Renal Denervation: A Review

Non-alcoholic fatty liver disease enhances the beneficial effect of renal denervation on gut microbiota aberrations in rats with heart failure

BACKGROUND

Renal denervation (RDN) contributes to improving cardiac function by ameliorating aberrations of the gut microbiota, and non-alcoholic fatty liver disease (NAFLD) is associated with gut microbiota dysbiosis and is critically involved in the development of heart failure (HF). It is unclear whether the beneficial effect of RDN on gut microbiota in HF can be affected by NAFLD and whether this effect changes with the severity of NAFLD.

METHODS

HF Sprague Dawley rats induced by transverse aortic constriction were fed a high-fat-fructose diet and underwent RDN, and sequencing of 16S rRNA gene in fecal samples was detected.

RESULTS

The dissimilarity coefficients and sample distances of the intestinal microbiome were elevated in HF rats with NAFLD. After RDN, HF rats with NAFLD had fewer bacteria harmful to cardiac function, such as Alphaproteobacteria, Bacteroidota and Prevotella-9, and more bacteria beneficial to HF, such as Monoglobaceae, Proteobacteria and Monoglobales, than HF rats without NAFLD (all p < 0.05). This tendency also existed but was much less significant when compared between HF rats with non-alcoholic steatohepatitis (NASH) and without NAFLD. Predictive functional profiling of microbial communities revealed that after RDN, the abundance of membrane transport, environmental and genetic information processing was significantly higher, and glycan biosynthesis and metabolism was significantly lower in HF rats with NAFLD than in those without NAFLD.

CONCLUSION

NAFLD could further enhance the beneficial role of RDN in mitigating gut microbiota aberrations in HF rats by increasing beneficial bacteria and decreasing bacteria harmful to cardiac function, but this effect was not apparent in NASH rats.

Multi-Organ Denervation: The Past, Present and Future

The sympathetic division of the autonomic nervous system plays a crucial role in maintaining homeostasis, but its overactivity is implicated in various pathological conditions, including hypertension, hyperglycaemia, heart failure, and rheumatoid arthritis. Traditional pharmacotherapies often face limitations such as side effects and poor patient adherence, thus prompting the exploration of device-based multi-organ denervation as a therapeutic strategy. Crucially, this procedure can potentially offer therapeutic benefits throughout the 24 h circadian cycle, described as an "always-on" effect independent of medication compliance and pharmacokinetics. In this comprehensive review, we evaluate the evidence behind targeted multi-organ sympathetic denervation by considering the anatomy and function of the autonomic nervous system, examining the evidence linking sympathetic nervous system overactivity to various cardiometabolic and inflammatory conditions and exploring denervation studies within the literature. So far, renal denervation, developed in 2010, has shown promise in reducing blood pressure and may have broader applications for conditions including arrhythmias, glucose metabolism disorders, heart failure, chronic kidney disease and obstructive sleep apnoea. We review the existing literature surrounding the denervation of other organ systems including the hepatic and splenic arteries, as well as the pulmonary artery and carotid body, which may provide additional physiological benefits and enhance therapeutic effects if carried out simultaneously. Furthermore, we highlight the challenges and future directions for implementing multi-organ sympathetic ablation, emphasising the need for further clinical trials to establish optimal procedural technique, efficacy and safety.

In these cases, I treat hypertension with renal ablation

Systemic arterial hypertension is one of the leading causes of mortality and morbidity worldwide. Despite therapeutic advancements, a significant proportion of hypertensive patients fail to achieve adequate blood pressure control. Renal denervation (RDN) is emerging as an innovative and minimally invasive procedure to treat hypertension by modulating the renal sympathetic nervous system. Recent clinical trials, including SYMPLICITY HTN-3, SPYRAL HTN-OFF MED, and RADIANCE-HTN SOLO, have shown variable results, influenced by patient selection and study design. The latest 2024 ESC guidelines on systemic arterial hypertension recommend RDN as a therapeutic option in selected cases, especially in patients with resistant hypertension not adequately controlled by pharmacological therapy. However, the response to this approach varies according to individual pathophysiology and the level of sympathetic activation. This article highlights how RDN, performed using ultrasound or radiofrequency technologies, may represent a breakthrough for difficult-to-treat patients, bridging current therapeutic gaps and reducing long-term cardiovascular risk. Finally, it emphasizes the importance of a multi-disciplinary assessment to maximize the benefits of the procedure.

