Effects of Renal Sympathetic Denervation on Exercise Blood Pressure, Heart Rate, and Capacity in Patients With Resistant Hypertension

Renal denervation for resistant hypertension

BACKGROUND

Resistant hypertension is highly prevalent among the general hypertensive population and the clinical management of this condition remains problematic. Different approaches, including a more intensified antihypertensive therapy, lifestyle modifications or both, have largely failed to improve patients' outcomes and to reduce cardiovascular and renal risk. As renal sympathetic hyperactivity is a major driver of resistant hypertension, in the last decade renal sympathetic ablation (renal denervation) has been proposed as a possible therapeutic alternative to treat this condition.

OBJECTIVES

We sought to evaluate the short- and long-term effects of renal denervation in individuals with resistant hypertension on clinical end points, including fatal and non-fatal cardiovascular events, all-cause mortality, hospital admissions, quality of life, blood pressure control, left ventricular hypertrophy, cardiovascular and metabolic profile and kidney function, as well as the potential adverse events related to the procedure.

SEARCH METHODS

For this updated review, the Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to 3 November 2020: Cochrane Hypertension's Specialised Register, CENTRAL (2020, Issue 11), Ovid MEDLINE, and Ovid Embase. The World Health Organization International Clinical Trials Registry Platform (via CENTRAL) and the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov were searched for ongoing trials. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) that compared renal denervation to standard therapy or sham procedure to treat resistant hypertension, without language restriction.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed study risk of bias. We summarised treatment effects on available clinical outcomes and adverse events using random-effects meta-analyses. We assessed heterogeneity in estimated treatment effects using Chi² and I² statistics. We calculated summary treatment estimates as a mean difference (MD) or standardised mean difference (SMD) for continuous outcomes, and a risk ratio (RR) for dichotomous outcomes, together with their 95% confidence intervals (CI). Certainty of evidence has been assessed using the GRADE approach.

MAIN RESULTS

We found 15 eligible studies (1416 participants). In four studies, renal denervation was compared to sham procedure; in the remaining studies, renal denervation was tested against standard or intensified antihypertensive therapy. Most studies had unclear or high risk of bias for allocation concealment and blinding.  When compared to control, there was low-certainty evidence that renal denervation had little or no effect on the risk of myocardial infarction (4 studies, 742 participants; RR 1.31, 95% CI 0.45 to 3.84), ischaemic stroke (5 studies, 892 participants; RR 0.98, 95% CI 0.33 to 2.95), unstable angina (3 studies, 270 participants; RR 0.51, 95% CI 0.09 to 2.89) or hospitalisation (3 studies, 743 participants; RR 1.24, 95% CI 0.50 to 3.11). Based on moderate-certainty evidence, renal denervation may reduce 24-hour ambulatory blood pressure monitoring (ABPM) systolic BP (9 studies, 1045 participants; MD -5.29 mmHg, 95% CI -10.46 to -0.13), ABPM diastolic BP (8 studies, 1004 participants; MD -3.75 mmHg, 95% CI -7.10 to -0.39) and office diastolic BP (8 studies, 1049 participants; MD -4.61 mmHg, 95% CI -8.23 to -0.99). Conversely, this procedure had little or no effect on office systolic BP (10 studies, 1090 participants; MD -5.92 mmHg, 95% CI -12.94 to 1.10). Moderate-certainty evidence suggested that renal denervation may not reduce serum creatinine (5 studies, 721 participants, MD 0.03 mg/dL, 95% CI -0.06 to 0.13) and may not increase the estimated glomerular filtration rate (eGFR) or creatinine clearance (6 studies, 822 participants; MD -2.56 mL/min, 95% CI -7.53 to 2.42).  AUTHORS' CONCLUSIONS: In patients with resistant hypertension, there is low-certainty evidence that renal denervation does not improve major cardiovascular outomes and renal function. Conversely, moderate-certainty evidence exists that it may improve 24h ABPM and diastolic office-measured BP. Future trials measuring patient-centred instead of surrogate outcomes, with longer follow-up periods, larger sample size and more standardised procedural methods are necessary to clarify the utility of this procedure in this population.

