The role of baroreflex activation therapy in sympathetic modulation for the treatment of resistant hypertension

Hypertension remains a leading cause of morbidity and mortality in the world, and the prevalence of resistant and refractory hypertension continues to increase dramatically. Conditions associated with long-term poorly controlled hypertension include ischaemic heart disease, cardiomyopathy, stroke and renal failure. Pharmacologic therapy has long been the hallmark of treatment for the many patients for whom therapeutic lifestyle modifications fail. There is now a vast array of drug classes in the armamentarium, including beta-blockers, ACE inhibitors, ARBs, calcium channel blockers, to name a few. Despite the advances and addition of novel drug classes and more potent agents within the classes, a substantial proportion of patients fail to achieve the goal even with available therapies. Poly-pharmacy is wrought with side-effects and patients have psychological limits regarding how many medications they are willing to take. Manipulation of the sympathetic system has demonstrated benefit in patients with malignant hypertension in the pre-antihypertensive medication era. Currently, two separate and distinct approaches have been revived and evaluated in new ways. Surgical sympathectomy was first attempted in the 1930s for patients with peripheral vascular disease, in an attempt to improve circulation by reducing vasoconstrictive effects of the sympathetic system. In the 1940s and 1950s, the scope of the technique was extended to patients with malignant hypertension.1–5 Unfortunately, the side-effect profile associated with surgical splanchnicectomy (eg, impotence, severe orthostatic hypotension and urinary/faecal incontinence) was significant enough that, not surprisingly, the technique fell out of favour.6 More recently, with advances in technology for percutaneous delivery of radiofrequency energy to create deep thermal injury …