Renal denervation therapy beyond resistant hypertension

Renal denervation and long-term results

Arterial hypertension is a condition with a high prevalence in the global population and represents a major risk factor for adverse cardiovascular events, including stroke and death. Non-pharmacological and pharmacological interventions, with combination therapy as a standard strategy, are very effective in achieving optimal blood pressure (BP) goals. Nevertheless, in a non-negligible proportion of patients, drug therapy is ineffective at achieving BP targets or there is intolerance to specific anti-hypertensive medications. In this context, the use of invasive treatments for BP control, including renal denervation, represents a valuable therapeutic option. Renal denervation has experienced ups and downs over the years, with an initial growth period and a decline mainly linked to the initial negative results of a large, randomized trial. However, recent data from new trials and long-term follow-up of initial trials have confirmed the benefit and safety of the procedure by relaunching it in daily clinical practice. Additional research evaluating ablation methods other than radiofrequency are needed to be able to more clearly define the role of this procedure and the type of patients that can benefit most from it.

[Renal sympathetic denervation can significantly reduce blood pressure and improve arterial stiffness in hypertensive beagles]

OBJECTIVE

To investigate the effect of renal sympathetic denervation (RDN) on blood pressure and arterial stiffness in hypertensive beagles and explore the underlying mechanism.

METHODS

Sixteen beagles were randomly divided into RDN group (n=8, fed with a high-salt high-fat diet to establish models of hypertension and treated with RDN), sham-operated group (n=4, fed with a high-salt high-fat diet to induce hypertension but only examined with renal arteriography) and control group (n=4, fed with formula dog food). The changes in blood pressure, arterial stiffness, endothelial function, and sympathetic activity were compared among the 3 groups and correlation analysis was performed.

RESULTS

All the animal models of hypertension were established successfully in the beagles. At 3 months after the RDN, the changes in systolic blood pressure (SBP) differed significantly among the 3 groups (P=0.006), and the reduction in SBP was significantly greater in RDN group than in the other two groups (P < 0.05). The variations of diastolic blood pressure (DBP) also differed significantly among the 3 groups (P=0.016), and DBP reduction was more obvious in RDN group than in the control group (P=0.007), but similar to that in the sham-operated group (P=0.052). The changes of resistance index (RI) after the procedure were significantly different among the 3 groups (P=0.043), and the RDN group showed a greater reduction of RI than the control group (P=0.032) and sham group (P=0.043). Serum levels of eNOS, NO and Ang Ⅱ did not differ significantly among the groups either before or after RDN (P>0.05), but serum NE level was significantly higher in RDN group than in the control groupafter successful modeling (P=0.014), but similar to that in the sham group (P=0.560). Compared with the sham operation, RDN in the hypertensive beagles resulted in a significantly greater decrease of serum NE level (P=0.032) to almost the control level (P= 0.080). The changes of RI following RDN were significantly correlated with the changes of SBP, DBP and serum levels of NO and NE (P < 0.05).

CONCLUSION

RDN can significantly reduce blood pressure and improve arterial stiffness in hypertensive beagles possibly by reducing sympathetic activity and blood pressure and promoting NO synthesis.

Sensory signals mediating high blood pressure via sympathetic activation: role of adipose afferent reflex

Blood pressure regulation in health and disease involves a balance between afferent and efferent signals from multiple organs and tissues. Although there are numerous reviews focused on the role of sympathetic nerves in different models of hypertension, few have revised the contribution of afferent nerves innervating adipose tissue and their role in the development of obesity-induced hypertension. Both clinical and basic research support the beneficial effects of bilateral renal denervation in lowering blood pressure. However, recent studies revealed that afferent signals from adipose tissue, in an adipose-brain-peripheral pathway, could contribute to the increased sympathetic activation and blood pressure during obesity. This review focuses on the role of adipose tissue afferent reflexes and briefly describes a number of other afferent reflexes modulating blood pressure. A comprehensive understanding of how multiple afferent reflexes contribute to the pathophysiology of essential and/or obesity-induced hypertension may provide significant insights into improving antihypertensive therapeutic approaches.