Abstract P152: Acute Effect of Unilateral Unipolar Electrical Carotid Sinus Stimulation in Patients with Treatment-Resistant Arterial Hypertension

Electrical carotid sinus stimulation has been developed for treatment of resistant arterial hypertension. The first-generation device (Rheos™) relying on bilateral placement of bipolar electrodes acutely reduced muscle sympathetic nerve activity (MSNA) and blood pressure (BP) but is no longer available. The second-generation device (Neo™) utilizes a smaller unilateral unipolar disk electrode to reduce invasiveness while saving battery life. We tested acute effects of the latter on BP and MSNA. We studied 18 treatment-resistant hypertensive patients (9 women, 53±11 years, 34±5 kg/m 2 ) on stable medication who had been implanted with the second-generation device. We assessed acute BP (oscillometry), heart rate (HR, ECG), and MSNA (microneurography) responses to electrical stimulation in the supine position. Without stimulation, BP was 165±31/91±18 mmHg, HR was 75±17 bpm, and MSNA was 48±14 bursts/min. Acute stimulation with intensities producing side effects that were tolerable in the short term elicited variable changes in systolic BP (SBP: -16.9±15.0 mmHg, range: 0.0 to -40.8 mmHg, p=0.002), HR (-3.6±3.6 bpm, p=0.004), and MSNA (-1.9±5.3 bursts/min, p=0.194). Stimulation intensities had to be lowered in 12 patients to avoid side effects at the expense of efficacy (SBP: -6.3±7.0 mmHg, range: 2.8 to -14.5 mmHg, p=0.028; HR: -1.5±2.3 bpm, p=0.078; comparison against responses with side effects). Reductions in diastolic BP and MSNA (total activity) tended to be correlated (r 2 =0.202, p=0.093). In our patient cohort, unilateral unipolar electrical baroreflex stimulation acutely lowered BP. Side effects may limit efficacy. The novel approach should be tested in a controlled comparative study.