Reduction of neurofilaments following renal denervation with radiofrequency current in a sheep model

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.

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.

Comparison of Histopathologic Analysis Following Renal Sympathetic Denervation Over Multiple Time Points

Background—

The pathology of radiofrequency-derived sympathetic renal denervation has not been studied over time and may provide important understanding of the mechanisms resulting in sustained blood pressure reduction. The purpose of this study was to investigate chronological changes after radiofrequency-renal denervation in the swine model.

Methods and Results—

A total of 49 renal arteries from 28 animals with 4 different time points (7, 30, 60, and 180 days) were examined. Semiquantitative histological assessment of arteries and associated tissue was performed to characterize the chronological progression of the radiofrequency lesions. Arterial medial circumferential injury (%) was greatest at 7 days (38±13%), followed by 30 days (31±6%) and 60 days (31±15%), and least at 180 days (21±12%) ( P =0.046). Nerve injury score was significantly greater ( P <0.001) at 7 days (3.9±0.4) compared with 30 days (2.5±0.5), 60 days (2.6±0.5), and 180 days (1.9±0.9). Tyrosine hydroxylase score, which assesses functional nerve damage, was significantly less after 7 (1±1) and 30 days (0.7±0.6) compared with 60 (2.7±0.6) and 180 days (2.7±0.6; P =0.01). Focal nerve regeneration at the sites of radiofrequency ablation was observed in 17% of renal arteries at 60 days and 71% of 180 days.

Conclusions—

Nerve injury after radiofrequency ablation was greatest at 7 days, with maximum functional nerve damage sustained ≤30 days. Focal terminal nerve regeneration was observed only at the sites of ablation as early as 60 days and continued to 180 days. Renal artery and peri-arterial soft tissue injury is greatest in the subacute phase, and least in the chronic phase, suggesting gradual recovery of the renal arterial wall and surrounding tissue.