Device-Based Therapy for Resistant Hypertension: An Up-to-Date Review

Hypertension is the major risk factor for cardiovascular morbidity and mortality. Matter of fact, untreated hypertension can worsen the overall health, whereas pharmacotherapy can play an important role in lowering the risk of high blood pressure in hypertensive patients. However, persistent uncontrolled hypertension remains an unsolved condition characterized by non-adherence to medication and increased sympathetic activity. This paper will review the non-pharmacological treatments for resistant hypertension (RH) that have emerged in recent years. In addition, the technologies developed in device-based RH therapy, as well as the clinical trials that support their use, will be discussed. Indeed, the novel device-based approaches that target RH present a promising therapy which has been supported by several studies and clinical trials, whereas drug non-adherence and high sympathetic activity are known to be the main causes of RH. Nevertheless, some additional aspects of these RH systems need to be tested in the near future, with a particular focus on the device’s design and availability of randomized controlled trials.

Validation of a Novel Renal Denervation System With Cryoablation: A Preclinical Study and Case Series

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With the concept of cryoablation, we innovatively applied liquid nitrogen in RDN and designed a dedicated balloon catheter and system for Cryo-RDN.

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In a swine model, this Cryo-RDN system demonstrated device-related safety and efficacy. The extent and depth of nerve ablation were efficient and stable. Sustained decreases in renal and serum norepinephrine also suggested effective ablation in the long term.

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Cryo-RDN also met safety endpoints in 6 patients with resistant hypertension. The 24-hour ambulatory blood pressure and office blood pressure of all 6 patients were reduced after 6 months compared with their baseline values, providing clinical support for further large-scale clinical studies.

Recently, we designed a renal denervation with cryoablation (Cryo-RDN) system using liquid nitrogen and proved its short-term safety and effectiveness. In this study, we first conducted a 6-month follow-up in a swine model. Renal sympathetic nerve activity remained at a significantly lower level than that of the control group after 6 months. In patients with resistant hypertension, Cryo-RDN demonstrated preliminary safety. Renal function fluctuations and vascular-related complications were not detected. In addition, the average 24-hour systolic and diastolic blood pressure decreased by 12.17 ± 8.35 mm Hg and 8.50 ± 3.83 mm Hg at the 6-month follow-up, respectively, compared with their baseline values.

A Pilot Study of Perioperative External Circumferential Cryoablation of Human Renal Arteries for Sympathetic Denervation

Purpose

Cryoablation, which induces cellular death without extensive tissue damage, has been extensively used to denervate the myocardium. However, periadventitial external circumferential application of cryotherapy to denervate the renal artery sympathetic nerves has, to our knowledge, never been tested in humans. The main aim of this study was to examine the safety and potential effects of cryotherapy on ambulatory blood pressure levels and other outcomes that are indirectly related to sympathetic tone, including pulse-wave velocity, central pulse pressure, and glucose levels.

Materials and Methods

Five patients who underwent the denervation of the renal arteries during open surgery of the abdominal aortic aneurysm and four controls who did not undergo denervation during the surgery were enrolled. An argon-powered cryotherapy catheter (Cardioblate; Medtronic Inc., USA) was applied periadventitially to each renal artery in the five patients and then activated by infusion with liquid nitrogen for 1 minute.

Results

No cryoablation-related complications occurred in the five consecutive patients. Their ambulatory blood pressures 3 to 5 months after surgery did not demonstrate any general blood pressure-reducing effects, but two patients responded favorably with the reduction of antihypertensive medication and decreased 24-hour blood pressure. The patients’ mean HbA1C levels decreased from 5.9±0.78% to 5.6±0.71% (P=0.042).

Conclusion

This pilot study suggests that periadventitial cryoablation during open surgery can be used in the study of renal denervation in humans, as it had no complications in five patients in this study. The effectiveness of cryoablation for treating hypertension should be proven in a phase II clinical trial.

