Eligible patients were those scheduled to undergo elective surgical procedure that therapeutically indicated exposure of the carotid bifurcation and vascular sheath (e.g. carotid endarterectomy, neck dissection, or carotid tumor Resection) regardless of a HTN diagnosis. Exclusion criteria included disease states such as a history of stroke, or prior ipsilateral neck surgery or radiation treatment. Cardiovascular disease that precluded enrollment were diagnoses which independently increased surgical and anesthetic risk (American Society for Anesthesia Classification System).

Using a novel surgical approach, a custom electrode was implanted around tissue including CSN branches in anesthetized adults. Following functional mapping, presumed baroafferent fibers were identified via response and stimulated. Outcome measures included change in systolic BP (SBP), diastolic BP (DBP), and heart rate (HR) during and after stimulation using multi-level modeling. Secondarily, dose dependency was examined.

The primary outcome was maximum drops and recovery in systolic blood pressure (SBP) as a function of carotid sinus nerve (CSN) stimulation as measured in mmHg. The maximum drop was calculated as the maximum change in SBP while stimulus was active, relative to the baseline value 30 seconds before starting stimulus. Maximum recovery was calculated as the largest change in SBP within 30 seconds of ending stimulus relative to the nadir in SBP (mmHg) during stimulation.

The generalized drops and recoveries of systolic and diastolic blood pressure (SBP & DBP) measured in mmHg across all stimulation epochs as a function of CSN stimulation and stimulation withdrawal using the same timeframe as that used in the primary outcome.