Responsivity to Carotid Baroreceptor Stimulation for the Treatment of Resistant Hypertension

Objective: Surgically-implanted carotid baroreceptor stimulators are presently being evaluated in a prospective multicenter research trial. We examined the clinical variables affecting responsivity to baroreceptor stimulation in reducing multi-drug resistant hypertension.
Methods: Patients were recruited to participate on the basis of resistant hypertension with a blood pressure (BP) > 180/85 while on maximal doses of three antihypertensive medications. The Rheos Baroreflex system consists of a pacemaker-like battery/pulse generator unit implanted subcutaneously in an infraclavicular position. Electrical stimulator leads were tunneled subcutaneously and, through separate neck incisions, circumferentially wrapped around the carotid bifurcation. Optimal positioning was determined intra-operatively through dose-response voltage testing. Repeat testing was repeated on the first post-operative day prior to discharge. Data is reported as mean + sem.
Results: A total of 131 patients with a mean age of 54 + 1 years were treated. The study group was composed of 59% males who were obese at 96 + 2 kg. Pre-implantation systolic BP was 181 + 2 mmHg, diastolic 105 + 1 mmHg, and heart rate 75 +1 bpm. The implantation procedure was 211 + 4 minutes in duration. At time of discharge, baroreceptor stimulation induced a significant decrease in the systolic BP of 43 + 2 mmHg, diastolic 20 + 1mmHg, and heart rate 11 + 1 bpm [p < 0.0001]. Multivariate analysis demonstrated that a significantly greater decrease in systolic BP was associated with male gender (16 + 7 mmHg) and higher baseline heart rate (3 +1 mmHg/10 bpm) while a decrease in diastolic BP was also affected by a shorter localization time intraoperatively [all p < 0.05].
Conclusions: Baroreceptor stimulation is effective in significantly decreasing both systolic and diastolic blood pressure in patients with resistant hypertension. Males and those with a faster heart rate are more responsive to such stimulation. These results show promise for the future use of baroreceptor simulation in the treatment of hypertension.