Sustained Decrease in Blood Pressure and Reduced Anatomical and Functional Reinnervation of Renal Nerves in Hypertensive Sheep 30 Months After Catheter-Based Renal Denervation

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 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.

Ultra-long-term efficacy and safety of catheter-based renal denervation in resistant hypertension: 10-year follow-up outcomes

BACKGROUND

Randomized sham-controlled trials have confirmed the efficacy and safety of catheter-based renal denervation in hypertension. Data on the very long-term effects of renal denervation are scarce.

AIMS

This study evaluates the 10-year safety and efficacy of renal denervation in resistant hypertension.

METHODS

This prospective single-center study included patients with resistant hypertension undergoing radio-frequency renal denervation between 2010 and 2012. Office blood pressure, 24-h ambulatory blood pressure, antihypertensive medication, color duplex sonography, and renal function were assessed after 1-, 2- and 10-years.

RESULTS

Thirty-nine patients completed the 10-year follow-up (mean follow-up duration 9.4 ± 0.7 years). Baseline office and 24-h ambulatory systolic blood pressure were 164 ± 23 mmHg and 153 ± 16 mmHg, respectively. After 10 years, 24-h ambulatory and office systolic blood pressure were reduced by 16 ± 17 mmHg (P < 0.001) and 14 ± 23 mmHg (P = 0.001), respectively. The number of antihypertensive drugs remained unchanged from 4.9 ± 1.4 to 4.5 ± 1.2 drugs (P = 0.087). The estimated glomerular filtration rate declined within the expected range from 69 (95% CI 63 to 74) to 60 mL/min/1.73m2 (95% CI 53 to 68; P < 0.001) through 10-year follow-up. Three renal artery interventions were documented for progression of pre-existing renal artery stenosis in two patients and one patient with new-onset renal artery stenosis. No other adverse events were observed during the follow-up.

CONCLUSION

Renal denervation was safe and sustainedly reduced ambulatory and office blood pressure out to 10 years in patients with resistant hypertension.

Renal sympathetic denervation 2024 in Austria: recommendations from the Austrian Society of Hypertension : Endorsed by the Austrian Society of Nephrology and the Working Group of Interventional Cardiology of the Austrian Society of Cardiology

Renal sympathetic denervation (RDN) is an interventional supplement to medical treatment in patients with arterial hypertension. While the first sham-controlled trial, SYMPLICITY HTN‑3 was neutral, with improved procedural details, patient selection and follow-up, recent randomized sham-controlled trials of second-generation devices show a consistent blood pressure lowering effect of RDN, as compared to sham controls. These new data and the recent U.S. Food and Drug Administration (FDA) premarket approval of two RDN devices are the basis for the present recommendations update.This joint position paper from the Austrian Society of Hypertension, together with the Austrian Society of Nephrology and the Working Group of Interventional Cardiology from the Austrian Society of Cardiology includes an overview about the available evidence on RDN and gives specific recommendations for the work-up, patient selection, pretreatment, procedural management and follow-up in patients undergoing RDN in Austria. Specifically, RDN may be used in clinical routine care, together with lifestyle measures and antihypertensive drugs, in patients with resistant hypertension (i.e. uncontrolled blood pressure on 3 antihypertensive drugs) and in those with uncontrolled hypertension, after adequate work-up, if institutional, patient-related and procedural conditions are fulfilled.

Permanent Pacing Reduces Blood Pressure in Older Patients with Drug-resistant Hypertension: A New Pacing Paradigm?

Hypertension (HTN) is a major contributor to cardiovascular mortality. Many patients with drug-resistant hypertension (DRH) also require permanent pacing (PP). This large retrospective study evaluated the effect of PP for conventional PP indications in older patients with DRH. We reviewed the charts of 176 patients with dual-chamber PP and DRH. The effects of PP on systolic and diastolic blood pressure (sBP and dBP), the number of HTN-related medications, and left ventricular ejection fraction (LVEF) were assessed at 6 months post-implantation and compared with pre-implantation values. Patients were followed up with for ≥72 months. Patients with a decline of >5 mmHg in sBP and decrease in at least one anti-HTN medication were defined as responders (126/176; P < .01). The mean decline in sBP was 9 mmHg, while that in dBP was 3 mmHg (P < .001 for both). Among responders, optimal reductions in sBP, dBP, and medications were seen at a stratification of >50% atrial pacing and <40% ventricular pacing (-12, -6.3, and -1.6, respectively). When right ventricular pacing of <50% was used for dichotomizing, the optimal atrial/ventricular pacing stratification was atrial pacing > 50% and ventricular pacing < 40% (-11.3, -6.3, and -1.6, respectively). A relationship between increasing atrial pacing and a decline in sBP was noted but did not reach statistical significance. However, of those responders who had a >10-mmHg decline in sBP, the majority were paced between 60%-100% in the atria. The LVEF did not change post-PP in either group. In conclusion, PP results in significant improvement in BP control. The observed association warrants further investigation.

Effects of catheter-based renal denervation in hypertension: a systematic review and meta-analysis

Background

Several sham-controlled trials have investigated the efficacy and safety of catheter-based renal denervation (RDN) with mixed outcomes.

Aim

To perform a comprehensive meta-analysis of all randomized, sham-controlled trials investigating RDN with first- and second-generation devices in hypertension.

Methods

We searched MEDLINE and Cochrane Library for eligible trials. Outcomes included both efficacy (24-hour and office systolic [SBP] and diastolic blood pressure [DBP]) and safety (all-cause death, vascular complication, renal artery stenosis >70%, hypertensive crisis) of RDN. We performed a study-level, pairwise, random-effects meta-analysis of the summary data.

Results

Ten trials comprising 2,478 patients with hypertension while being either off- or on-treatment were included. Compared with sham, RDN reduced 24-hour and office systolic BP by 4.4 mmHg (95%CI -6.1, -2.7, p<0.00001) and 6.6 mmHg (95%CI -9.7, -3.6, p<0.0001), respectively. The 24-hour and office diastolic BP paralleled these findings (-2.6 mmHg, 95%CI - 3.6, -1.5, p<0.00001; -3.5 mmHg, 95%CI -5.4, -1.6, p=0.0003). There was no difference in 24-hour and office SBP reduction between trials with and without concomitant antihypertensive medication (p for interaction 0.62 and 0.73, respectively). There was no relevant difference concerning vascular complications (OR 1.69, 95%CI 0.57-5.0, p=0.34), renal artery stenosis (OR 1.50, 95%CI 0.06-36.97, p=0.80), hypertensive crisis (OR 0.65, 95%CI 0.30-1.38, p=0.26) and all-cause death (OR 1.76, 95%CI 0.34-9.20, p=0.50) between RDN and sham groups. Change of renal function based on eGFR was comparable between groups (p for interaction 0.84). There was significant heterogeneity between trials.

