needed to explore potential targets and therapeutic options. Compared with rodents, pigs have many advantages, with their anatomy, physiology, metabolism and immune system being more similar to humans. Here we present an overview of the available pig models for cardiovascular diseases, discuss their advantages over other models and propose the concept of standardized models to improve translation to the clinical setting and control research costs.

Early Renal Denervation Attenuates Cardiac Dysfunction in Heart Failure With Preserved Ejection Fraction

BACKGROUND

The renal sympathetic nervous system modulates systemic blood pressure, cardiac performance, and renal function. Pathological increases in renal sympathetic nerve activity contribute to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). We investigated the effects of renal sympathetic denervation performed at early or late stages of HFpEF progression.

METHODS AND RESULTS

Male ZSF1 obese rats were subjected to radiofrequency renal denervation (RF-RDN) or sham procedure at either 8 weeks or 20 weeks of age and assessed for cardiovascular function, exercise capacity, and cardiorenal fibrosis. Renal norepinephrine and renal nerve tyrosine hydroxylase staining were performed to quantify denervation following RF-RDN. In addition, renal injury, oxidative stress, inflammation, and profibrotic biomarkers were evaluated to determine pathways associated with RDN. RF-RDN significantly reduced renal norepinephrine and tyrosine hydroxylase content in both study cohorts. RF-RDN therapy performed at 8 weeks of age attenuated cardiac dysfunction, reduced cardiorenal fibrosis, and improved endothelial-dependent vascular reactivity. These improvements were associated with reductions in renal injury markers, expression of renal NLR family pyrin domain containing 3/interleukin 1β, and expression of profibrotic mediators. RF-RDN failed to exert beneficial effects when administered in the 20-week-old HFpEF cohort.

CONCLUSIONS

Our data demonstrate that early RF-RDN therapy protects against HFpEF disease progression in part due to the attenuation of renal fibrosis and inflammation. In contrast, the renoprotective and left ventricular functional improvements were lost when RF-RDN was performed in later HFpEF progression. These results suggest that RDN may be a viable treatment option for HFpEF during the early stages of this systemic inflammatory disease.

Renal denervation improves cardiac function independently of afterload and restores myocardial norepinephrine levels in a rodent heart failure model

Renal nerves play a critical role in cardiorenal interactions. Renal denervation (RDN) improved survival in some experimental heart failure (HF) models. It is not known whether these favorable effects are indirect, explainable by a decrease in vascular afterload, or diminished neurohumoral response in the kidneys, or whether RDN procedure per se has direct myocardial effects in the failing heart. To elucidate mechanisms how RDN affects failing heart, we studied load-independent indexes of ventricular function, gene markers of myocardial remodeling, and cardiac sympathetic signaling in HF, induced by chronic volume overload (aorto-caval fistula, ACF) of Ren2 transgenic rats. Volume overload by ACF led to left ventricular (LV) hypertrophy and dysfunction, myocardial remodeling (upregulated Nppa, MYH 7/6 genes), increased renal and circulating norepinephrine (NE), reduced myocardial NE content, increased monoaminoxidase A (MAO-A), ROS production and decreased tyrosine hydroxylase (+) nerve staining. RDN in HF animals decreased congestion in the lungs and the liver, improved load-independent cardiac function (Ees, PRSW, Ees/Ea ratio), without affecting arterial elastance or LV pressure, reduced adverse myocardial remodeling (Myh 7/6, collagen I/III ratio), decreased myocardial MAO-A and inhibited renal neprilysin activity. RDN increased myocardial expression of acetylcholinesterase (Ache) and muscarinic receptors (Chrm2), decreased circulating and renal NE, but increased myocardial NE content, restoring so autonomic control of the heart. These changes likely explain improvements in survival after RDN in this model. The results suggest that RDN has remote, load-independent and favorable intrinsic myocardial effects in the failing heart. RDN therefore could be a useful therapeutic strategy in HF.

Neuromodulation interventions in the management of heart failure

Despite remarkable improvements in the management of heart failure (HF), HF remains one of the most rapidly growing cardiovascular condition resulting in a substantial burden on healthcare systems worldwide. In clinical practice, however, a relevant proportion of patients are treated with suboptimal combinations and doses lower than those recommended in the current guidelines. Against this background, it remains important to identify new targets and investigate additional therapeutic options to alleviate symptoms and potentially improve prognosis in HF. Therefore, non-pharmacological interventions targeting autonomic imbalance in HF have been evaluated. This paper aims to review the physiology, available clinical data, and potential therapeutic role of device-based neuromodulation in HF.

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.

A kidney-brain neural circuit drives progressive kidney damage and heart failure

Chronic kidney disease (CKD) and heart failure (HF) are highly prevalent, aggravate each other, and account for substantial mortality. However, the mechanisms underlying cardiorenal interaction and the role of kidney afferent nerves and their precise central pathway remain limited. Here, we combined virus tracing techniques with optogenetic techniques to map a polysynaptic central pathway linking kidney afferent nerves to subfornical organ (SFO) and thereby to paraventricular nucleus (PVN) and rostral ventrolateral medulla that modulates sympathetic outflow. This kidney-brain neural circuit was overactivated in mouse models of CKD or HF and subsequently enhanced the sympathetic discharge to both the kidney and the heart in each model. Interruption of the pathway by kidney deafferentation, selective deletion of angiotensin II type 1a receptor (AT1a) in SFO, or optogenetic silence of the kidney-SFO or SFO-PVN projection decreased the sympathetic discharge and lessened structural damage and dysfunction of both kidney and heart in models of CKD and HF. Thus, kidney afferent nerves activate a kidney-brain neural circuit in CKD and HF that drives the sympathetic nervous system to accelerate disease progression in both organs. These results demonstrate the crucial role of kidney afferent nerves and their central connections in engaging cardiorenal interactions under both physiological and disease conditions. This suggests novel therapies for CKD or HF targeting this kidney-brain neural circuit.

Renal denervation in management of heart failure with reduced ejection fraction: A systematic review and meta-analysis

BACKGROUND

Some, but not all, recent studies have shown that renal denervation (RDN) can improve cardiac function and exercise tolerance in people who have heart failure with reduced ejection fraction (HFrEF). This study assessed the efficacy and safety of RDN as a treatment for HFrEF.

METHODS

The Medline, Cochrane Library, Embase, and PubMed databases were searched through to September 28, 2022 for clinical studies that evaluated the effect of RDN on HFrEF. The primary endpoints were changes in left ventricular ejection fraction (LVEF) and 6-min walk distance (6MWD). Secondary endpoints were changes in echocardiographic parameters, including left ventricular end-diastolic and end-systolic diameters, left atrial diameter, and interventricular septal thickness. N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, New York Heart Association (NYHA) class, heart rate, and systolic and diastolic blood pressure were also evaluated. Major adverse events were defined as death and rehospitalization for heart failure during follow-up. The estimated glomerular filtration rate (eGFR) and serum creatinine level were extracted as measures of renal function.

RESULTS

Eleven trials comprising 313 patients were eligible for quantitative analysis. Pooled analyses showed a mean increase in LVEF of 4.25 % (95 % CI 1.77-6.72; p < 0.001, I² = 69 %) and an increase in 6MWD (mean difference 50.28 m, 95 % CI 8.78-91.78; p = 0.02; I² = 81 %) after RDN. Left ventricular end-diastolic and end-systolic diameters, left atrial diameter, and interventricular septal thickness also improved after RDN. NT-proBNP, NYHA class, and heart rate were significantly decreased after RDN. There were no significant changes in blood pressure after RDN. Mortality and HF-related hospitalization rates were relatively low. There was no significant change in eGFR or creatinine after RDN.

CONCLUSIONS

Our findings suggest that RDN can effectively increase LVEF and 6MWD in patients with HFrEF but require confirmation in studies with larger sample sizes and longer follow-up durations.

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.

