Curr Hypertens Rep (2010) 12:61–66 DOI 10.1007/s11906-009-0087-5 Carotid Baroreflex Activation: Past, Present, and Future Ingrid J. M. Scheffers & Abraham A. Kroon & Peter W. de Leeuw Published online: 10 February 2010 # The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Electrical activation of the carotid baroreceptor system is an attractive therapy for the treatment of resistant hypertension. In the past, several attempts were made to directly activate the baroreceptor system in humans, but the method had to be restricted to a few selected patients. Adverse effects, the need for better electrical devices and better surgical techniques, and the lack of knowledge about long-term effects has greatly hampered developments in this area for many years. Recently, a new and promising device was evaluated in a multicenter feasibility trial, which showed a clinically and statistically significant reduction in office systolic blood pressure (>20 mm Hg). This reduction could be sustained for at least 2 years with an acceptable safety profile. In the future, this new device may stimulate further application of electrical activation of the carotid baroreflex in treatment-resistant hypertension. Keywords Baroreceptor system . Electrical activation . Hypertension Introduction Lowering blood pressure to values below 140/90 mm Hg is of great value for patients with essential hypertension. For those with comorbidities such as diabetes mellitus or renal impairment, the target should even be lower, but with the available antihypertensive drugs, many patients either cannot obtain full control of their hypertension with I. J. M. Scheffers : A. A. Kroon : P. W. de Leeuw (*) Department of Internal Medicine, Maastricht University Medical Centre, PO Box 5800, 6202 AZ Maastricht, The Netherlands e-mail: p.deleeuw@intmed.unimaas.nl medical therapy alone or cannot tolerate the adverse effects of the treatment. Drug-resistant hypertension thus remains a significant clinical problem in a number of patients, who could benefit from alternative treatments such as electrical activation of the carotid baroreceptors. This review summarizes early observations on the baroreceptor system and past experiments on electrical activation of the carotid baroreceptor system. These observations and experiments have contributed to our current understanding of the baroreceptor system in the regulation of blood pressure. It also discusses recent experiences with a newly developed baropacing device, which is still under investigation, and the future role of carotid baroreflex activation therapy in the treatment of hypertension and other diseases. A comprehensive search of databases (PubMed, MEDLINE, and OLDMEDLINE) was performed, covering the years 1950 to 2009. The keywords carotid sinus, baroreflex, electrical activation, hypertension, and angina pectoris were used in the literature search. Reference lists in found articles were also reviewed for other relevant articles. Articles in languages other than English, French, German, or Dutch were excluded. Early Observations on the Baroreceptor System In 1836, Cooper [1] was among the first to describe the role of the baroreceptor system in the regulation of blood pressure. More than 85 years later, Hering [2] demonstrated in dogs that electrical stimulation of the carotid sinus nerve induced both bradycardia and hypotension, and that transection of this nerve reversed these changes. He was also able to show that bilateral transection of the carotid sinus nerve resulted in systemic hypertension. Similar results were reported later by Korner [3], who observed in