Differences in resting cardiovascular parameters in 10-to 15-year-old children of different ethnicity: The contribution of physiological and psychological factors

Background: The health status of children in the North West Province of South Africa was examined using the Transition and Health during Urbanization in South Africa in Children study. This is an epidemiological, cross-sectional study for which 1,244 children between 10 and 15 years of age were recruited from 44 schools. Purpose: Our objective was to investigate whether differences exist between resting cardiovascular parameters of Black, White, colored, and Indian children and evaluate the contribution of physiological and psychological factors. Methods: Blood pressure was monitored with the Finapres apparatus. By means of the Fast Modelflo software program, the systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure, heart rate, cardiac output (CO), total peripheral resistance (TPR), and "Windkessel" compliance (Cw) of the arterial system were obtained. The psychological data were obtained by validated questionnaires. Results: After correction for body mass index, the SBP of the White children was significantly higher (p<.05) than the SBP of the other ethnic groups. The DBP showed no significant differences. The TPR measurements of the Black and colored children were significantly higher (p<.05) than the TPR of the White children, and the Cw measurements of the Black and colored children were significantly lower than the Cw of the White children. Significant correlations (p<.05) were found between the SV CO, TPR, Cw, and the total score on violence in the Black and col-, ored children. Conclusions: There are differences in the resting cardiovascular parameters in the different ethnic groups studied. The higher levels of violence to which the Black and colored children are exposed could alter vascular sensitivity, to sympathetic stimulation. This may contribute via the higher alpha-adrenergic sensitivity, to the pathogenesis of hypertension in their later lives.