Conclusions

RDN safely reduces ambulatory and office SBP/DBP vs. a sham procedure in the presence and absence of antihypertensive medication.

Clinical Perspective

What is new?Several sham-controlled trials have investigated the efficacy and safety of catheter-based renal denervation (RDN) with mixed outcomes.This comprehensive meta-analysis comprising 2,478 patients shows that irrespective of the utilized method (radiofrequency-, ultrasound-or alcohol-mediated), renal denervation effectively reduced ambulatory and office systolic blood pressure.Renal denervation exhibited no additional risk concerning vascular injury or renal function impairment.What are the clinical implications?This meta-analysis supports current guidelines/consensus statements that renal denervation represents an additive treatment option in carefully selected patients with uncontrolled hypertension.

Long-Term Blood Pressure Reductions Following Catheter-Based Renal Denervation: A Systematic Review and Meta-Analysis

BACKGROUND

Renal denervation is a recognized adjunct therapy for hypertension with clinically significant blood pressure (BP)-lowering effects. Long-term follow-up data are critical to ascertain durability of the effect and safety. Aside from the 36-month follow-up data available from randomized control trials, recent cohort analyses extended follow-up out to 10 years. We sought to analyze study-level data and quantify the ambulatory BP reduction of renal denervation across contemporary randomized sham-controlled trials and available long-term follow-up data up to 10 years from observational studies.

METHODS

A systematic review was performed with data from 4 observational studies with follow-up out to 10 years and 2 randomized controlled trials meeting search and inclusion criteria with follow-up data out to 36 months. Study-level data were extracted and compared statistically.

RESULTS

In 2 contemporary randomized controlled trials with 36-month follow-up, an average sham-adjusted ambulatory systolic BP reduction of -12.7±4.5 mm Hg from baseline was observed (P=0.05). Likewise, a -14.8±3.4 mm Hg ambulatory systolic BP reduction was found across observational studies with a mean long-term follow-up of 7.7±2.8 years (range, 3.5-9.4 years; P=0.0051). The observed reduction in estimated glomerular filtration rate across the long-term follow-up was in line with the predicted age-related decline. Antihypertensive drug burden was similar at baseline and follow-up.

CONCLUSIONS

Renal denervation is associated with a significant and clinically meaningful reduction in ambulatory systolic BP in both contemporary randomized sham-controlled trials up to 36 months and observational cohort studies up to 10 years without adverse consequences on renal function.

Long-Term Safety and Efficacy of Transcatheter Microwave and Radiofrequency Denervation in a Chronic Ovine Model

BACKGROUND

Transcatheter renal denervation (RDN) has had inconsistent efficacy and concerns for durability of denervation. We aimed to investigate long-term safety and efficacy of transcatheter microwave RDN in vivo in normotensive sheep in comparison to conventional radiofrequency ablation.

METHODS AND RESULTS

Sheep underwent bilateral RDN, receiving 1 to 2 microwave ablations (maximum power of 80-120 W for 240 s-480 s) and 12 to 16 radiofrequency ablations (180 s-240 s) in the main renal artery in a paired fashion, alternating the side of treatment, euthanized at 2 weeks (acute N=15) or 5.5 months (chronic N=15), and compared with undenervated controls (N=4). Microwave RDN produced substantial circumferential perivascular injury compared with radiofrequency at both 2 weeks [area 239.8 (interquartile range [IQR] 152.0-343.4) mm2 versus 50.1 (IQR, 32.0-74.6) mm2, P <0.001; depth 16.4 (IQR, 13.9-18.9) mm versus 7.5 (IQR, 6.0-8.9) mm P <0.001] and 5.5 months [area 20.0 (IQR, 3.4-31.8) mm2 versus 5.0 (IQR, 1.4-7.3) mm2, P=0.025; depth 5.9 (IQR, 1.9-8.8) mm versus 3.1 (IQR, 1.2-4.1) mm, P=0.005] using mixed models. Renal denervation resulted in significant long-term reductions in viability of renal sympathetic nerves [58.9% reduction with microwave (P=0.01) and 45% reduction with radiofrequency (P=0.017)] and median cortical norepinephrine levels [71% reduction with microwave (P <0.001) and 72.9% reduction with radiofrequency (P <0.001)] at 5.5 months compared with undenervated controls.

CONCLUSIONS

Transcatheter microwave RDN produces deep circumferential perivascular ablations without significant arterial injury to provide effective and durable RDN at 5.5 months compared with radiofrequency RDN.

Possible organ-protective effects of renal denervation: insights from basic studies

Inappropriate sympathetic nervous activation is the body's response to biological stress and is thought to be involved in the development of various lifestyle-related diseases through an elevation in blood pressure. Experimental studies have shown that surgical renal denervation decreases blood pressure in hypertensive animals. Recently, minimally invasive catheter-based renal denervation has been clinically developed, which results in a reduction in blood pressure in patients with resistant hypertension. Accumulating evidence in basic studies has shown that renal denervation exerts beneficial effects on cardiovascular disease and chronic kidney disease. Interestingly, recent studies have also indicated that renal denervation improves glucose tolerance and inflammatory changes. In this review article, we summarize the evidence from animal studies to provide comprehensive insight into the organ-protective effects of renal denervation beyond changes in blood pressure.

Late outcomes of renal denervation are more favourable than early ones: facts or fancies?

