Efeitos agudos da estimulação transcutânea auricular do nervo vago sobre a pressão arterial e a modulação autonômica cardíaca em jovens adultos e idosos hipertensos

Abstract

Introduction: Arterial hypertension (AH) is associated with cardiovascular autonomic changes, characterized by sympathetic hyperactivation and reduced vagal modulation. Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a promising non-invasive strategy for cardiovascular modulation and acute blood pressure (BP) reduction. However, the effects of aging on cardiovascular responsiveness to taVNS remain poorly understood, especially in hypertensive individuals. Objective: To compare the acute response of BP and heart rate variability (HRV) to taVNS on the cymba concha between young and older hypertensive adults. Methodology: Young hypertensive adults (18–39 years) (n=21) and older hypertensive adults (≥60 years) (n=17) underwent a single session of taVNS on the cymba concha region. Hemodynamic variables, including systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR, were assessed before and after stimulation. Additionally, HRV parameters, including high-frequency band (HFnu), low-frequency band (LFnu), LF/HF ratio, standard deviation of normal-to-normal RR intervals (SDNN), root mean square of successive differences between adjacent RR intervals (RMSSD), percentage of adjacent RR intervals with a difference greater than 50 ms (pNN50), standard deviation perpendicular to the line of identity (SD1), standard deviation along the line of identity (SD2), and sample entropy (SampEn), were analyzed to assess cardiac autonomic modulation. The acute cardiovascular response was determined by changes in variables between pre and post-stimulation periods, comparing young and older hypertensive adults. Results: A significant reduction in systolic and diastolic blood pressure was observed after a single session of taVNS on the cymba concha in both young and older hypertensive adults (p < 0.05). Regarding heart rate variability, significant changes were identified only in the older hypertensive group, characterized by a reduction in the LFnu band and an increase in the HFnu band after the intervention, suggesting a mild parasympathetic modulation. In the young hypertensive adult group, no significant changes in autonomic parameters were observed after taVNS. Conclusion: taVNS on the cymba concha promoted a significant acute reduction in SBP and DPB in both young and older hypertensive adults. Furthermore, mild autonomic changes were observed only in older hypertensive adults, suggesting greater vagal responsiveness in this group. These findings indicate that taVNS has an acute hypotensive potential effect in hypertensive individuals, regardless of age group, although the effects on autonomic modulation appear more evident in older adults.