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.

Histological examination of renal nerve distribution, density, and function in humans

BACKGROUND

Renal denervation is optimised when guided by knowledge of nerve distribution.

AIMS

We aimed to assess sympathetic nerve distribution along the renal arteries, especially in post-bifurcation vessel segments.

METHODS

Renal arteries and surrounding tissue from 10 body donors were collected and examined histologically. Immunohistochemical staining was used to analyse nerve distribution and to identify afferent and efferent sympathetic nerves.

RESULTS

A total of 6,781 nerves surrounding 18 renal arteries were evaluated. The mean lumen-nerve distance of the left renal artery (2.32±1.95 mm) was slightly greater than the right (2.29±2.03 mm; p=0.161); this varied across the arteries' courses: 3.7±2.3 mm in proximal segments, 2.5±2.0 mm in middle segments, 1.9±1.6 mm in distal prebifurcation segments and 1.3±1.0 mm in post-bifurcation segments (p<0.001). The number of nerves per quadrant was highest in the proximal segments (13.7±18.6), followed by the middle (9.7±7.9), distal prebifurcation (8.0±7.6), and distal post-bifurcation (4.3±4.0) segments (p<0.001). Circumferentially, the number of nerves was highest in the superior (7.8±9.4) and the ventral (7.6±13.1) quadrants (p=0.638). The mean tyrosine hydroxylase (TH) to calcitonin gene-related peptide (CGRP) ratio increased from proximal (37.5±33.5) to distal (72.0±7.2 in the post-bifurcation segments; p<0.001). Thirty-eight neuroganglia were identified along 14 (78%) renal arteries.

CONCLUSIONS

Nerves converge to the renal arteries' lumen in the distal segments and along branches, resulting in the lowest number of nerves per quadrant and the shortest lumen-nerve distance in the distal post-bifurcation segments. Efferent nerves occur predominantly, and the ratio of efferent to afferent nerves continues to increase in the vessels' course.

Translational value of preclinical models for renal denervation: a histological comparison of human versus porcine renal nerve anatomy

BACKGROUND

Preclinical models have provided key insights into the response of local tissues to radiofrequency (RF) renal denervation (RDN) that is unobtainable from human studies. However, the anatomic translatability of these models to the procedure in humans is incompletely understood.  Aims: We aimed to compare the renal arterial anatomy in normotensive pigs treated with RF-RDN to that of human cadavers to evaluate the suitability of normotensive pigs for determining the safety of RF-RDN.

METHODS

Histopathologic analyses were performed on RF-treated renal arteries in a porcine model and untreated control renal arteries. Similar analyses were performed on untreated renal arteries from human cadavers.  Results: In both human and porcine renal arteries, the median number of nerves was lower in the more distal sections (the numbers in the proximal, middle, distal, 1st bifurcation, and 2nd bifurcation sections were 65, 58, 47, 22.5, and 14.7 in humans, respectively, and 39, 26, 29, 16.5, and 9.3 in the porcine models, respectively). Renal nerves were common in the regions between arteries and adjacent veins, but only 3% and 13% of the renal nerves in humans and pigs, respectively, were located behind the renal vein. The semiquantitative score of RF-induced renal arterial nerve necrosis was significantly greater at 7 days than 28 days (0.98 vs 0.75; p=0.01), and injury to surrounding organs was rarely observed.

CONCLUSIONS

The distribution of nerve tissue and the relative distribution of extravascular anatomic structures along the renal artery was similar between humans and pigs, which validates the translational value of the normotensive porcine model for RDN.

Mapping Renal Innervations by Renal Nerve Stimulation and Characterizations of Blood Pressure Response Patterns

Increased sympathetic nervous activity is one of main contributors to pathogenesis and progression of hypertension. Renal denervation (RDN) has been demonstrated as a potential therapy for treatment of hypertension; however, lack of indicators of intra-/post-procedure results in inconsistent clinical outcomes. Renal nerve stimulation (RNS), a simple and promising method, could evoke elevated blood pressure as an intraoperative indicator for RDN. But related researches on patterns of blood pressure responses to RNS are still incomplete. To investigate and categorize the phenotypes of blood pressure response to RNS and heart rate alteration before and after RNS, 24 Chinese Kunming dogs were used to perform RNS from bifurcation to ostium of renal arteries after angiography, and a total of 483 stimulated sites were complete. We identified five different patterns of blood pressure response to RNS in 483 stimulated sites, (1) continuous ascending and finally keeping steady above baseline (26.9%), (2) declining and then rising over baseline (11.8%), (3) declining and then rising but below baseline (14.5%), (4) fluctuating in the vicinity of baseline (39.5%), and (5) continuous declining and finally keeping steady below baseline (7.2%), and found no difference in RR intervals among five blood pressure responses before and after renal nerve stimulation. Renal nerve stimulation could elicit different patterns of blood pressure response, which could potentially assist in distinguishing sympathetic-excitatory sites and sympathetic-inhibitory sites from mixed nerve components, which might help to improve the efficacy of RDN.

Ultrasound renal denervation for hypertension resistant to a triple medication pill (RADIANCE-HTN TRIO): a randomised, multicentre, single-blind, sham-controlled trial

BACKGROUND

Endovascular renal denervation reduces blood pressure in patients with mild-to-moderate hypertension, but its efficacy in patients with true resistant hypertension has not been shown. We aimed to assess the efficacy and safety of endovascular ultrasound renal denervation in patients with hypertension resistant to three or more antihypertensive medications.

METHODS

In a randomised, international, multicentre, single-blind, sham-controlled trial done at 28 tertiary centres in the USA and 25 in Europe, we included patients aged 18-75 years with office blood pressure of at least 140/90 mm Hg despite three or more antihypertensive medications including a diuretic. Eligible patients were switched to a once daily, fixed-dose, single-pill combination of a calcium channel blocker, an angiotensin receptor blocker, and a thiazide diuretic. After 4 weeks of standardised therapy, patients with daytime ambulatory blood pressure of at least 135/85 mm Hg were randomly assigned (1:1) by computer (stratified by centres) to ultrasound renal denervation or a sham procedure. Patients and outcome assessors were masked to randomisation. Addition of antihypertensive medications was allowed if specified blood pressure thresholds were exceeded. The primary endpoint was the change in daytime ambulatory systolic blood pressure at 2 months in the intention-to-treat population. Safety was also assessed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT02649426.

FINDINGS

Between March 11, 2016, and March 13, 2020, 989 participants were enrolled and 136 were randomly assigned to renal denervation (n=69) or a sham procedure (n=67). Full adherence to the combination medications at 2 months among patients with urine samples was similar in both groups (42 [82%] of 51 in the renal denervation group vs 47 [82%] of 57 in the sham procedure group; p=0·99). Renal denervation reduced daytime ambulatory systolic blood pressure more than the sham procedure (-8·0 mm Hg [IQR -16·4 to 0·0] vs -3·0 mm Hg [-10·3 to 1·8]; median between-group difference -4·5 mm Hg [95% CI -8·5 to -0·3]; adjusted p=0·022); the median between-group difference was -5·8 mm Hg (95% CI -9·7 to -1·6; adjusted p=0·0051) among patients with complete ambulatory blood pressure data. There were no differences in safety outcomes between the two groups.

INTERPRETATION

Compared with a sham procedure, ultrasound renal denervation reduced blood pressure at 2 months in patients with hypertension resistant to a standardised triple combination pill. If the blood pressure lowering effect and safety of renal denervation are maintained in the long term, renal denervation might be an alternative to the addition of further antihypertensive medications in patients with resistant hypertension.

FUNDING

ReCor Medical.

Impact of Renal Pelvic Denervation on Systemic Hemodynamics and Neurohumoral Changes in a Porcine Model

INTRODUCTION

The blood pressure (BP) response to arterial renal denervation (RDN) is variable.

METHODS

This study examined the effectiveness of renal pelvic denervation (RPD) on BP, heart rate (HR), norepinephrine (NE), and histopathology in 42 swine. NE levels were measured immediately, 7, 14, 30, and 90 days after RPD. Intra-arterial BP and HR were measured throughout RPD and after 14 days in 5 swine.