Following second-generation randomized trials, there is evidence that renal denervation (RDN) decreases blood pressure (BP), although to a lesser extent than suggested in the initial controlled and observational studies. The recent publication of the 36-month follow-up of the Symplicity HTN-3 trial has raised expectations, suggesting increasing, late benefits of the procedure, despite initially negative results. These findings come after those obtained at 36 months in the sham-controlled trial SPYRAL HTN-ON MED and in the Global Symplicity Registry. However, they are susceptible to biases inherent in observational studies (after unblinding for sham-control) and non-random, substantial attrition of treatment groups at 36 months, and used interpolation of missing BPs. More importantly, in SPYRAL HTN-ON MED and Symplicity HTN-3, long-term BP changes in patients from the initial RDN group were compared with those in a heterogeneous control group, including both control patients who did not benefit from RDN and patients who eventually crossed over to RDN. In crossover patients, the last BP before RDN was imputed to subsequent follow-up. In Symplicity HTN-3, this particular approach led to the claim of increasing long-term benefits of RDN. However, comparison of BP changes in patients from the RDN group and control patients who did not undergo RDN, without imputation of BPs from crossover patients, does not support this view. The good news is that despite the suggestion of sympathetic nerve regrowth after RDN in some animal models, there is no strong signal in favour of a decreasing effect of RDN over time, up to 24 or even 36 months. Still, current data do not support a long-term increase in the effect of RDN and the durability of RDN-related BP reduction remains to be formally demonstrated.

Long-Term Safety and Antihypertensive Effects of Renal Denervation: Current Insights

Hypertension is the most potent modifiable risk factor for the development of cardiovascular morbidity and mortality worldwide. Nevertheless, blood pressure (BP) control on a broad scale appears to be insurmountable and has even worsened in the US. Barriers to sustained hypertension control are multifactorial and although lack of patient awareness and socioeconomic barriers to healthcare access may play a role, medication non-compliance and therapeutic inertia are major causes. Renal denervation (RDN) is a minimally invasive procedure that has been the subject of interest in clinical trials for more than a decade and although the first sham-controlled trial could not detect group difference between treated and untreated hypertensives, subsequent, better designed sham-controlled trials clearly demonstrated the BP lowering effect of RDN, as well as its safety. While to-date, RDN is not available for routine clinical practice, one major requirement for broad implementation is that the BP lowering effect is durable. Therefore, this review will summarize the available long-term data of the different RDN modalities with respect to both effectiveness and safety.

Emerging topics on renal denervation in hypertension: anatomical and functional aspects of renal nerves

Inappropriate sympathetic activation is closely associated with the development and progression of hypertension. Renal denervation (RDN) is a neuromodulation therapy performed using an intraarterial catheter in patients with hypertension. Recent randomized sham-operated controlled trials have shown that RDN has significant antihypertensive effects that last for at least 3 years. Based on this evidence, RDN is nearly ready for general clinical application. On the other hand, there are remaining issues to be addressed, including elucidation of the precise antihypertensive mechanisms of RDN, the appropriate endpoint of RDN during the procedure, and the association between reinnervation after RDN and the long-term effects of RDN. This mini review focuses on studies implicating anatomy of the renal nerves, which consist of afferent or efferent and sympathetic or parasympathetic nerves, the response of blood pressure to renal nerve stimulation, and reinnervation of renal nerves after RDN. A comprehensive understanding of the anatomical and functional aspects of the renal nerves and the antihypertensive mechanisms of RDN, including its long-term effects, will enhance our ability to incorporate RDN into strategies to treat hypertension in clinical practice. This mini review focuses on studies implicating anatomy of the renal nerves, which consist of afferent or efferent and sympathetic or parasympathetic nerves, the response of blood pressure to renal nerve stimulation, and reinnervation of renal nerves after renal denervation. Whether the ablation site is sympathetic dominant or parasympathetic dominant, and afferent dominant or efferent dominant, would in turn determine the final output of renal denervation. BP: blood pressure.

The position of renal denervation in treatment of hypertension: an expert consensus statement

Hypertension is an important risk factor for cardiovascular disease. In the Netherlands, there are approximately 2.8 million people with hypertension. Despite treatment recommendations including lifestyle changes and antihypertensive drugs, most patients do not meet guideline-recommended blood pressure (BP) targets. In order to improve BP control and lower the risk of subsequent cardiovascular events, renal sympathetic denervation (RDN) has been introduced and studied as a non-pharmacological approach. While early data on the efficacy of RDN showed conflicting results, improvements in treatment protocols and study design resulted in robust new evidence supporting the potential of the technology to improve patient care in hypertensive subjects. Recently, 5 randomised sham-controlled trials demonstrated the safety and efficacy of the technology. Modelling studies have further shown that RDN is cost-effective in the Dutch healthcare setting. Given the undisputable disease burden along with the shortcomings of current therapeutic options, we postulate a new, clearly framed indication for RDN as an adjunct in the treatment of hypertension. The present consensus statement summarises current guideline-recommended BP targets, proposed workup and treatment for hypertension, and position of RDN for those patients with primary hypertension who do not meet guideline-recommended BP targets (see central illustration).

Long-term follow-up of patients undergoing renal sympathetic denervation

OBJECTIVES

Renal denervation (RDN) proved to significantly lower blood pressure (BP) at 2-6 months in patients on and off antihypertensive drugs. Given a lack of longer-term follow-up data, our aim was to assess the safety and efficacy of RDN up to five years taking into account antihypertensive drug regimen changes over time.

METHODS

In the present single-center study, patients underwent RDN for (therapy resistant) hypertension. Patients underwent protocolized yearly follow-up out to five years. Data were collected on 24-h ambulatory BP and office BP monitoring, renal function, antihypertensive drug regimen, and safety events, including non-invasive renal artery imaging at 6/12 months. Efficacy analyses were performed using linear mixed-effects models.

RESULTS

Seventy-two patients with mean age 63.3 ± 9.5 (SD) years (51% female) were included. Median follow-up time was 3.5 years and Clark's Completeness Index was 72%. Baseline ambulatory daytime BP was 146.1/83.7 ± 17.4/12.2 mmHg under a mean number of 4.9 ± 2.7 defined daily doses (DDD). At five years, ambulatory daytime systolic BP as calculated from the mixed model was 120.8 (95% CI 114.2-127.5) mmHg and diastolic BP was 73.3 (95% CI 69.4-77.3) mmHg, implying a reduction of -20.9/-8.3 mmHg as compared to baseline estimates (p < 0.0001). The number of DDDs remained stable over time (p = 0.87). No procedure-related major adverse events resulting in long-term consequences were observed.

