Elaine S. Willey

Race and gender influence ambulatory blood pressure patterns of adolescents.

&NA; The purpose of this study was to examine ambulatory blood pressure and heart rate patterns in healthy, normotensive adolescents and to determine the influence of race and gender on these patterns. Ambulatory blood pressure recordings were performed on 199 adolescents; 42 were black males, 55 were white males, 65 were black females, and 37 were white females. The mean age (±SD) was 13±2 years. Blood pressure readings were obtained with an automatic, noninvasive recorder. Black adolescents and white adolescents had similar blood pressures while awake (116/69 vs. 116/69 mm Hg), with boys having higher levels of systolic blood pressure (118 vs. 114 mm Hg) and comparable levels of diastolic blood pressure (69 vs. 69 mm Hg) relative to girls. The patterns while the adolescents were asleep, however, were different. White boys (106 mm Hg), white girls (105 mm Hg), and black girls (105 mm Hg) had similar systolic blood pressures during sleep. Black boys (112 mm Hg), however, had significantly higher systolic blood pressures while asleep. Black adolescents, as a group, had significantly higher diastolic blood pressures than white adolescents while asleep (64 vs. 61 mm Hg). Changes in blood pressure from awake to asleep were not related to changes in heart rate. Results of this study indicate that both race and gender are important determinants of the diurnal pattern of blood pressure and heart rate in adolescents. (Hypertension 1989;14:598‐603)

Sodium excretion and racial differences in ambulatory blood pressure patterns.

The influence of Na+ excretion and race on casual blood pressure and ambulatory blood pressure patterns was examined in a biracial sample of healthy, normotensive children and adolescents (10–18 years; n=140). The slopes relating 24-hour urinary Na+ excretion to systolic blood pressure were different for both black and white subjects for casual blood pressure (p<0.001) and blood pressure during sleep (p<0.03). For casual blood pressure, the slope was significant for black subjects (β=0.17;p<0.001) but not for white subjects. For blood pressure during sleep, the slope was again significant for black subjects (β=0.08; p<0.0l) but not for white subjects. Na+ excretion was also related to awake levels of systolic blood pressure for black subjects (β=0.08, r=0.36; p<0.01), although the slopes for both black and white subjects were not significantly different. Further analyses indicated the results were not due to racial differences in 24-hour urinary K+ excretion. However, plasma renin activity was marginally related to Na+ excretion in white subjects (r=0.22; p<0.06) but not black subjects, a finding that is consistent with previous studies. Na+ excretion was not associated with diastolic blood pressure or heart rate in either group under any condition. The results of this study support research that has demonstrated a stronger relation between Na+ handling and casual blood pressure in black subjects and extend these findings to blood pressure while the subject is both awake and asleep.

Aerobic fitness and the diurnal rhythm of blood pressure in adolescents.

We examined the effects of aerobic fitness and race on the diurnal rhythm of blood pressure of 175 healthy adolescents who performed a cycle ergometer maximal exercise test while oxygen consumption was measured. A median split of maximum oxygen consumption for boys and girls separately classified them as either “more-fit” or “less-fit” subjects. Ambulatory blood pressure recordings were also performed, and the data were analyzed for means while subjects were awake and asleep. Less-fit black boys had higher systolic pressures than more-fit black boys while awake (124 vs. 115 mm Hg;p < 0.009) and asleep (117 vs. 108;p < 0.001). Less-fit black boys also had higher systolic pressures than less-fit white boys while awake (114;/?< 0.002) and asleep (105; /?< 0.001), and they had higher systolic pressures than more-fit white boys while asleep (105;p < 0.01). Less-fit black girls had higher systolic pressures than more-fit black girls while awake (116 vs. 109;p < 0.004) and asleep (109 vs. 100;p < 0.001). Less-fit black girls also had higher diastolic pressures than more-fit black girls while awake (71 vs. 66; p < 0.002) and asleep (66 vs. 61;p < 0.001). In addition, less-fit black girls had higher systolic pressures than more-fit white girls while asleep (104; p < 0.05), higher diastolic pressures than more-fit white girls while awake (68;p < 0.05) and asleep (60; p < 0.006), and higher diastolic pressures than less-fit white girls while asleep (61;p < 0.001). These findings indicate that fitness influences ambulatory blood pressure profiles, particularly in black adolescents.

Race and cardiovascular reactivity. A replication.