RESULTS

During the procedure, RPD immediately reduced systolic BP (-20.6 ± 18.3 mm Hg), diastolic BP (-6.0 ± 8.3 mm Hg), and HR (-5.4 ± 5.6 bpm), which remained decreased at follow-up. The porcine kidneys had a mean NE reduction of 76% directly post procedure and 60% after 7 days, 64% after 14 days, 57% after 30 days, and 65% after 90 days. Histopathological examination confirmed nerve ablation.

CONCLUSIONS

These preliminary findings suggest that the renal pelvis nerve ablation is an encouraging target for RDN. Clinical trials are required to test the feasibility of RPD in human hypertension.

The current status of renal denervation for the treatment of arterial hypertension

Despite the availability of safe and effective antihypertensive drugs, blood pressure (BP) control to guideline-recommended target values is poor. Several device-based therapies have been introduced to lower BP. The most extensively investigated approach is catheter-based renal sympathetic denervation (RDN), which aims to interrupt the activity of afferent and efferent renal sympathetic nerves by applying radiofrequency energy, ultrasound energy, or injection of alcohol in the perivascular space. The second generation of placebo-controlled trials have provided solid evidence for the BP-lowering efficacy of radiofrequency- and ultrasound-based RDN in patients with and without concomitant pharmacological therapy. In addition, the safety profile of RDN appears to be excellent in all registries and clinical trials. However, there remain unsolved issues to be addressed. This review summarizes the rationale as well as the current evidence and discusses open questions and possible future indications of catheter-based RDN.

A Systematic Review of Randomized Controlled Trials Comparing Renal Sympathetic Denervation Versus Sham Procedure for the Management of Uncontrolled Hypertension

ABSTRACT

The efficacy of renal sympathetic denervation (RSD) in the treatment of uncontrolled hypertension (HTN) remains uncertain. A systematic review of randomized controlled trials was performed to evaluate the efficacy and safety of RSD for resistant HTN. PubMed, EMBASE, MEDLINE, Cochrane, Directory of Open Access Journals, CINAHL, and Google Scholar were searched from January 01, 2001, through July 30, 2020. Randomized controlled trials comparing RSD with the sham procedure for uncontrolled HTN were selected. The primary efficacy outcome was the reduction in ambulatory systolic blood pressure. We used random-effects models. Nine prospective clinical trials met the inclusion criteria. The ReSet and Symplicity HTN-3 Trial showed no significant changes because of discrepancies in complete circumferential ablation during RSD. The Relief study, The Radiance HTN solo, and the SPYRAL HTN OFF medical trials showed a significant reduction in systolic blood pressure in the group that had undergone the intervention compared with the sham group attributed to rigorous trial design. In conclusion, our systematic review suggests that efficacy of RSD seems to be superior to sham-controlled interventions provided circumferential denervation is performed. However, difference in efficacy is marginal.

Copeptin Levels in Patients With Treatment-Resistant Hypertension Before and 6 Months After Renal Denervation

BACKGROUND

Copeptin, the C-terminal peptide of provasopressin, is released from the neurohypophysis and reflects the activity of the hormone arginine vasopressin in patients with hypertension. Elevated copeptin levels are associated with increased cardiovascular and all-cause mortality. The aim of this study is to compare copeptin levels in patients with treatment-resistant hypertension (TRH) before and 6 months after renal denervation (RDN).

METHODS

Copeptin was measured in 34 patients with TRH and 30 patients with primary hypertension stage 1 or 2 (HT). In addition, copeptin levels were measured in patients with TRH at 6-month follow-up visit after RDN. RDN was performed by an experienced interventionalist applying at least 4 ablations longitudinally and rotationally within the lengths of each renal artery to cover a full 4-quadrant ablation.

RESULTS

In patients with TRH 24-hour ambulatory blood pressure (BP) decreased from 154 ± 15/87 ± 12 mm Hg to 146 ± 13/83 ± 7.9 mm Hg after RDN (systolic: P = 0.001, diastolic: P = 0.034). There was no significant change in copeptin levels in these 34 patients with TRH before vs. 6 months after RDN (median 8.4 [interquartile range 3.6-14] vs. 8.5 [4.5-13] pmol/l, P = 0.334). Patients with TRH had higher copeptin levels (P = 0.024) than patients with HT (24-hour ambulatory BP: 142 ± 11/91 ± 8.3 mm Hg, copeptin: 4.2 [2.8-6.3] pmol/l).

CONCLUSION

Patients with TRH showed 2-fold higher copeptin levels than patients with HT. RDN did not lead to any change of copeptin levels in patients with TRH 6 months after procedure despite significant fall in BP.

CLINICAL TRIAL REGISTRATION

NCT01318395, NCT01687725.

The Current Status of Devices for the Treatment of Resistant Hypertension

Arterial hypertension is associated with increased cardiovascular morbidity and mortality. Although blood pressure-lowering therapies significantly reduce the risk of major cardiovascular events, blood pressure control remains unsatisfactorily low. Several device-based antihypertensive therapies have been investigated in patients with treatment-resistant hypertension and in patients unable or unwilling to adhere to antihypertensive medication. As the field of device-based therapies is subject to constant change, this review aims at providing an up-to-date overview of different device-based approaches for the treatment of hypertension. These approaches target the sympathetic nervous system (renal denervation, baroreflex amplification therapy, baroreflex activation therapy, and carotid body ablation) or alter mechanical arterial properties by creating an iliac arteriovenous fistula. Notably, the use of all of these treatment options is not recommended for the routine treatment of hypertension by current guidelines but should be investigated in the context of controlled clinical studies.

Resistant hypertension: Renal denervation or pharmacovigilance? Insights from a renal denervation screening program

BACKGROUND

With emerging new therapeutic concepts including renal denervation (RDN), there is a renewed interest in resistant hypertension (ResH). Among patients suspected of having ResH, a definitive diagnosis needs to be established.

OBJECTIVES

This study presents observations from a standardized single-center screening program for RDN candidates, including medical therapy modification and reassessment.

MATERIAL AND METHODS

All patients referred to our center for RDN underwent a standardized screening protocol. Candidates were recruited from among patients receiving no less than 3 antihypertensive drugs, including diuretics with office blood pressure (BP) >140/90 mm Hg. The assessment included 2 measurements of BP and ambulatory BP monitoring (ABPM). If needed, pharmacotherapy was intensified and the diagnosis of ResH was reconfirmed after 6 weeks. If ResH was persistent, patients were hospitalized with repeated ABPM on day 4. Further, renal CT-angio was performed and a multidisciplinary team discussed the patients' suitability for RDN.

RESULTS

A total of 87 patients with a ResH diagnosis were referred for RDN. Mean office BP was 159/92 (±7.0/6.5) mm Hg and mean ABPM was 154/90 (±9.0/4.8) mm Hg. The initial medication included angiotensin convertase inhibitors (ACE-I, 78%), angiotensin receptor blockers (12%), β-blockers (85%), calcium channel blockers (36%), and diuretics (93%). During the 18 months of the RDN program, 5 patients underwent RDN and 2 further had ineligible renal anatomy. A new diagnosis of secondary hypertension was made in 21 patients. However, in 59 patients, BP control was achieved after optimization of medical therapy, with a mean ABPM of 124/74 mm Hg. The final treatment included ACE-I (100%), β-blockers (92%), indapamide (94%), amlodipine (72%), and spironolactone (61%). Medication in most of these patients (88%) included single-pill triple combination (52.5%) or double combination (35.6%).

CONCLUSIONS

Patients with elevated BP screened for RDN require a rigorous diagnostic workup. Up to 2/3 of patients can be managed with strict pharmacotherapy compliance and pharmaceutical intensification, including single-pill combinations and improved drug compliance. Hasty use of RDN may be a result of poor drug optimization and/or compliance. It does remain a viable treatment option in thoroughly vetted ResH patients.

New approaches for treating atrial fibrillation: Focus on autonomic modulation

Atrial fibrillation (AF) is a rapidly growing clinical problem in routine practice, both for cardiologists as well as general practitioners. Current therapies aimed at the management of AF include anti-arrhythmic drug therapy and catheter ablation. These therapies have a number of limitations and risks, and have disappointing long-term efficacy in maintaining sinus rhythm and improving hard clinical outcomes. Because of this, there is growing interest in pursuing alternative management strategies in patients with AF. This review seeks to highlight emerging AF therapies, with a specific focus on several modalities aimed at modulation of the autonomic nervous system. These therapies have shown promise in early pre-clinical and clinical trials, and represent exciting alternatives to standard AF treatment.