CONCLUSIONS

The BP-lowering effect of RDN was safely maintained at least five years post-procedure as reflected by a significant decrease in ambulatory daytime BP in the absence of escalating antihypertensive drug therapy over time.

Histological evidence supporting the durability of successful radiofrequency renal denervation in a normotensive porcine model

BACKGROUND

Sustained blood pressure reductions after radiofrequency (RF) renal denervation (RDN) have been reported to 3 years in patients with uncontrolled hypertension. However, mechanistic data to support procedural durability are lacking. We aimed to quantify the long-term nerve anatomic and functional effects of RF RDN in a preclinical model.

METHODS

Bilateral RF RDN was performed in 20 normotensive swine. Renal tissue samples were obtained in the RDN-treated groups at 7 ( n  = 6), 28 ( n  = 6), and 180 days ( n  = 8) postprocedure for quantification of cortical norepinephrine (NE) levels and renal cortical axon density. Tissue fibrosis, necrosis and downstream nerve fiber atrophy (axonal loss) were also scored for each sample. Three additional untreated groups ( n  = 6, n  = 6 and n  = 8, respectively) served as control.

RESULTS

Pathologic nerve changes were characterized by necrosis in the ablated region at 7 days that partially resolved by 28 days and fully resolved at 180 days. Axonal loss was apparent within and downstream to the ablation regions and was evident at 7, 28 and 180 days in the main vessel and branch vessels. Consequently, renal cortical axon density and corresponding cortical NE levels were significantly reduced at 7 days in the RDN vs. control group and remained suppressed at 180 days.

CONCLUSIONS

Reductions in renal NE, cortical axon density and downstream axonal loss caused by axonal destruction persisted through 180 days post-RDN in a normotensive swine model. These results suggest functional nerve regrowth after RF RDN is unlikely and support published clinical evidence that the procedure results in durable blood pressure reduction.

Renal Sympathetic Denervation for Hypertension

Arterial hypertension is the most prevalent global modifiable risk factor for cardiovascular morbidity and mortality. Despite the availability of numerous pharmacologic treatments, many patients do not achieve guideline-recommended blood pressure targets. Therefore, renal sympathetic denervation (RDN), a process in which catheter-directed techniques are used to ablate portions of the renal artery to reduce sympathetic activity, has been extensively investigated as a complementary and nonpharmacologic approach for the treatment of arterial hypertension. This review seeks to discuss the pathophysiological rationale of this strategy, to survey its history and development, and to highlight the current clinical evidence and possible future directions of its employment. In sum, RDN has demonstrated itself to be a safe and well-tolerated endovascular intervention that can reliably contribute to improved blood pressure control and, perhaps ultimately, significant cardiovascular prognosis.

The role of renal nerve stimulation in percutaneous renal denervation for hypertension: A mini-review

Recent trials have demonstrated the efficacy and safety of percutaneous renal sympathetic denervation (RDN) for blood pressure (BP)-lowering in patients with uncontrolled hypertension. Nevertheless, major challenges exist, such as the wide variation of BP-lowering responses following RDN (from strong response to no response) and lack of feasible and reproducible peri-procedural predictors for patient response. Both animal and human studies have demonstrated different patterns of BP responses following renal nerve stimulation (RNS), possibly related to varied regional proportions of sympathetic and parasympathetic nerve tissues along the renal arteries. Animal studies of RNS have shown that rapid electrical stimulation of the renal arteries caused renal artery vasoconstriction and increased norepinephrine secretion with a concomitant increase in BP, and the responses were attenuated after RDN. Moreover, selective RDN at sites with strong RNS-induced BP increases led to a more efficient BP-lowering effect. In human, when RNS was performed before and after RDN, blunted changes in RNS-induced BP responses were noted after RDN. The systolic BP response induced by RNS before RDN and blunted systolic BP response to RNS after RDN, at the site with maximal RNS-induced systolic BP response before RDN, both correlated with the 24-h ambulatory BP reductions 3-12 months following RDN. In summary, RNS-induced BP changes, before and after RDN, could be used to assess the immediate effect of RDN and predict BP reductions months following RDN. More comprehensive, large-scale and long term trials are needed to verify these findings.

Renal denervation in patients with chronic kidney disease: current evidence and future perspectives

Supported by several high-quality randomised clinical trials and registry analyses, catheter-based renal denervation is becoming an important adjunctive treatment modality for the safe and efficacious treatment of hypertension besides lifestyle modifications and antihypertensive medication. Renal denervation is of particular interest to nephrologists as the intervention may provide additional benefits to hypertensive people with chronic kidney disease (CKD), a condition typically characterised by sympathetic hyperactivity. A growing body of clinical evidence supports the safety and efficacy of renal denervation in this difficult-to-control population. In addition, preclinical and clinical research indicate potential nephroprotective effects in CKD patients. The current review examines recent research on renal denervation with focus on renal disease and assesses the latest findings and their implications from a nephrologist's perspective.

Long-term efficacy and safety of renal denervation in the presence of antihypertensive drugs (SPYRAL HTN-ON MED): a randomised, sham-controlled trial

BACKGROUND

Renal denervation has been shown to lower blood pressure in the presence of antihypertensive medications; however, long-term safety and efficacy data from randomised trials of renal denervation are lacking. In this pre-specified analysis of the SPYRAL HTN-ON MED study, we compared changes in blood pressure, antihypertensive drug use, and safety up to 36 months in renal denervation versus a sham control group.

METHODS

This randomised, single-blind, sham-controlled trial enrolled patients from 25 clinical centres in the USA, Germany, Japan, the UK, Australia, Austria, and Greece, with uncontrolled hypertension and office systolic blood pressure between 150 mm Hg and 180 mm Hg and diastolic blood pressure of 90 mm Hg or higher. Eligible patients had to have 24-h ambulatory systolic blood pressure between 140 mm Hg and less than 170 mm Hg, while taking one to three antihypertensive drugs with stable doses for at least 6 weeks. Patients underwent renal angiography and were randomly assigned (1:1) to radiofrequency renal denervation or a sham control procedure. Patients and physicians were unmasked after 12-month follow-up and sham control patients could cross over after 12-month follow-up completion. The primary endpoint was the treatment difference in mean 24-h systolic blood pressure at 6 months between the renal denervation group and the sham control group. Statistical analyses were done on the intention-to-treat population. Long-term efficacy was assessed using ambulatory and office blood pressure measurements up to 36 months. Drug surveillance was used to assess medication use. Safety events were assessed up to 36 months. This trial is registered with ClinicalTrials.gov, NCT02439775; prospectively, an additional 260 patients are currently being randomly assigned as part of the SPYRAL HTN-ON MED Expansion trial.

