Resistant Hypertension and Renal Nerve Denervation

Assessing the efficacy of renal denervation in patients with resistant arterial hypertension : Systematic review and meta-analysis

BACKGROUND

Renal denervation (RDN) is an innovative procedure designed to regulate the renal sympathetic nervous system for the control of arterial hypertension (HTN). RDN has emerged as an alternative for patients with resistant HTN. However, the clinical efficacy of RDN remains incompletely elucidated.

METHODS

PubMed, Embase, and Cochrane databases were searched for randomized controlled trials (RCTs) comparing the use of RDN with sham procedure or pharmacological treatment in patients with resistant HTN. Statistical analyses were performed using R Studio 4.3.2 (R Foundation for Statistical Computing, Vienna, Austria). Heterogeneity was examined with the Cochran Q test I2 statistics. Mean difference (MD) with 95% confidence interval (CI) were pooled across trials. P values of <0.05 were considered statistically significant. The primary outcomes of interest were changes from baseline in systolic blood pressure (SBP), diastolic blood pressure (DBP), and serum creatinine.

RESULTS

Twenty-one RCTs comprising 3345 patients were included in this meta-analysis, whereby 2004 (59.91%) received renal denervation and 1341 (40.09%) received pharmacological treatment or sham procedure. Follow-up ranged from 2 to 48 months. Compared to control group, RDN significantly reduced SBP (MD -3.53 mm Hg; 95% CI -5.94 to -1.12; p = 0.004; I2 = 74%) and DBP (MD -1.48 mm Hg; 95% CI -2.56 to -0.40; p = 0.007; I2 = 51%). Regarding serum creatinine (MD -2.51; 95% CI -7.90 to 2.87; p = 0.36; I2 = 40%), there was no significant difference between RDN and control groups.

CONCLUSION

In this meta-analysis of RCTs of patients with resistant HTN, RDN was associated with a reduction in SBP and DBP compared to sham procedure or pharmacological treatment.

Controversies related to renal artery denervation and devices

PURPOSE OF REVIEW

This review article discusses the controversies, strengths, and limitations of the current literature on renal artery denervation in the management of resistant hypertension, as well as the future directions of this intervention.

RECENT FINDINGS

There have been conflicting data from the different randomized control trials assessing the efficacy of renal artery denervation in the management of resistant hypertension.

SUMMARY

Renal artery denervation is achieved by ablating the sympathetic nerves surrounding the renal arteries using endovascular ultrasound, radiofrequency, or alcohol. Our review article highlights that renal artery denervation is generally effective in improving blood pressure in patients with resistant hypertension. The Food and Drug Administration (FDA) has recently approved the ReCor Medical Paradise system, and the Symplicity Spyral RDN systems for renal artery denervation.

Renal denervation by radiofrequency in patients with hypertension: systematic review and meta-analysis

The Guidelines Project, which is an initiative of the Brazilian Medical Association, aims to combine information from the medical field to standardize how to conduct and assist in the reasoning and decision-making of doctors. The information provided by this project must be critically evaluated by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical condition of each patient.

Beyond Conventional Control: Insights Into Drug-Resistant Hypertension

It is believed that 9-18% of patients with hypertension have resistant hypertension, a serious medical disease. The increased cardiovascular risk associated with this illness demands appropriate diagnosis and treatment. It is necessary to conduct an in-depth investigation of the various etiologies, indicators of risk, and multiple disorders of resistant hypertension. This is crucial in order to establish the diagnosis and make the best decisions regarding therapy. Treatment should also take lifestyle changes into account in addition to medicinal and interventional therapy. When there is a suspicion of resistant hypertension, examining the medications used to treat the hypertensive patient after ruling out pseudo hypertension, improper blood pressure monitoring and control, and the white-coat effect are necessary. Resistant hypertension, according to a specific definition, is a condition that cannot be treated with more than two antihypertensive drugs, including a diuretic. An effective multidrug therapy for the treatment of resistant hypertension includes angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta-blockers, diuretics, long-acting calcium channel blockers, and mineralocorticoid receptor antagonists. However, alternative, cutting-edge treatments, such as renal denervation or baroreflex activation, could develop a brand-new avenue for decreasing blood pressure. These new surgical interventions might prove out to be of immense importance in coming times. Secondary causes of resistant hypertension, such as obstructive sleep apnea, coronary artery diseases, nephropathy, or endocrinal diseases, must be checked out in order to make an accurate diagnosis of this illness. This review article briefly summarizes the epidemiology, risk factors, causes, pathogenesis, diagnosis, and treatment approaches that may help with the long-term management of resistant hypertension.

