Effects of carotid baroreceptor stimulation on retinal arteriole remodeling evaluated with adaptive optics camera in...

Baroreceptor activation therapy (BAT) leads to a decrease in blood pressure (BP) in patients affected by resistant hypertension (RH) by reducing sympathetic outflow. This study aimed at evaluating the effects of BAT on RH patients' retinal arteriolar microvasculature, a territory devoid of adrenergic innervation.

Five patients defined as affected by RH after excluding secondary causes of hypertension and based on number of antihypertensive treatments, underwent the implantation of Barostim™ neo™. Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) were assessed by office and 24-hours ambulatory BP monitoring (ABPM). Adaptive Optics Camera RTX1^® (ImagineEye, Orsay, France) was used to measure wall thickness (WT), internal diameter (ID), wall cross-sectional area (WCSA) and wall-to-lumen ratio (WLR). A cohort of 21 not-controlled hypertensive patients matched for age, gender and follow-up time, undergoing standard-antihypertensive therapy changes, was selected as a control group. SBP and DBP were assessed by office and home BP monitoring (HBPM). Evaluations were performed at baseline and after 6 months mean follow-up.

Office SBP decreased by 9.7±12.3% and 29.7±12.4% in standard-therapy and BAT group respectively, while office DBP decreased by 7.6±17.4% and 14.8±15.7%. Concerning ABPM/HBPM, a mean reduction of both SBP and DBP of 7.9±11% was observed for the standard-therapy while a reduction of 15.8±10.5% and 15.8%±5.3% was observed for SBP and DBP respectively in BAT group. While in the standard-therapy group a significant reduction in WLR (-5.9%) due to both ID increase (+2.3%) and WT reduction (-5.7%) was observed, without changes in WCSA (-0.3%), RH patients had a significant reduction in WCSA (-12.1%), due to a trend in both WT and ID reduction (-6.5% and -1.7% respectively), without significant changes in WLR (-2%).

While a reverse eutrophic remodeling was observed in patients undergoing a standard-antihypertensive treatment, hypotrophic changes were found in RH patients undergoing BAT. Despite the lack of adrenergic receptors on retinal vessels, chronic baroreflex stimulation may exert an effect on retinal microvasculature in RH patients by more systemic than local mechanisms.