FINDINGS

Between July 22, 2015, and June 14, 2017, among 467 enrolled patients, 80 patients fulfilled the qualifying criteria and were randomly assigned to undergo renal denervation (n=38) or a sham control procedure (n=42). Mean ambulatory systolic and diastolic blood pressure were significantly reduced from baseline in the renal denervation group, and were significantly lower than the sham control group at 24 and 36 months, despite a similar treatment intensity of antihypertensive drugs. The medication burden at 36 months was 2·13 medications (SD 1·15) in the renal denervation group and 2·55 medications (2·19) in the sham control group (p=0·26). 24 (77%) of 31 patients in the renal denervation group and 25 (93%) of 27 patients in the sham control group adhered to medication at 36 months. At 36 months, the ambulatory systolic blood pressure reduction was -18·7 mm Hg (SD 12·4) for the renal denervation group (n=30) and -8·6 mm Hg (14·6) for the sham control group (n=32; adjusted treatment difference -10·0 mm Hg, 95% CI -16·6 to -3·3; p=0·0039). Treatment differences between the renal denervation group and sham control group at 36 months were -5·9 mm Hg (95% CI -10·1 to -1·8; p=0·0055) for mean ambulatory diastolic blood pressure, -11·0 mm Hg (-19·8 to -2·1; p=0·016) for morning systolic blood pressure, and -11·8 mm Hg (-19·0 to -4·7; p=0·0017) for night-time systolic blood pressure. There were no short-term or long-term safety issues associated with renal denervation.

INTERPRETATION

Radiofrequency renal denervation compared with sham control produced a clinically meaningful and lasting blood pressure reduction up to 36 months of follow-up, independent of concomitant antihypertensive medications and without major safety events. Renal denervation could provide an adjunctive treatment modality in the management of patients with hypertension.

FUNDING

Medtronic.

Brief Early Life Angiotensin Converting Enzyme Inhibition Offers Reno-Protection in Sheep with a Solitary Functioning Kidney at 8 Months of Age

Background: Children born with a solitary functioning kidney (SFK) are predisposed to develop hypertension and kidney injury. Glomerular hyperfiltration and hypertrophy contribute to the pathophysiology of kidney injury. Angiotensin converting enzyme inhibitors (ACEi) can mitigate hyperfiltration and may be therapeutically beneficial in reducing progression of kidney injury in SFK. Methods: SFK was induced in male sheep fetuses at 100 days gestation (term=150 day). Between 4-8 weeks of age, SFK lambs received enalapril (SFK+ACEi; 0.5mg/kg/day, once daily, orally) or vehicle (SFK). At 8 months we examined whether SFK+ACEi reduced elevation in blood pressure (BP) and improved basal kidney function, renal functional reserve (RFR; glomerular filtration rate (GFR) response to combined amino acid and dopamine infusion), GFR response to nitric oxide synthase (NOS) inhibition and basal nitric oxide (NO) bioavailability (basal urinary total nitrate+nitrite (NOx)). Results: SFK+ACEi prevented albuminuria, resulted in lower basal GFR (16%), higher renal blood flow (~22%), and lower filtration fraction ( 35%), but similar BP compared to ~ vehicle-treated SFK sheep. Together with greater recruitment of RFR (~14%) in SFK+ACEi animals than SFK, this indicates reduction in glomerular hyperfiltration-mediated kidney dysfunction. During NOS inhibition, the decrease in GFR ( 14%) was greater among SFK+ACEi than among SFK animals. Increased ( 85%) basal urinary total NOx in SFK+ACEi animals compared to SFK indicates elevated NO bioavailability likely contributing to improvements in kidney function and prevention of albuminuria. Conclusions: Brief and early ACEi in SFK is associated with reduced glomerular hyperfiltration-mediated kidney disease up to 8 months of age in a sheep model.

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.

Effect of Renal Denervation for the Management of Heart Rate in Patients With Hypertension: A Systematic Review and Meta-Analysis

Objective:

The effect of renal denervation (RDN) on heart rate (HR) in patients with hypertension had been investigated in many studies, but the results were inconsistent. This meta-analysis was performed to evaluate the efficacy of RDN on HR control.

Methods:

Databases, such as PubMed, EMBASE, Cochrane, and ClinicalTrials.gov, were searched until September 2021. Randomized controlled trials (RCTs) or non-RCTs of RDN in hypertensive patients with outcome indicators, such as HR, were selected. Weighted mean difference (WMD) was calculated for evaluating the changes in HR from baseline using fixed-effects or random-effects models. The Spearman's correlation coefficients were used to identify the relationship between the changes of HR and systolic blood pressure (SBP).

Results:

In the current meta-analysis, 681 subjects from 16 individual studies were included. This study showed that RDN could reduce office HR in patients with hypertension [WMD = −1.93 (95% CI: −3.00 to −0.85, p < 0.001)]. In addition, 24-h HR and daytime HR were decreased after RDN [WMD = −1.73 (95% CI: −3.51 to −0.31, p = 0.017) and −2.67 (95% CI: −5.02 to −0.32, p = 0.026) respectively], but nighttime HR was not significantly influenced by RDN (WMD = −2.08, 95% CI: −4.57 to 0.42, p = 0.103). We found that the reduction of HR was highly related to the decrease of SBP (r = 0.658, p < 0.05).

Conclusion:

Renal denervation could reduce office, 24-h, and daytime HR, but does not affect nighttime HR. And the effect is highly associated with blood pressure (BP) control.

Systematic Review Registration:

https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42021283065.

