Brett L. Cross, Meral N. Culver, Nate K. McMillan, Andrew A. Flatt, Gregory J. Grosicki. Georgia Southern University (Armstrong), Savannah, GA.

Cardiovascular disease (CVD) is the leading cause of death globally. Uncontrolled high blood pressure, largely owing to non-compliant vasculature, is a leading risk factor for CVD. Further, males are disproportionately affected by CVD, but whether detriments in blood pressure and arterial stiffness at a young age contribute to this phenomenon is uncertain. PURPOSE: To compare central hemodynamics, arterial stiffness, and cardio-autonomic indices between apparently healthy young males and females. METHODS: Eleven males (25.5±4 yrs; BMI 25.3±3 kg/m2) and 12 females (22.3±2 yrs; BMI 25.3±5 kg/m2) made 2 visits to the laboratory (2-14 days apart) during morning hours following a 12-hour fast. After 10 minutes of supine rest, central blood pressure was assessed via pulse waveform analysis. Applanation tonometry was used to acquire carotid-femoral pulse wave velocity (cf-PWV; a non-invasive index of arterial stiffness). A Continuous Non-invasive Arterial Pressure device was used to measure beat-to-beat blood pressure changes over a 5-minute period to assess blood pressure variability (average real variability, successive variation, and blood pressure standard deviation (BPSD)) and cardiovagal baroreflex sensitivity (BRS). Sequences of at least 3 consecutive cardiac cycles in which changes in systolic pressure (≥1mmHg) and R-R interval (≥4ms) were the same were identified for BRS analysis. The mean values from the 2 visits were used to perform sex comparisons via independent t-tests. RESULTS: Aortic systolic pressure was greater (P=0.023) in males (107.0±7mmHg) than females (99.9±7mmHg). Similarly, cf-PWV was greater (P=0.017) in males (6.22±1m/s) than females (5.48±1m/s), however when mean arterial pressure was controlled for the results were inconclusive (P=0.05). Systolic BPSD was greater (P=0.028) in females (6.58±1mmHg) than males (5.35±1mmHg). An insufficient number of subjects (n=6) met criteria for BRS analysis. CONCLUSIONS: We observed higher blood pressure and greater aortic stiffness in apparently healthy young males vs females, changes that may precede the development of CVD. Unexpectedly, females exhibited greater BPSD, however this method has been criticized as it fails to account for beat-to-beat blood pressure variation. Observation periods of 5 minutes were inadequate to obtain viable BRS data using liberal sequence inclusion criteria, portending to the need for extended data collection sessions.

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