Critical Reanalysis of the Mechanisms Underlying the Cardiorenal Benefits of SGLT2 Inhibitors and Reaffirmation of the Nutrient Deprivation Signaling/Autophagy Hypothesis

SGLT2 (sodium-glucose cotransporter 2) inhibitors produce a distinctive pattern of benefits on the evolution and progression of cardiomyopathy and nephropathy, which is characterized by a reduction in oxidative and endoplasmic reticulum stress, restoration of mitochondrial health and enhanced mitochondrial biogenesis, a decrease in proinflammatory and profibrotic pathways, and preservation of cellular and organ integrity and viability. A substantial body of evidence indicates that this characteristic pattern of responses can be explained by the action of SGLT2 inhibitors to promote cellular housekeeping by enhancing autophagic flux, an effect that may be related to the action of these drugs to produce simultaneous upregulation of nutrient deprivation signaling and downregulation of nutrient surplus signaling, as manifested by an increase in the expression and activity of AMPK (adenosine monophosphate-activated protein kinase), SIRT1 (sirtuin 1), SIRT3 (sirtuin 3), SIRT6 (sirtuin 6), and PGC1-α (peroxisome proliferator-activated receptor γ coactivator 1-α) and decreased activation of mTOR (mammalian target of rapamycin). The distinctive pattern of cardioprotective and renoprotective effects of SGLT2 inhibitors is abolished by specific inhibition or knockdown of autophagy, AMPK, and sirtuins. In the clinical setting, the pattern of differentially increased proteins identified in proteomics analyses of blood collected in randomized trials is consistent with these findings. Clinical studies have also shown that SGLT2 inhibitors promote gluconeogenesis, ketogenesis, and erythrocytosis and reduce uricemia, the hallmarks of nutrient deprivation signaling and the principal statistical mediators of the ability of SGLT2 inhibitors to reduce the risk of heart failure and serious renal events. The action of SGLT2 inhibitors to augment autophagic flux is seen in isolated cells and tissues that do not express SGLT2 and are not exposed to changes in environmental glucose or ketones and may be related to an ability of these drugs to bind directly to sirtuins or mTOR. Changes in renal or cardiovascular physiology or metabolism cannot explain the benefits of SGLT2 inhibitors either experimentally or clinically. The direct molecular effects of SGLT2 inhibitors in isolated cells are consistent with the concept that SGLT2 acts as a nutrient surplus sensor, and thus, its inhibition causes enhanced nutrient deprivation signaling and its attendant cytoprotective effects, which can be abolished by specific inhibition or knockdown of AMPK, sirtuins, and autophagic flux.

Update on Renal Sympathetic Denervation for the Treatment of Hypertension

PURPOSE OF REVIEW

Hypertension is a leading risk factor for all-cause mortality in adults; however, medication non-adherence and intolerance present an enormous treatment challenge. Given the critical role of renal sympathetic nerves in neurogenic control of blood pressure and pathophysiology of hypertension, renal sympathetic denervation (RDN) has been explored as a therapeutic strategy in hypertension treatment over the last 15 years. In this review, we will discuss the role of renal sympathetic nerves in the pathophysiology of hypertension, provide an update on the available evidence regarding the short- and long-term safety and effectiveness of RDN in the treatment of hypertension, and consider its future perspectives.

RECENT FINDINGS

RDN is a percutaneous endovascular catheter-based neuromodulation approach that enables ablation of renal sympathetic nerve fibers within the adventitial layer of the renal arteries using radiofrequency (most extensively studied), ultrasound energy, or neurolytics (e.g., alcohol). In the last decade, advancements in procedural techniques and well-designed sham-controlled trials utilizing 24-h ambulatory blood pressure measurements have demonstrated that RDN has an excellent safety profile and results in a modest reduction of blood pressure, in a wide range of hypertensive phenotypes (mild to resistant), irrespective of antihypertensive drug use and this effect is sustained over a 3-year period. Superiority of a particular RDN modality has not been yet established. Despite strong evidence demonstrating efficacy and safety of RDN, current data does not support its use as a primary approach in the treatment of hypertension due to its modest treatment effect and concerns around long-term sustainability. Perhaps the best utility of RDN is in hypertensives intolerant to antihypertensive medications or as an adjunct to aldosterone antagonists in the management of resistant hypertension. Patient selection will be critical to demonstrate a meaningful benefit of RDN. Future well-designed studies are necessary to determine predictors and measures of response to RDN, long-term efficacy given question of renal nerve regeneration, comparison of available technologies, safety in patients with advanced kidney disease, and improvement in patient quality of life measures.

Could Repeated Cardio-Renal Injury Trigger Late Cardiovascular Sequelae in Extreme Endurance Athletes?

Regular exercise confers multifaceted and well-established health benefits. Yet, transient and asymptomatic increases in markers of cardio-renal injury are commonly observed in ultra-endurance athletes during and after competition. This has raised concerns that chronic recurring insults could cause long-term cardiac and/or renal damage. Indeed, extreme endurance exercise (EEE) over decades has sometimes been linked with untoward cardiac effects, but a causal relation with acute injury markers has not yet been established. Here, we summarize the current knowledge on markers of cardiac and/or renal injury in EEE athletes, outline the possible interplay between cardiac and kidney damage, and explore the roles of various factors in the development of potential exercise-related cardiac damage, including underlying diseases, medication, sex, training, competition, regeneration, mitochondrial dysfunction, oxidative stress, and inflammation. In conclusion, despite the undisputed health benefits of regular exercise, we speculate, based on the intimate link between heart and kidney diseases, that in rare cases excessive endurance sport may induce adverse cardio-renal interactions that under specific, hitherto undefined conditions could result in persistent cardiac damage. We highlight future research priorities and provide decision support for athletes and clinical consultants who are seeking safe strategies for participation in EEE training and competition.

The Potential Role of Renal Denervation in the Management of Heart Failure

Sympathetic nervous system activation in patients with heart failure is one of the main pathophysiologic mechanisms associated with the worse outcomes. Pharmacotherapies targeting neurohormonal activation have been at the center of heart failure management. Despite the advancement of therapies and the available treatments, heart failure continues to have an overall poor prognosis. Renal denervation was originally developed to lower systemic blood pressure in patients with poorly controlled hypertension, by modulating sympathetic outflow. However, more recently, multiple studies have investigated the effect of renal denervation in heart failure patients with both preserved (HFpEF) and reduced ejection fractions (HFrEF). This paper provides an overview of the potential effect of renal denervation in altering the various pathophysiologic, sympathetically mediated pathways that contribute to heart failure, and reviews the literature that supports its future use in those patients.

Metabolism regulator adiponectin prevents cardiac remodeling and ventricular arrhythmias via sympathetic modulation in a myocardial infarction model

The stellate ganglia play an important role in cardiac remodeling after myocardial infarction (MI). This study aimed to investigate whether adiponectin (APN), an adipokine mainly secreted by adipose tissue, could modulate the left stellate ganglion (LSG) and exert cardioprotective effects through the sympathetic nervous system (SNS) in a canine model of MI. APN microinjection and APN overexpression with recombinant adeno-associated virus vector in the LSG were performed in acute and chronic MI models, respectively. The results showed that acute APN microinjection decreased LSG function and neural activity, and suppressed ischemia-induced ventricular arrhythmia. Chronic MI led to a decrease in the effective refractory period and action potential duration at 90% and deterioration in echocardiography performance, all of which was blunted by APN overexpression. Moreover, APN gene transfer resulted in favorable heart rate variability alteration, and decreased cardiac SNS activity, serum noradrenaline and neuropeptide Y, which were augmented after MI. APN overexpression also decreased the expression of nerve growth factor and growth associated protein 43 in the LSG and peri-infarct myocardium, respectively. Furthermore, RNA sequencing of LSG indicated that 4-week MI up-regulated the mRNA levels of macrophage/microglia activation marker Iba1, chemokine ligands (CXCL10, CCL20), chemokine receptor CCR5 and pro-inflammatory cytokine IL6, and downregulated IL1RN and IL10 mRNA, which were reversed by APN overexpression. Our results reveal that APN inhibits cardiac sympathetic remodeling and mitigates cardiac remodeling after MI. APN-mediated gene therapy may provide a potential therapeutic strategy for the treatment of MI.