Renal Denervation: Is It Ready for Prime Time?

PURPOSE OF REVIEW

Interventional cardiology and in particular the field of renal denervation is subject to constant change. This review provides an up to date overview of renal denervation trials and an outlook on what to expect in the future.

RECENT FINDINGS

After the sham-controlled SYMPLICITY HTN-3 trial dampened the euphoria following early renal denervation trials, the recently published results of the sham-controlled SPYRAL HTN and RADIANCE HTN trials provided proof-of-principle for the blood pressure-lowering efficacy of renal denervation. However, these studies underline the major issue of patients' non-adherence to antihypertensive medication as well as the need for reliable patient- and procedure-related predictors of response. The second generation of sham-controlled renal denervation trials provided proof of principle for the blood pressure-lowering efficacy of RDN. However, larger trials have to assess long-term safety and efficacy.

Renal Denervation in Isolated Systolic Hypertension Using Different Catheter Techniques and Technologies

Patients with isolated systolic hypertension (ISH) are thought to show a diminished blood pressure (BP)-lowering effect after renal sympathetic denervation (RDN). This conclusion is mostly derived from unipolar radiofrequency catheter ablation studies. Limited data for newer RDN technologies exist. We used data from the RADIOSOUND-HTN (Three-Arm Randomized Trial of Different Renal Denervation Devices and Techniques in Patients With Resistant Hypertension) comparing 3 different RDN approaches to investigate a possible interaction between ISH and RDN response. One hundred twenty patients were stratified by having ISH or combined systolic-diastolic hypertension (CH). Of these, 39 underwent radiofrequency ablation of the renal main arteries, 39 combined radiofrequency ablation of the main and branch arteries, and 42 were treated with ultrasound-based ablation of the main renal artery. Patients with ISH (n=61) were older and had lower systolic and diastolic BP on ambulatory measurement (ambulatory BP measurement) at baseline in comparison to CH (n=59). At 3 months, patients with ISH showed a less pronounced BP-lowering effect of RDN as compared to patients with CH (daytime average -5.9±11.8 versus -13.3±11.7 mm Hg, P=0.001). This difference was significant for radiofrequency ablation of the renal main arteries and ultrasound-based ablation of the main renal artery treatment but did not reach significance in the radiofrequency ablation of the main and branch arteries group. After adjustment for baseline BP values and age, there was no significant difference in BP reduction between ISH and CH. Using unadjusted BP values, RDN seems to be more effective in CH than in ISH. However, adjusting for baseline BP values revealed similar BP reduction in ISH and CH patients, irrespective of the RDN treatment used. The value of ISH as predictor for successful RDN might have been overestimated in the past. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT02920034.

Is renal denervation still a treatment option in cardiovascular disease?

The role of renal sympathetic denervation (RDN) has been the topic of ongoing debate ever since the impressive initial results. The rationale of RDN is strong and supported by non-clinical studies, which lies in uncoupling the autonomic nervous crosstalk between the kidneys and the central nervous system. Since we know that cardiovascular diseases, such as hypertension, atrial, ventricular arrhythmias and heart failure (HF) are related to sympathetic (over)activity, modulation of the renal nerve activity appears to be a reasonable and attractive therapeutic target in these patients. This review will focus on the existing evidence and potential future perspectives for RDN as treatment option in cardiovascular disease.

[European guidelines for the management of arterial hypertension 2018-what has changed?]

BACKGROUND

In November 2017, the latest American guidelines for the management of arterial hypertension were published. With these guidelines lowering the threshold for hypertension to 130/80 mm Hg, the latest European guidelines were expected with excitement.

OBJECTIVES

This article gives an overview on the European Society of Cardiology (ESC) and European Society of Hypertension (ESH) 2018 guidelines for the management of arterial hypertension, thereby identifying the most relevant changes in comparison to previous guidelines.

CURRENT DATA

The latest 2018 ESC/ESH guidelines adhere to the previous definition of hypertension, in which a blood pressure of 140/90 mm Hg is considered as threshold for diagnosis. In contrast, there was a change in blood pressure treatment target from below 140/90 to between 120-129/70-79 mm Hg in patients < 65 years if well tolerated. Among patients ≥ 65 years, a systolic blood pressure between 130 and 139 mm Hg is recommended, whereas a diastolic blood pressure between 70 and 79 mm Hg should be targeted. Additionally the guidelines recommend the use of fixed dose combinations as first choice instead of monotherapy to improve adherence. Interventional treatment strategies should only be applied in carefully selected patients at experienced centers and are not recommended outside of clinical studies and registers. Furthermore, the chapters regarding initiation of blood pressure-lowering therapy and clinical evaluation as well as management of hypertension emergencies have been outlined.

CONCLUSIONS

The latest European guidelines for the management of hypertension include several changes. One of the most important aspects is that-in contrast to the American guidelines-the threshold for diagnosis remains at 140/90 mm Hg, whereas treatment target range has been lowered by roughly 10 mm Hg and single pill fixed dose combinations are recommended.

Reduced blood pressure-lowering effect of catheter-based renal denervation in patients with isolated systolic hypertension: data from SYMPLICITY HTN-3 and the Global SYMPLICITY Registry

Aims

Catheter-based renal artery denervation (RDN) has been shown to lower blood pressure (BP) in certain patients with uncontrolled hypertension. Isolated systolic hypertension (ISH) (systolic BP [SBP] ≥140 mmHg and diastolic BP <90 mmHg), characterized by increased vascular stiffness, is the predominant hypertensive phenotype in elderly patients. This study compared baseline characteristics and SBP change at 6 months between patients with ISH and combined systolic–diastolic hypertension (CH).

Methods and results

This study pooled data from 1103 patients from SYMPLICITY HTN-3 and the Global SYMPLICITY Registry. A total of 429 patients had ISH, and 674 had CH. Patients with ISH were significantly older than those with CH (66 vs. 55 years), had more type 2 diabetes mellitus (52.9 vs. 34.6%), and a lower estimated glomerular filtration rate (71.8 vs. 78.6 mL/min/1.73 m²); all P < 0.001. At 6 months, the SBP drop for CH patients was −18.7 ± 23.7 mmHg compared with a reduction of −10.9 ± 21.7 mmHg for ISH patients −7.8 mmHg, 95% confidence interval, CI, −10.5, −5.1, P < 0.001). The change in 24-h SBP at 6 months was −8.8 ± 16.2 mmHg in patients with CH vs. −5.8 ± 15.4 mmHg in ISH (−3.0 mmHg, 95% CI −5.4, −0.6, P = 0.015). Presence of ISH at baseline but not age was associated with less pronounced BP changes following the procedure. The strongest predictor of office SBP reduction at 6 months was CH, followed by aldosterone antagonist use and non-use of vasodilators.

Conclusion

The reduction in BP among patients with ISH following RDN was less pronounced than the reduction in patients with CH.

Clinical.Trials.gov identifiers

NCT01534299 and NCT01418261.

Effect of renal denervation on blood pressure in the presence of antihypertensive drugs: 6-month efficacy and safety results from the SPYRAL HTN-ON MED proof-of-concept randomised trial

BACKGROUND

Previous catheter-based renal denervation studies have reported variable efficacy results. We aimed to evaluate safety and blood pressure response after renal denervation or sham control in patients with uncontrolled hypertension on antihypertensive medications with drug adherence testing.

