Recent advancements in the treatment of resistant hypertension

Renin angiotensin aldosterone inhibition in the treatment of cardiovascular disease

A collective century of discoveries establishes the importance of the renin angiotensin aldosterone system in maintaining blood pressure, fluid volume and electrolyte homeostasis via autocrine, paracrine and endocrine signaling. While research continues to yield new functions of angiotensin II and angiotensin-(1-7), the gap between basic research and clinical application of these new findings is widening. As data accumulates on the efficacy of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers as drugs of fundamental importance in the treatment of cardiovascular and renal disorders, it is becoming apparent that the achieved clinical benefits is suboptimal and surprisingly no different than what can be achieved with other therapeutic interventions. We discuss this issue and summarize new pathways and mechanisms effecting the synthesis and actions of angiotensin II. The presence of renin-independent non-canonical pathways for angiotensin II production are largely unaffected by agents inhibiting renin angiotensin system activity. Hence, new efforts should be directed to develop drugs that can effectively block the synthesis and/or action of intracellular angiotensin II. Improved drug penetration into cardiac or renal sites of disease, inhibiting chymase the primary angiotensin II forming enzyme in the human heart, and/or inhibiting angiotensinogen synthesis would all be more effective strategies to inhibit the system. Additionally, given the role of angiotensin II in the maintenance of renal homeostatic mechanisms, any new inhibitor should possess greater selectivity of targeting pathogenic angiotensin II signaling processes and thereby limit inappropriate inhibition.

Addition of Propranolol in Resistant Arterial hypertension Treatment (APROPRIATE study): study protocol for a randomized double-blind placebo-controlled trial

Background

Resistant hypertension is defined as an uncontrolled blood pressure despite treatment at best-tolerated doses with at least three antihypertensive agents including a diuretic. It is an emerging public health problem. At present clinical trial data on management of resistant hypertension is limited. Management is largely based on observational studies and expert opinions. Propranolol is a nonselective beta blocker. Several studies have confirmed that propranolol has a significant hypotensive action, both when used alone and as an adjuvant therapy. At present there are no prospective, randomized, clinical studies evaluating the effectiveness of propranolol in patients with resistant hypertension. Therefore, we have designed a prospective randomized trial to evaluate the safety and efficacy of propranolol in patients with resistant hypertension.

Methods/design

The study will be conducted as a randomized, double-blind, placebo-controlled clinical trial for a period of 3 months. The study has been approved by the Ethics Review Committee of the Faculty of Medicine, University of Colombo. A total of 200 adults with resistant hypertension will be recruited for the study. They will be randomly assigned to the test and placebo groups on a 1:1 ratio. The test group will receive propranolol 40 mg three times a day and the control group will receive an identical placebo capsule. The study drugs will be double blinded to both investigators and subjects. The visits and the evaluations will be done as follows: screening (visit 0), 1 month (visit 1), 2 months (visit 2) and 3 months (visit 3). The primary outcomes of the study is to find a statistically significant difference between the fall in mean systolic and mean diastolic blood pressure measured by ABPM (ambulatory blood pressure monitoring) from baseline between the two groups. Data will be analyzed using SPSS v16.

Discussion

To our knowledge this is one of the first randomized controlled trials evaluating the effects of propranolol in resistant hypertension. This study will provide the necessary groundwork for future large-scale, multicentered clinical trials. The result, positive or negative, should provide a step change in the evidence guiding current and future policies regarding treatment of resistant hypertension.

Trial registration

Sri Lanka Clinical Trials Registry, identifier: SLCTR/2016/002. Registered on 27 January 2016; Study protocol version 2.1.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1863-1) contains supplementary material, which is available to authorized users.

Increased aldosterone: mechanism of hypertension in obesity

The prevalence of both obesity and hypertension are increasing worldwide. Hypertension is a common consequence of obesity. Increased central adiposity is associated with increased aldosterone levels and blood pressure in human beings. A number of small studies have shown an association between obesity-mediated hypertension and mechanisms directly linked to increased levels of aldosterone. These studies have shown a trend toward relatively greater blood pressure reduction using aldosterone-receptor blockers compared with other classes of antihypertensive agents. Other than treatment for weight loss, treatment of hypertension with specific antihypertensive medications that block or reduce aldosterone action are appropriate in obese patients. Further research is needed to understand the exact role of the adipocyte in obesity-mediated hypertension.

Renal sympathetic denervation for resistant hypertension treatment : current perspectives

The authors review the concept of resistant hypertension and the involvement of the sympathetic nervous system in hypertension as a rational basis for the technique of renal sympathetic denervation (RSD) performed percutaneously. This revision is the result of an active search for scientific articles with the term "renal denervation" in the Medline and PubMed databases. The techniques and devices used in the procedure are presented, as well as clinical outcomes at six, 12 and 24 months after the intervention with the Symplicity catheter. Significant decreases and progressively higher reductions of systolic and diastolic blood pressure were observed after RSD. The complication rate was minimal. New devices for RSD and its ongoing clinical studies are cited. In conclusion, the RSD presents itself as an effective and safe approach to resistant hypertension. Results from ongoing studies and longer follow-up of these patients are expected to confirm the initial results and put into perspective the expansion of the procedure use in hypertension approach.

Aldosterone and the risk of hypertension

Aldosterone, the key hormone in the mineralocorticoid pathway, plays a fundamental role in salt and water homeostasis, blood pressure regulation, and cardiovascular remodeling. Both genomic and nongenomic mechanisms influence aldosterone-induced renal sodium reabsorption. Furthermore, the mineralocorticoid receptors in nonepithelial tissues, including the heart and vascular smooth muscle cells, have recently been discovered. Thus, aldosterone likely has pleiotropic effects that contribute to the modulation of blood pressure. Among patients with hypertension in general, and among those with more severe or resistant hypertension in particular, a higher-than-expected prevalence of primary hyperaldosteronism is noted. Among individuals with resistant hypertension, aldosterone antagonists have also been shown to be effective in lowering blood pressure. Most significantly, recent community-based studies among non-hypertensive individuals in the general population have demonstrated that both higher serum aldosterone concentrations and a higher aldosterone to renin ratio portend a greater risk of developing hypertension. The combination of the aforementioned observations underscores the importance of the mineralocorticoid pathway in the pathogenesis of hypertension.