Serum Metabolomics Reveals Distinct Profiles during Ischemia and Reperfusion in a Porcine Model of Myocardial Ischemia-Reperfusion

Acute myocardial infarction (MI) is one of the leading causes of death worldwide. Early identification of ischemia and establishing reperfusion remain cornerstones in the treatment of MI, as mortality and morbidity can be significantly reduced by establishing reperfusion to the affected areas. The aim of the current study was to investigate the metabolomic changes in the serum in a swine model of MI induced by ischemia and reperfusion (I/R) injury, and to identify circulating metabolomic biomarkers for myocardial injury at different phases. Female Yucatan minipigs were subjected to 60 min of ischemia followed by reperfusion, and serum samples were collected at baseline, 60 min of ischemia, 4 h of reperfusion, and 24 h of reperfusion. Circulating metabolites were analyzed using an untargeted metabolomic approach. A bioinformatic approach revealed that serum metabolites show distinct profiles during ischemia and during early and late reperfusion. Some notable changes during ischemia include accumulation of metabolites that indicate impaired mitochondrial function and N-terminally modified amino acids. Changes in branched-chain amino-acid metabolites were noted during early reperfusion, while bile acid pathway derivatives and intermediates predominated in the late reperfusion phases. This indicates a potential for such an approach toward identification of the distinct phases of ischemia and reperfusion in clinical situations.

Intravascular Renal Denervation Reduces Ambulatory and Office Blood Pressure in Patients with Essential Hypertension: A Meta-Analysis of Randomized Sham-Controlled Trials

BACKGROUND

This meta-analysis was designed to evaluate the antihypertensive efficacy of intravascular renal denervation (RDN) in patients with essential hypertension, especially to determine the magnitude of blood pressure (BP) reduction with RDN therapy using second-generation catheters.

METHODS

PubMed was searched to identify randomized sham-controlled trials from inception through August 2021. The endpoints were changes in 24-h ambulatory BP or office BP. This meta-analysis was performed by calculating the weighted mean difference (WMD) with 95% confidence interval (CI) using the random-effects model when the I2 index was <50%. A fixed-effects model was used when the I2 index was ≥50%.

RESULTS

A total of 1,297 patients were included in 8 randomized, sham-controlled trials in this meta-analysis. Intravascular RDN reduced 24-h ambulatory systolic BP (SBP) -3.02 (WMD, 95% CI: -4.95, -1.10, p < 0.01) and diastolic BP (DBP) -1.66 (WMD, 95% CI: -2.44, -0.88, p < 0.001) mm Hg, respectively. In the studies using first-generation catheters, the WMDs of 24-h ambulatory SBP and DBP changes between intravascular RDN and sham control were -2.67 (95% CI: -5.08, -0.27; p < 0.05; I2 = 0%, p = 0.53) and -0.82 (95% CI: -2.19, 0.56; p > 0.05; I2 = 0%, p = 0.64) mm Hg. In the studies using second-generation catheters, the WMDs of 24-h ambulatory SBP and DBP changes between intravascular RDN and sham control were -3.14 (95% CI: -5.94, -0.33, p < 0.05; I2 = 71%, p = 0.008) and -2.06 (95% CI: -3.02, -1.11, p < 0.001; I2 = 50%, p = 0.09) mm Hg. Intravascular RDN using second-generation catheters reduced office SBP -6.30 (WMD, 95% CI: -7.67, -4.93, p < 0.001; I2 = 43%, p = 0.14) and DBP -3.88 (WMD, 95% CI: -4.44, -3.33, p < 0.001; I2 = 42%, p = 0.14) mm Hg, respectively.

CONCLUSIONS

Intravascular RDN using second-generation catheters reduces ambulatory and office BP in patients with essential hypertension. The selection of appropriate hypertensive patients may be the major challenge for the performance of intravascular RDN in routine clinical practice.

Cardiac Spinal Afferent Denervation Attenuates Renal Dysfunction in Rats With Cardiorenal Syndrome Type 2

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Epicardial application of RTX at the time of MI largely prevented renal dysfunction, attenuated renal congestion, and partially restored renal blood flow in rats with CHF.

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RNA sequencing analysis showed that renal injury, inflammation, hypoxia, and apoptosis genes were significantly up-regulated in the renal tissue of CHF rats, which was largely prevented by epicardial RTX at the time of MI.

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Cardiac afferent ablation by intra–stellate ganglia injection of RTX or unilateral renal denervation 4 weeks after MI had similar renal protective effects on renal tubular damage in CHF rats.

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These data provide evidence for cardiac spinal afferent modulation of renal function and a potential targeted therapy.

Cardiorenal syndrome type 2 (CRS2) is defined as a chronic cardiovascular disease, usually chronic heart failure (CHF), resulting in chronic kidney disease. We hypothesized that the cardiac spinal afferent reflex (CSAR) plays a critical role in the development of CRS2. Our data suggest that cardiac afferent ablation by resiniferatoxin not only improves cardiac function but also benefits the kidneys and increases long-term survival in the myocardial infarction model of CHF. We also found that renal denervation has a similar reno-protective effect in CHF rats. We believe this novel work contributes to the development of a unique neuromodulation therapy to treat CHF patients.

Left ventricular remodelling post-myocardial infarction: pathophysiology, imaging, and novel therapies

Most patients survive acute myocardial infarction (MI). Yet this encouraging development has certain drawbacks: heart failure (HF) prevalence is increasing and patients affected tend to have more comorbidities worsening economic strain on healthcare systems and impeding effective medical management. The heart’s pathological changes in structure and/or function, termed myocardial remodelling, significantly impact on patient outcomes. Risk factors like diabetes, chronic obstructive pulmonary disease, female sex, and others distinctly shape disease progression on the ‘road to HF’. Despite the availability of HF drugs that interact with general pathways involved in myocardial remodelling, targeted drugs remain absent, and patient risk stratification is poor. Hence, in this review, we highlight the pathophysiological basis, current diagnostic methods and available treatments for cardiac remodelling following MI. We further aim to provide a roadmap for developing improved risk stratification and novel medical and interventional therapies.

Renal Denervation Attenuates Adverse Remodeling and Intramyocardial Inflammation in Acute Myocardial Infarction With Ischemia–Reperfusion Injury

Background

Inhibition of sympathetic activity and renin–angiotensin system with renal denervation (RDN) was proved to be effective in managing refractory hypertension, and improving left ventricular (LV) performance in chronic heart failure. The inhibition of sustained sympathetic activation prevents or delays the development of cardiac fibrosis and dysfunction that occurs after myocardial infarction and ischemia–reperfusion (I/R) injury. The translational efficiency of RDN remains to be defined in preclinical animal studies.

Objectives

This study investigated the therapeutic role of RDN in adverse remodeling and intramyocardial inflammation in myocardial ischemia–reperfusion (MI/R) injury.

Methods

Herein, 15 minipigs were subjected to 90-min percutaneous occlusion of the left anterior descending artery followed by reperfusion. Eight animals received simultaneous RDN using catheter-based radiofrequency ablation (MI/R-RDN). Cardiac function and infarct volume were measured in vivo, followed by histological and biochemical analyses.

Results

The infarct volume in I/R-RDN pigs reduced at 30 days postreperfusion, compared to I/R-Sham animals. The levels of catecholamine and cytokines in the serum, kidney cortex, the border, and infarcted regions of the heart were significantly reduced in I/R-RDN group. Moreover, the gene expression of collagen and the protein expression of adrenergic receptor beta 1 in heart were also decreased in I/R-RDN mice. Additionally, RDN therapy alleviated myocardial oxidative stress.

Conclusion

RDN is an effective therapeutic strategy for counteracting postreperfusion myocardial injury and dysfunction, and the application of RDN holds promising prospects in clinical practice.

Renal denervation ameliorates cardiac metabolic remodeling in diabetic cardiomyopathy rats by suppressing renal SGLT2 expression

This study aimed to investigate the effects of renal denervation (RDN) on diabetic cardiomyopathy (DCM) and explore the related mechanisms. Male Sprague-Dawley rats were fed high-fat chow and injected with low-dose streptozotocin to establish a DCM model. Six rats served as controls. The surviving rats were divided into three groups: control group, DCM group and DCM + RDN group. RDN surgery was performed in the fifth week. At the end of the experiment, all rats were subjected to ¹⁸F-FDG PET/CT and metabolic cage studies. Cardiac function and structure were evaluated by echocardiography and histology. Myocardial substrate metabolism and mitochondrial function were assessed by multiple methods. In the 13th week, the DCM rats exhibited cardiac hypertrophy and interstitial fibrosis accompanied by diastolic dysfunction. RDN ameliorated DCM-induced cardiac dysfunction (E/A ratio: RDN 1.07 ± 0.18 vs. DCM 0.93 ± 0.12, P < 0.05; E/E' ratio: RDN 10.74 ± 2.48 vs. DCM 13.25 ± 1.99, P < 0.05) and pathological remodeling (collagen volume fraction: RDN 5.05 ± 2.05% vs. DCM 10.62 ± 2.68%, P < 0.05). Abnormal myocardial metabolism in DCM rats was characterized by suppressed glucose metabolism and elevated lipid metabolism. RDN increased myocardial glucose uptake and oxidation while reducing the absorption and utilization of fatty acids. Meanwhile, DCM decreased mitochondrial ATP content, depolarized the membrane potential and inhibited the activity of respiratory chain complexes, but RDN attenuated this mitochondrial damage (ATP: RDN 30.98 ± 7.33 μmol/gprot vs. DCM 22.89 ± 5.90 μmol/gprot, P < 0.05; complexes I, III and IV activity: RDN vs. DCM, P < 0.05). Furthermore, both SGLT2 inhibitor and the combination treatment produced similar effects as RDN alone. Thus, RDN prevented DCM-induced cardiac dysfunction and pathological remodeling, which is related to the improvement of metabolic disorders and mitochondrial dysfunction.