Catheter-Based Renal Denervation Therapy: Evolution of Evidence and Future Directions

Motivated by the persistence of uncontrolled blood pressure and its public health impact, the development and evaluation of device-based therapies for hypertension has advanced at an accelerated pace to complement pharmaceutical and lifestyle intervention strategies. Countering widespread interest from early studies, the lack of demonstrable efficacy for renal denervation (RDN) in a large, sham-controlled randomized trial motivated revision of trial design and conduct to account for confounding variables of procedural technique, medication variability, and selection of both patients and end points. Now amidst varied trial design and methods, several sham-controlled, randomized trials have demonstrated clinically meaningful reductions in blood pressure with RDN. With this momentum, additional studies are underway to position RDN as a potential part of standard therapy for the world's leading cause of death and disability. In parallel, further studies will address unresolved issues including durability of blood pressure lowering and reduction in antihypertensive medications, late-term safety, and impact on clinical outcomes. Identifying predictors of treatment effect and surveys of patient-reported outcomes and treatment preferences are also evolving areas of investigation. Aside from confirmatory studies of safety and effectiveness, these additional studies will further inform patient selection, expand experience with RDN in broader populations with hypertension, and provide guidance to how RDN may be incorporated into treatment pathways.

Renal denervation inhibits the renin-angiotensin-aldosterone system in spontaneously hypertensive rats

This study was conducted to explore the effect of renal denervation (RDN) on the renin-angiotensin-aldosterone system (RAAS) in spontaneously hypertensive rats (SHRs). Our experimental rats were randomly divided into the RDN group conducted by painting 10% phenol on the bilateral renal nerves (RDNX), the shamoperation group simply painting with saline (Sham), and the normotension control group (WKY) following all the animal blood and tissues of kidney, hypothalamus, and adrenal gland collected and examined 2 weeks after RDN operation. We found that the aldosterone (ALD) levels in serum and tissues all decreased in the RDNX group compared with the Sham group (p < .05). Meantime, the expression of angiotensin II type1 receptor (AT1R) mRNA also exhibited significantly reduced by 2.22-fold in the RDNX group compared to the Sham group identical to the expression of AT1R protein in the renal cortex and outer stripe of the outer medulla (OSOM) subjected to denervation surgery, which manifested the lower ATIR protein expression than the Sham group (p < .05). Besides, the expression of angiotensin II (Ang II) protein in the cortex , OSOM, and inner stripe of the outer medulla were all attenuated by RDN in comparison with the Sham group (p < .05). RDN reduced intrarenal RAAS and circulating RAAS to lower blood pressure and repair renal function.

Renal Denervation for Hypertension: A Systematic Review and Meta-Analysis of Randomized, Blinded, Placebo-Controlled Trials

OBJECTIVES

The authors performed an updated meta-analysis of randomized placebo-controlled trials of renal denervation and specifically compared the effect of renal denervation in patients taking medications and in those not taking medications.

BACKGROUND

Renal denervation has now undergone several blinded placebo-controlled trials, covering the spectrum from patients with drug-resistant hypertension to those not yet taking antihypertensive medications.

METHODS

All blinded placebo-controlled randomized trials of catheter-based renal sympathetic denervation for hypertension were systematically identified, and a random-effects meta-analysis was performed. The primary efficacy outcome was the change in ambulatory systolic blood pressure beyond the effect of the placebo procedure. Analysis was stratified by whether there was background antihypertensive medication use.

RESULTS

There were 7 eligible trials, totaling 1,368 patients. Denervation significantly reduced ambulatory systolic (mean difference -3.61 mm Hg; 95% confidence interval [CI]: -4.89 to -2.33 mm Hg; P < 0.0001), ambulatory diastolic (-1.85 mm Hg; 95% CI: -2.78 to -0.92 mm Hg; P < 0.0001), office systolic (-5.86 mm Hg; 95% CI: -7.77 to -3.94 mm Hg; P < 0.0001), and office diastolic (-3.63 mm Hg; 95% CI: -4.77 to -2.50; P < 0.0001) blood pressure. There was no evidence that the use of concomitant antihypertensive medication had a significant impact on the effect of denervation on any of these endpoints (P_interaction = NS for each comparison).

CONCLUSIONS

The randomized placebo-controlled trials show consistently that renal denervation provides significant reduction in ambulatory and office blood pressure. Although the magnitude of benefit, about 4/2 mm Hg, is modest, it is similar between patients on background antihypertensive medications and those who are not. Denervation could therefore be a useful strategy at various points for patients who are not willing to add antihypertensive agents. Whether the effect changes with time is currently unknown.

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.

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

[Figure: see text].

12-Month Results From the Unblinded Phase of the RADIANCE-HTN SOLO Trial of Ultrasound Renal Denervation

OBJECTIVES

This study reports the 12-month results of the RADIANCE-HTN (A Study of the ReCor Medical Paradise System in Clinical Hypertension) SOLO trial following unblinding of patients at 6 months.

BACKGROUND

The blood pressure (BP)-lowering efficacy and safety of endovascular ultrasound renal denervation (RDN) in the absence (2 months) and presence (6 months) of antihypertensive medications were previously reported.

METHODS

Patients with daytime ambulatory BP ≥135/85 mm Hg after 4 weeks off medication were randomized to RDN (n = 74) or sham (n = 72) and maintained off medication for 2 months. A standardized medication escalation protocol was instituted between 2 and 5 months (blinded phase). Between 6 and 12 months (unblinded phase), patients received antihypertensive medications at physicians' discretion. Outcomes at 12 months included medication burden, change in daytime ambulatory systolic BP (dASBP) and office or home systolic BP (SBP), visit-to-visit variability in SBP, and safety.

RESULTS

Sixty-five of 74 RDN patients and 67 of 72 sham patients had 12-month dASBP measurements. The proportion of patients on ≥2 medications (27.7% vs. 44.8%; p = 0.041), the number of medications (0 vs. 1.4; p = 0.015), and defined daily dose (1.4 vs. 2.2; p = 0.007) were less with RDN versus sham. The decrease in dASBP from baseline in the RDN group (-16.5 ± 12.9 mm Hg) remained stable at 12 months. The RDN versus sham adjusted difference at 12 months was -2.3 mm Hg (95% confidence interval [CI]: -5.9 to 1.3 mm Hg; p = 0.201) for dASBP, -6.3 mm Hg (95% CI: -11.1 to -1.5 mm Hg; p = 0.010) for office SBP, and -3.4 mm Hg (95% CI: -6.9 to 0.1 mm Hg; p = 0.062) for home SBP. Visit-to-visit variability in SBP was smaller in the RDN group. No renal artery injury was detected on computed tomographic or magnetic resonance angiography.