The effect of catheter-based sham renal denervation in hypertension: systematic review and meta-analysis

BACKGROUND

Renal denervation (RDN) has emerged in recent years as a possible treatment for hypertension. The first sham-controlled trial showed a small magnitude and non-significant in the blood pressure (BP) lowering effect, also due to a substantial decrease of BP in sham arm. Considering this, we aimed to quantify the magnitude of BP decrease within the sham arm of Randomized Controlled Trials (RCT) with RDN in patients with hypertension.

METHODS

Electronic databases were searched since inception until January 2022 for randomized sham-controlled trials which assessed the efficacy in lowering BP of the sham intervention for catheter-based RDN in adult patients with hypertension. The outcomes were change in ambulatory/office systolic and diastolic BP.

RESULTS

A total of 9 RCT were included in the analysis enrolling a total of 674 patients. Sham intervention showed a decrease in all evaluated outcomes. Office systolic BP had a reduction of -5.52 mmHg [95%CI -7.91, -3.13] and office diastolic BP of -2.13 mmHg [95%CI -3.08, -1.17]. Sham procedure for RDN also showed a reduction of -3.41 mmHg [95%CI -5.08, -1.75] in ambulatory systolic BP and - 2.44 mmHg [95%CI -3.31, -1.57] in ambulatory diastolic BP.

CONCLUSION

Despite recent data indicating that RDN might be an effective treatment for patients with resistant hypertension when compared to a sham intervention, our results indicate that the sham intervention for RDN also has a significant effect on lowering Office and Ambulatory (24-h) Blood Pressure in adult patients with hypertension. This highlights that BP itself might be sensitive to placebo-like effect and also brings further difficulties in establishing the BP lowering efficacy of invasive interventions due to the magnitude of the sham effect.

Effect of combined renal denervation and pulmonary vein isolation in atrial fibrillation recurrence in hypertensive patients: A meta-analysis

BACKGROUND

Atrial Fibrillation (AF) is the most common cardiac arrhythmia and hypertension is the most common risk factor associated with AF. The addition of renal sympathetic nerve denervation (RSDN) to pulmonary vein isolation (PVI) in AF patients with hypertension has been reported to improve clinical outcomes.

METHODS

A systematic search was performed for studies on patients with AF and hypertension that compared RSDN with PVI versus PVI-alone. Risk ratio (RR) for categorical variables and mean difference (MD) for continuous variables with 95% confidence intervals were used.

RESULTS

Seven studies with a total of 734 patients were included. A total of 340 patients were in the RSDN + PVI group (46.32%) and 394 (53.67%) in the PVI group. A total of 608 patients had paroxysmal AF (83%) while 126 patients had persistent AF (17%). At 12 months follow-up, RSDN + PVI decreased the overall risk of AF recurrence in hypertensive patients with RR 0.60 [95% CI 0.50-0.72, P < .00001]. A subgroup analysis performed in patients with drug-resistant hypertension showed a similar reduction in AF recurrence with RR 0.61 [95% CI: 0.47-0.79, P = .0002). Procedure duration MD + 28.05 min [95% CI: 18.88-37.23, P < .00001] and fluoroscopy duration MD + 5.59 min [95% CI: 3.31-8.19, P < .00001] were significantly longer with the RSDN + PVI group. There was no significant difference in complications between the two groups.

CONCLUSION

The addition of RSDN to PVI in patients with AF and hypertension appears safe and decreases AF recurrence. Similar results were observed in patients with drug-resistant hypertension. Larger trials are needed to confirm these results.

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

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

Renal denervation restrains the inflammatory response in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion (I/R) injury leads to intensive sympathetic nervous system (SNS) activation and inflammatory reactions. Whether renal sympathetic denervation (RDN) could be a new therapeutic strategy to modulate I/R inflammation and reduce infarct size after myocardial I/R injury needs to be explored. First, we investigated the correlation between plasma norepinephrine concentrations and circulating myeloid cell numbers in patients with acute myocardial infarction. And then, C57BL/6 mice underwent a "two-hit" operation, with 10% phenol applied to bilateral renal nerves to abrogate sympathoexcitation, and a 45-min ligation of the left coronary artery to induce myocardial I/R injury. The effects of RDN on the mobilization of immune cells in mice following myocardial I/R injury were explored. We observed a strong association between SNS overactivation and myeloid cell excessive accumulation in patients. In animal experiments, there was a significant reduction in infarct size per area at risk in the denervated-I/R group when compared to that of the innervated-I/R group (39.2% versus 49.8%; p < 0.005), and RDN also improved the left ventricular ejection fraction by 20% after 1 week. Furthermore, the denervated-I/R group showed a decrease in the number of neutrophils and macrophages in the blood and the myocardium as reflected by immunohistochemical staining and flow cytometry analysis (p < 0.05); the decrease was associated with a significant reduction in the circulating production of IL-1, IL-6 and TNF-α (p < 0.05). In summary, our study reveals a novel link between the SNS activity and inflammatory response undergoing myocardium I/R injury and identifies RDN as a potential therapeutic strategy against myocardium I/R injury via preserving the spleen immune cells mobilization.