METHODS

In this international, randomised, single-blind, sham-control, proof-of-concept trial, patients with uncontrolled hypertension (aged 20-80 years) were enrolled at 25 centres in the USA, Germany, Japan, UK, Australia, Austria, and Greece. Eligible patients had an office systolic blood pressure of between 150 mm Hg and 180 mm Hg and a diastolic blood pressure of 90 mm Hg or higher; a 24 h ambulatory systolic blood pressure of between 140 mm Hg and 170 mm Hg at second screening; and were on one to three antihypertensive drugs with stable doses for at least 6 weeks. Patients underwent renal angiography and were randomly assigned to undergo renal denervation or sham control. Patients, caregivers, and those assessing blood pressure were masked to randomisation assignments. The primary efficacy endpoint was blood pressure change from baseline (measured at screening visit two), based on ambulatory blood pressure measurements assessed at 6 months, as compared between treatment groups. Drug surveillance was used to assess medication adherence. The primary analysis was done in the intention-to-treat population. Safety events were assessed through 6 months as per major adverse events. This trial is registered with ClinicalTrials.gov, number NCT02439775, and follow-up is ongoing.

FINDINGS

Between July 22, 2015, and June 14, 2017, 467 patients were screened and enrolled. This analysis presents results for the first 80 patients randomly assigned to renal denervation (n=38) and sham control (n=42). Office and 24 h ambulatory blood pressure decreased significantly from baseline to 6 months in the renal denervation group (mean baseline-adjusted treatment differences in 24 h systolic blood pressure -7·0 mm Hg, 95% CI -12·0 to -2·1; p=0·0059, 24 h diastolic blood pressure -4·3 mm Hg, -7·8 to -0·8; p=0.0174, office systolic blood pressure -6·6 mm Hg, -12·4 to -0·9; p=0·0250, and office diastolic blood pressure -4·2 mm Hg, -7·7 to -0·7; p=0·0190). The change in blood pressure was significantly greater at 6 months in the renal denervation group than the sham-control group for office systolic blood pressure (difference -6·8 mm Hg, 95% CI -12·5 to -1·1; p=0·0205), 24 h systolic blood pressure (difference -7·4 mm Hg, -12·5 to -2·3; p=0·0051), office diastolic blood pressure (difference -3·5 mm Hg, -7·0 to -0·0; p=0·0478), and 24 h diastolic blood pressure (difference -4·1 mm Hg, -7·8 to -0·4; p=0·0292). Evaluation of hourly changes in 24 h systolic blood pressure and diastolic blood pressure showed blood pressure reduction throughout 24 h for the renal denervation group. 3 month blood pressure reductions were not significantly different between groups. Medication adherence was about 60% and varied for individual patients throughout the study. No major adverse events were recorded in either group.

INTERPRETATION

Renal denervation in the main renal arteries and branches significantly reduced blood pressure compared with sham control with no major safety events. Incomplete medication adherence was common.

FUNDING

Medtronic.

Endovascular ultrasound renal denervation to treat hypertension (RADIANCE-HTN SOLO): a multicentre, international, single-blind, randomised, sham-controlled trial

BACKGROUND

Early studies suggest that radiofrequency-based renal denervation reduces blood pressure in patients with moderate hypertension. We investigated whether an alternative technology using endovascular ultrasound renal denervation reduces ambulatory blood pressure in patients with hypertension in the absence of antihypertensive medications.

METHODS

RADIANCE-HTN SOLO was a multicentre, international, single-blind, randomised, sham-controlled trial done at 21 centres in the USA and 18 in Europe. Patients with combined systolic-diastolic hypertension aged 18-75 years were eligible if they had ambulatory blood pressure greater than or equal to 135/85 mm Hg and less than 170/105 mm Hg after a 4-week discontinuation of up to two antihypertensive medications and had suitable renal artery anatomy. Patients were randomised (1:1) to undergo renal denervation with the Paradise system (ReCor Medical, Palo Alto, CA, USA) or a sham procedure consisting of renal angiography only. The randomisation sequence was computer generated and stratified by centres with randomised blocks of four or six and permutation of treatments within each block. Patients and outcome assessors were blinded to randomisation. The primary effectiveness endpoint was the change in daytime ambulatory systolic blood pressure at 2 months in the intention-to-treat population. Patients were to remain off antihypertensive medications throughout the 2 months of follow-up unless specified blood pressure criteria were exceeded. Major adverse events included all-cause mortality, renal failure, an embolic event with end-organ damage, renal artery or other major vascular complications requiring intervention, or admission to hospital for hypertensive crisis within 30 days and new renal artery stenosis within 6 months. This study is registered with ClinicalTrials.gov, number NCT02649426.

FINDINGS

Between March 28, 2016, and Dec 28, 2017, 803 patients were screened for eligibility and 146 were randomised to undergo renal denervation (n=74) or a sham procedure (n=72). The reduction in daytime ambulatory systolic blood pressure was greater with renal denervation (-8·5 mm Hg, SD 9·3) than with the sham procedure (-2·2 mm Hg, SD 10·0; baseline-adjusted difference between groups: -6·3 mm Hg, 95% CI -9·4 to -3·1, p=0·0001). No major adverse events were reported in either group.

INTERPRETATION

Compared with a sham procedure, endovascular ultrasound renal denervation reduced ambulatory blood pressure at 2 months in patients with combined systolic-diastolic hypertension in the absence of medications.

FUNDING

ReCor Medical.

The effect of renal denervation in an experimental model of chronic renal insufficiency, The REmnant kidney Denervation In Pigs study (REDIP study)

BACKGROUND

Renal denervation (RDN) is a promising therapeutic method in cardiology. Its currently most investigated indication is resistant hypertension. Other potential indications are atrial fibrillation, type 2 diabetes mellitus and chronic renal insufficiency among others. Previous trials showed conflicting but promising results, but the real benefits of RDN are still under investigation. Patients with renal insufficiency and resistant hypertension are proposed to be a good target for this therapy due to excessive activation of renal sympathetic drive. However, only limited number of studies showed benefits for these patients. We hypothesize that in our experimental model of chronic kidney disease (CKD) due to ischemia with increased activity of the renin-angiotensin-aldosterone system (RAAS), renal denervation can have protective effects by slowing or blocking the progression of renal injury.

METHODS

An experimental biomodel of chronic renal insufficiency induced by ischemia was developed using selective renal artery embolization (remnant kidney porcine model). 27 biomodels were assessed. Renal denervation was performed in 19 biomodels (denervated group), and the remaining were used as controls (n = 8). The extent of renal injury and reparative process between the two groups were compared and assessed using biochemical parameters and histological findings.

RESULTS

Viable remnant kidney biomodels were achieved and maintained in 27 swine. There were no significant differences in biochemical parameters between the two groups at baseline. Histological assessment proved successful RDN procedure in all biomodels in the denervated group. Over the 7-week period, there were significant increases in serum urea, creatinine, and aldosterone concentration in both groups. The difference in urea and creatinine levels were not statistically significant between the two groups. However, the level of aldosterone in the denervated was significantly lower in comparison to the controls. Histological assessment of renal arteries showed that RDN tends to produce more damage to the arterial wall in comparison to vessels in subjects that only underwent RAE. In addition, the morphological damage of kidneys, which was expressed as a ratio of damaged surface (or scar) to the overall surface of kidney, also did not show significant difference between groups.

CONCLUSIONS

In this study, we were not able to show significant protective effect of RDN alone on ischemic renal parenchymal damage by either laboratory or histological assessments. However, the change in aldosterone level shows some effect of renal denervation on the RAAS system. We hypothesize that a combined blockade of the RAAS and the sympathetic system could provide more protective effects against acute ischemia. This has to be further investigated in future studies.

Renal Sympathetic Denervation: A Viable Option for Treating Resistant Hypertension

Accumulating evidence from mainly uncontrolled clinical studies with various types of ablation catheters have shown that renal denervation (RDN) can be applied safely and is effective in lowering blood pressure (BP) in patients with treatment-resistant hypertension. Sustained BP lowering has been documented up to 3 years. Furthermore, RDN has been associated with regression of target organ damage, such as left ventricular hypertrophy, arterial stiffness, and others. Several studies indicate potential benefit in other common clinical conditions associated with increased sympathetic tone including chronic kidney disease and heart failure. However, the recently published Symplicity HTN-3 study, the largest and most rigorously designed sham-controlled clinical trial, while confirming the safety of the procedure, failed to demonstrate a BP lowering effect beyond that of a sham procedure in patients with resistant hypertension. Efforts to unravel the reasons for the discrepant results from Symplicity HTN-3 have focused on a range of potential confounders including anatomical and procedural aspects. Indeed, data from post-hoc analyses indicate that sufficient RDN may not have been achieved in the majority of patients in Symplicity HTN-3. Furthermore, recent evidence from human postmortem and functional animal studies revealed new insights into the anatomical distribution of renal nerves and their accessibility by intravascular approaches. Initial results from recent clinical trials integrating these important findings indeed seem to confirm that RDN remains a viable option for the treatment of hypertension. Thorough further investigations will be key to determine the true potential of RDN in clinical conditions characterized by increased sympathetic drive.

