Central arteriovenous anastomosis for hypertension: it is not all about sympathomodulation

Hypertension is described as resistant in patients who do not achieve target blood pressure (BP) control despite the prescription of at least three recognized antihypertensive medications and thus remain exposed to increased cardiovascular risk. It is clear that noncompliance with medication is in part responsible, but nonetheless there is a clear and unmet clinical need to find alternative means to improve BP control in such patients.In recent years, several nonpharmacological device-based technologies for hypertension have been trialed. Such approaches, underpinned by sound scientific rationale, have largely sought to perturb the sympathetic autonomic nervous system, termed ‘sympathomodulation.’ Renal denervation has gained the most attention to date but other procedures under clinical evaluation include carotid baroreceptor activation and carotid body ablation, while approaches such as vagal nerve stimulation are subject to ongoing preclinical research. The focus on sympathomodulation as a means of affecting BP reduction has overshadowed other aspects of hypertension pathophysiology, including classic Windkessel-based hemodynamic models. Arterial compliance, chiefly the function of central conduit arteries, is recognized as being inversely correlated with cardiovascular morbidity and mortality. The recently published efficacy of a central arteriovenous (AV) anastomosis in lowering BP in resistant hypertensive patients has generated great excitement in hypertension research and management. Although requiring further clarification, it seems probable that the ROX Coupler acts, at least partly, to offset the effects of central arterial stiffness. The ROX Control HTN trial result becomes even more significant in the context of ongoing uncertainty regarding the future of renal denervation.