Arterial baroreceptors are mechanosensitive sensory nerve endings in the walls of the carotid sinuses and aortic arch that buffer the increases and decreases in arterial blood pressure. Electrical field stimulation of the carotid sinus, known as carotid baroreflex activation therapy, holds promise as a novel device-based intervention to supplement, but not replace, drug therapy for patients with resistant hypertension. Acute electrical field stimulation of even one carotid sinus can cause a sufficiently large reflex decrease in blood pressure to overcome offsetting reflexes from the contralateral carotid baroreceptors and aortic baroreceptors that are not paced. However, the initial phase III Rheos Pivotal Trial on continuous carotid baroreceptor pacing for resistant hypertension with the first-generation baroreceptor pacemaker yielded equivocal data on efficacy and adverse effects due to facial nerve injury during surgical implantation. A miniaturized second-generation pacing electrode has seemingly overcome the safety issue, and early results with the new device suggest efficacy of unilateral carotid sinus stimulation in heart failure. A phase III trial of this new device for resistant hypertension has been registered.