CONCLUSIONS

Despite unblinding, the BP-lowering effect of RDN was maintained at 12 months with fewer prescribed medications compared with sham.

Blunted natriuretic response to saline loading in sheep with hypertensive kidney disease following radiofrequency catheter-based renal denervation

Renal sympathetic nerves contribute to renal excretory function during volume expansion. We hypothesized that intact renal innervation is required for excretion of a fluid/electrolyte load in hypertensive chronic kidney disease (CKD) and normotensive healthy settings. Blood pressure, kidney hemodynamic and excretory response to 180 min of isotonic saline loading (0.13 ml/kg/min) were examined in female normotensive (control) and hypertensive CKD sheep at 2 and 11 months after sham (control-intact, CKD-intact) or radiofrequency catheter-based RDN (control-RDN, CKD-RDN) procedure. Basal blood pressure was ~ 7 to 9 mmHg lower at 2, and 11 months in CKD-RDN compared with CKD-intact sheep. Saline loading did not alter glomerular filtration rate in any group. At 2 months, in response to saline loading, total urine and sodium excretion were ~ 40 to 50% less, in control-RDN and CKD-RDN than intact groups. At 11 months, the natriuretic and diuretic response to saline loading were similar between control-intact, control-RDN and CKD-intact groups but sodium excretion was ~ 42% less in CKD-RDN compared with CKD-intact at this time-point. These findings indicate that chronic withdrawal of basal renal sympathetic activity impairs fluid/electrolyte excretion during volume expansion. Clinically, a reduced ability to excrete a saline load following RDN may contribute to disturbances in body fluid balance in hypertensive CKD.

Device Therapy of Hypertension

In the past decade, efforts to improve blood pressure control have looked beyond conventional approaches of lifestyle modification and drug therapy to embrace interventional therapies. Based upon animal and human studies clearly demonstrating a key role for the sympathetic nervous system in the etiology of hypertension, the newer technologies that have emerged are predominantly aimed at neuromodulation of peripheral nervous system targets. These include renal denervation, baroreflex activation therapy, endovascular baroreflex amplification therapy, carotid body ablation, and pacemaker-mediated programmable hypertension control. Of these, renal denervation is the most mature, and with a recent series of proof-of-concept trials demonstrating the safety and efficacy of radiofrequency and more recently ultrasound-based renal denervation, this technology is poised to become available as a viable treatment option for hypertension in the foreseeable future. With regard to baroreflex activation therapy, endovascular baroreflex amplification, carotid body ablation, and programmable hypertension control, these are developing technologies for which more human data are required. Importantly, central nervous system control of the circulation remains a poorly understood yet vital component of the hypertension pathway and mandates further investigation. Technology to improve blood pressure control through deep brain stimulation of key cardiovascular control territories is, therefore, of interest. Furthermore, alternative nonsympathomodulatory intervention targeting the hemodynamics of the circulation may also be worth exploring for patients in whom sympathetic drive is less relevant to hypertension perpetuation. Herein, we review the aforementioned technologies with an emphasis on the preclinical data that underpin their rationale and the human evidence that supports their use.

Role of the sympathetic nervous system in cardiometabolic control: implications for targeted multiorgan neuromodulation approaches

Sympathetic overdrive plays a key role in the perturbation of cardiometabolic homeostasis. Diet-induced and exercise-induced weight loss remains a key strategy to combat metabolic disorders, but is often difficult to achieve. Current pharmacological approaches result in variable responses in different patient cohorts and long-term efficacy may be limited by medication intolerance and nonadherence. A clinical need exists for complementary therapies to curb the burden of cardiometabolic diseases. One such approach may include interventional sympathetic neuromodulation of organs relevant to cardiometabolic control. The experience from catheter-based renal denervation studies clearly demonstrates the feasibility, safety and efficacy of such an approach. In analogy, denervation of the common hepatic artery is now feasible in humans and may prove to be similarly useful in modulating sympathetic overdrive directed towards the liver, pancreas and duodenum. Such a targeted multiorgan neuromodulation strategy may beneficially influence multiple aspects of the cardiometabolic disease continuum offering a holistic approach.

Increase in Bioavailability of Nitric Oxide After Renal Denervation Improves Kidney Function in Sheep With Hypertensive Kidney Disease

[Figure: see text].

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

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

A Simplified Iohexol-Based Method to Measure Renal Function in Sheep Models of Renal Disease

Sheep are highly adequate models for human renal diseases because of their many similarities in the histology and physiology of kidney and pathogenesis of kidney diseases. However, the lack of a simple method to measure glomerular filtration rate (GFR) limits its use as a model of renal diseases. Hence, we aimed to develop a simple method to measure GFR based on the plasma clearance of iohexol by assessing different pharmacokinetic models: (a) CL2: two-compartment (samples from 15 to 420 min; reference method); (b) CL1: one-compartment (samples from 60 to 420 min); (c) CLlf: CL1 adjusted by a correction formula and (d) SM: simplified CL2 (15 to 300 min). Specific statistics of agreement were used to test the models against CL2. The agreement between CL1 and CL2 was low, but both CL1f and SM showed excellent agreement with CL2, as indicated by a total deviation index of ~5-6%, a concordance correlation of 0.98-0.99% and a coverage probability of 99-100%, respectively. Hence, the SM approach is preferable due to a reduced number of samples and shorter duration of the procedure; two points that improve animal management and welfare.

Development and Evaluation of a Disease Large Animal Model for Preclinical Assessment of Renal Denervation Therapies

New-generation catheters-based renal denervation (RDN) is under investigation for the treatment of uncontrolled hypertension (HTN). We assessed the feasibility of a large animal model of HTN to accommodate the human RDN devices. Ten minipigs were instrumented to measure blood pressure (BP) in an awake-state. HTN was induced with subcutaneous 11-deoxycorticosterone (DOCA, 100 mg/kg) implants. Five months after, the surviving animals underwent RDN with the Symplicity^® system. Norepinephrine (NE) renal gradients were determined before and 1 month after RDN. Renal arteries were processed for histological (hematoxylin-eosin, Movat pentachrome) and immunohistochemical (S100, tyrosine-hydroxylase) analyses. BP significantly rose after DOCA implants. Six animals died prematurely, mainly from infectious causes. The surviving animals showed stable BP levels after 5 months. One month after RDN, nerve damage was showed in three animals, with impedance drop >10%, NE gradient drop and reduction in BP. The fourth animal showed no nerve damage, impedance drop <10%, NE gradient increase and no change in BP. In conclusion, the minipig model of DOCA-induced HTN is feasible, showing durable effects. High mortality should be addressed in next iterations of this model. RDN may partially offset the DOCA-induced HTN. Impedance drop and NE renal gradient could be markers of RDN success.