Renal Denervation in Combination With Angiotensin Receptor Blockade Prolongs Blood Pressure Trough During Hemorrhage

Majority of patients with hypertension and chronic kidney disease (CKD) undergoing renal denervation (RDN) are maintained on antihypertensive medication. However, RDN may impair compensatory responses to hypotension induced by blood loss. Therefore, continuation of antihypertensive medications in denervated patients may exacerbate hypotensive episodes. This study examined whether antihypertensive medication compromised hemodynamic responses to blood loss in normotensive (control) sheep and in sheep with hypertensive CKD at 30 months after RDN (control-RDN, CKD-RDN) or sham (control-intact, CKD-intact) procedure. CKD-RDN sheep had lower basal blood pressure (BP; ≈9 mm Hg) and higher basal renal blood flow (≈38%) than CKD-intact. Candesartan lowered BP and increased renal blood flow in all groups. 10% loss of blood volume alone caused a modest fall in BP (≈6-8 mm Hg) in all groups but did not affect the recovery of BP. 10% loss of blood volume in the presence of candesartan prolonged the time at trough BP by 9 minutes and attenuated the fall in renal blood flow in the CKD-RDN group compared with CKD-intact. Candesartan in combination with RDN prolonged trough BP and attenuated renal hemodynamic responses to blood loss. To minimize the risk of hypotension-mediated organ damage, patients with RDN maintained on antihypertensive medications may require closer monitoring when undergoing surgery or experiencing traumatic blood loss.

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.

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

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

Blood Pressure and Renal Responses to Orthostatic Stress Before and After Radiofrequency Renal Denervation in Patients with Resistant Hypertension

Background/Aims

In patients with resistant hypertension, renal denervation (RDN) studies have mainly focused their outcomes on blood pressure (BP). The aim of this study was to evaluate the long-term effect of RDN on neurohormonal profiles, renal hemodynamics and sodium excretion in a resting state and during stress induced by lower body negative pressure (LBNP).

Materials and methods

This was a single center prospective observational study. Norepinephrine, plasma renin activity (PRA), glomerular filtration rate (GFR), renal plasma flow (RPF) and sodium excretion were measured in unstimulated conditions (rest) and after one hour of LBNP at three different time points: before (M0), one (M1) and twelve months (M12) after RDN.

Results

Thirteen patients with resistant hypertension were included. In the resting state, no differences were observed in norepinephrine, PRA, sodium excretion and mean BP levels after RDN. GFR (78 ± 32 ml/min at M0 vs 66 ± 26 ml/min at M12 (p = 0.012) and filtration fraction (22.6 ±5.4% at M0 vs 15.1 ±5.3% at M12 (p = 0.002)) both decreased after RDN. During LBNP, the magnitude of the mean BP increase was reduced from +6.8 ± 6.6 mm Hg at M0 to +2.3 ± 1.3 mm Hg at M12 (p = 0.005). The LBNP-induced increase in norepinephrine and decrease in GFR and sodium excretion observed before RDN were blunted after the procedure.

Conclusion

A decrease in GFR and filtration fraction was observed one year after RDN. In addition, our results suggest that RDN blunts not only the norepinephrine but also the mean BP, the GFR and the sodium excretion responses to an orthostatic stress one year after the intervention.

Registry number

NCT01734096

Renal denervation for resistant hypertension

BACKGROUND

Resistant hypertension is highly prevalent among the general hypertensive population and the clinical management of this condition remains problematic. Different approaches, including a more intensified antihypertensive therapy, lifestyle modifications, or both, have largely failed to improve patients' outcomes and to reduce cardiovascular and renal risk. As renal sympathetic hyperactivity is a major driver of resistant hypertension, renal sympathetic ablation (renal denervation) has been recently proposed as a possible therapeutic alternative to treat this condition.

OBJECTIVES

We sought to evaluate the short- and long-term effects of renal denervation in individuals with resistant hypertension on clinical end points, including fatal and non-fatal cardiovascular events, all-cause mortality, hospital admissions, quality of life, blood pressure control, left ventricular hypertrophy, cardiovascular and metabolic profile, and kidney function, as well as the potential adverse events related to the procedure.

SEARCH METHODS

We searched the following databases to 17 February 2016 using relevant search terms: the Cochrane Hypertension Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and ClinicalTrials.gov SELECTION CRITERIA: We considered randomised controlled trials (RCTs) that compared renal denervation to standard therapy or sham procedure to treat resistant hypertension, without language restriction.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed study risks of bias. We summarised treatment effects on available clinical outcomes and adverse events using random-effects meta-analyses. We assessed heterogeneity in estimated treatment effects using Chi² and I² statistics. We calculated summary treatment estimates as a mean difference (MD) or standardised mean difference (SMD) for continuous outcomes, and a risk ratio (RR) for dichotomous outcomes, together with their 95% confidence intervals (CI).