ReferencesEfficiency and safety of renal denervation via cryoablation (Cryo-RDN) in Chinese patients with uncontrolled hypertension: study protocol for a randomized controlled trial

BACKGROUND

Clinical data show that due to the limited effects of lifestyle regulation and unsatisfactory drug adherence, only half of the hypertensive population have their blood pressure (BP) under control. In recent years, catheter-based renal denervation (RDN) has been used as a novel approach for treating uncontrolled hypertension. The safety and efficacy of catheter-based RDN have been confirmed by a number of studies and trials in which the participants were all non-Chinese and RDN was conducted via radiofrequency or ultrasound.

METHODS/DESIGN

This study is a prospective multicenter randomized sham-controlled trial that aims to investigate the safety and efficacy of cryoablation RDN (cryo-RDN) using a novel dedicated cryoablation balloon catheter (Cryofocus, China). A total of 200 Chinese patients who have uncontrolled hypertension despite standard medical treatment will be enrolled. With drug standardization, eligible participants will be randomized in a 1:1 ratio to undergo cryo-RDN treatment or renal angiography alone as a sham treatment. The primary endpoint is defined as the change in 24-h ambulatory systolic blood pressure from baseline to 6 months. Office BP and other 24-h ambulatory BP are included as secondary endpoints. Safety endpoints primarily include any adverse effects.

DISCUSSION

This study was designed to verify the safety and efficacy of cryo-RDN with Cryofocus balloon catheters in uncontrolled hypertensive patients on polypharmacy. The aim is to provide a new way to improve the control of hypertension in China as a complement to drug therapy.

TRIAL REGISTRATION

ChiCTR, ChiCTR1800017707. Registered on 10 August 2018.

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.

Endovascular ultrasound for renal sympathetic denervation in patients with therapy-resistant hypertension not responding to radiofrequency renal sympathetic denervation

AIMS

Recent studies have reported a considerable number of non-responders after renal sympathetic de-nervation (RSD) with radiofrequency technology. Here we report our results of repeat RSD using ultrasound in these patients.

METHODS AND RESULTS

A cohort study was performed in patients who underwent ultrasound RSD after non-response to RSD with radiofrequency. Non-response was defined as mean daytime systolic blood pressure ≥140 mmHg and/or a reduction of ≤10 mmHg in ambulatory blood pressure measurement (ABPM) ≥6 months after radiofrequency denervation. ABPM was recorded at baseline, post radiofrequency RSD as well as at three and six months post ultrasound RSD. A total of 24 non-responders underwent retreatment with the ultrasound device at a mean 15.3±8.2 months after radiofrequency RSD. Ultrasound RSD was performed successfully in all patients without severe adverse events. Mean daytime systolic blood pressure changed from 161.7±14.6 mmHg at baseline to 158.5±9.5 mmHg post radiofrequency RSD and to 150.5±10.4 mmHg and 151.6±11.0 mmHg at three and six months, respectively, post ultrasound RSD (p<0.01 with repeated measures analysis of variance). The main results of post hoc testing were as follows: baseline versus post radiofrequency RSD, p=0.83; baseline versus three months post ultrasound RSD, p=0.01; and baseline versus six months post ultrasound RSD, p=0.04.

CONCLUSIONS

Ultrasound RSD appears to be safe and an effective therapeutic approach in patients not responding to previous RSD with radiofrequency technology.

Redo renal denervation using a multi-electrode radiofrequency system in patients with persistent therapy-resistant hypertension

Objectives

Renal sympathetic denervation has been studied as a potential therapeutic option for patients with therapy-resistant hypertension; however, a significant proportion of patients do not show a significant reduction in blood pressure and are classified as non-responders. The objective of the present study was to assess whether a redo renal denervation procedure increases response rates.

Methods

We present a case series of three consecutive renal denervation non-responders treated with the multi-electrode radiofrequency St. Jude EnligHTN catheter after an average of 22 months. Patients were followed for 6 months.