Catheter-Based Renal Denervation for Resistant Hypertension: Will It Ever Be Ready for "Prime Time"?

The year 2014 was a turning point for the field of renal denervation (RDN) and its potential use to treat resistant hypertension. Tremendous enthusiasm shifted to sober reflection on the efficacy of a technology once touted as the cure to resistant hypertension. The following review highlights 2 major questions: First, does catheter-based RDN lower blood pressure and, second, will RDN using catheter-directed therapy for the treatment of resistant hypertension ever become more than an investigational technology.

Blood pressure reduction in patients with accessory renal arteries and bilateral single renal arteries after catheter-based renal denervation: a prospective study with 3-year follow-up

INTRODUCTION

Catheter‑based renal denervation (RD) is an effective treatment leading to a significant reduction of systolic and diastolic blood pressure (BP) in patients with resistant hypertension.

OBJECTIVES

The aim of this prospective study was to assess the BP-lowering and pulse pressure (PP)- lowering effects in patients with accessory and bilateral single renal arteries after catheter‑based RD during a 3‑year follow‑up.

PATIENTS AND METHODS

The study included 31 patients with diagnosed resistant hypertension. Patients were classified into 2 groups: group 1 included patients with accessory renal arteries, and group 2, with bilateral single renal arteries. The BP and PP reduction levels were measured before the procedure and at 6, 12, 24, and 36 months after the procedure.

RESULTS

All procedures were successful. In group 1, mean systolic BP, diastolic BP, and PP at baseline were 172.7 mm Hg, 98.9 mm Hg, and 74.4 mm Hg, respectively. Systolic BP, diastolic BP, and PP reduction levels were, respectively, -26.9, 19.2, and 7.5 at 6 months; -33.3, 16.1, and 16.4 at 12 months; -29.2, 14, and 18.2 at 24 months; and -28.6, 13.6, and 13.7 at 36 months. In group 2, mean systolic BP, diastolic BP, and PP at baseline were 175.6 mm Hg, 100.1 mm Hg, and 75.5 mm Hg, respectively. Systolic BP, diastolic BP, and PP reduction levels were, respectively, -26, 10.5, and 15.5 at 6 months; -22, 8.9, and 13 at 12 months; -28, 12.4, and 15.6 at 24 months; and -24.6, 14.97, and 9.2 at 36 months. Significant reductions were observed for systolic BP in group 1 and for PP and systolic and diastolic BP in group 2.

CONCLUSIONS

RD successfully reduced systolic BP in patients with resistant hypertension and accessory renal arteries. PP reduction after RD in patients with accessory renal arteries was less pronounced than in patients with bilateral single renal arteries.

Effect of catheter-based renal denervation on left ventricular function, mass and (un)twist with two-dimensional speckle tracking echocardiography

Background

Speckle tracking echocardiography (STE) is an echocardiography modality that is able to measure left ventricular (LV) characteristics, including rotation, strain and strain rate. Strain measures myocardial fibre contraction and relaxation. This study aims to assess the effect of renal sympathetic denervation (RDN) on functional myocardial parameters, including STE, and to identify potential differences between responders and non-responders.

Methods

The study population consisted of 31 consecutive patients undergoing RDN in the context of treatment for resistant hypertension. Patients were included between December 2012 and June 2014. Transthoracic echocardiography and speckle tracking analysis was performed at baseline and at 6 months follow-up.

Results

The study population consisted of 31 patients with treatment-resistant hypertension treated with RDN (mean age 64 ± 10 years, 15 men). The total study population could be divided into responders (n = 19) and non-responders (n = 12) following RDN. RDN reduced office blood pressure by 18.9 ± 26.8/8.5 ± 13.5 mmHg (p < 0.001). A significant decrease was seen in LV posterior wall thickness (LVPWd) (0.47 ± 1.0 mm; p = 0.020), without a significant change in the LV mass index (LVMI). In the total cohort, only peak late diastolic filling velocity (A-wave velocity) decreased significantly by 5.3 ± 13.2 cm/s (p = 0.044) and peak untwisting velocity decreased significantly by 14.5 ± 28.9°/s (p = 0.025).

Conclusion

RDN reduced blood pressure and significantly improved functional myocardial parameters such as A-wave velocity and peak untwisting velocity in patients with treatment-resistant hypertension, suggesting a potential beneficial effect of RDN on myocardial mechanics.

Safety and performance of the second generation EnligHTN™ Renal Denervation System in patients with drug-resistant, uncontrolled hypertension

BACKGROUND AND AIMS

Catheter-based renal denervation for the treatment of drug-resistant hypertension has been intensively investigated in recent years. To date, only limited data have been published using multi-electrode radiofrequency ablation systems that can deliver lesions with a pre-determined pattern. This study was designed to evaluate the safety and performance of the second generation EnligHTN™ Renal Denervation System.

METHODS

This first-in-human, prospective, multi-center, non-randomized study included 39 patients (62% male, mean age 63 years, and mean baseline office blood pressure 174/93 mmHg) with drug-resistant hypertension. The primary safety and performance objectives were to characterize, from baseline to 6 months post procedure, the rate of serious procedural and device related adverse events, as adjudicated by an independent Clinical Events Committee, and the reduction of office systolic blood pressure.

RESULTS

Renal artery denervation, using the second generation EnligHTN multi-electrode system significantly reduced office blood pressure from baseline to 1, 3, 6, 12, 18 and 24 months by 19/7, 26/9, 25/7, 23/7, 25/8 and 27/9 mmHg, respectively (p ≤ 0.0005). No serious device or procedure related adverse events affecting the renal arteries or renal function occurred through 24 months of follow-up.

CONCLUSIONS

Renal sympathetic denervation using the second generation EnligHTN Renal Denervation System resulted in safe, rapid, and significant mean office blood pressure reduction that was sustained through 24 months. Future studies will need to address the utility of this system against an appropriate sham based comparator.

Perivascular radiofrequency renal denervation lowers blood pressure and ameliorates cardiorenal fibrosis in spontaneously hypertensive rats

Background

Catheter-based renal denervation (RDN) is a promising approach to treat hypertension, but innervation patterns limit the response to endovascular RDN and the post-procedural renal artery narrowing or stenosis questions the endovascular ablation strategy. This study was performed to investigate the anti-hypertensive and target organ protective effects of perivascular RDN in spontaneously hypertensive rats (SHR).

Methods

SHR and normotensive Wistar-Kyoto (WKY) rats were divided into sham group (n = 10), radiofrequency ablation group (n = 20) in which rats received bilateral perivascular ablation with radiofrequency energy (2 watts), and chemical (10% phenol in 95% ethanol) ablation group (n = 12). The tail-cuff blood pressure was measured before the ablation and on day 14 and day 28 after the procedure. The plasma levels of creatinine, urea nitrogen, and catecholamines, urinary excretion of electrolytes and protein, and myocardial and glomerular fibrosis were analyzed and compared among the groups on day 28 after the procedure.

Results

We identified that 2-watt is the optimal radiofrequency power for perivascular RDN in rats. Perivascular radiofrequency and chemical ablation achieved roughly comparable blood pressure reduction in SHR but not in WKY on day 14 and day 28 following the procedure. Radiofrequency-mediated ablation substantially destroyed the renal nerves surrounding the renal arteries of both SHR and WKY without damaging the renal arteries and diminished the expression of tyrosine hydroxylase, the enzyme marker for postganglionic sympathetic nerves. Additionally, perivascular radiofrequency ablation also decreased the plasma catecholamines of SHR. Interestingly, both radiofrequency and chemical ablation decreased the myocardial and glomerular fibrosis of SHR, while neither increased the plasma creatinine and blood urea nitrogen nor affected the urinary excretion of electrolytes and protein when compared to sham group.