Modulation of Sympathetic Overactivity to Treat Resistant Hypertension

PURPOSE OF REVIEW

To review the role and evidence for sympathetic overactivity in resistant hypertension and review the therapies that have been studied to modulate the sympathetic nervous system to treat resistant hypertension, with a focus on non-pharmacologic therapies such as renal denervation, baroreflex activation therapy, and carotid body ablation.

RECENT FINDINGS

Based on the two best current techniques available for assessing sympathetic nerve activity, resistant hypertension is characterized by increased sympathetic nerve activity. Several device therapies, including renal denervation baroreflex activation therapy and carotid body ablation, have been developed as non-pharmacologic means of reducing blood pressure in resistant hypertension. With respect to renal denervation, the technologies for renal denervation have evolved since the unfavorable results from the HTN-3 study, and the revised technologies are being actively studied. Data from the first phase of the SPYRAL HTN Clinical Trial Program have been published. Results from the SPYRAL HTN-OFF MED trial suggest that ablating renal nerves can reduce blood pressure in patients with untreated mild-to-moderate hypertension. The SPYRAL HTN-ON MED trial demonstrated the safety and efficacy of catheter-based renal denervation in patients with uncontrolled hypertension on antihypertensive treatment. Interestingly, there was a high rate of medication non-adherence among patients with hypertension in this study. One attractive alternative to radiofrequency ablation is the use of ultrasound for renal denervation. Proof of concept data for the Paradise endovascular ultrasound renal denervation system was recently published in the RADIANCE-HTN SOLO trial. The results of this trial indicate that, among patients with mild to moderate hypertension on no medications, renal denervation with the Paradise system results in a greater reduction in both SBP and DBP at 2months compared with a sham procedure. Overall reductions were similar in magnitude to those noted in the SPYRAL HTN-OFF MED study. With respect to carotid body ablation, there is an ongoing proof of concept study that is investigating the safety and feasibility of ultrasound-based endovascular carotid body ablation in 30 subjects with treatment-resistant hypertension outside of the USA. The sympathetic nervous system is an important contributor to resistant hypertension. Modulation of sympathetic overactivity should be an important goal of treatment. Innovative therapies using non-pharmacologic means to suppress the sympathetic nervous system are actively being studied to treat resistant hypertension.

Renal denervation attenuates hypertension and renal dysfunction in a model of cardiovascular and renal disease, which is associated with reduced NADPH and xanthine oxidase activity

Oxidative stress is considered a central pathophysiological event in cardiovascular disease, including hypertension. Early age reduction in renal mass is associated with hypertension and oxidative stress in later life, which is aggravated by increased salt intake. The aim of the present study was to examine if renal sympathetic denervation can exert blood pressure lowering effects in uninephrectomized (UNX) rats (3-week old) fed with high salt (HS, 4%; w/w) diet for 4 weeks. Moreover, we investigated if renal denervation is associated with changes in NADPH and xanthine oxidase-derived reactive oxygen species.

Rats with UNX + HS had reduced renal function, elevated systolic and diastolic arterial pressures, which was accompanied by increased heart weight, and cardiac superoxide production compared to sham operated Controls. UNX + HS was also associated with higher expression and activity of NADPH and xanthine oxidase in the kidney. Renal denervation in rats with UNX + HS attenuated the development of hypertension and cardiac hypertrophy, but also improved glomerular filtration rate and reduced proteinuria. Mechanistically, renal denervation was associated with lower expression and activity of both NADPH oxidase and xanthine oxidase in the kidney, but also reduced superoxide production in the heart.

In conclusion, our study shows for the first time that renal denervation has anti-hypertensive, cardio- and reno-protective effects in the UNX + HS model, which can be associated with decreased NADPH oxidase- and xanthine oxidase-derived reactive oxygen species (i.e., superoxide and hydrogen peroxide) in the kidney.

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Uninephrectomy + high salt intake (UNX + HS) is linked with hypertension and renal dysfunction.

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UNX + HS increases renal NADPH oxidase-mediated O₂^•− and H₂O₂ production.

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UNX + HS increases renal xanthine oxidase-mediated H₂O₂ production.

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Renal denervation attenuates development of hypertension and renal dysfunction.

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Renal denervation is associated with lower NADPH and xanthine oxidase activity.