Inverse Relationship between Cardio-Ankle Vascular Index and Body Mass Index in Healthy Children.

OBJECTIVE: To establish reference scores for cardio-ankle vascular index (CAVI), a noninvasive measure of vascular function, which reflects the stiffness of arteries, in healthy children, to test for racial and ethnic differences, and to compare CAVI scores between overweight and normal weight children. STUDY DESIGN: Subjects included 292 children aged 10-18 years: 100 non-Hispanic whites, 89 non-Hispanic blacks, and 103 Hispanics. Subjects were grouped as normal weight (body mass index [BMI] <85th percentile for age) and overweight (BMI >85th percentile for age). Blood pressure (BP) and CAVI scores were measured in all subjects. RESULTS: After controlling for age, sex, and BMI, normal weight black males had a higher CAVI score (indicating stiffer arteries) in comparison with Hispanic males and white males (5.53 ± 0.15 vs 5.13 ± 0.15 vs 5.02 ± 0.15, P = .04). BMI had an inverse association on the CAVI score (r = -0.335, P < .0001). In multivariable analysis, BMI and average CAVI scores were significant predictors of each other (R(2) = 0.37, P < .0001, R(2) = 0.21, P < .0001). There was no significant correlation between CAVI scores and resting BP values, confirming that CAVI scores were independent of concurrent BP values. CONCLUSIONS: Significant differences in vascular function exist among ethnic groups of children. Overweight children had lower CAVI scores, suggestive of vascular adaptation to obesity in early life. CAVI, by providing a noninvasive measure of vascular health, may help identify children at increased risk for cardiovascular disease.

Blood aldosterone-to-renin ratio, ambulatory blood pressure, and left ventricular mass in children.

OBJECTIVE: To assess the blood aldosterone-to-renin ratio (ARR) and its relationship to ambulatory blood pressure (ABP) and left ventricular mass (LVM) in children. STUDY DESIGN: A cross-sectional clinical study was conducted in 102 children (71.6% African American; 62.7% male) ranging in age from 7 to 18 years (mean, 13.6 years; median, 14 years). ABP (24-hour monitoring) was expressed as blood pressure index (BPI; mean blood pressure/95th percentile by sex and height). LVM was measured by echocardiography and expressed as an index (LVMI = g/height [m](2.7)). Regression analyses were used to estimate associations. RESULTS: African-American children had significantly lower serum aldosterone concentration and plasma renin activity compared with European-American children (aldosterone: 5.9 ng/dL vs 11.4 ng/dL, P < .0001; renin: 1.6 ng/mL/hour vs 2.8 ng/mL/hour, P = .01). However, ARR was not significantly different by race. ARR was not associated with 24-hour ABP but was significantly associated with LVMI (beta = 0.4 g/m(2.7); P = .02) after adjustment for the ratio of 24-hour urine Na to creatinine excretion, body mass index z- score, and ABP index. CONCLUSIONS: The data indicated a significant association between ARR and LVMI, but not ABP, in children, suggesting early cardiac remodeling associated with a high ARR.

Ambulatory blood pressure and increased left ventricular mass in children at risk for hypertension.

OBJECTIVE: To relate ambulatory blood pressure (ABP) to cardiac target organ measurement in children at risk for primary hypertension (HTN). STUDY DESIGN: Left ventricular mass index (LVMI) and ABP were measured concomitantly in children (6 to 18 years) at risk for hypertension using a cross-sectional study design. RESULTS: LVMI showed a significant positive correlation with 24-hour systolic blood pressure (SBP) load, SBP index (SBPI), and standard deviation score (SDS). When subjects were stratified by LVMI percentile, there were significant differences in SBP load, 24-hour SBPI, and 24-hour SSDS. The odds ratio (OR) of having elevated LVMI increased by 54% for each incremental increase of SDS in 24-hour SSDS after controlling for race and BMI (OR = 1.54, unit = 1 SDS, CI = 1.1, 2.15, P = .011) and increased by 88% for each increase of 0.1 in BPI (OR = 1.88, CI = 1.03, 3.45, P = .04). Subjects with stage 3 HTN had significantly greater mean LVMI compared with normal subjects (P = .002 by ANOVA; LMVI, 31.6 +/- 7.9 versus 39.5 +/- 10.4). CONCLUSIONS: As systolic ABP variables increase, there is greater likelihood for increased LVMI. Staging based on ABPM allows assessment of cardiovascular risk in children with primary hypertension.

Longitudinal relationship of parental hypertension with body mass index, blood pressure, and cardiovascular reactivity in children.

OBJECTIVE: To investigate whether parental hypertension (HTN) affects children's body mass index (BMI) and cardiovascular reactivity (CVR) over time. STUDY DESIGN: A longitudinal study of 315 students (black: 23 females, 19 males; white: 142 females, 131 males) was conducted in the public schools of Obion County, Tennessee, between 1987 and 1992. BMI and BMI z scores were calculated. The CVR task was a series of video games (taking approximately 10 minutes to play) given to the same students in their third-, fourth-, fifth-, seventh-, and eighth-grade years. CVR was defined as the change in blood pressure (delta_BP) or heart rate (delta_HR) between before playing and while playing the video game. Positive parental history of HTN (27.6%) was defined as at least 1 parent with HTN. Multivariable regression analyses were performed to estimate the effects of parental HTN on children's BMI and CVR over time. RESULTS: Children with parental HTN had significant higher BMI, BMI z score, and R_BP than did children without parental HTN (BMI: 21.6 vs 19.9, P = .001; BMI z score: 1.6 vs 1.1, P = .003; R_SBP: 112.6 vs 110.4 mm Hg, P = .01; R_DBP 62.7 vs 60.6 mm Hg, P = .003) after adjustment for covariates. Increased CVR was observed in children with parental HTN compared with children without parental HTN but was statistically significant only for SBP (delta_SBP: 17.2 vs 14.9 mm Hg; P = .01) after adjustment for covariates. CONCLUSIONS: Parental HTN independently predicted children's BMI, BMI z score, resting BP, and BP reactivity.