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Abstract

INTRODUCTION: Cardiovascular Disease (CVD) is the leading cause of death in the United States, and blood pressure (BP) is the leading modifiable risk factor. Elevated BP (Systolic BP > 120 mmHg or diastolic BP >80 mmHg) increases CVD risk through increased cardiac stress and endothelial damage, thereby impairing microvascular function. Assessing microvascular function may identify early risk before clinical CVD develops. However, no study has examined whether BP status alters microvascular function using the Near-Infrared Spectroscopy Vascular Occlusion Test (NIRS-VOT) and whether factors such as cardiac autonomic activity, as assessed by heart rate variability (HRV), are also BP status dependent. PURPOSE: We determined whether BP status influences microvascular function, using NIRS-VOT, and if there were corresponding changes in central BP, augmentation index 75 (AIx75), wave reflection, and cardiac autonomic activity. METHODS: Brachial BP was measured in 57 adults (n=26 normotensive, n=31 elevated) to categorize the participants by BP status. Microvascular function was assessed using NIRS-VOT, in addition to assessment of heart rate variability (HRV), blood lipid profile, and central blood pressure with pulse waveform analysis. RESULTS: Compared to the normotensives, hypertensives demonstrated greater weight (p=0.004), body mass index (BMI) (p<0.001), central SBP, DBP, AIx75, and wave reflection (all p<0.001), heart rate (p=0.021), and lower HRV, namely LnRMSSD (p=0.032) and pNN50 (p=0.009). However, no significant differences were observed in NIRS-VOT slope-1 (p=0.581), slope-2 (p=0.486), time-to-halfway (p=0.250), or time-to-peak (p=0.175). CONCLUSION: NIRS-VOT did not detect differences in microvascular function with BP status, though alterations in cardiac autonomic activity and central hemodynamics were noted.

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