MAIN RESULTS

We found 12 eligible studies (1149 participants). In four studies, renal denervation was compared to sham procedure; one study compared a proximal ablation to a complete renal artery denervation; in the remaining, renal denervation was tested against standard or intensified antihypertensive therapy.None of the included trials was designed to look at hard clinical end points as primary outcomes.When compared to control, there was low quality evidence that renal denervation did not reduce the risk of myocardial infarction (4 studies, 742 participants; RR 1.31, 95% CI 0.45 to 3.84), ischaemic stroke (4 studies, 823 participants; RR 1.15, 95% CI 0.36 to 3.72), or unstable angina (2 studies, 201 participants; RR 0.63, 95% CI 0.08 to 5.06), and moderate quality evidence that it had no effect on 24-hour ambulatory blood pressure monitoring (ABPM) systolic BP (5 studies, 797 participants; MD 0.28 mmHg, 95% CI -3.74 to 4.29), diastolic BP (4 studies, 756 participants; MD 0.93 mmHg, 95% CI -4.50 to 6.36), office measured systolic BP (6 studies, 886 participants; MD -4.08 mmHg, 95% CI -15.26 to 7.11), or diastolic BP (5 studies, 845 participants; MD -1.30 mmHg, 95% CI -7.30 to 4.69). Furthermore, low quality evidence suggested that this procedure produced no effect on either serum creatinine (3 studies, 736 participants, MD 0.01 mg/dL; 95% CI -0.12 to 0.14), estimated glomerular filtration rate (eGFR), or creatinine clearance (4 studies, 837 participants; MD -2.09 mL/min, 95% CI -8.12 to 3.95). Based on low-quality evidence, renal denervation significantly increased bradycardia episodes compared to control (3 studies, 220 participants; RR 6.63, 95% CI 1.19 to 36.84), while the risk of other adverse events was comparable or not assessable.Data were sparse or absent for all cause mortality, hospitalisation, fatal cardiovascular events, quality of life, atrial fibrillation episodes, left ventricular hypertrophy, sleep apnoea severity, need for renal replacement therapy, and metabolic profile.The quality of the evidence was low for cardiovascular outcomes and adverse events and moderate for lack of effect on blood pressure and renal function.

AUTHORS' CONCLUSIONS

In patients with resistant hypertension, there is low quality evidence that renal denervation does not change major cardiovascular events, and renal function. There was moderate quality evidence that it does not change blood pressure and and low quality evidence that it caused an increaseof bradycardia episodes. Future trials measuring patient-centred instead of surrogate outcomes, with longer follow-up periods, larger sample size and more standardized procedural methods are necessary to clarify the utility of this procedure in this population.

Renal Denervation vs Pharmacotherapy for Resistant Hypertension: A Meta-Analysis

The effect of renal denervation (RD) for resistant hypertension remains controversial because of the conflicting results of finished and ongoing studies. The authors performed a meta-analysis of case-control studies to identify whether renal sympathetic denervation or pharmacotherapy (PHAR) was more effective for resistant hypertension. A systematic Internet database search of relevant papers written in English was performed. A total of nine studies met the inclusion criteria, with a total of 1096 patients. When comparing the RD group with the PHAR group, there was a significant decrease in systolic blood pressure (SBP) (weighted mean difference, -12.81 mm Hg; 95% confidence interval [CI], -22.77 mm Hg to -2.85 mm Hg; P=.01) and diastolic blood pressure (DBP) (weighted mean difference, -5.56; 95% CI, -8.15 mm Hg to -2.97 mm Hg; P<.0001). This pooled analysis shows that for patients with resistant hypertension, RD is more effective in reducing SBP and DBP than PHAR. RD may be more effective in special subgroups of patients, which needs to be identified in future investigations.

Renal denervation, adjusted drugs, or combined therapy for resistant hypertension: A meta-regression

The objective of this study is to systematically evaluate the efficacy of renal denervation (RD), adjusted drugs, or combined therapy for resistant hypertension (RH) through a systematic review and meta-analysis of controlled studies.Publications were comprehensively searched. Studies that investigated the effects of RD and/or adjusted drugs in lowering blood pressure (BP) were included. After quality assessment and data extraction, subgroup analyzes were first performed according to blinding method. Meta-regression and inverted funnel plots were also conducted.A total of 13 studies containing 1604 RH patients were included. Compared with control, the meta-analysis showed that RD significantly reduced office-based BP and ambulatory BP in 6 months in the unblinded studies, while no significant difference was found in the blinded studies. Meta-regression demonstrated the significant influence of blinding method on BP reduction, and further analysis revealed a significant BP reduction compared with baseline even in the control arm of blinded studies. RD had similar effects compared with adjusted drugs, and combined therapy seemed to further reduce the level of BP.The efficacy of RD was different between blinded and unblinded studies, and our data revealed a significant BP-lowering effect in the control arm of blinded studies, which was helpful to explain this finding. Furthermore, RD seemed to be equivalent to adjusted drugs, and also we suggested a potential advantage of combined therapy of RD and adjusted drugs compared with monotherapy for RH. However, more studies are warranted to better address the issue.