Physiology and Pathophysiology of Compensatory Adaptations of a Solitary Functioning Kidney

Children born with a solitary functioning kidney (SFK) have an increased risk of hypertension and kidney disease from early in adulthood. In response to a reduction in kidney mass, the remaining kidney undergoes compensatory kidney growth. This is associated with both an increase in size of the kidney tubules and the glomeruli and an increase in single nephron glomerular filtration rate (SNGFR). The compensatory hypertrophy and increase in filtration at the level of the individual nephron results in normalization of total glomerular filtration rate (GFR). However, over time these same compensatory mechanisms may contribute to kidney injury and hypertension. Indeed, approximately 50% of children born with a SFK develop hypertension by the age of 18 and 20–40% require dialysis by the age of 30. The mechanisms that result in kidney injury are only partly understood, and early biomarkers that distinguish those at an elevated risk of kidney injury are needed. This review will outline the compensatory adaptations to a SFK, and outline how these adaptations may contribute to kidney injury and hypertension later in life. These will be based largely on the mechanisms we have identified from our studies in an ovine model of SFK, that implicate the renal nitric oxide system, the renin angiotensin system and the renal nerves to kidney disease and hypertension associated with SFK. This discussion will also evaluate current, and speculate on next generation, prognostic factors that may predict those children at a higher risk of future kidney disease and hypertension.

Renal Sympathetic Denervation: A Comprehensive Review

In 2017, the American College of Cardiology and American Heart Association released its updated blood pressure guidelines, redefining hypertension to be any systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg. Among United States adults, these new parameters increased the prevalence of hypertension from 72.2 million (31.9%) to 103.3 million (45.6%) adults and decreased the rate of medication-controlled hypertension from 53.4% to 39% with the prevalence of resistant hypertension ranging from 12% to 18%. Results of the pivotal SPRINT trial showed that more intensive blood pressure control in diabetic patients decreased both cardiovascular events and all-cause mortality. However, even with ideal goals in mind, compliance remains an issue due to multiple causes, and approximately half of study participants had stopped taking their antihypertensive drug within a year. Renal sympathetic denervation is a process in which catheter-based techniques are used to ablate specific portions of the renal artery nerves with the goal of decreasing sympathetic nerve activity and reducing blood pressure. Several studies using renal artery denervation have already shown benefit in patients with resistant hypertension, and now newer trials are beginning to focus on those with stage II hypertension as an additional potential treatment population. This review will seek to summarize the current evidence surrounding renal artery denervation and discuss some of its future trials, current issues, and potential roles both in hypertension and other comorbidities.

Thoracolumbar Junction Syndrome Accompanying Renal Artery Stenosis: A Case Report

Flank pain is a common reason for visits to the emergency room. The most common reason warranting hospital visits are urology-related problems. However, there are many other causes, such as musculoskeletal lesions, that difficult to achieve a correct diagnosis. Here, we describe a rare case of flank pain caused by thoracolumbar junction syndrome, accompanying renal artery stenosis. A 54-year-old male with hypertension presented with severe left flank pain for 1 week. Initially, he was diagnosed with left renal artery stenosis by computed tomography and decreased renal function on renal scan (Tc-99m DTPA). Although a stent was inserted into the left renal artery, flank pain persisted with only minor improvement. Through detailed physical examination, he was finally diagnosed with thoracolumbar junction syndrome. After three injections in the left deep paravertebral muscles at the T10–T12 levels, flank pain completely ceased. Clinicians must consider thoracolumbar junction syndrome, when treating patients with flank pain.

Renal Sympathetic Nerve-Derived Signaling in Acute and Chronic kidney Diseases

The kidney is innervated by afferent sensory and efferent sympathetic nerve fibers. Norepinephrine (NE) is the primary neurotransmitter for post-ganglionic sympathetic adrenergic nerves, and its signaling, regulated through adrenergic receptors (AR), modulates renal function and pathophysiology under disease conditions. Renal sympathetic overactivity and increased NE level are commonly seen in chronic kidney disease (CKD) and are critical factors in the progression of renal disease. Blockade of sympathetic nerve-derived signaling by renal denervation or AR blockade in clinical and experimental studies demonstrates that renal nerves and its downstream signaling contribute to progression of acute kidney injury (AKI) to CKD and fibrogenesis. This review summarizes our current knowledge of the role of renal sympathetic nerve and adrenergic receptors in AKI, AKI to CKD transition and CKDand provides new insights into the therapeutic potential of intervening in its signaling pathways.

Joint UK societies' 2019 consensus statement on renal denervation

Improved and durable control of hypertension is a global priority for healthcare providers and policymakers. There are several lifestyle measures that are proven to result in improved blood pressure (BP) control. Moreover, there is incontrovertible evidence from large scale randomised controlled trials (RCTs) that antihypertensive drugs lower BP safely and effectively in the long-term resulting in substantial reduction in cardiovascular morbidity and mortality. Importantly, however, evidence is accumulating to suggest that patients neither sustain long-term healthy behaviours nor adhere to lifelong drug treatment regimens and thus alternative measures to control hypertension warrant further investigation. Endovascular renal denervation (RDN) appears to hold some promise as a non-pharmacological approach to lowering BP and achieves renal sympathectomy using either radiofrequency energy or ultrasound-based approaches. This treatment modality has been evaluated in clinical trials in humans since 2009 but initial studies were compromised by being non-randomised, without sham control and small in size. Subsequently, clinical trial design and rigour of execution has been greatly improved resulting in recent sham-controlled RCTs that demonstrate short-term reduction in ambulatory BP without any significant safety concerns in both medication-naïve and medication-treated hypertensive patients. Despite this, the joint UK societies still feel that further evaluation of this therapy is warranted and that RDN should not be offered to patients outside of the context of clinical trials. This document reviews the updated evidence since our last consensus statement from 2014 and provides a research agenda for future clinical studies.