Renal denervation: time to refine the focus of research

Renal Denervation: A Review

Uncontrolled hypertension persists as an important health issue despite the availability of many medications and nondrug therapies that lower blood pressure. Increasingly, nonadherence to medication is found in approximately 2 of every 5 patients with uncontrolled hypertension. In the search for interventions that lower blood pressure that do not rely on adherence to a regimen requiring daily ingestion of medication or repeated physical activity, device-based methods that denervate the renal arteries have emerged as a potential complement to standard antihypertensive treatments. At least 3 different approaches to renal artery denervation are under active investigation, including the use of radiofrequency energy, ultrasound, or the injection of neurolytic agents into the renal perivascular tissue. In this review, we cover what is currently known about the mechanisms of antihypertensive effects of renal denervation, summarize the efficacy and safety of renal denervation using recent controlled trial publications in a number of hypertensive populations, and conclude with some thoughts about challenges in the field, including the optimization of patient selection for the procedure and what the reader can expect in the near future in this rapidly developing field.

Open-loop analysis on sympathetically mediated arterial pressure and urine output responses in spontaneously hypertensive rats: effect of renal denervation

Primary acute sympathetic activation (PASA) causes a subsequent arterial pressure (AP) elevation. In this case, an antidiuretic effect via the renal innervation and pressure diuresis can act antagonistically on the kidneys. We examined the effect of PASA on urine output in spontaneously hypertensive rats (SHR) 4-7 days after unilateral renal denervation (RDN) (n = 9). The slope of the plot of urine flow versus AP was positive (0.120 ± 0.031 μL min-1 kg-1 mmHg-1) on the intact side, but it was less than 1/3 of the slope observed previously in normotensive Wistar-Kyoto rats (WKY). RDN did not normalize the slope of urine flow versus AP (0.179 ± 0.025 μL min-1 kg-1 mmHg-1, P = 0.098 versus the intact side). The urine flow at the operating point of the AP tended to be greater on the denervated than the intact side (29.0 ± 1.8 vs. 25.3 ± 1.9 μL min-1 kg-1, P = 0.055). The percent increase (17.2 ± 7.2%) was not different from that observed previously in WKY. Although high-resting sympathetic nerve activity is prerequisite for maintaining hypertension in SHR, the effect of sympathetic innervation on the urine output function was not greater than that in WKY.