Acute Device-Based Blood Pressure Reduction: Electrical Activation of the Carotid Baroreflex in Patients Undergoing Elective Carotid Surgery

Abstract

Carotid sinus baroreceptors are involved in controlling blood pressure (BP) by providing input to the cardiovascular regulatory centers of the medulla. The acute effect of temporarily placing an electrode on the carotid sinus wall to electrically activate the baroreflex was investigated. We studied 11 patients undergoing elective carotid surgery. Baseline BP was 146+30/66±17 mm Hg and heart rate (HR) 72±7 bpm (mean ± standard deviation). An electrode was placed upon the carotid sinus and after obtaining a steady state baseline of BP and HR, an electric current was applied and increased in 1-volt increments. A voltage dependent and highly significant reduction in BP was observed which averaged 18±26* and 8.0±12 mm Hg for systolic BP and diastolic BP, respectively. Maximal reductions occurred at 4.4±1.2 V: 23±24 mm Hg*, 16±10 mm Hg* and 7±12 bpm* for systolic BP, diastolic BP and HR, respectively (= p <.05). Thus, electrical stimulation of the carotid sinus activates the carotid baroreflex resulting in a reduction in BP and HR. This presents a proof of concept for device based baroreflex modulation in acute BP regulation and adds to the available data which provide a rationale for evaluating this system in the context of chronic BP reduction in hypertensive patients.