Plasma renin and aldosterone concentrations related to endovascular ultrasound renal denervation in the RADIANCE-HTN SOLO trial

OBJECTIVE

The RADIANCE-HTN SOLO trial demonstrated a greater reduction in daytime ambulatory SBP at 2 months by endovascular ultrasound renal denervation than sham procedure. We hypothesized that plasma renin and aldosterone concentrations would be associated with the SBP response to renal denervation.

METHODS

Hypertensive patients were randomized to renal denervation (n = 74) or sham (n = 72) after a 4-week washout of antihypertensive medications. In a 53-patient subset, 2-month and 6-month plasma renin and aldosterone concentration were measured. Dietary sodium was not controlled.

RESULTS

Mean age of the 29 treatment and 24 sham patients was 54 years; 62% were men; 17% black. Daytime ambulatory SBP fell in the denervation but not the sham group at 2 months (-7.8 ± 10.7 vs. -0.1 ± 10.1 mmHg; P = 0.048). Baseline plasma renin and aldosterone concentrations were in the low-normal range, did not change significantly at 2 months in either group and did not predict response to renal denervation. At 6 months, after the addition of antihypertensive medications, there was a significant rise in renin in the sham but not the denervation group.

CONCLUSION

Although renal denervation but not sham resulted in a decrease in daytime ambulatory SBP at 2 months, renin and aldosterone concentrations did neither predict the BP response to renal denervation; nor did they fall after denervation. A rise in renin at 6 months in the sham group likely represents confounding from antihypertensive medications. Whether the BP-lowering effect of renal denervation depends on reducing local intrarenal renin release requires further study.

Renal denervation: basic and clinical evidence

Renal nerves have critical roles in regulating blood pressure and fluid volume, and their dysfunction is closely related with cardiovascular diseases. Renal nerves are composed of sympathetic efferent and sensory afferent nerves. Activation of the efferent renal sympathetic nerves induces renin secretion, sodium absorption, and increased renal vascular resistance, which lead to increased blood pressure and fluid retention. Afferent renal sensory nerves, which are densely innervated in the renal pelvic wall, project to the hypothalamic paraventricular nucleus in the brain to modulate sympathetic outflow to the periphery, including the heart, kidneys, and arterioles. The effects of renal denervation on the cardiovascular system are mediated by both efferent denervation and afferent denervation. The first half of this review focuses on basic research using animal models of hypertension and heart failure, and addresses the therapeutic effects of renal denervation for hypertension and heart failure, including underlying mechanisms. The second half of this review focuses on clinical research related to catheter-based renal denervation in patients with hypertension. Randomized sham-controlled trials using second-generation devices, endovascular radiofrequency-based devices and ultrasound-based devices are reviewed and their results are assessed. This review summarizes the basic and clinical evidence of renal denervation to date, and discusses future prospects and potential developments in renal denervation therapy for cardiovascular diseases.

Safety and efficacy of renal denervation in patients with heart failure with reduced ejection fraction (HFrEF): A systematic review and meta-analysis

INTRODUCTION

A systematic analysis of clinical trials was performed in order to assess the effectiveness and risks of bilateral renal denervation (RDN) in patients with chronic heart failure with reduced ejection fraction (HFrEF).

METHODS

A systematic review was conducted of all clinical trials exploring the effectiveness of RDN in patients with HF who had reduced (<50%) EF. Primary outcomes were NYHA class, 6-min walk test, N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, left ventricular ejection fraction (LVEF) and other cardiac parameters including left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD), and left atrium diameter (LAD). Secondary outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), glomerular filtration rate (GFR), and creatinine.

RESULTS

Seven studies were included in this analysis. From baseline to 6 months after RDN, the pooled mean NYHA class was decreased (mean difference [MD], -0.9; 95% confidence interval [CI], -1.6 to -0.2; P = 0.018), the mean 6-min walk test was increased (MD, 79.5 m; 95% CI, 26.9 to 132.1; P = 0.003), and the average NT-proBNP level was decreased (MD, -520.6 pg/mL; 95% CI, -1128.4 to 87.2; P = 0.093). Bilateral RDN increased the LVEF (MD, 5.7%; 95% CI, 1.6 to 9.6; P = 0.004), decreased the LVESD (MD, -0.4 cm; 95% CI, -0.5 to -0.2; P < 0.001), decreased the LVEDD (MD, -0.5 cm; 95% CI, -0.6 to -0.3; P < 0.001), and decreased the LAD (MD, -0.4 cm; 95% CI, -0.8 to 0; P = 0.045). In addition, RDN significantly decreased systolic BP (MD, -9.4 mmHg; 95% CI, -16.3 to -2.4; P = 0.008) and diastolic BP (MD, -4.9 mmHg; 95% CI, -9.5 to -0.4; P = 0.033), and decreased HR (MD, -4.5 bpm; 95% CI, -8.2to -0.9; P = 0.015). RDN did not significantly change GFR (MD, 7.9; 95% CI, -5.0 to 20.8; P = 0.230), or serum creatinine levels (MD, -7.2; 95% CI, -23.7 to 9.4; P = 0.397).

CONCLUSION

Bilateral RDN appears safe and well-tolerated in patients with HF. RDN improved the signs and symptoms of HF and slightly decreased systolic and diastolic BP without affecting renal function in the clinical trials performed to date.

Device-Based Sympathetic Nerve Regulation for Cardiovascular Diseases

Sympathetic overactivation plays an important role in promoting a variety of pathophysiological processes in cardiovascular diseases (CVDs), including ventricular remodeling, vascular endothelial injury and atherosclerotic plaque progression. Device-based sympathetic nerve (SN) regulation offers a new therapeutic option for some CVDs. Renal denervation (RDN) is the most well-documented method of device-based SN regulation in clinical studies, and several large-scale randomized controlled trials have confirmed its value in patients with resistant hypertension, and some studies have also found RDN to be effective in the control of heart failure and arrhythmias. Pulmonary artery denervation (PADN) has been clinically shown to be effective in controlling pulmonary hypertension. Hepatic artery denervation (HADN) and splenic artery denervation (SADN) are relatively novel approaches that hold promise for a role in cardiovascular metabolic and inflammatory-immune related diseases, and their first-in-man studies are ongoing. In addition, baroreflex activation, spinal cord stimulation and other device-based therapies also show favorable outcomes. This review summarizes the pathophysiological rationale and the latest clinical evidence for device-based therapies for some CVDs.

Renal denervation based on experimental rationale

Excessive activation of the sympathetic nervous system is one of the pathophysiological hallmarks of hypertension and heart failure. Within the central nervous system, the paraventricular nucleus (PVN) of the hypothalamus and the rostral ventrolateral medulla in the brain stem play critical roles in the regulation of sympathetic outflow to peripheral organs. Information from the peripheral circulation, including serum concentrations of sodium and angiotensin II, is conveyed to the PVN via adjacent structures with a weak blood-brain barrier. In addition, signals from baroreceptors, chemoreceptors and cardiopulmonary receptors as well as afferent input via the renal nerves are all integrated at the level of the PVN. The brain renin-angiotensin system and the balance between nitric oxide and reactive oxygen species in these brain areas also determine the final sympathetic outflow. Additionally, brain inflammatory responses have been shown to modulate these processes. Renal denervation interrupts both the afferent inputs from the kidney to the PVN and the efferent outputs from the PVN to the kidney, resulting in the suppression of sympathetic outflow and eliciting beneficial effects on both hypertension and heart failure.