Neurocardiology: translational advancements and potential

In our original white paper published in the The Journal of Physiology in 2016, we set out our knowledge of the structural and functional organization of cardiac autonomic control, how it remodels during disease, and approaches to exploit such knowledge for autonomic regulation therapy. The aim of this update is to build on this original blueprint, highlighting the significant progress which has been made in the field since and major challenges and opportunities that exist with regard to translation. Imbalances in autonomic responses, while beneficial in the short term, ultimately contribute to the evolution of cardiac pathology. As our understanding emerges of where and how to target in terms of actuators (including the heart and intracardiac nervous system (ICNS), stellate ganglia, dorsal root ganglia (DRG), vagus nerve, brainstem, and even higher centres), there is also a need to develop sensor technology to respond to appropriate biomarkers (electrophysiological, mechanical, and molecular) such that closed-loop autonomic regulation therapies can evolve. The goal is to work with endogenous control systems, rather than in opposition to them, to improve outcomes.

Novel role of GRK2 in isoprenaline-induced activation of Na+/H+ exchanger 3 independent of β2-adrenergic receptor signaling

BACKGROUND

The activation of Na+/H+ exchanger 3 (NHE3) by β2-adrenergic receptor (β2-AR) signaling is well-established. Our research indicates that isoprenaline (ISO) induces activation of NHE3 independent of β2AR signaling but through a different way that has not been elucidated before.

METHODS

The activation of NHE3 in HK-2 cell lines was quantified using the fluorescence probe BCECF/AM. The expression levels of G protein-coupled receptor kinase 2 (GRK2) and its downstream effector, β-arrestin 1 (ARRB1), were assessed through Western blot analysis and immunohistochemical staining. ISO-induced β2-AR signaling was blocked by ICI 118,551, a β2-AR antagonist, in HK-2 cells.

RESULTS

ISO treatment significantly enhanced NHE3 activity, which was reduced by 64.5% with a GRK2 inhibitor (GRK2-IN) and completely inhibited by propranolol (PRO), a non-selective β-adrenergic receptor blocker. Neither GRK2-IN nor PRO impacted NHE3 activity in the absence of ISO. Additionally, while GRK2 expression remained unchanged, ISO markedly decreased ARRB1 expression. This decrease was mitigated by 64.08% with GRK2-IN and entirely blocked by PRO. GRK2-IN and PRO alone did not significantly alter ARRB1 expression.

CONCLUSION

Our study suggests that ISO triggers downstream GRK2/ARRB1 signaling to increase NHE3 activity independent of traditional β2AR signaling. Given the fundamental role of NHE3 in renal water-sodium reabsorption, these insights may contribute to new strategies for the prevention and treatment of hypertension.

Renal denervation in the setting of heart failure

Renal Denervation (RDN) has emerged over the last decade as a third pillar in the treatment of arterial hypertension, alongside pharmacotherapy and lifestyle modifications. Mechanistically, it reduces central sympathetic overactivation, a process also relevant to heart failure. In this mini-review, we summarize the development of RDN for heart failure, discuss the current evidence supporting its effects, and provide an outlook on future developments.

Ultrasound renal denervation in hypertensive patients: A systematic review and meta-analysis

INTRODUCTION

Hypertension is the leading noncommunicable disease case affecting 1.28 billion individuals worldwide, with most cases located in low- and middle-income countries. While there are numerous techniques for treating mild to moderate hypertension, properly controlling severe or resistant hypertension poses substantial challenges. Ultrasound-based renal denervation (uRDN) has emerged as a promising non-pharmacological approach. This study aims to investigate the safety and efficacy of uRDN in hypertensive patients.

METHODS

The literature search across PubMed, ScienceDirect, BMJ Journals, ProQuest, and Springer databases yielded 419 articles. A total of 395 articles were filtered, leading to 24 articles assessed for eligibility and overall analysis, which resulted in eight included studies for quantitative synthesis. Quality appraisal used RoB 2.0, while meta-analysis used RevMan 5.4.

