Greater Beat‐To‐Beat Resting Blood Pressure Variability in Young Healthy African American Men

Abstract

It is well documented that African Americans (AA) are at a greater risk for the development of hypertension than Caucasian Americans (CA). Our laboratory has recently demonstrated exaggerated transduction of sympathetic nerve activity to blood pressure (BP) in young, healthy AA men compared to CA men. The influence of this greater sympathetic vascular transduction on BP variability is unclear. Although previous studies have reported greater BP variability in AA than CA based on 24‐hr ambulatory BP measurements, to date, no studies have investigated resting BP variability on a beat‐to‐beat basis in AA. Thus, we tested the hypothesis that young AA men would exhibit greater beat‐to‐beat BP variability in comparison to CA men. Heart rate (ECG), and beat‐to‐beat arterial BP (finger photoplethysmography) were continuously measured during a 20‐minute resting period in young, healthy CA (n=15) and AA (n=14) men. The arterial BP waveform was analyzed via Modelflow to estimate stroke volume, and used to calculate cardiac output (CO) and total peripheral resistance [TPR: mean arterial pressure (MAP) divided by CO]. Variance, range, and interquartile range were calculated for MAP, CO and TPR. Data are presented as mean ± standard error (SE). Despite similar average absolute resting systolic BP, diastolic BP, and MAP, compared to CA, AA exhibited larger MAP variance (CA: 19.2±2.6 mmHg2, AA: 32.3±4.0 mmHg2, p=0.009). In addition, the range (CA: 26.9±2.0 mmHg; AA: 33.2±1.8 mmHg, p=0.03) and interquartile range (CA: 5.7±0.4 mmHg; AA: 7.6±0.5 mmHg, p=0.007) of MAP were greater in AA than CA. Similar results were found for both systolic BP and diastolic BP. Interestingly, the variance of CO was not significantly different between groups (P=0.63), whereas the variance of TPR was significantly greater in AA than CA (P=0.03). Likewise, the TPR (but not CO) range, and interquartile range were greater in AA than CA. These findings demonstrate that, relative to CA, AA exhibit greater beat‐to‐beat BP variability which appears to be related to greater variability in TPR. Overall, these greater fluctuations in resting BP may constitute a source of future cardiovascular risk in AA men, and predispose them to the development of hypertension.Support or Funding InformationSupported by NIH R15 HL130906.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.