Results

Mean age was 66 years and two patients were male. Patients were previously treated using either ReCor’s Paradise system, the Vessix V2 system or the Covidien OneShot system. Mean office blood pressure one year after the initial procedure was 187/102 mm Hg with a mean 24 h ambulatory blood pressure of 166/102 mm Hg. All patients underwent a successful redo procedure using the EnligHTN system because of persistent therapy-resistant hypertension. At 6 months a significant drop in both office and ambulatory blood pressure of −27/−6 mm Hg and −15/−13 mm Hg, respectively, was observed. No significant renal artery stenosis was observed at 6 months.

Conclusions

In patients with therapy-resistant hypertension who do not respond to an initial renal denervation procedure, a redo procedure using the St. Jude EnligHTN system may help to significantly improve blood pressure control.

Renal denervation in the era of HTN-3. Comprehensive review and glimpse into the future

The pathophysiological role of sympathetic overactivity in conditions such as hypertension has been well documented. Catheter-based renal denervation (RDN) is a minimally invasive percutaneous procedure which aims to disrupt sympathetic nerve afferent and efferent activity through the application of radiofrequency energy directly within the renal artery wall. This technique has emerged as a very promising treatment with dramatic effects on refractory hypertension but also in other conditions in which a sympathetic influence is present. Several studies have evaluated the safety and efficacy of this procedure, presently surrounded by controversy since the recent outcome of Symplicity HTN-3, the first randomized, sham-control trial, which failed to confirm RDN previous reported benefits on BP and cardiovascular risk lowering. Consequently, although some centers halted their RDN programs, research continues and both the concept of denervation and treatment strategies are being redefined to identify patients who can drive the most benefit from this technology. In the United States, the Food and Drug Administration (FDA) has appropriately mandated that RDN remains an investigative procedure and a new generation of sham-controlled trials are ongoing and aimed to assess not only its efficacy against pharmacotherapy but also trials in drug free patients with the objective of demonstrating once and for all whether the procedure actually does lower BP in comparison to a placebo arm. In this article, we present an overview of the sympathetic nervous system and its role in hypertension, examine the current data on RDN, and share some insights and future expectations.

Renal denervation with standard radiofrequency ablation catheter is effective in 24-hour ambulatory blood pressure reduction - follow-up at 1/3/6/12 months

Aims

To examine the effect of renal denervation (RDN) on 24‑h ambulatory blood pressure (ABP) with a standard radiofrequency ablation catheter (RF catheter).

Methods

Seventy-five patients with resistant hypertension received bilateral RDN with an RF catheter (6 RF applications, 1 minute each, 8–12 watts). Seventy patients fulfilled inclusion criteria with mean systolic ABP ≥140 mmHg (mean 165/89) despite treatment with ≥3 antihypertensive drugs (mean 5.9) including a diuretic, and were further analysed for ABP changes. Follow-up at 1/3/6/12 months comprised biochemical evaluations and ABP measurement. At 6/12 months, duplex sonography of the renal arteries was additionally performed.

Results

At 1/3/6/12 months we observed a significant reduction in systolic ABP of −15/−17/−18/−15 mmHg (n = 55/53/57/50; non-parametric Friedman test, p < 0.001) and diastolic ABP of −6/−9/−10/−7 mmHg (p < 0.001). Of the patients, 70 %/64 % showed a systolic ABP reduction of ≥10 mmHg, and 77 %/70 % of ≥5 mmHg at 6/12-month follow-up. Two patients (2.7 %) developed renal artery stenosis (>70 %) with subsequent stenting without complications. Logistic regression analysis with systolic ABP reduction ≥10 mmHg at 12 months follow-up as criterion revealed that only the mean baseline systolic ABP was significant, OR = 2.174.

Conclusions

RDN with a standard RF catheter can be used safely to reduce mean ABP in resistant hypertension as shown in long-term follow-up.