Conclusions

Radiofrequency-mediated perivascular RDN may become a feasible procedure against hypertension, and provide similar anti-hypertensive and target organ protective effects as does the chemical ablation.

First Clinical Experience With Targeted REnal Nerve Demodulation (TREND-1) Using a Neurotropic Agent for the Treatment of Sympathetic Hypertension

AIMS

To evaluate the feasibility and safety of a novel targeted neuromodulatory treatment for sympathetic hypertension involving a one-time local injection of neurotropic agents near renal nerves.

METHODS AND RESULTS

Seven patients suffering from uncontrolled hypertension per ESH-ESC guidelines were treated using a single dose of NW2013, a neurotropic Na+/K+ ATPase antagonist. A microneedle catheter was used to administer 1.2 mL of NW2013 (0.6 mL per artery) to the perivascular space surrounding renal arteries using percutaneous endovascular procedures under fluoroscopic guidance. All patients were successfully treated without any procedural complications. Patients were followed for 12 months post procedure, and office and 24-hour ambulatory blood pressure measurements were made. Both office and ambulatory blood pressures were lower at 24 hours, 1 month, and 3 months after treatment. The decrease in office blood pressure was greater than the decrease in ambulatory blood pressure. A reduction in medication regimen was also observed in 2 patients. One patient suffered a cerebrovascular event after 6-month follow-up and died from stroke, unrelated to the treatment. Overall, the reduction in office and ambulatory blood pressure was sustained over the course of 12 months.

CONCLUSIONS

Treatment of hypertension using local administration of NW2013 near renal nerves appears to be feasible and safe. Large, controlled, randomized, and blinded clinical studies with monitoring of patient compliance to daily oral medication are recommended to further establish the efficacy of this novel treatment.

Effects of Renal Denervation on Insulin Sensitivity and Inflammatory Markers in Nondiabetic Patients with Treatment-Resistant Hypertension

Increased sympathetic activity is important in the pathogenesis of hypertension and insulin resistance. Afferent signaling from the kidneys elevates the central sympathetic drive. We investigated the effect of catheter-based renal sympathetic denervation (RDN) on glucose metabolism, inflammatory markers, and blood pressure in nondiabetic patients with treatment-resistant hypertension. Eight subjects were included in an open-labelled study. Each patient was studied before and 6 months after RDN. Endogenous glucose production was assessed by a 3-³H glucose tracer, insulin sensitivity was examined by hyperinsulinemic euglycemic clamp, hormones and inflammatory markers were analyzed, and blood pressure was measured by office blood pressure readings and 24-hour ambulatory blood pressure monitoring. Insulin sensitivity (M-value) increased nonsignificantly from 2.68 ± 0.28 to 3.07 ± 0.41 (p = 0.12). A significant inverse correlation between the increase in M-value and BMI 6 months after RDN (p = 0.03) was found, suggesting beneficial effects on leaner subjects. Blood pressure decreased significantly, but there were no changes in hormones, inflammatory markers, or endogenous glucose production. Our results indicate that RDN may improve insulin sensitivity in some patients with treatment-resistant hypertension, albeit confirmation of these indications of beneficial effects on leaner subjects awaits the outcome of larger randomized controlled studies.

Sympathoinhibitory Effect of Radiofrequency Renal Denervation in Spontaneously Hypertensive Rats With Established Hypertension

BACKGROUND

Radiofrequency ablation of the renal arteries (RF-ABL) has been shown to decrease blood pressure (BP) in drug-resistant hypertensive patients who receive antihypertensive drug therapy. However, there remain questions regarding how RF-ABL influences BP independent of drug therapy and whether complete renal denervation is necessary to maximally lower BP. To study these questions, we examined the cardiovascular, sympathetic, and renal effects produced by RF-ABL of the proximal renal arteries in spontaneously hypertensive rats (SHR) with established hypertension.

METHODS

SHR were instrumented (telemetry) for measurement of systolic/diastolic BP (SBP/DBP). Rats then underwent Sham-ABL or RF-ABL adjacent to the renal ostium and BP was recorded for 8 weeks. Changes in sympathetic activity, 24-hour water/sodium excretion, and levels of urinary angiotensinogen (AGT), plasma renin activity, and kidney renin content (KRC) were measured in SHR.

RESULTS

Compared with Sham-ABL, RF-ABL produced a sustained decrease in BP. At 8 weeks, SBP/DBP was 171±6/115±3 and 183±4/129±3mm Hg for RF-ABL and Sham-ABL SHR, respectively. Correlating with the reduction in BP, RF-ABL significantly decreased the low frequency/total and low frequency/high frequency of BP variability and attenuated the hypotensive response to chlorisondamine. Kidney norepinephrine levels were markedly decreased at 8 weeks in RF-ABL vs. Sham-ABL SHR. There were no group differences in 24-hour sodium/water excretion or urinary AGT excretion rate (6 weeks) or plasma renin activity or KRC (8 weeks). In other studies, concurrent RF-ABL plus surgical denervation initially decreased BP to a greater level than RF-ABL alone, but thereafter the reduction in BP between groups was not different.

CONCLUSIONS

In hypertensive SHR, bilateral RF-ABL of the proximal renal arteries produced a sustained decease in sympathetic activity and BP without changes in sodium/water excretion or activity of the systemic/renal renin-angiotensin system.

Could careful patient selection for renal denervation warrant a positive effect on arterial stiffness and left ventricular mass reduction?

AIMS

After the sequence of Symplicity HTN trials, the impact of the procedure on lowering blood pressure (BP) and cardiovascular risk is still debatable. We present initial results of the multimodal pilot study that aimed at carefully selecting proper patients and investigating the effects of RASD on cardiac morphology and central haemodynamic parameters in 15 patients with resistant arterial hypertension prior and 6 months after RASD.

METHODS AND RESULTS

The multimodal (applanation tonometry, echocardiography and cardiac magnetic resonance (CMR)) study findings have shown a significant BP decrease (190/112 ± 23/12 to 153/91 ± 18/11 mm Hg, P < 0.002), a decrease of the arterial markers (carotid-femoral pulse wave velocity decreased from 11.46 ± 2.92 m/s to 9.17 ± 2.28 m/s and the augmentation index decreased from 25.47 ± 10.55 to 21 ± 12.19, P < 0.006), a significant left ventricular mass index decrease by 10% both by echocardiography (140.83 ± 38.46 to 115.26 ± 25.37 g/m2, n = 14, P < 0.001) and CMR (108.32 ± 39.02 to 97.25 ± 30.06 g/m2, n = 15, P = 0.003). A significant decrease of CMR retrograde flow volume in the ascending aorta non-dependent on BP was also found.

CONCLUSIONS

Our study is characterised by strict and extensive patient selection criteria for renal artery sympathetic denervation (RASD), which seem to warrant a positive effect of the procedure on BP, arterial stiffness and left ventricular mass 6 months after RASD, although it should be confirmed in larger controlled trials.

Renal sympathetic denervation improves rate control in patients with symptomatic persistent atrial fibrillation and hypertension

AIM

The aim of this study was to investigate whether renal sympathetic denervation (RSD) improves ventricular heart rate (HR) control in patients with persistent atrial fibrillation (AF).

METHODS AND RESULTS

Twenty-one patients (aged 57.5 ± 10.2 years, 76.2% male) with persistent AF and hypertension underwent RSD and completed 7-days follow-up evaluations, including 24-hour Holter monitoring (Holter), blood pressure (BP), 24-hour ambulatory BP monitoring (ABPM). Patients were grouped into tertiles of average HR at baseline Holter recording for evaluation of RSD effects on atrioventricular (AV) node (group 1: HR ≧ 90 bpm; group 2: 80 bpm ≦ HR < 90 bpm; group 3: HR < 80 bpm).

RESULTS

All patients successfully underwent RSD without any complications. The clinical and procedural characteristics were similar in all groups of patients. No significant changes in BP were observed in the three groups before and after RSD. Compared with baseline, the average HR (Holter) of patients in group 1, 2 and 3 had a reduction of 22.6 ± 13.2 bpm (83.3 ± 4.9 vs 106.0 ± 14.6, P = 0.004), 9.7 ± 7.8 bpm (75.7 ± 7.6 vs 85.4 ± 3.7, P = 0.017) and 2.3 ± 2.9 bpm (71.4 ± 4.0 vs 73.7 ± 4.7, P = 0.089) at 7 days after RSD, respectively.

