Effects and Mechanisms of Radiofrequency Ablation of Renal Sympathetic Nerve on Anti-Hypertension in Canine

Patient-Specific Factors Predicting Renal Denervation Response in Patients With Hypertension: A Systematic Review and Meta-Analysis

BACKGROUND

The accurate selection of patients likely to respond to renal denervation (RDN) is crucial for optimizing treatment outcomes in patients with hypertension. This systematic review was designed to evaluate patient-specific factors predicting the RDN response.

METHODS AND RESULTS

We focused on individuals with hypertension who underwent RDN. Patients were categorized based on their baseline characteristics. The primary outcome was blood pressure (BP) reduction after RDN. Both randomized controlled trials and nonrandomized studies were included. We assessed the risk of bias using corresponding tools and further employed the Grading of Recommendations Assessment, Development, and Evaluation approach to assess the overall quality of evidence. A total of 50 studies were ultimately included in this systematic review, among which 17 studies were for meta-analysis. Higher baseline heart rate and lower pulse wave velocity were shown to be associated with significant antihypertensive efficacy of RDN on 24-hour systolic BP reduction (weighted mean difference, -4.05 [95% CI, -7.33 to -0.77]; weighted mean difference, -7.20 [95% CI, -9.79 to -4.62], respectively). In addition, based on qualitative analysis, higher baseline BP, orthostatic hypertension, impaired baroreflex sensitivity, and several biomarkers are also reported to be associated with significant BP reduction after RDN.

CONCLUSIONS

In patients with hypertension treated with the RDN, higher heart rate, and lower pulse wave velocity were associated with significant BP reduction after RDN. Other factors, including higher baseline BP, hypertensive patients with orthostatic hypertension, BP variability, impaired cardiac baroreflex sensitivity, and some biomarkers are also reported to be associated with a better BP response to RDN.

Effects of different ablation points of renal denervation on the efficacy of resistant hypertension

Objective

To explore the blood pressure response to different ablation points of renal denervation (RDN) in patients with resistant hypertension

Methods

A total of 42 cases with resistant hypertension treated by RDN in our center from 2013 to 2015 were retrospectively analyzed. The patients were divided into two groups according to the different ablation points of RDN: the standard treatment group (spiral ablation from near to proximal, with less than 8 points per artery) and the intensive treatment group (from near to far by spiral ablation, with at least 8 points per artery), with 21 patients in each group. The ablation parameters, including points, impedance, actual wattage, and actual temperature, were recorded intraoperatively. Renal angiography was performed again after RDN. Ambulatory blood pressure (ABP) images were taken for all patients at the baseline and 6 months after operation.

Results

The mean 24-h blood pressure of the standard treatment group was lower than that of the baseline (24-h systolic blood pressure decreased by 7.4 ± 10.6 mmHg and 24-h diastolic blood pressure decreased by 4.6  ± 6.1 mmHg), and the mean 24-h blood pressure decreased significantly from baseline to 6 months in the intensive treatment group (24–h systolic blood pressure decreased by 27.4 ±  11.4 mmHg, P < 0.0001; 24–h diastolic blood pressure decreased by 10.9 ±  9.6 mmHg, P = 0.005). There was a positive correlation between the decrease of systolic/diastolic 24-hour mean and the number of ablation points used in the procedure. The mean value of systolic and diastolic blood pressure was positively correlated with ablation points at 24-hour (R² = 0.777 and 0.633 respectively, P < 0.01). There were no adverse events in either group after the operation and during the follow-up.

Conclusions

RDN could significantly reduce BP in patients with resistant hypertension. Our study showed that the antihypertensive effect appeared to be positively correlated with the number of ablation points.

Catheter-Based Renal Denervation Attenuates Kidney Interstitial Fibrosis in a Canine Model of High-Fat Diet-Induced Hypertension

BACKGROUND/AIMS

Catheter-based renal denervation (RDN) has emerged as an innovative interventional approach for reducing blood pressure (BP), suppressing ventricular substrate remodeling, and attenuating heart failure, which suggests that it might reduce kidney fibrosis in a canine model of high-fat diet-induced hypertension. This study thus sought to assess whether RDN could reduce kidney fibrosis and halt the progression of renal impairment in a canine model of high-fat diet-induced hypertension.

METHODS

Thirty-two beagles were randomized into either the normal control group (normal diet, n = 10) or the hypertension group (high-fat diet, n = 22). After successful establishment of the model, the hypertension model group was randomized to either the RDN group (n = 9) or the sham-surgery group (n = 8). Renal artery angiography, BP, heart rate (HR), and blood and urine biochemistry results were assessed at 1, 3, and 6 months after surgery. Canines were sacrificed at 6 months after surgery. The extent of kidney interstitial fibrosis, transforming growth factor-beta 1, alpha-smooth muscle actin, connective tissue growth factor, and E-cadherin protein were measured.

RESULTS

The group fed a high-fat diet had significantly (p ˂ 0.05) increased body weight, BP, and HR and higher levels of urine albumin, serum noradrenaline (NE), and angiotensin II (AngII) than the control group. The sham-surgery group and RDN group also had higher levels than the control group (p ˂ 0.05). Compared with the sham-surgery group, the RDN group had lower BP, urine albumin, serum NE, and AngII and less fibrotic tissue (all p ˂ 0.05).

CONCLUSION

RDN reduced BP, slowed progression of albuminuria, and suppressed renal remodeling in a canine model of high-fat diet-induced hypertension.