Renal Denervation Mitigated Fecal Microbiota Aberrations in Rats with Chronic Heart Failure

Background

Changes in the composition and diversity of gut microbiota, which can be altered by autonomic nerve activity, contribute to the development of heart failure (HF). Renal denervation (RDN) can improve cardiac function by reducing sympathetic nerve activity. However, whether the beneficial role of RDN on HF is related to gut microbiota is unknown.

Methods

Thirty rats were assigned to a control, HF (with induced transverse aortic constriction (TAC)), RDN (with RDN induced 10 weeks after TAC), Nog (HF rats with Nogo-P4-administered 8 weeks after RDN), and NEP (HF rats with NEP1-40-administered 8 weeks after RDN) group. Then, 16SrRNA amplicon sequencing and analyses of fecal samples were performed.

Results

Beta diversity analyses revealed that compared to the HF group, the RDN, Nog, and NEP groups clustered closer to the control group. The Firmicutes/Bacteroidetes ratio was reduced in the HF group (1.59) compared with the control group (3.21) and was significantly decreased compared to the Nog (7.19), RDN (6.20), and NEP (4.42) groups. At the genus level, the HF group showed decreased abundances of Lactobacillus and Alistipes and increased abundances of Bacteroides and Clostridium compared with the control group. The abundances of Lactobacillus and Alistipes were increased, and those of Bacteroides and Clostridium were decreased in the RDN, Nog, and NEP groups compared to the HF group. However, no differences were observed between the three groups that underwent RDN. The microbial function showed the same tendency.

Conclusions

RDN reversed the abnormal changes in the gut microbiome in HF rats. Inhibition of reinnervation after RDN did not affect intestinal bacteria.

The influence of inhibiting renal neural regeneration on the efficacy of renal denervation to chronic heart failure

Aims

Some studies support the occurrence of nerve regeneration in renal arteries after renal denervation (RDN). But it is unclear whether inhibiting reinnervation after RDN is beneficial to enhancing the effect of RDN on chronic heart failure (CHF).

Methods and results

Chronic heart failure Sprague Dawley rats induced by transverse aortic constriction were administered with the analogue of Nogo‐B (Nogo group) or its antagonist (NEP group) respectively after RDN. Echocardiography, messenger RNA, and protein expression of calcitonin gene‐related peptide (CGRP) in renal artery and nerves surrounding renal artery were detected. Relative protein expression of CGRP was significantly decreased in the Nog group compared with the RDN group (0.64 ± 0.51 vs. 1.68 ± 1.07, P = 0.048). The number of nerves surrounding renal artery was higher in the NEP group than in the Nog group. Left ventricular end‐systolic volume and diameter (LVVs and LVDs) were greatly decreased, and left ventricular ejection fraction (LVEF) and fractional shortening (FS) increased significantly in the RDN, Nog and NEP groups when compared with the HF group (all P < 0.05). No significant differences were observed in left ventricular end‐diastolic volume and diameter; LVDs; LVVs; FS; LVEF; and the levels of plasma renin, noradrenaline, and N‐terminal pro‐B‐type natriuretic peptide among three groups: the RDN, Nog, and NEP groups.

Conclusions

Reinnervation of renal artery occurred in CHF rats after RDN, which had no effect on therapeutic role of RDN in CHF, and inhibiting this neural regeneration had no clinical significance and did not affect the efficacy of RDN to CHF.

Immediate Renal Denervation After Acute Myocardial Infarction Mitigates the Progression of Heart Failure via the Modulation of IL-33/ST2 Signaling

Objective: Previous studies have demonstrated the protective effects of renal denervation (RDN) in pre-existing heart failure, but the effects of immediate RDN after acute myocardial infarction (AMI) on subsequent cardiac remodeling have not been reported. This study aimed to investigate the cardioprotective effects of immediate RDN after AMI and its underlying mechanism.

Methods: AMI was induced by intracoronary gelatin sponge embolization in 14 Shanghai white pigs that were randomized to undergo either renal angiography (AMI+sham group) or RDN (AMI+RDN group) after 1 h of hemodynamic monitoring. Cardiac function of the two groups was measured at baseline, 1 h post-AMI and at the 1 month follow-up (1M-FU) by transthoracic echocardiography (TTE). Plasma NT-proBNP, soluble ST2 (sST2), norepinephrine (NE), and renin-angiotensin-aldosterone system activity were detected simultaneously. The renal cortex was harvested for NE measurement after the 1M-FU, and the renal arteries were stained with tyrosine hydroxylase for the evaluation of sympathetic activity. Heart tissues in the non-ischemic areas were collected to assess histological and molecular left ventricular (LV) remodeling by pathological staining, RT-PCR, and western blotting.

Results: There was no difference in the hemodynamic stability or cardiac function between the two groups at baseline and 1 h post-AMI. Six pigs from each of the two groups completed the 1M-FU. TTE analysis revealed the improved cardiac function of immediate RDN in the AMI+RDN group and circulating NT-proBNP levels were lower than those in the AMI+sham group. Further analysis showed significantly less interstitial fibrosis in the remote non-ischemic myocardium after immediate RDN, together with decreased cardiomyocyte hypertrophy and inflammatory cell infiltration. sST2 levels in circulating and myocardial tissues of animals in the AMI+RDN group were significantly higher than those in the AMI+sham group, accompanied by corresponding alterations in IL-33/ST2 and downstream signaling.

Conclusions: Immediate RDN can improve cardiac function and myocardial remodeling after AMI via modulation of IL-33/ST2 and downstream signaling.

Endovascular renal sympathetic denervation to improve heart failure with reduced ejection fraction: the IMPROVE-HF-I study

Introduction

The aim of the present study was to assess the safety and efficacy of renal sympathetic denervation (RDN) in patients with heart failure with reduced ejection fraction (HFrEF).

Methods

We randomly assigned 50 patients with a left ventricular ejection fraction (LVEF) ≤ 35% and NYHA class ≥ II, in a 1:1 ratio, to either RDN and optimal medical therapy (OMT) or OMT alone. The primary safety endpoint was the occurrence of a combined endpoint of cardiovascular death, rehospitalisation for heart failure, and acute kidney injury at 6 months. The primary efficacy endpoint was the change in iodine-123 meta-iodobenzylguanidine (¹²³I‑MIBG) heart-to-mediastinum ratio (HMR) at 6 months.

Results

Mean age was 60 ± 9 years, 86% was male and mean LVEF was 33 ± 8%. At 6 months, the primary safety endpoint occurred in 8.3% vs 8.0% in the RDN and OMT groups, respectively (p = 0.97). At 6 months, the mean change in late HMR was −0.02 (95% CI: −0.08 to 0.12) in the RDN group, versus −0.02 (95% CI: −0.09 to 0.12) in the OMT group (p = 0.95) whereas the mean change in washout rate was 2.34 (95% CI: −6.35 to 1.67) in the RDN group versus −2.59 (95% CI: −1.61 to 6.79) in the OMT group (p-value 0.09).

Conclusion

RDN with the Vessix system in patients with HFrEF was safe, but did not result in significant changes in cardiac sympathetic nerve activity at 6 months as measured using ¹²³I‑MIBG.

Supplementary Information

The online version of this article (10.1007/s12471-021-01633-z) contains supplementary material, which is available to authorized users.

Sympatho-adrenergic mechanisms in heart failure: new insights into pathophysiology

The sympathetic nervous system is activated in the setting of heart failure (HF) to compensate for hemodynamic instability. However, acute sympathetic surge or sustained high neuronal firing rates activates β-adrenergic receptor (βAR) signaling contributing to myocardial remodeling, dysfunction and electrical instability. Thus, sympatho-βAR activation is regarded as a hallmark of HF and forms pathophysiological basis for β-blocking therapy. Building upon earlier research findings, studies conducted in the recent decades have significantly advanced our understanding on the sympatho-adrenergic mechanism in HF, which forms the focus of this article. This review notes recent research progress regarding the roles of cardiac β2AR or α1AR in the failing heart, significance of β1AR-autoantibodies, and βAR signaling through G-protein independent signaling pathways. Sympatho-βAR regulation of immune cells or fibroblasts is specifically discussed. On the neuronal aspects, knowledge is assembled on the remodeling of sympathetic nerves of the failing heart, regulation by presynaptic α2AR of NE release, and findings on device-based neuromodulation of the sympathetic nervous system. The review ends with highlighting areas where significant knowledge gaps exist but hold promise for new breakthroughs.