RESULTS

Our analysis results indicated significant improvements in 24-hour, daytime, and home ambulatory blood pressure measurements, favoring the uRDN over control. The mean difference (MD) for 24-hour measurements was -0.84 mmHg [95% CI -1.14, -0.55; p < 0.00001], for daytime measurements -1.27 mmHg [95% CI -1.59, -0.95; p < 0.00001], and for home measurements -1.98 mmHg [95% CI -2.32, -1.64; p < 0.00001], with moderate heterogeneity observed. Office ambulatory measurements also favored the uRDN with a significant MD of -1.51 mmHg [95% CI -1.91; -1.10; p < 0.00001]. Funnel plots revealed some outliers, indicating true heterogeneity among the studies.

CONCLUSION

uRDN was associated with a significant reduction (-2.32 to -0.10 mmHg) in blood pressure of hypertensive patients.

Renal nerves in physiology, pathophysiology and interoception

Sympathetic efferent renal nerves have key roles in the regulation of kidney function and blood pressure. Increased renal sympathetic nerve activity is thought to contribute to hypertension by promoting renal sodium retention, renin release and renal vasoconstriction. This hypothesis led to the development of catheter-based renal denervation (RDN) for the treatment of hypertension. Two RDN devices that ablate both efferent and afferent renal nerves received FDA approval for this indication in 2023. However, in animal models, selective ablation of afferent renal nerves resulted in comparable anti-hypertensive effects to ablation of efferent and afferent renal nerves and was associated with a reduction in sympathetic nerve activity. Selective afferent RDN also improved kidney function in a chronic kidney disease model. Notably, the beneficial effects of RDN extend beyond hypertension and chronic kidney disease to other clinical conditions that are associated with elevated sympathetic nerve activity, including heart failure and arrhythmia. These findings suggest that the kidney is an interoceptive organ, as increased renal sensory nerve activity modulates sympathetic activity to other organs. Future studies are needed to translate this knowledge into novel therapies for the treatment of hypertension and other cardiorenal diseases.

Renal Artery Denervation for the Management of Hypertension: Current Trends and Future Direction

Renal artery denervation has re-emerged as a potential therapeutic option for patients with hypertension, especially those resistant to conventional pharmacotherapy. This comprehensive review explores the importance of careful patient selection, procedural techniques, clinical efficacy, safety considerations, and future directions of renal artery denervation in hypertension management. Drawing upon a wide range of available evidence, this review aims to provide a thorough understanding of the procedure and its role in contemporary hypertension treatment paradigms.

Multiple Treatment Strategies of Accessory Renal Artery Related Hypertension: Report of Two Cases and Literature Review

Renovascular hypertension (RVH) is a primary cause of secondary hypertension, primarily driven by the activation of the renin-angiotensin-aldosterone system activation. Recently, growing studies suggested accessory renal artery (ARA) might also contribute to RVH. However, the treatment of ARA-related hypertension and whether to take interventional treatment lack consensus. Herein, we report two cases of ARA-related hypertension in our hospital. Imaging studies of both patients showed ARA stenosis. One patient had ARA occlusion well-compensated through tortuous collateral branches, achieving normal blood pressure by medical treatment alone. The other patient had ARA stenosis coexisted with main renal artery stenosis, and revascularization of both arteries led to a significant postoperative reduction in blood pressure. A literature review was conducted to summarize overall treatment strategies for ARA-related hypertension and clarify the relationship between ARA and hypertension. Recent research supported an association between ARA and hypertension. While medical therapy remains the first-line treatment for ARA-related hypertension, interventional procedures should be considered for patients whose blood pressure remains uncontrolled despite conservative management.

Epidural block with lidocaine ameliorates kidney function deterioration and fibrosis of chronic kidney disease in rats

BACKGROUND

According to evidences from clinical practices and experiments, renal denervation achieved by removing both the afferent and sympathetic nerves has therapeutic impacts on poor renal function and hypertension in chronic kidney disease (CKD). Epidural anesthesia is presumed to function on the target spine segments with a complete sympathetic block. Based on this perspective, we hypothesized that epidural block with lidocaine could ameliorate renal injury in CKD rats.

METHOD AND RESULTS

Male Sprague-Dawley rats weighing 250-300 g were randomized into four groups: control, CKD, CKD + sham, and CKD + epidural block with lidocaine groups. CKD was induced by resection of the lower and upper thirds of the left kidney followed by right nephrectomy one week later. Significant differences in renal function, sympathetic activation as well as renal fibrosis parameters were observed between CKD and control rats. These parameters corresponded with typical phenotypes of CKD rats. Epidural block with lidocaine improved renal function as well as renal fibrosis, and reversed the abnormalities of the renal function and cardiovascular parameters either fully or partially.

