Catheter-Based Renal Denervation for Resistant Hypertension: Will It Ever Be Ready for "Prime Time"?

Contemporary Strategies to Manage High Blood Pressure in Patients with Coexistent Resistant Hypertension and Heart Failure With Reduced Ejection Fraction

Resistant hypertension (RH) represents an advanced subtype of hypertension that is complex to diagnose and treat. Compared with general hypertension, RH increases the risk patients will develop more advanced cardiovascular complications, including heart failure with reduced ejection fraction (HFrEF). As expected, the prevalence of RH has increased since the introduction of lower blood pressure targets included in the recent 2017 American blood pressure guidelines. The array of pharmacotherapies available to treat both hypertension and HFrEF has also expanded within the past decade. However, the efficacy of these cutting-edge pharmacotherapies has not come without a more advanced understanding of the important adjunct role non-pharmacological therapies play in helping with the management of both hypertension and HFrEF. In this review, we provide a summary of the latest pharmacological and non-pharmacological strategies that can be used to initiate treatment and optimize long-term blood pressure control in patients with coexistent RH and HFrEF.

Renal perivascular adipose tissue: Form and function

Renal sympathetic activity affects blood pressure in part by increasing renovascular resistance via release of norepinephrine (NE) from sympathetic nerves onto renal arteries. Here we test the idea that adipose tissue adjacent to renal blood vessels, i.e. renal perivascular adipose tissue (RPVAT), contains a pool of NE which can be released to alter renal vascular function. RPVAT was obtained from around the main renal artery/vein of the male Sprague Dawley rats. Thoracic aortic PVAT and mesenteric PVAT also were studied as brown-like and white fat comparators respectively. RPVAT was identified as a mix of white and brown adipocytes, because of expression of both brown-like (e.g. uncoupling protein 1) and white adipogenic genes. All PVATs contained NE (ng/g tissue, RPVAT:524 ± 68, TAPVAT:740 ± 16, MPVAT:96 ± 24). NE was visualized specifically in RPVAT adipocytes by immunohistochemistry. The presence of RPVAT (+RPVAT) did not alter the response of isolated renal arteries to NE compared to responses of arteries without RPVAT (-RPVAT). By contrast, the maximum contraction to the sympathomimetic tyramine was ~2× greater in the renal artery +PVAT versus -PVAT. Tyramine-induced contraction in +RPVAT renal arteries was reduced by the α₁-adrenoceptor antagonist prazosin and the NE transporter inhibitor nisoxetine. These results suggest that tyramine caused release of NE from RPVAT. Renal denervation significantly (>50%) reduced NE content of RPVAT but did not modify tyramine-induced contraction of +RPVAT renal arteries. Collectively, these data support the existence of a releasable pool of NE in RPVAT that is independent of renal sympathetic innervation and has the potential to change renal arterial function.