The role and mechanism of hyperoside against myocardial infarction in mice by regulating autophagy via NLRP1 inflammation pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Hypericum are widely distributed in China. Hypericum perforatum L. (genus Hypericum, family Hypericaceae) has a long history as a traditional Chinese medicine, which was traditionally used for the treatment of emotional distress, cardiothoracic depression, and acute mastitis. Hyperoside (Hyp) extracted from Hypericum perforatum L. has been affirmed to exert therapeutic effects on cardiovascular diseases, with widespread existence in plants of genus Hypericum. Hyp could also be extracted from Crataegus pinnatifida Bunge (genus Crataegus pinnatifida Bunge, family Rosaceae), another traditional Chinese medicine that traditionally prevented and treated heart disease in China. The cardioprotection and mechanism of Hyp comprise anti-inflammation, anti-fibrosis, activation of autophagy, and reversal of cardiac remodeling.

AIM OF THE STUDY

This study aimed to explore the Hyp effect against MI and its underlying mechanism.

MATERIALS AND METHODS

The MI model was constructed in the KM mice via a ligating surgery of the left anterior descending (LAD) coronary artery. Subsequently, the mice were divided into following seven groups: Sham group, MI group, MI + Hyp 9 mg/kg group, MI + Hyp18 mg/kg group, MI + Hyp36 mg/kg group, MI + Fosinopril group, and MI + Hyp-36 mg/kg+3-MA group. Each group was treated with Hyp in different concentrations or positive medicine for two weeks except for the sham group. After two weeks, we examined the cardiac function, electrocardiogram (ECG), myocardial hypertrophy in the non-infarct area, collagen volume fraction (CVF), perivascular collagen area (PVCA) in the infarct area, and several serum cytokines. Autophagy and inflammation in cardiomyocytes were assessed via measuring autophagy-associated proteins and NLRP1 inflammasome pathway related proteins.

RESULTS

Hyp reversed LV remodeling and adverse ECG changes through reducing CVF and myocardial hypertrophy. Additionally, Hyp treatment could reduce inflammation levels in cardiomyocytes, compared with those in MI group. Moreover, NLRP1inflammation pathway was activated after MI. Up-regulation of autophagic flux suppressed NLRP1 inflammation pathway after Hyp treatment. However, co-treatment with 3-MA abrogated above effects of Hyp.

CONCLUSIONS

Hyp had obvious protective effect on heart injury in MI mice. Echocanrdiographic and histological measurements demonstrated that Hyp treatment improved cardiac function, and ameliorated myocardial hypertrophy and fibrinogen deposition after MI. The partial mechanism is that Hyp could up-regulate autophagy after MI. Furthermore, the promotion of autophagic flux would suppress NLRP1 inflammation pathway induced by MI.

Renal, Cardiac, and Autonomic Effects of Catheter-Based Renal Denervation in Ovine Heart Failure

[Figure: see text].

Impact of renal sympathetic denervation on cardiac magnetic resonance-derived cardiac indices in hypertensive patients - A meta-analysis

BACKGROUND

Renal sympathetic denervation (RDN) is a safe device-based option for the treatment of hypertension although current guidelines do not recommend its use in routine clinical practice. In this meta-analysis, we investigated the effects of RDN in cardiac magnetic resonance (CMR)-derived cardiac indices.

METHODS

This meta-analysis was performed in accordance with the PRISMA statement. A comprehensive systematic search of MEDLINE database and Cochrane library through to January 2021 was performed. The inclusion criteria were studies that enrolled patients undergoing RDN in whom CMR data were provided for left ventricular end-diastolic volume indexed to body surface area (BSA) (LVEDVI), left ventricular end-systolic volume indexed (LVESVI), left ventricular mass indexed (LVMI), and left ventricular ejection fraction (LVEF) pre and post RDN. A random effects model was used for the analyses.

RESULTS

Our search strategy revealed 9 studies that were finally included in the meta-analysis (n=300 patients, mean age: 60 years old, males: 59%). Compared to control group, RDN patients showed significantly lower values in the attained volumes (LVEDVI: -6.70 ml/m², p=0.01; LVESVI: -3.63 ml/m², p=0.006). Moreover, RDN group achieved a statistically significant higher attained LVEF (3.49%, p=0.01). A non-significant difference was found in the attained LVMI between RDN and control groups (-2.59 g/m², p=0.39). Compared to pre-RDN values, RDN reduces significantly the LVMI, the LVEDVI, and the LVESVI while a non-significant change of LVEF was found.

CONCLUSIONS

In conclusion, the current study demonstrates the potential beneficial role of RDN in CMR-derived cardiac indices that reflect adverse remodeling. However, large, randomized studies are needed to elucidate the role of RDN in cardiac remodeling in hypertension, heart failure, and other clinical settings.

AT II Receptor Blockade and Renal Denervation: Different Interventions with Comparable Renal Effects?

BACKGROUND

Angiotensin II (Ang II) and the renal sympathetic nervous system exert a strong influence on renal sodium and water excretion. We tested the hypothesis that already low doses of an Ang II inhibitor (candesartan) will result in similar effects on tubular sodium and water reabsorption in congestive heart failure (CHF) as seen after renal denervation (DNX).

METHODS

Measurement of arterial blood pressure, heart rate (HR), renal sympathetic nerve activity (RSNA), glomerular filtration rate (GFR), renal plasma flow (RPF), urine volume, and urinary sodium. To assess neural control of volume homeostasis, 21 days after the induction of CHF via myocardial infarction rats underwent volume expansion (0.9% NaCL; 10% body weight) to decrease RSNA. CHF rat and controls with or without DNX or pretreated with the Ang II type-1 receptor antagonist candesartan (0.5 ug i.v.) were studied.

RESULTS

CHF rats excreted only 68 + 10.2% of the volume load (10% body weight) in 90 min. CHF rats pretreated with candesartan or after DNX excreted from 92 to 103% like controls. Decreases of RSNA induced by volume expansion were impaired in CHF rats but unaffected by candesartan pointing to an intrarenal drug effect. GFR and RPF were not significantly different in controls or CHF.

CONCLUSION

The prominent function of increased RSNA - retaining salt and water - could no longer be observed after renal Ang II receptor blockade in CHF rats.

Renal Denervation Attenuates Neuroinflammation in the Brain by Regulating Gut-Brain Axis in Rats With Myocardial Infarction

Aims: The development of neuroinflammation deteriorates the prognosis of myocardial infarction (MI). We aimed to investigate the effect of renal denervation (RDN) on post-MI neuroinflammation in rats and the related mechanisms.

Methods and Results: Male adult Sprague-Dawley rats were subjected to sham or ligation of the left anterior descending coronary artery to induce MI. One week later, the MI rats received a sham or RDN procedure. Their cardiac functions were analyzed by echocardiography, and their intestinal structures, permeability, and inflammatory cytokines were tested. The intestinal microbiota were characterized by 16S rDNA sequencing. The degrees of neuroinflammation in the brains of rats were analyzed for microglia activation, inflammatory cytokines, and inflammation-related signal pathways. In comparison with the Control rats, the MI rats exhibited impaired cardiac functions, intestinal injury, increased intestinal barrier permeability, and microbial dysbiosis, accompanied by increased microglia activation and pro-inflammatory cytokine levels in the brain. A RDN procedure dramatically decreased the levels of renal and intestinal sympathetic nerve activity, improved cardiac functions, and mitigated the MI-related intestinal injury and neuroinflammation in the brain of MI rats. Interestingly, the RDN procedure mitigated the MI-increased intestinal barrier permeability and pro-inflammatory cytokines and plasma LPS as well as ameliorated the gut microbial dysbiosis in MI rats. The protective effect of RDN was not significantly affected by treatment with intestinal alkaline phosphatase but significantly reduced by L-phenylalanine treatment in MI rats.

Conclusions: RDN attenuated the neuroinflammation in the brain of MI rats, associated with mitigating the MI-related intestinal injury.

Myocardial Angiotensin Metabolism in End-Stage Heart Failure

BACKGROUND

The myocardium exhibits an adaptive tissue-specific renin-angiotensin system (RAS), and local dysbalance may circumvent the desired effects of pharmacologic RAS inhibition, a mainstay of heart failure with reduced ejection fraction (HFrEF) therapy.