CONCLUSION

Epidural block with lidocaine confers renal protection, which is presumably mediated by decreasing sympathetic nerve activities in the renal region and other target organs in CKD.

Elucidating the complex interplay between chronic kidney disease and hypertension

Chronic kidney disease (CKD) and hypertension share a complex relationship, each exacerbating the progression of the other. CKD contributes to hypertension by decreasing renal function, leading to fluid retention and increased plasma volume, whereas hypertension exacerbates CKD by increasing glomerular pressure and causing renal damage. This review examines the intertwined nature of CKD and hypertension, exploring the factors driving hypertension in CKD and how hypertension accelerates CKD progression. It discusses the role of the renin-angiotensin system and inflammatory cytokines in this relationship, as well as the potential of blood pressure management to slow renal decline. While studies suggest that meticulous blood pressure control can help attenuate CKD progression, optimal management strategies remain unclear and require further investigation. This review also evaluates the evidence surrounding strict antihypertensive therapy in patients with CKD, considering both diabetic and non-diabetic cases. It recommends blood pressure targets based on CKD stage and presence of diabetes, emphasizing the importance of individualized treatment approaches. Renin-angiotensin system inhibitors are highlighted as a key pharmacological intervention due to their renal protective effects, particularly in patients with CKD with proteinuria. However, evidence regarding their efficacy in patients with CKD but without proteinuria is inconclusive. This review underscores the need for comprehensive approaches to effectively address the intertwined nature of CKD and hypertension and calls for further research to optimize clinical management strategies in this complex interplay.

The renin-angiotensin-aldosterone system: An old tree sprouts new shoots

The intricate physiological and pathological diversity of the Renin-Angiotensin-Aldosterone System (RAAS) underpins its role in maintaining bodily equilibrium. This paper delves into the classical axis (Renin-ACE-Ang II-AT1R axis), the protective arm (ACE2-Ang (1-7)-MasR axis), the prorenin-PRR-MAP kinases ERK1/2 axis, and the Ang IV-AT4R-IRAP cascade of RAAS, examining their functions in both physiological and pathological states. The dysregulation or hyperactivation of RAAS is intricately linked to numerous diseases, including cardiovascular disease (CVD), renal damage, metabolic disease, eye disease, Gastrointestinal disease, nervous system and reproductive system diseases. This paper explores the pathological mechanisms of RAAS in detail, highlighting its significant role in disease progression. Currently, in addition to traditional drugs like ACEI, ARB, and MRA, several novel therapeutics have emerged, such as angiotensin receptor-enkephalinase inhibitors, nonsteroidal mineralocorticoid receptor antagonists, aldosterone synthase inhibitors, aminopeptidase A inhibitors, and angiotensinogen inhibitors. These have shown potential efficacy and application prospects in various clinical trials for related diseases. Through an in-depth analysis of RAAS, this paper aims to provide crucial insights into its complex physiological and pathological mechanisms and offer valuable guidance for developing new therapeutic approaches. This comprehensive discussion is expected to advance the RAAS research field and provide innovative ideas and directions for future clinical treatment strategies.

Efficacy and Safety of Ultrasound Renal Denervation on Office Blood Pressure of Patients with Resistant Arterial Hypertension: A Systematic Review and Meta-analysis

INTRODUCTION

Resistant arterial hypertension (RAH) is one of the main causes of increased cardiovascular risk around the world. The benefits of ultrasound renal denervation (uRDN) as a non-invasive treatment are still not fully clear.

AIM

 We aim to demonstrate the efficacy of uRDN in reducing office blood pressure of patients in treatment for RAH.

METHODS

PubMed, Embase, and Cochrane were searched for randomized trials comparing uRDN to sham or medical control groups in RAH patients undergoing renal denervation. Mean Differences (MD) with 95% confidence intervals (CIs) were calculated, and I2 statistics assessed heterogeneity. Statistical significance was set at p < 0.05. Statistical analysis was performed using R software version 4.2.3.