The effects of renal denervation on resistant hypertension patients: a meta-analysis

We carried out this meta-analysis to assess the effects of renal denervation (RDN) on resistant hypertension patients. According to the collaborative review group search strategy, we searched MEDLINE (1996 to 2015.10); EBCO (1996 to 2015.10) and CNKI. A meta-analysis was carried out using RevMan 5.0. We identified 11 reports that fulfilled the inclusion criteria for our review. Controlled trials reporting systolic blood pressure (SBP), diastolic blood pressure in RDN, and control groups at the 6-month follow-up in patients with resistant hypertension were systematically reviewed. Pooled analysis of all 11 included studies showed significant reductions in SBP (weighted mean difference -13.9 mmHg, 95% confidence interval -21.17 to -6.63, P=0.00025, I=93%) and diastolic blood pressure (weighted mean difference -4.41 mmHg, 95% confidence interval -6.95 to -1.88, P=0.004, I=90%) compared with the control group at the 6-month follow-up. Six controlled trials reported specific values of ambulatory SBP that showed no significant difference between two groups. It has also been found that RDN has benefits in protecting cardiac and renal function compared with the control group without increasing adverse events. In conclusion, this meta-analysis shows that RDN is superior to the control group in lowering office blood pressure rather than ambulatory SBP, and might have other potential benefits to protect heart and renal function.

Renal denervation improves exercise blood pressure: insights from a randomized, sham-controlled trial

INTRODUCTION

Despite the ongoing debate on the role of renal sympathetic denervation (RSD) in the management of therapy-resistant hypertension, little is known about its possible effects on exercise blood pressure (BP), a known predictor for future cardiovascular events. We sought to evaluate the effect of RSD on exercise BP in a randomized, sham-controlled trial in patients with mild hypertension.

METHODS AND RESULTS

Patients with therapy-resistant mild hypertension (defined by mean daytime systolic BP between 135 and 149 mmHg or mean daytime diastolic BP between 90 and 94 mmHg on 24-h ambulatory BP measurement) were randomized to either radiofrequency-based RSD or a sham procedure. Patients underwent cardiopulmonary exercise testing at baseline and after 6 months. Of the 71 patients randomized, data from cardiopulmonary exercise testing were available for 48 patients (22 in the RSD group, 26 in the sham group). After 6 months, patients undergoing RSD had a significantly lower systolic BP at maximum exercise workload compared to baseline (-14.2 ± 26.1 mmHg, p = 0.009). In contrast, no change was observed in the sham group (0.6 ± 22.9 mmHg, p = 0.45, p = 0.04 for between-group comparison). When analyzing patients with exaggerated baseline exercise BP only, the effect was even more pronounced (RSD vs. sham -29.5 ± 23.4 vs. 0.1 ± 25.3 mmHg, p = 0.008).

CONCLUSION

Exercise systolic BP values in patients with mild therapy-resistant hypertension are reduced after RSD as compared to a sham-procedure.

Renal denervation for the management of resistant hypertension

Renal sympathetic denervation (RSD) as a therapy for patients with resistant hypertension has attracted great interest. The majority of studies in this field have demonstrated impressive reductions in blood pressure (BP). However, these trials were not randomized or sham-controlled and hence, the findings may have been overinflated due to trial biases. SYMPLICITY HTN-3 was the first randomized controlled trial to use a blinded sham-control and ambulatory BP monitoring. A surprise to many was that this study was neutral. Possible reasons for this neutrality include the fact that RSD may not be effective at lowering BP in man, RSD was not performed adequately due to limited operator experience, patients’ adherence with their anti-hypertensive drugs may have changed during the trial period, and perhaps the intervention only works in certain subgroups that are yet to be identified. Future studies seeking to demonstrate efficacy of RSD should be designed as randomized blinded sham-controlled trials. The efficacy of RSD is in doubt, but many feel that its safety has been established through the thousands of patients in whom the procedure has been performed. Over 90% of these data, however, are for the Symplicity™ system and rarely extend beyond 12 months of follow-up. Long-term safety cannot be assumed with RSD and nor should it be assumed that if one catheter system is safe then all are. We hope that in the near future, with the benefit of well-designed clinical trials, the role of renal denervation in the management of hypertension will be established.

