Ambulatory blood pressure monitoring in children with aortic coarctation and kidney transplantation.

BACKGROUND: Ambulatory blood pressure monitoring (ABPM) has been found to be of significant importance in clinical practice because numerous blood pressure (BP) measurements may be made throughout the 24-hour period. OBJECTIVE: To assess the clinical utility of ABPM in children with secondary hypertension. METHODS: We studied 37 patients (21 boys and 16 girls), with a mean age of 16.4 +/- 4.1 years, after kidney transplantation and 38 patients (27 boys and 11 girls), with a mean age of 10.2 +/- 2.1 years, after surgical correction of aortic coarctation. Data, expressed as mean +/- SD, were analyzed after dividing the patients into 4 groups. Group A consisted of 25 patients receiving antihypertensive therapy; group B included 12 patients not receiving antihypertensive therapy. Group C included 25 patients operated on before 3 years of age (8 +/- 7 months of age); group D included 13 patients operated on after 3 years of age (74 +/- 29 months of age). RESULTS: In groups A and B, casual BP measurement showed that 16 of 37 patients (43%) were hypertensive; 24-hour ABPM detected a larger number of patients who were hypertensive (23 of 37, 62%); there were 18 in group A and 5 in group B. In groups C and D, casual BP measurement identified 6 of 38 (15%) patients as hypertensive, whereas 24-hour ABPM again identified a higher number (13 of 38, 34%). CONCLUSIONS: Our findings confirm that 24-hour ABPM is more sensitive than casual BP in detecting abnormal BP in patients at high risk for secondary hypertension.

Renin-angiotensin-aldosterone system in healthy subjects aged ten to eighteen years.

We obtained normative data for plasma renin activity (PRA) and plasma aldosterone concentration from a biracial sample of 195 healthy, normotensive children and adolescents aged 10 to 18 years. The sample included 119 boys and 76 girls, of whom 103 were black and 92 were white. The mean PRA value (+/- SD) was 2.52 +/- 1.95 ng/ml per hour, with minimal and maximal values of 0.1 and 13.50 ng/ml per hour. The mean plasma aldosterone concentration was 12.56 +/- 8.59 ng/ml, with minimal and maximal values of 1.6 and 50.1 ng/ml. We also examined the effects of subject characteristics and electrolyte intake. The slope relating sodium excretion to PRA was negative and highly significant (slope = -0.01; p < 0.003). The slope relating PRA to plasma aldosterone concentration was positive and highly significant (slope = 1.59; p < 0.0001). We did not observe differences in either variable as a function of age, sex, race, or family history of hypertension. These results suggest that differences based on race and family history of hypertension observed in adults are not present in youth.

Effect of age and serum creatinine on endogenous digoxin-like substances in infants and children.

An apparent digoxin-like immunoreactive substance(s) (DLIS) was evaluated in 374 pediatric patients, 0 to 72 months of age, not receiving digoxin. The relationship between DLIS presence or concentration and age, weight, gender, race, and serum creatinine was investigated. Twenty-seven percent of patients had a positive apparent DLIS concentration (greater than or equal to 0.2 ng/ml). The mean +/- SD concentration of DLIS in the positive group was 0.39 +/- 0.18 ng/ml (range 0.2 to 1.37 ng/ml). Patients in the DLIS-positive group were younger than those in the negative group (P less than 0.01). Although a greater percentage of infants younger than 6 months of age had measurable DLIS, the mean DLIS concentrations, when present, were not significantly different for all age groups (P greater than 0.05). No significant relationship was found between race or gender and DLIS. A weakly positive correlation between serum creatinine concentration and DLIS was noted (r = 0.22, P less than 0.03), but elevated serum creatinine measurements (greater than 0.6 mg/dL) did not correlate with DLIS concentration. These results support the hypothesis that the presence of DLIS is age related, but DLIS appears to be present in a much larger and older population of pediatric patients than previously reported.

Responses to ergometer exercise in a healthy biracial population of children.

To determine normal values for the exercise variables heart rate, blood pressure, maximal workload, physical working capacity index, J point displacement, and ST segment slope, we stress tested 405 healthy children. We analyzed the data for four body surface area-determined groups, to discover whether there were any racial differences between healthy white children and black children. There were numerous racial differences in blood pressure, maximal workload, and physical working capacity index; there were no differences in the heart rate values. The incidence of false-positive J point displacement was less than or equal to 3% when the PR isoelectric line method was used. The ST segment slope in healthy children was always greater than zero at maximal exercise. Thus, norms for exercise variables must be expressed in relation to both sex and race. The nomograms presented in this report provide an easy-to-use set of normative data for cycle ergometer stress testing in children.

Blood pressure response to dynamic exercise in healthy children--black vs white.

In order to determine normal values for systolic blood pressure response to cycle ergometer stress testing in children, we performed 405 studies in subjects from 6 to 15 years of age, of whom 184 were black and 221 were white. We analyzed the data in relation to sex, color, age, and body surface area. Resting systolic blood pressure showed no differences between groups of black and white children, analyzed either by age or surface area. Peak exercise blood pressures were higher in the black females, in comparison to their white counterparts, only when separated into groups by body surface area. The black males had higher exercise blood pressure values than the whites, both by age and surface area evaluation. Our data suggest a difference in the blood pressure response to dynamic exercise within the black population. Further studies are needed to define the mechanism of this difference and whether this difference may provide a clue to the identification of children at increased risk for developing hypertension later in life.