Arterial baroreceptors in the management of systemic hypertension.

Hypertension is a multifactorial disease associated with significant morbidity. Increased sympathetic nervous system activity has been noted as an important etiologic factor and is, in part, regulated by afferent input arising from arterial and cardiopulmonary baroreceptors, activation of which causes inhibition of sympathetic output. It was thought for many years that baroreceptors control only short-term blood pressure changes, a conclusion stemming from observations in sinoaortic denervation (SAD) animal models and the phenomenon of rapid baroreceptor resetting, also seen in animal models. Newer observations, however, indicate that SAD is rather imperfect and resetting is rarely complete. Recent studies reveal that baroreceptors control sympathetic output on a more long-term basis and participate in fluid volume regulation by the kidney, and thus have the potential to adjust blood pressure chronically. Importantly, these findings are consistent with studies and observations in humans. Meanwhile, a model of electrical stimulation of the carotid sinus has been developed and successfully tested in animals. Following these encouraging results human trials to evaluate the clinical application of electrical carotid sinus manipulation in the treatment of systemic hypertension have commenced, and results so far indicate that this represents an exciting potential tool in the clinician's armament against chronic arterial hypertension.