CONCLUSIONS

RSD could improve ventricular HR control in patients with persistent AF. RSD slowed AV node conduction in baseline HR-dependent manner. RSD may become an alternative non-pharmaceutical tool for rate control in patients with persistent AF.

[EFFICACY OF RADIOFREQUENCY ABLATION OF AORTORENAL SYMPATHETIC NODES IN PATIENTS IN ARTERIAL HYPERTENSION]

Efficacy of radiofrequency ablation (RFA) of prevertebral sympathetic nodes, concern- ing the arterial pressure lowering in 36 patients, suffering hypertonic disease and coex- istent heart diseases, was analyzed. In 12 mo after RFA a systolic arterial pressure lowering at average throughout the group by (3.24 ± 1.15) kPa, or (24.3 ± 8.6) mm Hg, diastolic arterial pressure--by (1.51 ± 0.45) kPa, or (11.3 ± 3.4) mm Hg was noted. RFA of prevertebral sympathetic nodes have had promoted a stable lowering of arterial pressure in patients, suffering chronic hypersympathicotony.

Drug resistant hypertension – no simple way out

Hypertension poses growing challenge for health policy-makers and doctors worldwide. Recently published results of Symplicity-III trial (HTN-3), the first blinded, randomized, multicenter study on the efficacy of renal denervation for the treatment of resistant hypertension did not show a significant reduction of BP in patients with resistant hypertension 6 months after renal-artery denervation, as compared with controls. In this paper we review clinical and experimental studies on renal denervation. In order to identify causes of inconsistent results in renal denervation studies we look at basic science support for renal denervation and at designs of clinical trials.

Retrospective morphometric study of the suitability of renal arteries for renal denervation according to the Symplicity HTN2 trial criteria

OBJECTIVE

The aim of this study was to describe the renal arteries of humans in vivo, as precisely as possible, and to formulate an expected value for the exclusion of renal denervation due to the anatomical situation based on the criteria of the Symplicity HTN trials.

DESIGN AND SETTING

In a retrospective cohort study, the renal arteries of 126 patients (57 women, 69 men, mean age 60 ± 17.2 years (CI 57.7 to 63.6)) were segmented semiautomatically from high-contrast CT angiographies.

RESULTS

Among the 300 renal arteries, there were three arteries with fibromuscular dysplasia and one with ostial renal artery stenosis. The first left renal artery was shorter than the right (34 ± 11.4 mm (CI 32 to 36) vs 45.9 ± 15 mm (CI 43.2 to 48.6); p<0.0001), but had a slightly larger diameter (5.2 ± 1.4 mm (CI 4.9 to 5.4) vs 4.9 ± 1.2 mm (CI 4.6 to 5.1); p>0.05). The first left renal arteries were 1.1 ± 0.4 mm (CI 0.9 to 1.3), and the first right renal arteries were 0.3 ± 0.6 mm (CI 0.1 to 0.5) thinner in women than in men (p<0.05). Ostial funnels were up to 14 mm long. The cross-sections were elliptical, more pronounced on the right side (p<0.05). In 23 cases (18.3%), the main artery was shorter than 2 cm; in 43 cases (34.1%), the diameter was not >4 mm. Some 46% of the patients, or 58.7% when variants and diseases were taken into consideration, were theoretically not suitable for denervation.

CONCLUSIONS

Based on these precise measurements, the anatomical situation as a reason for ruling out denervation appears to be significantly more common than previously suspected. Since this can be the cause of the failure of treatment in some cases, further development of catheters or direct percutaneous approaches may improve success rates.

Safety and long-term effects of renal denervation: Rationale and design of the Dutch registry

BACKGROUND

Percutaneous renal denervation (RDN) has recently been introduced as a treatment for therapy-resistant hypertension. Also, it has been suggested that RDN may be beneficial for other conditions characterised by increased sympathetic nerve activity. There are still many uncertainties with regard to efficacy, safety, predictors for success and long-term effects. To answer these important questions, we initiated a Dutch RDN registry aiming to collect data from all RDN procedures performed in the Netherlands.

METHODS

The Dutch RDN registry is an ongoing investigator-initiated, prospective, multicentre cohort study. Twenty-six Dutch hospitals agreed to participate in this registry. All patients who undergo RDN, regardless of the clinical indication or device that is used, will be included. Data are currently being collected on eligibility and screening, treatment and follow-up.

RESULTS

Procedures have been performed since August 2010. At present, data from 306 patients have been entered into the database. The main indication for RDN was hypertension (n = 302, 99%). Patients had a mean office blood pressure of 177/100 (±29/16) mmHg with a median use of three (range 0-8) blood pressure lowering drugs. Mean 24-hour blood pressure before RDN was 157/93 (±18/13) mmHg. RDN was performed with different devices, with the Simplicity™ catheter currently used most frequently.

CONCLUSION

Here we report on the rationale and design of the Dutch RDN registry. Enrolment in this investigator-initiated study is ongoing. We present baseline characteristics of the first 306 participants.

Comparison of Saline-Irrigated Catheter vs. Temperature-Controlled Catheter for Renal Denervation in a Canine Model

BACKGROUND

The effectiveness of catheter-based renal denervation (RDN) remains controversial. Although the reasons for this have not yet been elucidated, ineffective denervation appears to be an important factor. The present study aimed to investigate the difference in RDN between a saline-irrigated catheter (SIC) and a temperature-controlled catheter (TCC).

METHODS

Dogs (n = 6) from the Kunming province in Chinese were ablated; the SIC was introduced into the right renal artery, while the TCC was introduced into the left renal artery. After 6 months, histopathology and renal angiography were performed, and the change in neural density was evaluated using morphometric software. The average values of heart rate (HR), blood pressure (BP), and catecholamine metabolites were assessed at baseline and follow-up.

RESULTS

Histopathology showed nerve demyelination and denaturation, as well as interstitial hyperplasia, although these changes were more pronounced when the SIC was used. The change in neural density was greater and ablation was deeper when the SIC was used. Intimal hyperplasia was greater when the TCC was used, whereas medial hyperplasia was greater when the SIC was used. A trend toward a decrease in HR, BP, metanephrine, and normetanephrine between baseline and follow-up was observed.

CONCLUSIONS

Our findings suggest that SIC ablation results in more extensive neural degeneration, deeper penetration, and less extensive intimal hyperplasia than TCC ablation for RDN.

The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model

Rationale

Recently, the efficacy of renal denervation (RDN) has been debated. It is discussed whether RDN is able to adequately target the renal nerves.

Objective

We aimed to investigate how effective RDN was by means of functional hemodynamic measurements and nerve damage on histology.

Methods and Results

We performed hemodynamic measurements in both renal arteries of healthy pigs using a Doppler flow and pressure wire. Subsequently unilateral denervation was performed, followed by repeated bilateral hemodynamic measurements. Pigs were terminated directly after RDN or were followed for 3 weeks or 3 months after the procedure. After termination, both treated and control arteries were prepared for histology to evaluate vascular damage and nerve damage. Directly after RDN, resting renal blood flow tended to increase by 29±67% (P = 0.01). In contrast, renal resistance reserve increased from 1.74 (1.28) to 1.88 (1.17) (P = 0.02) during follow-up. Vascular histopathology showed that most nerves around the treated arteries were located outside the lesion areas (8±7 out of 55±25 (14%) nerves per pig were observed within a lesion area). Subsequently, a correlation was noted between a more impaired adventitia and a reduction in renal resistance reserve (β: -0.33; P = 0.05) at three weeks of follow-up.

Conclusion

Only a small minority of renal nerves was targeted after RDN. Furthermore, more severe adventitial damage was related to a reduction in renal resistance in the treated arteries at follow-up. These hemodynamic and histological observations may indicate that RDN did not sufficiently target the renal nerves. Potentially, this may explain the significant spread in the response after RDN.