In a previous study, we reported that black children demonstrated greater cardiovascular reactivity than did white children to the psychological stress of a television video game. Reliance on urban volunteers and the wide age range of the children may have limited conclusions concerning the generalizability of those results. In the present study, 481 of 484 children enrolled in the third grade of the public schools of an entire rural county in Tennessee were examined with the same video game procedure used previously. Results indicated greater heart rate and blood pressure reactivity among black children than among white children. Thus, the previous results were replicated. The greater prevalence of hypertension among black adults may relate to the greater reactivity among black children; reactivity may be either a marker or a mechanism in the development of hypertension.

Race, sex, and family history of hypertension and erythrocyte sodium pump [3H]ouabain binding.

We studied the binding properties of [3H]ouabain to erythrocytes from normotensive children (n=83) between the ages of 10 and 18 years (mean resting arterial pressure: 102/57 mm Hg) from normotensive and essential hypertensive parents. Arterial blood pressures of 101/57 and 104/57 mm Hg (subjects with normotensive and hypertensive parents, respectively) were not significantly different between the two groups. Forty-four children had normotensive parents and 39 had hypertensive parents, 51 were white and 32 were black, and 41 were girls and 42 were boys. By using the [3H]ouabain-binding technique, we determined the density of sodium pump sites and the equilibrium dissociation constants in erythrocytes from these children. Possible effects of race, sex, or parental hypertension status on pump sites and dissociation constants were tested with a three-way analysis of variance (ANOVA). Race had a major effect on the dissociation constant: blacks had a significantly higher value than did whites (p=0.002). We also found a race by sex by parental hypertension status interaction (p=0.04) with black girls with hypertensive parents having the highest value. There was no effect of race, sex, or status on sodium pump site density. Age, height, weight, resting arterial blood pressure, and plasma Na+ and K+ concentrations did not correlate with the dissociation constants. These data suggest that, among the groups we studied, black girls with hypertensive parents had erythrocytes with the lowest binding affinity for ouabain. In addition, race had a strong effect on the binding affinity of ouabain to human erythrocytes, with blacks having lower affinities than whites. Because the black population has a much higher prevalence of hypertension than the white population and black women have the highest prevalence of hypertension, this decrease in the affinity of ouabain-binding to the erythrocyte sodium pump molecule may be a possible predictor of adult hypertension.

Doppler estimation of pressure gradient in pulmonary stenosis: maximal instantaneous vs peak-to-peak, vs mean catheter gradient.

SummaryWe undertook a study to identify the hemodynamic significance of a Doppler-derived gradient across a stenotic pulmonary valve. Furthermore, we attempted to define the optimal plane for velocity data acquisition. A total of 17 children with valvar pulmonary stenosis were evaluated using Doppler echocardiography. Flow-velocity profiles were obtained from both the parasternal and subxiphoid windows. Ten of 17 patients were studied before and after balloon valvotomy. Therefore, 27 different transvalvar gradients were assessed by Doppler and these data were compared with the catheter-derived maximal instantaneous, peak-to-peak, and mean pressure gradients. The maximal Doppler gradient correlated well with the catheter-derived peak-to-peak pressure gradient (r=0.95) and catheter maximal instantaneous pressure gradient (r=0.95). Although these correlation coefficients were similar, the Doppler maximal gradient consistently overestimated the peak-to-peak catheter gradient by as much as 25%–40%. Such an overestimation was not observed when we compared the maximal Doppler gradient with the catheter-derived maximal instantaneous gradient. Moreover, the regression line of the latter comparison closely approximated the line of identity. The correlation coefficient between Doppler mean and catheter mean gradients was only 0.91. Doppler velocities were best derived when multiple transducer positions were employed to interrogate pulmonary artery velocity.

CARDIOVASCULAR RISK FACTORS IN CHILDREN: SOCIOECONOMIC VARIABLED AFFECTING THE COLLECTION OF VALID DATA

Though physical fitness and activity level (AL) have been associated with disease and mortality reductions, few studies have examined methods applicable to epidemiologic studies of children. In this study, parents classified their childs AL as (1) sedentary, (2) slightly active, or (3) active. Children (25 black females [BM], 32 white females [WM], 47 black males [BM], and 52 white males [WM] aged 6-18) completed a maximal exercise test. AL reports correlated significantly with maximal oxygen consumption (VO2 max) largely due to the association among WM. Analysis of household (HH) demographic variables indicated that in mother-headed HH, AL reports were uncorrelated with VO2 max (Table of means and correlations; *p≤.05; **p≤.01). Indirectly, race affected AL reports, i.e., 59% of black children were from mother-headed HH versus 13% of white children. Thus, a single question provided an approximation of childrens fitness; the accuracy was affected by family structure, e.q., mothers who head HHs may have less time to observe their children.