RESULTS

It was included 5 studies with 709 patients, of which 395 (55.71%) received uRDN treatment and 314 (44.29%) in the sham group. Mean follow-up time ranged from 2 to 48 months and mean age ranged from 52.3 to 62 years. The uRDN decreased systolic blood pressure (SBP) and diastolic blood pressure (DBP) in all measures significantly, including reductions in Office SBP (MD - 4.459 mmHg; 95% CI - 7.710 to - 1.208; p = 0.007; I2 = 47%) and Office DBP (MD - 2.039 mmHg; 95% CI - 3.975 to - 0.102; p = 0.039; I2 = 27%).

CONCLUSIONS

This meta-analysis highlights uRDN's superiority over the sham group in controlling SBP and DBP in RAH. However, further studies are needed to fully understand the efficacy of uRDN procedure in the management of RAH.

Renal Denervation for the Treatment of Hypertension: A Scientific Statement From the American Heart Association

Hypertension is a leading risk factor for cardiovascular morbidity and mortality. Despite the widespread availability of both pharmacological and lifestyle therapeutic options, blood pressure control rates across the globe are worsening. In fact, only 23% of individuals with high blood pressure in the United States achieve treatment goals. In 2023, the US Food and Drug Administration approved renal denervation, a catheter-based procedure that ablates the renal sympathetic nerves, as an adjunctive treatment for patients in whom lifestyle modifications and antihypertensive medications do not adequately control blood pressure. This approval followed the publication of multiple randomized clinical studies using rigorous trial designs, all incorporating renal angiogram as the sham control. Most but not all of the new generation of trials reached their primary end point, demonstrating modest efficacy of renal denervation in lowering blood pressure across a spectrum of hypertension, from mild to truly resistant. Individual patient responses vary, and further research is needed to identify those who may benefit most. The initial safety profile appears favorable, and multiple ongoing studies are assessing longer-term efficacy and safety. Multidisciplinary teams that include hypertension specialists and adequately trained proceduralists are crucial to ensure that referrals are made appropriately with full consideration of the potential risks and benefits. Incorporating patient preferences and engaging in shared decision-making conversations will help patients make the best decisions given their individual circumstances. Although further research is clearly needed, renal denervation presents a novel treatment strategy for patients with uncontrolled blood pressure.

Renal interoception in health and disease

Catheter based renal denervation has recently been FDA approved for the treatment of hypertension. Traditionally, the anti-hypertensive effects of renal denervation have been attributed to the ablation of the efferent sympathetic renal nerves. In recent years the role of the afferent sensory renal nerves in the regulation of blood pressure has received increased attention. In addition, afferent renal denervation is associated with reductions in sympathetic nervous system activity. This suggests that reductions in sympathetic drive to organs other than the kidney may contribute to the non-renal beneficial effects observed in clinical trials of catheter based renal denervation. In this review we will provide an overview of the role of the afferent renal nerves in the regulation of renal function and the development of pathophysiologies, both renal and non-renal. We will also describe the central projections of the afferent renal nerves, to give context to the responses seen following their ablation and activation. Finally, we will discuss the emerging role of the kidney as an interoceptive organ. We will describe the potential role of the kidney in the regulation of interoceptive sensitivity and in this context, speculate on the possible pathological consequences of altered renal function.

Super-response to renal denervation in treatment-resistant essential hypertension

Renal denervation may be indicated in patients with treatment-resistant essential hypertension to decrease sympathetic nervous activity and optimise blood pressure. We present the case of a woman in her 50s with long-standing essential hypertension, a previous transient ischaemic attack, obesity and a family history of cardiovascular disease, who presented with persistent 24-hour ambulatory hypertension despite ongoing lifestyle modifications and being on five antihypertensive agents with no evidence of an alternative primary aetiology. She had intermittent palpitations and blurring of vision alongside evidence of left ventricular hypertrophy on a CT scan. She underwent renal denervation, following which, not only was she able to cease all antihypertensive therapy but managed to maintain optimised blood pressure with subsequent reversal of left ventricular hypertrophy. Trials have demonstrated modest but inconsistent reductions in blood pressure whereas our case represents a 'super-response' likely due to a higher number of circumferential ablations in comparison to previous studies.

