Year: 2009
Type: dissertation
Abstract: Vagal baroreflex sensitivity (BRS) is a measure of short term blood pressure (BP) \nregulation through alterations in heart rate. Low BRS reflects impaired autonomic system \nregulation and has been found to be a surrogate marker for cardiovascular health. In \nparticular, it has found to be associated with the pathogenesis of adult hypertension. \nHowever, only limited information exists as to the negative consequences of childhood \nBP on baroreflex function. The objective of this study was to investigate BRS in children \nwith 2 different BP profiles while controlling for the effects of age, maturation, sex, and \nbody composition. A preliminary subsample of 11-14 year-old children from the HBEAT \n(Heart Behavioural Environmental Assessment Team) Study was selected. The children \nwere divided into 2 BP groups; high BP (HBP; 2:95tl1 percentile, n=21) and normal BP \n(NBP; <90th percentile, n=85). Following an initial 15 minutes of supine rest, 5 minutes of \ncontinuous beat-to-beat BP (Finapres) and RR interval (RRI) were recorded (standard \nECG). Spectral indices were computed using Fast Fourier Transform and transfer \nfunction analysis was used to compute BRS. High frequency (HF) and low frequency \n(LF) power spectral areas were set to 0.15-0.4 Hz and 0.04-0.15 Hz, respectively. Body \ncomposition was measured using body mass index. After adjusting for body composition, \nmaturation, age and sex ANCOV A results were as follows; LF and HF BRS, LF and HF \nRRI, and RRI total power were lower in the HBP versus NBP participants (p<0.05). As \nwell, LF IHF SBP ratio was significantly higher in the HBP compared to the NBP group \n(p<0.05). The regression coefficients (unstandardized B) indicated that in changing \ngroups (NBP to HBP) LF and HF BRS decreases by 4.04 and 6.18 ms/mmHg, \nrespectively. Thus, as BP increases, BRS decreases. These data suggest that changes in \nautonomic activity occur in children who have HBP, regardless of age, sex, maturation, \nand body composition. Thus, despite their young age and relatively short amount of time \nhaving high BP compared with adults, these children are already demonstrating poor BP \nregulation and reduced cardiovagal activity. Given that childhood BP is associated with \nhypertension in adulthood, there is a growing concern in regards to the current \ncardiovascular health of our children and future adults.
Author: Laura K. Fitzgibbon
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W289686190