Case Report: Renal Sympathetic Denervation as a Tool for the Treatment of Refractory Inappropriate Sinus Tachycardia

Inappropriate sinus tachycardia is defined as sinus tachycardia at rest (heart rate ≥100 bpm) in sitting position or/and as an average heart rate ≥90 bpm during 24-hour Holter monitoring. The most common symptoms are palpitation, dizziness, chest discomfort, orthostatic intolerance, and fatigue. Sometimes, the symptoms can be severe and debilitating, and its etiology is not well understood. Pharmacological approaches present limitation because of their relatively small effectiveness, intolerance, or side effects.In this series of cases of inappropriate sinus tachycardia, the authors report 3 cases refractory to conventional pharmacological therapy, in which the authors were not tempted for ablation of the sinus node. The authors, however, use another therapeutic approach, which was renal sympathetic denervation, to reduce sympathetic activity in the sinus node, and consequently reduce tachycardia with improvement of symptoms.Three months after renal sympathetic denervation, all patients were not using any type of medication, and reported no more symptoms. The authors know that this is the first report using the renal sympathetic denervation for the treatment of inappropriate sinus tachycardia. Studies with a larger number of patients, a longer time of follow-up, and a control group, however, should be performed.

Catheter-Based Radiofrequency Renal Denervation: Location Effects on Renal Norepinephrine

BACKGROUND

Clinical studies indicate that blood pressure (BP)-lowering effects of radiofrequency (RF) renal denervation (RD) are sustained for up to 2 years, although a recent clinical trial failed to find a major effect compared to sham treatment. In most previous studies, the efficacy of RD has not been assessed. The current study determined whether RD in different regions of the renal artery causes different degrees of RD as assessed with renal norepinephrine (NE) levels.

METHODS AND RESULTS

Unilateral RD was performed on 14 pigs divided into 3 groups: RD near the ostium, in the main renal artery near the bifurcation, and in extrarenal branches of the renal artery. After 2 weeks post-RD, the pigs were euthanized, renal cortex tissue was collected for NE measurement, and renal arteries were prepared for histological analysis. Renal NE decreased by 12% with RD at the ostium, 45% with RD near the bifurcation in the main renal artery, and 74% when RD was performed in extrarenal artery branches. The number of renal nerves was greatest in extrarenal branches and in the main artery compared to the ostium and the average distance from the lumen was greatest for nerves at the ostium and least at the branches.

CONCLUSIONS

RF RD lowers renal NE more significantly when performed in branches of the renal artery closer to the kidney. Increased efficacy of RF RD in extrarenal arterial branches may be due to the greater number of nerves in close proximity to the artery lumen in the branches.

Optimum and stepped care standardised antihypertensive treatment with or without renal denervation for resistant hypertension (DENERHTN): a multicentre, open-label, randomised controlled trial

BACKGROUND

Conflicting blood pressure-lowering effects of catheter-based renal artery denervation have been reported in patients with resistant hypertension. We compared the ambulatory blood pressure-lowering efficacy and safety of radiofrequency-based renal denervation added to a standardised stepped-care antihypertensive treatment (SSAHT) with the same SSAHT alone in patients with resistant hypertension.

METHODS

The Renal Denervation for Hypertension (DENERHTN) trial was a prospective, open-label randomised controlled trial with blinded endpoint evaluation in patients with resistant hypertension, done in 15 French tertiary care centres specialised in hypertension management. Eligible patients aged 18-75 years received indapamide 1·5 mg, ramipril 10 mg (or irbesartan 300 mg), and amlodipine 10 mg daily for 4 weeks to confirm treatment resistance by ambulatory blood pressure monitoring before randomisation. Patients were then randomly assigned (1:1) to receive either renal denervation plus an SSAHT regimen (renal denervation group) or the same SSAHT alone (control group). The randomisation sequence was generated by computer, and stratified by centres. For SSAHT, after randomisation, spironolactone 25 mg per day, bisoprolol 10 mg per day, prazosin 5 mg per day, and rilmenidine 1 mg per day were sequentially added from months two to five in both groups if home blood pressure was more than or equal to 135/85 mm Hg. The primary endpoint was the mean change in daytime systolic blood pressure from baseline to 6 months as assessed by ambulatory blood pressure monitoring. The primary endpoint was analysed blindly. The safety outcomes were the incidence of acute adverse events of the renal denervation procedure and the change in estimated glomerular filtration rate from baseline to 6 months. This trial is registered with ClinicalTrials.gov, number NCT01570777.

FINDINGS

Between May 22, 2012, and Oct 14, 2013, 1416 patients were screened for eligibility, 106 of those were randomly assigned to treatment (53 patients in each group, intention-to-treat population) and 101 analysed because of patients with missing endpoints (48 in the renal denervation group, 53 in the control group, modified intention-to-treat population). The mean change in daytime ambulatory systolic blood pressure at 6 months was -15·8 mm Hg (95% CI -19·7 to -11·9) in the renal denervation group and -9·9 mm Hg (-13·6 to -6·2) in the group receiving SSAHT alone, a baseline-adjusted difference of -5·9 mm Hg (-11·3 to -0·5; p=0·0329). The number of antihypertensive drugs and drug-adherence at 6 months were similar between the two groups. Three minor renal denervation-related adverse events were noted (lumbar pain in two patients and mild groin haematoma in one patient). A mild and similar decrease in estimated glomerular filtration rate from baseline to 6 months was observed in both groups.

INTERPRETATION

In patients with well defined resistant hypertension, renal denervation plus an SSAHT decreases ambulatory blood pressure more than the same SSAHT alone at 6 months. This additional blood pressure lowering effect may contribute to a reduction in cardiovascular morbidity if maintained in the long term after renal denervation.

FUNDING

French Ministry of Health.

Sodium excretion and sympathetic activity in relation to severity of hypertension

The relationship between the severity of hypertensive disease and sodium excretion and sympathetic activity has been studied in normotensive (n = 19) and hypertensive (n = 19) men of the same derived from screening a total population. Sympathetic activity was determined from noradrenaline excretion and the severity of hypertension was assessed by measuring resting diastolic BP, left ventricular hypertrophy on orthogonal ECG and the glomerular filtration rate. In the hypertensive group the resting BP correlated well both with signs of left ventricular hypertrophy, i.e. with the degree of severity of the hypertensive disease. Up to the level of 90 mm Hg resting diastolic BP, sodium excretion rose in agreement with theory of pressure diuresis. Above 90 mm Hg, however, both sodium and noradrenaline excretion fell with increasing BP. This indicated that in more advanced hypertension the sodium balance overrides the sympathetic activity in the long-term relation of BP. In another series of 49-year-old-men noradrenaline excretion fell with increasing renal vascular resistance indicating that the increase in the latter variable could not be explained by increased sympathetic tone. On the basis of the results a hypothesis on the sequence of events leading to development of hypertension, is presented.

Renal denervation

PURPOSE OF REVIEW

Renal denervation (RDN) has, within recent years, been suggested as a novel treatment option for patients with resistant hypertension. This review summarizes the current knowledge on this procedure as well as limitations and questions that remain to be answered.

RECENT FINDINGS

The Symplicity HTN-1 (2009) and HTN-2 (2010) studies re-introduced an old treatment approach for resistant hypertension and showed that catheter-based RDN was feasible and resulted in substantial blood pressure (BP) reductions. However, they also raised questions of durability of BP reduction, correct patient selection, anatomical and physiological effects of RDN as well as possible beneficial effects on other diseases with increased sympathetic activity. The long awaited Symplicity HTN-3 (2014) results illustrated that the RDN group and the sham-group had similar reductions in BP.

SUMMARY

Initial studies demonstrated that RDN in patients with resistant hypertension was both feasible and safe and indicated that RDN may lead to impressive reductions in BP. However, recent controlled studies question the BP lowering effect of RDN treatment. Large-scale registry data still supports the favorable BP reducing effect of RDN. We suggest that, in the near future, RDN should not be performed outside clinical studies. The degree of denervation between individual operators and between different catheters and techniques used should be clarified. The major challenge ahead is to identify which patients could benefit from RDN, to clarify the lack of an immediate procedural success parameter, and to establish further documentation of overall effect of treatment such as long-term cardiovascular morbidity and mortality.