Doppler Ultrasound of the Renal Vasculature

Ultrasound is the first-line imaging modality used in patients with suspected renovascular disease. Common indications include renovascular hypertension and unexplained renal dysfunction. We review the ultrasound imaging findings of various pathologies involving the renal vessels, including the renal arteries (atherosclerotic stenosis, fibromuscular dysplasia, dissection, arteriovenous fistula, and aneurysm) and veins (tumor and bland thrombus as well as vascular compression syndromes). The current role of renal artery stent placement for atherosclerotic stenosis is also discussed.

Opportunities and Limitations of Renal Denervation: Where Do We Stand?

Hypertension is a primary contributor to cardiovascular disease, and the leading risk factor for loss of quality adjusted life years. Up to 50% of the cases of hypertension in the United States remain uncontrolled. Additionally, 8%-18% of the hypertensive population have resistant hypertension; uncontrolled pressure despite 3 different antihypertensive agents. Recently, catheter-based percutaneous renal denervation emerged as a method for ablating renal sympathetic nerves for difficult-to-control hypertension. Initial randomized (non-sham) trials and registry analyses showed impressive benefit, but the first sham-controlled randomized controlled trial using monopolar radiofrequency ablation showed limited benefit. With refinement of techniques to include multipolar radiofrequency, ultrasound denervation, and direct ethanol injection, randomized controlled trials demonstrated significant blood pressure improvement, leading to US Food and Drug Administration approval of radiofrequency- and ultrasound-based denervation technologies. In this review article, we summarize the major randomized sham-controlled trials and societal guidelines regarding the efficacy and safety of renal artery denervation for the treatment of uncontrolled hypertension.

Efficacy and Safety of Radiofrequency-Based Renal Denervation on Resistant Hypertensive Patients: A Systematic Review and Meta-analysis

INTRODUCTION

New therapies for resistant hypertension (RH), including renal denervation (RDN), have been studied.

AIM

Access the safety and effectiveness of radiofrequency-based RDN vs pharmacological treatment for RH.

METHODS

A thorough literature search was conducted across PubMed, EMBASE, and the Cochrane databases, focusing on studies that compared the effects of radiofrequency-based RDN versus pharmacological treatment for RH. Treatment effects for binary and continuous endpoints were pooled and used, respectively, odds-ratio (OR) and mean differences (MD) with 95% confidence intervals (CI) to analyze continuous outcomes.

RESULTS

In the 10 included studies, involving 1.182 patients, 682 received radiofrequency-based RDN. The follow-up period ranged from 6 to 84 months. Analysis revealed that the RDN group had a significant reduction in office systolic blood pressure (BP) (MD - 9.5 mmHg; 95% CI - 16.81 to - 2.29; P = 0.01), office diastolic BP (MD - 5.1 mmHg; 95% CI - 8.42 to - 2.80; P < 0.001), 24 h systolic BP (MD - 4.8 mmHg; 95% CI - 7.26 to - 2.42; P < 0.001). For 24 h diastolic BP RDN did not have a significant reduction (MD - 2.3 mmHg; 95% CI - 4.19 to - 0.52; P = 0.012). The heterogeneity between the studies was high, visible in the funnel and Baujat plots. The OR was non-significant for non-serious adverse events, but also clinically significant for hypertensive crises and strokes for the RDN group.

CONCLUSIONS

While the pharmacological regimen of 3 or more anti-hypertensive, including a diuretic, still be the first-line option for RH treatment, our results support that radiofrequency-based RDN is superior in reducing global BP and is safe.

Can catheter-based renal denervation reduce frequency of hospitalization in patients who have resistant hypertension and heart failure with reduced ejection fraction?

Hypertension is one of the most powerful and modifiable risk factors for the development, progression and even decompensation of heart failure. Uncontrolled hypertension increases to frequency of heart failure hospitalizations by increase sympathetic tone. Catheter-based renal denervation has been shown to reduce blood pressure in the treatment of multidrug-resistant hypertension. We report the improvement in clinical status after renal denervation in a 47-year-old male patient with a history of hypertension, chronic ischemic heart failure, and recurrent hospitalizations for acute hypertensive pulmonary edema despite optimal medical therapy.

Comment on "renal denervation for hypertension"

We have attentively reviewed the article "Renal Denervation for Hypertension" and commend the author's dedication to addressing this intricate subject. However, we wish to highlight a few points that, in our assessment, could enhance the overall quality of the article.

