Ryan Aultman, Marshall Dearmon, Kenneth R. Ladner, Barry Faulkner, Ta'quoris Newsome, Jon Stavres. The University of Southern Mississippi, Hattiesburg, MS.

BACKGROUND: Evidence suggests that Black and African American (BAA) individuals are more susceptible to autonomic dysfunction compared to White individuals. However, it remains unclear if these findings extend to the autonomic responses to the Valsalva (VL) maneuver. Accordingly, this study compared blood pressure and heart rate responses to the VL maneuver between BAA and White individuals. METHODS: Twenty individuals (10 BAA, 10 White) completed two VLs, each separated by 45 seconds, in both the seated and supine positions (4 VLs in total). VLs were maintained at 45 mmHg, and the order of conditions was counterbalanced between participants. Cardiac rhythm and beat-by-beat blood pressure were continuously recorded throughout each VL, and the relative changes in mean arterial pressure (ΔMAP), systolic blood pressure (ΔSBP), diastolic blood pressure (ΔDBP), pulse pressure (ΔPP), and heart rate (ΔHR) were recorded for phases I (initial hypertensive response), IIa (early phase II depressor response), IIb (late phase II blood pressure recovery), III (rebound hypotensive response after exhalation), and IV (45 second period following exhalation) of each VL. Responses were averaged across both VLs performed within each condition (seated vs. supine), and compared across conditions and between races using repeated measures analyses of variance. RESULTS: At baseline, the BAA group demonstrated a significantly lower mean PP compared to White individuals (-18 ± 8 mmHg, P=0.01), and tended to demonstrate an elevated mean DBP (+10 ± 4 mmHg, P=0.05). When VL responses were compared between groups and across conditions, a significant race by condition interaction was observed for the ΔMAP response during phase IIa (F1,18=6.80, P=0.01). This was explained by a significant exaggeration of the phase IIa ΔMAP response in White individuals during the seated condition (-9 ± 2 ΔmmHg, P<0.01), which was not observed in the BAA group (-1 ± 2 ΔmmHg, P=0.64). Significant main effects of race were also observed for the absolute DBP responses, such that DBP was higher in the BAA group compared to White individuals during all phases (all P<0.04), with the exception of phase IIb (P=0.34). CONCLUSIONS: These findings suggest that phase IIa VL responses are altered in BAA individuals compared to White individuals. This may have important implications for better understanding autonomic dysfunction in this population.

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