OBJECTIVES

This study sought to investigate human myocardial tissue RAS regulation of the failing heart in the light of current therapy.

METHODS

Fifty-two end-stage HFrEF patients undergoing heart transplantation (no RAS inhibitor: n = 9; angiotensin-converting enzyme [ACE] inhibitor: n = 28; angiotensin receptor blocker [ARB]: n = 8; angiotensin receptor neprilysin-inhibitor [ARNi]: n = 7) were enrolled. Myocardial angiotensin metabolites and enzymatic activities involved in the metabolism of the key angiotensin peptides angiotensin 1-8 (AngII) and Ang1-7 were determined in left ventricular samples by mass spectrometry. Circulating angiotensin concentrations were assessed for a subgroup of patients.

RESULTS

AngII and Ang2-8 (AngIII) were the dominant peptides in the failing heart, while other metabolites, especially Ang1-7, were below the detection limit. Patients receiving an ARB component (i.e., ARB or ARNi) had significantly higher levels of cardiac AngII and AngIII (AngII: 242 [interquartile range (IQR): 145.7 to 409.9] fmol/g vs 63.0 [IQR: 19.9 to 124.1] fmol/g; p < 0.001; and AngIII: 87.4 [IQR: 46.5 to 165.3] fmol/g vs 23.0 [IQR: <5.0 to 59.3] fmol/g; p = 0.002). Myocardial AngII concentrations were strongly related to circulating AngII levels. Myocardial RAS enzyme regulation was independent from the class of RAS inhibitor used, particularly, a comparable myocardial neprilysin activity was observed for patients with or without ARNi. Tissue chymase, but not ACE, is the main enzyme for cardiac AngII generation, whereas AngII is metabolized to Ang1-7 by prolyl carboxypeptidase but not to ACE2. There was no trace of cardiac ACE2 activity.

CONCLUSIONS

The failing heart contains considerable levels of classical RAS metabolites, whereas AngIII might be an unrecognized mediator of detrimental effects on cardiovascular structure. The results underline the importance of pharmacologic interventions reducing circulating AngII actions, yet offer room for cardiac tissue-specific RAS drugs aiming to limit myocardial AngII/AngIII peptide accumulation and actions.

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.

Metabolic effects two years after renal denervation in insulin resistant hypertensive patients. The Re-Shape CV-risk study

BACKGROUND & AIMS

Denervation of renal sympathetic nerves (RDN) is an invasive endovascular procedure introduced as an antihypertensive treatment with a potential beneficial effect on insulin resistance (IR). We have previously demonstrated a reduction in blood pressure (BP) six months after RDN, but severe hepatic and peripheral IR, assessed by glucose tracer and two step hyperinsulinemic-euglycemic clamp (HEC), did not improve. The aim of the current study was to evaluate IR and adipokines profiles in relation to BP and arterial stiffness changes two years after RDN.

METHODS

In 20 non-diabetic patients with true treatment-resistant hypertension, ambulatory and office BP were measured after witnessed intake of medications prior to, six and 24 months after RDN. Arterial stiffness index (AASI) was calculated from ambulatory BP. Insulin sensitivity (IS) was assessed using an oral glucose tolerance test (OGTT), the Homeostasis Model Assessment (HOMA-IR), HOMA-Adiponectin Model Assessment (HOMA-AD), the Quantitative Insulin Sensitivity Check Index (QUICKI), the Triglyceride and Glucose Index (TyG) and the Leptin-to-Adiponectin Ratio (LAR). These surrogate indices of IS were compared with tracer/HEC measurements to identify which best correlated in this group of patients.

RESULTS

All measured metabolic variables and IS surrogate indices remained essentially unchanged two years after RDN apart from a significant increase in HOMA-AD. OGTT peak at 30 min correlated best with reduction in endogenous glucose release (EGR) during low insulin HEC (r = -0.6, p = 0.01), whereas HOMA-IR correlated best with whole-body glucose disposal (WGD) (r = -0.6, p = 0.01) and glucose infusion rate (r = -0.6, p = 0.01) during high insulin HEC. BP response was unrelated to IS prior to RDN. Nocturnal systolic BP and arterial stiffness before RDN correlated positively with a progression in hepatic IR at six-month follow-up.

CONCLUSION

IR, adiponectin and leptin did not improve two years after RDN. There was no correlation between baseline IS and BP response. Our study does not support the notion of a beneficial metabolic effect of RDN in patients with treatment resistant hypertension.

AT1 receptor blocker, but not an ACE inhibitor, prevents kidneys from hypoperfusion during congestive heart failure in normotensive and hypertensive rats

To provide novel insights into the pathogenesis of heart failure-induced renal dysfunction, we compared the effects of ACE inhibitor (ACEi) and AT₁ receptor blocker (ARB) on systemic and kidney hemodynamics during heart failure in normotensive HanSD and hypertensive transgenic (TGR) rats. High-output heart failure was induced by creating an aorto-caval fistula (ACF). After five weeks, rats were either left untreated or treatment with ACEi or ARB was started for 15 weeks. Subsequently, echocardiographic, renal hemodynamic and biochemical measurements were assessed. Untreated ACF rats with ACF displayed significantly reduced renal blood flow (RBF) (HanSD: 8.9 ± 1.0 vs. 4.7 ± 1.6; TGR: 10.2 ± 1.9 vs. 5.9 ± 1.2 ml/min, both P < .001), ACEi had no major RBF effect, whereas ARB completely restored RBF (HanSD: 5.6 ± 1.1 vs. 9.0 ± 1.5; TGR: 7.0 ± 1.2 vs. 10.9 ± 1.9 ml/min, both P < .001). RBF reduction in untreated and ACEi-treated rats was accompanied by renal hypoxia as measured by renal lactate dehydrogenase activity, which was ameliorated with ARB treatment (HanSD: 40 ± 4 vs. 42 ± 3 vs. 29 ± 5; TGR: 88 ± 4 vs. 76 ± 4 vs. 58 ± 4 milliunits/mL, all P < .01). Unlike improvement seen in ARB-treated rats, ACE inhibition didn’t affect urinary nitrates compared to untreated ACF TGR rats (50 ± 14 vs. 22 ± 13 vs. 30 ± 13 μmol/mmol Cr, both P < .05). ARB was more effective than ACEi in reducing elevated renal oxidative stress following ACF placement. A marker of ACEi efficacy, the angiotensin I/angiotensin II ratio, was more than ten times lower in renal tissue than in plasma. Our study shows that ARB treatment, in contrast to ACEi administration, prevents renal hypoperfusion and hypoxia in ACF rats with concomitant improvement in NO bioavailability and oxidative stress reduction. The inability of ACE inhibition to improve renal hypoperfusion in ACF rats may result from incomplete intrarenal RAS suppression in the face of depleted compensatory mechanisms.

Renal Sympathetic Denervation Attenuates Congestive Heart Failure in Angiotensin II-Dependent Hypertension: Studies with Ren-2 Transgenic Hypertensive Rats with Aortocaval Fistula

OBJECTIVE

We examined if renal denervation (RDN) attenuates the progression of aortocaval fistula (ACF)-induced heart failure or improves renal hemodynamics in Ren-2 transgenic rats (TGR), a model of angiotensin II (ANG II)-dependent hypertension.

METHODS

Bilateral RDN was performed 1 week after creation of ACF. The animals studied were ACF TGR and sham-operated controls, and both groups were subjected to RDN or sham denervation. In separate groups, renal artery blood flow (RBF) responses were determined to intrarenal ANG II (2 and 8 ng), norepinephrine (NE) (20 and 40 ng) and acetylcholine (Ach) (10 and 40 ng) 3 weeks after ACF creation.

RESULTS

In nondenervated ACF TGR, the final survival rate was 10 versus 50% in RDN rats. RBF was significantly lower in ACF TGR than in sham-operated TGR (6.2 ± 0.3 vs. 9.7 ± 0.5 mL min-1 g-1, p < 0.05), the levels unaffected by RDN. Both doses of ANG II decreased RBF more in ACF TGR than in sham-operated TGR (-19 ± 3 vs. -9 ± 2% and -47 ± 3 vs. -22 ± 2%, p < 0.05 in both cases). RDN did not alter RBF responses to the lower dose, but increased it to the higher dose of ANG II in sham-operated as well as in ACF TGR. NE comparably decreased RBF in ACF TGR and sham-operated TGR, and RDN increased RBF responsiveness. Intrarenal Ach increased RBF significantly more in ACF TGR than in sham-operated TGR (29 ± 3 vs. 17 ± 3%, p < 0.05), the changes unaffected by RDN. ACF creation induced marked bilateral cardiac hypertrophy and lung congestion, both attenuated by RDN. In sham-operated but not in ACF TGR, RDN significantly decreased mean arterial pressure.