Overview of the 2023 FDA Circulatory System Devices Advisory Panel Meeting on the Symplicity Spyral Renal Denervation System

Hypertension remains a leading preventable cause of myocardial infarction, stroke, kidney disease, and cardiovascular death worldwide. Despite lifestyle modifications and intensification of medical therapy, suboptimal blood pressure control is common, spurring the development of device-based therapies for hypertension. The US Food and Drug Administration (FDA) assembled the Circulatory System Devices Panel on August 22-23, 2023, to discuss the safety and effectiveness of renal denervation devices manufactured by Recor Medical and Medtronic. After reviewing the ultrasound-based Recor Paradise renal denervation system the day prior, the panel reconvened to discuss the radiofrequency-based Medtronic Symplicity Spyral Renal Denervation System. In this manuscript, we summarize the data presented by the sponsor and FDA and detail the deliberation and discussion during the meeting.

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.

Dapagliflozin and Apparent Treatment-Resistant Hypertension in Heart Failure With Mildly Reduced or Preserved Ejection Fraction: The DELIVER Trial

BACKGROUND

Apparent treatment-resistant hypertension (aTRH) is prevalent and associated with adverse outcomes in heart failure with mildly reduced or preserved ejection fraction. Less is known about the potential role of sodium-glucose co-transporter 2 inhibition in this high-risk population. In this post hoc analysis of the DELIVER trial (Dapagliflozin Evaluation to Improve the Lives of Patients with Preserved Ejection Fraction Heart Failure), we evaluated clinical profiles and treatment effects of dapagliflozin among participants with aTRH.

METHODS

DELIVER participants were categorized on the basis of baseline blood pressure (BP), with aTRH defined as BP ≥140/90 mm Hg (≥130/80 mm Hg if diabetes) despite treatment with 3 antihypertensive drugs including a diuretic. Nonresistant hypertension was defined as BP above threshold but not meeting aTRH criteria. Controlled BP was defined as BP under threshold. Incidence of the primary outcome (cardiovascular death or worsening heart failure event), key secondary outcomes, and safety events was assessed by baseline BP category.

RESULTS

Among 6263 DELIVER participants, 3766 (60.1%) had controlled BP, 1779 (28.4%) had nonresistant hypertension, and 718 (11.5%) had aTRH at baseline. Participants with aTRH had more cardiometabolic comorbidities and tended to have higher left ventricular ejection fraction and worse kidney function. Rates of the primary outcome were 8.7 per 100 patient-years in those with controlled BP, 8.5 per 100 patient-years in the nonresistant hypertension group, and 9.5 per 100 patient-years in the aTRH group. Relative treatment benefits of dapagliflozin versus placebo on the primary outcome were consistent across BP categories (Pinteraction=0.114). Participants with aTRH exhibited the greatest absolute reduction in the rate of primary events with dapagliflozin (4.1 per 100 patient-years) compared with nonresistant hypertension (2.7 per 100 patient-years) and controlled BP (0.8 per 100 patient-years). Irrespective of assigned treatment, participants with aTRH experienced a higher rate of reported vascular events, including myocardial infarction and stroke, over study follow-up. Dapagliflozin modestly reduced systolic BP (by ≈1 to 3 mm Hg) without increasing risk of hypotension, hypovolemia, or other serious adverse events, irrespective of BP category, but did not improve the proportion of participants with aTRH attaining goal BP over time.

CONCLUSIONS

aTRH was identified in >1 in 10 patients with heart failure and left ventricular ejection fraction >40% in DELIVER. Dapagliflozin consistently improved clinical outcomes and was well-tolerated, including among those with aTRH.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03619213.

Sympathetic Nervous System and Atherosclerosis

Atherosclerosis is characterized by the narrowing of the arterial lumen due to subendothelial lipid accumulation, with hypercholesterolemia being a major risk factor. Despite the recent advances in effective lipid-lowering therapies, atherosclerosis remains the leading cause of mortality globally, highlighting the need for additional therapeutic strategies. Accumulating evidence suggests that the sympathetic nervous system plays an important role in atherosclerosis. In this article, we reviewed the sympathetic innervation in the vasculature, norepinephrine synthesis and metabolism, sympathetic activity measurement, and common signaling pathways of sympathetic activation. The focus of this paper was to review the effectiveness of pharmacological antagonists or agonists of adrenoceptors (α1, α2, β1, β2, and β3) and renal denervation on atherosclerosis. All five types of adrenoceptors are present in arterial blood vessels. α1 blockers inhibit atherosclerosis but increase the risk of heart failure while α2 agonism may protect against atherosclerosis and newer generations of β blockers and β3 agonists are promising therapies against atherosclerosis; however, new randomized controlled trials are warranted to investigate the effectiveness of these therapies in atherosclerosis inhibition and cardiovascular risk reduction in the future. The role of renal denervation in atherosclerosis inhibition in humans is yet to be established.