Novel and nonpharmacologic approaches to cardio-protection in hypertension

Hypertension has wide (30-45 %) prevalence in the general population and is related to important increases in overall cardiovascular morbidity and mortality. Despite lifestyle modifications and optimal medical therapy (three drugs, one being diuretic), about 5-20 % of hypertensives are affected by resistant hypertension. Chronic high blood pressure has adverse effects on the heart and other organs such as the kidneys and vasculature. Renal sympathetic denervation and baroreceptor stimulation are invasive approaches initially investigated to treat resistant hypertension. Their pleiotropic effects appear promising in cardiovascular remodeling, heart failure and arrhythmias and could potentially affect cardiovascular morbidity and mortality.

Meta-analysis of the effect of renal denervation on blood pressure and pulse pressure in patients with resistant systemic hypertension

Data comparing the effect of renal denervation (RD) with those of maximal medical therapy (MMT) have shown conflicting results. Also, effect of RD on pulse pressure (PP) has not been evaluated. The aim of this meta-analysis was to compare the effect of RD with that of MMT on blood pressure (BP) and PP at 6-month follow-up in patients with resistant hypertension. Randomized controlled trials and nonrandomized controlled trials reporting systolic BP, diastolic BP, and PP results in RD and MMT groups at 6-month follow-up in patients with resistant hypertension were systematically reviewed, and eligible citations were pooled using a random-effects model. Five studies (3 randomized controlled trials, 2 nonrandomized controlled trials, n = 800) met the inclusion criteria. In the pooled analysis, RD was associated with a significant decrease in systolic BP (weighted mean difference -19.4 mm Hg, 95% confidence interval -32.8 to -5.9, p = 0.005), diastolic BP (weighted mean difference -6.4 mm Hg, 95% confidence interval -10.7 to -2.0 mm Hg, p = 0.004), and PP (weighted mean difference -12.7 mm Hg, 95% confidence interval -22.3 to -3.1 mm Hg, p = 0.009) compared with MMT at 6-month follow-up. Sensitivity analysis limited to randomized controlled trials showed a borderline significant difference in lowering systolic BP, a significant difference in lowering diastolic BP, and a nonsignificant difference in lowering PP when RD was compared with MMT. In conclusion, this meta-analysis shows that RD is superior to MMT in lowering BP, but heterogeneity among study populations in this pooled sample is high, and further data are needed to better compare these treatment strategies.

Renal sympathetic denervation modulates ventricular electrophysiology and has a protective effect on ischaemia-induced ventricular arrhythmia

Recently, a beneficial effect of renal sympathetic denervation (RSD) has been seen in patients with ventricular electrical storm. However, the effect of RSD on ventricular electrophysiology remains unclear. Thirty-three mongrel dogs were included in the present study. Renal sympathetic denervation was performed by radiofrequency ablation of the adventitial surface of the renal artery. In group 1 (n = 8), programmed stimulation was performed before and after RSD to determine the ventricular effective refractory period (ERP) and action potential duration (APD) restitution properties. The same parameters were measured in five other animals that underwent sham RSD to serve as controls. In group 2 (n = 10), acute myocardial ischaemia (AMI) was induced by ligating the proximal left anterior descending coronary artery after the performance of RSD, and the incidence of ventricular arrhythmia (VA) was calculated during 1 h of recording. In another 10 dogs (group 3), AMI was induced and VA was measured with sham RSD. In group 1, RSD significantly prolonged ventricular ERP and APD, reduced the maximal slope (Smax) of the restitution curve and suppressed APD alternans at each site. Renal sympathetic denervation also significantly decreased the spatial dispersion of ERP, APD and Smax. In the five control animals, no significant electrophysiological change was detected after sham RSD. The occurrence of spontaneous VA during 1 h of AMI in group 2 was significantly lower than that in group 3. These data suggest that RSD stabilizes ventricular electrophysiological properties in normal hearts and reduces the occurrence of VA in hearts experiencing AMI.

[Interventional hypertension therapy in diabetes mellitus. Effects on blood pressure and glucose metabolism?]

Hypertension is the most common chronic cardiovascular disease with increasing prevalence all over the world. Despite the availability of many effective antihypertensive drugs, blood pressure control to target values remains low. In the pathophysiology of therapy resistant hypertension, increased activity of the sympathetic nervous system with an imbalance between sympathetic and parasympathetic activity has been identified as a main contributor to the development and maintenance of hypertension. Catheter-based denervation of the renal sympathetic nerves has been described as reducing blood pressure and decreasing sympathetic activity in patients with resistant hypertension. Supplementary beneficial effects on common cardiovascular comorbidities, such as diabetes type 2, have been reported. The present review aims to give an overview about percutaneous renal denervation for treatment of hypertension and potential new therapeutic options to improve glycemic control.