Effects of Stellate Ganglion Blockade on Pulmonary Artery Pressure and Sympathetic Baroreflex Function at High Altitude: A Case Study in Treated Hypertension

In this case study, we explored whether transient inhibition of sympathetic outflow with stellate ganglion blockade (SGB) modifies pulmonary artery pressure and sympathetic arterial baroreflex regulation during high-altitude (HA) exposure in an individual with treated hypertension. Methods: A 44-year-old man with treated hypertension underwent physiological assessments at sea level (220 m) and after 5 to 8 days of exposure to HA (3,800 m). Pulmonary artery systolic pressure (PASP), muscle sympathetic nerve activity (MSNA), beat-by-beat blood pressure (BP), carotid artery diameter, and spontaneous sympathetic baroreflex function (integrative and mechanical components) were assessed at sea level and during HA exposure. During HA exposure, these measurements were obtained following right ultrasound-guided SGB and compared with subsequent time-control visits. Results: HA exposure increased PASP, MSNA, BP, and BP variability compared with sea level. SGB reduced PASP, whereas no meaningful change occurred during the time-control visit. BP variability was lower following SGB than during the control visit. The integrative sympathetic arterial baroreflex relationship appeared steeper following SGB, and the mechanical component demonstrated a greater slope than during the time-control visit, consistent with altered mechanical baroreceptor transduction. Conclusions: These observations suggest that regional sympathetic inhibition may exert distinct influences on pulmonary artery pressure and sympathetic baroreflex regulation during sustained high-altitude exposure in treated hypertension.