Native Renal Arteries Denervation as a Therapy of Refractory Hypertension in Patient after Heart and Kidney Transplantation-5 Years of Observation

This case report describes a 59-year-old male patient after heart and kidney transplantation, subsequently diagnosed with refractory hypertension since implemented antihypertensive pharmacotherapy consisting of six agents did not provide a substantial therapeutic response. Elevated blood pressure and its impact on a hypertrophied transplanted heart and impaired renal graft function have led to a significant deterioration in the patient's cardiovascular risk profile. To address this issue, a native renal arteries denervation was performed. It resulted in a noteworthy decrease in both systolic and diastolic pressure values, thus manifesting a positive hypotensive effect. Furthermore, a sustainable reduction of left ventricular mass and stabilization in kidney graft function were noticed. The presented case provides evidence that renal denervation can be an efficacious complementary treatment method in individuals who received kidney and heart grafts as it leads to a decrease in cardiovascular risk.

Ultrasound renal denervation: the future of hypertension management?

BACKGROUND

Hypertension, a leading cause of global mortality and morbidity, affects approximately 1.28 billion adults worldwide, with most cases occurring in low- and middle-income countries. Despite several methods for managing mild to moderate hypertension, effective management of severe or resistant hypertension remains challenging. Renal denervation, a promising non-pharmacological technique, has emerged as a potential solution.

MAIN BODY

Renal denervation works by modifying the renal sympathetic nerve supply through techniques such as ultrasound, radiofrequency energy, or injection of neurolytic agents, reducing blood pressure. Clinical trials, including the RADIANCE series, have shown consistent effectiveness of ultrasound renal denervation in lowering blood pressure, especially in patients who were previously unresponsive to anti-hypertensive medications. After a follow-up of 2 months, mean ambulatory systolic blood pressure during the daytime decreased significantly in the ultrasound renal denervation group compared to the sham group. However, further research is needed to determine renal denervation's long-term safety and efficacy.

CONCLUSIONS

In conclusion, renal denervation holds great potential in improving the treatment of uncontrolled or resistant hypertension treatment, but more investigations and trials are necessary to establish its effectiveness and safety.

Contribution of afferent renal nerve signals to acute and chronic blood pressure regulation in stroke-prone spontaneously hypertensive rats

The activation of sympathetic nervous system plays a critical role in the development of hypertension. The input from afferent renal nerves may affect central sympathetic outflow; however, its contribution to the development of hypertension remains unclear. We investigated the role of afferent renal nerves in acute and chronic blood pressure regulation using normotensive Wistar-Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). Acute chemical stimulation of afferent renal nerves elicited larger increases in blood pressure and renal sympathetic nerve activity in young 9-week-old SHRSP compared to WKY. Selective afferent renal denervation (ARDN) and conventional total renal denervation (TRDN) ablating both afferent and efferent nerves in young SHRSP revealed that only TRDN, but not ARDN, chronically attenuated blood pressure elevation. ARDN did not affect plasma renin activity or plasma angiotensin II levels, whereas TRDN decreased both. Neither TRDN nor ARDN affected central sympathetic outflow and systemic sympathetic activity determined by neuronal activity in the parvocellular region of hypothalamic paraventricular nucleus and rostral ventrolateral medulla and by plasma and urinary norepinephrine levels, respectively. Renal injury was not apparent in young SHRSP compared with WKY, suggesting that renal afferent input might not be activated in young SHRSP. In conclusion, the chronic input from afferent renal nerves does not contribute to the development of hypertension in SHRSP despite the increased blood pressure response to the acute stimulation of afferent renal nerves. Efferent renal nerves may be involved in the development of hypertension via activation of the renin-angiotensin system in SHRSP.