CONCLUSION

The results show that RDN significantly improved survival rate in ACF TGR; however, this beneficial effect was not associated with improvement of reduced RBF or with attenuation of exaggerated renal vascular responsiveness to ANG II.

Novel Göttingen Miniswine Model of Heart Failure With Preserved Ejection Fraction Integrating Multiple Comorbidities

A lack of preclinical large animal models of heart failure with preserved ejection fraction (HFpEF) that recapitulate this comorbid-laden syndrome has led to the inability to tease out mechanistic insights and to test novel therapeutic strategies. This study developed a large animal model that integrated multiple comorbid determinants of HFpEF in a miniswine breed that exhibited sensitivity to obesity, metabolic syndrome, and vascular disease with overt clinical signs of heart failure. The combination of a Western diet and 11-deoxycorticosterone acetate salt-induced hypertension in the Göttingen miniswine led to the development of a novel large animal model of HFpEF that exhibited multiorgan involvement and a full spectrum of comorbidities associated with human HFpEF.

Acute renal denervation normalizes aortic function and decreases blood pressure in spontaneously hypertensive rats

Mechanisms involved in the acute responses to renal denervation (RDN) have yet to be fully understood. We assessed urinary volume, autonomic control and aorta vascular reactivity after acute RDN. Male normotensive Wistar rats and spontaneously hypertensive rats (SHR) were divided into normotensive + RDN (ND) or sham surgery (NS), and hypertensive + RDN (HD) or sham surgery (HS). Metabolic parameters and hemodynamic measurements were recorded 72h and 4 days after intervention, respectively. Aortic rings were studied 7 days post RDN in an isometric myograph. Concentration–response curves to phenylephrine, sodium nitroprusside and acetylcholine (10^–10–10⁻⁵ M) were performed. Two-way ANOVA was used for group comparisons and differences reported when p < 0.05. Results are presented as mean ± SEM. Urinary volume was 112% higher in HD vs. HS (HS = 14.94 ± 2.5 mL; HD = 31.69 ± 2.2 mL) and remained unchanged in normotensive rats. Systolic BP was lower in HD rats (HS = 201 ± 12 vs. HD = 172 ± 3 mmHg) without changes in normotensive group. HD group showed increased HF and LF modulation (HS = 5.8 ± 0.7 ms²vs. HD = 13.4 ± 1.4 ms²; HS = 3.5 ± 0.7 ms²vs. HD = 10.5 ± 1.7 ms², respectively). RDN normalized vascular reactivity in HD rats and increased phenylephrine response in ND rats. Acute fall in BP induced by RDN is associated with increased urinary volume, which in turn may also have contributed to functional changes of the aorta.

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.

Renal denervation improves vascular endothelial dysfunction by inducing autophagy via AMPK/mTOR signaling activation in a rat model of type 2 diabetes mellitus with insulin resistance

BACKGROUND

Recent clinical and animal studies have shown that renal denervation (RDN) improves insulin sensitivity and endothelial dysfunction. However, the specific mechanism remains incompletely understood. The purpose of this study is to investigate the effects of RDN on endothelial dysfunction of type 2 diabetes mellitus (T₂DM) rat models with insulin resistance and to explore the underlying molecular mechanisms.

METHODS

Male Sprague-Dawley rats were fed with or without high-fat diet allocated in different groups, combined with low-dose streptozotocin which induces a rat model to develop T₂DM with insulin resistance. RDN was conducted 1 week after the rat models fully developed T₂DM. The animals were sub-divided into four groups randomly: control group (CON, n = 6), diabetic group (T₂DM, n = 6), diabetic with sham surgery group (Sham, n = 6) and diabetic with RDN group (RDN, n = 6). Rats in all groups were studied at baseline, both preoperatively and 4 weeks after RDN, respectively. Western blot was used to detect the expression of angiotensin-converting enzyme 2 (ACE2) protein and the expression of autophagy-related proteins Beclin1, LC3 and p62 and autophagy signaling pathway AMPK/mTOR proteins and apoptosis-related protein caspase-3 in the aorta endothelial cells. In addition, the effects of ACE2 on autophagy of human umbilical vein insulin resistance endothelial cell culture in vitro were also studied.

RESULTS

RDN decreased plasma and renal tissue norepinephrine levels. The Von Willebrand factor level was also decreased, while the plasma level of nitric oxide (NO) was significantly increased after RDN. Compared with the T₂DM group and the Sham group, the endothelium-dependent and endothelium-independent diastolic function of the RDN group was improved significantly, the expression of Beclin1, LC3, ACE2 and eNOS proteins was higher, and the level of p62 protein was decreased. Furthermore, we found that RDN can activate the expression of p-AMPK and inhibit the expression of p-mTOR. In cell culture experiment, ACE2 activated p-AMPK and inhibited p-mTOR, thus promoting autophagy.

CONCLUSIONS

RDN may not only increase the expression of ACE2 in the vascular endothelium, but also can via ACE2 activate p-AMPK and inhibit p-mTOR, thus promoting autophagy and improving endothelial dysfunction.

Role of spinal neurons in the maintenance of elevated sympathetic activity: a novel therapeutic target?

The control of sympathetic vasomotor activity involves a complex network within the brain and spinal circuits. An extensive range of studies has indicated that sympathoexcitation is a common feature in several cardiovascular diseases and that strategies to reduce sympathetic vasomotor overactivity in such conditions can be beneficial. In the present mini-review, we present evidence supporting the spinal cord as a potential therapeutic target to mitigate sympathetic vasomotor overactivity in cardiovascular diseases, focusing mainly on the actions of spinal angiotensin II on the control of sympathetic preganglionic neuronal activity.

Alterations of the renin angiotensin system in human end-stage heart failure before and after mechanical cardiac unloading by LVAD support

Heart transplantation is often an unrealizable therapeutic option for end-stage heart failure, which is why mechanical left ventricular assist devices (LVADs) become an increasingly important therapeutic alternative. Currently, there is a lack of information about molecular mechanisms which are influenced by LVADs, particularly regarding the pathophysiologically critical renin angiotensin system (RAS). We, therefore, determined regulation patterns of key components of the RAS and the β-arrestin signaling pathways in left ventricular (LV) tissue specimens from 8 patients with end-stage ischemic cardiomyopathy (ICM) and 12 patients with terminal dilated cardiomyopathy (DCM) before and after LVAD implantation and compared them with non-failing (NF) left ventricular tissue samples: AT1R, AT2R, ACE, ACE2, MasR, and ADAM17 were analyzed by polymerase chain reaction. ERK, phosphorylated ERK, p38, phosphorylated p38, JNK, phosphorylated JNK, GRK2, β-arrestin 2, PI3K, Akt, and phosphorylated Akt were determined by Western blot analysis. Angiotensin I and Angiotensin II were quantified by mass spectrometry. Patients were predominantly middle-aged (53 ± 10 years) men with severely impaired LV function (LVEF 19 ± 8%), when receiving LVAD therapy for a mean duration of 331 ± 317 days. Baseline characteristics did not differ significantly between ICM and DCM patients. By comparing failing with non-failing left ventricles, i.e., before LVAD implantation, a downregulation of AT1R, AT2R, and MasR and an upregulation of ACE, ACE2, GRK, β-arrestin, ERK, PI3K, and Akt were seen. Following LVAD support, then angiotensin I, ACE2, GRK, and β-arrestin were downregulated and AT2R, JNK, and p38 were upregulated. ACE, angiotensin II, AT1R, ADAM17, MasR, ERK, PI3K, and Akt remained unchanged. Some regulation patterns were influenced by the underlying etiology of heart failure, the severity of LV dysfunction at baseline, and the duration of LVAD therapy. Key components of the RAS and β-arrestin signaling pathways were divergently altered in failing left ventricles both before and after LVAD implantation, whereas a remarkable fraction remained unchanged. This indicates a rather incomplete molecular reverse remodeling, whose functional relevance has to be further evaluated.