Renal Sympathetic Denervation and Daily Life Blood Pressure in Resistant Hypertension

Abstract

Drug-resistant hypertension is a clinically relevant problem that has attracted increasing attention over the past few years. This is certainly attributable to a growing awareness of the importance of blood pressure (BP) control in reducing hypertension-related cardiovascular risk. It is also due, however, to a recent major breakthrough in the management of resistant hypertension, because of the introduction of 2 novel invasive therapeutic approaches: carotid baroreceptor stimulation and catheter-based renal sympathetic denervation (RDN).1,2 For a number of reasons, the latter method seems to be taking the upper hand and is used with growing enthusiasm all over the world, even if the strength of the evidence in its support is not currently overwhelming. The concept of RDN derives from a known pressor effect of sympathetic stimuli, arriving to the kidney via efferent fibers located in the adventitia of renal arteries, in the frame of a complex regulation of sympathetic activity also including reflex modulation by renal afferent neural influences.3–5 Hence, the hypothesis was made that destruction of these fibers, by bilaterally applying radiofrequency electric current through an ablation catheter positioned inside renal artery, might reduce sympathetic activity in general. It was also hypothesized that, in particular, renal sympathetic fiber ablation might interfere with sympathetic renal modulation, leading to increased sodium and water excretion and to vasodilation, thereby effectively lowering elevated BP levels. This hypothesis was first tested in animal studies3,4 and subsequently explored in 2 major studies in humans: Renal sympathetic denervation in patients with Refractory Hypertension (The Symplicity HTN-1 Trial) and Renal sympathetic denervation in patients with treatment-resistant hypertension (The Symplicity HTN-2 Trial),7 followed by a growing number of reports from registries. Although the results of Symplicity studies clearly supported the efficacy of RDN in lowering office BP, their design …