Blood pressure nomograms for children and adolescents, by height, sex, and age, in the United States

Short-term predictors of overweight in early adolescence

OBJECTIVE

To identify short-term predictors of risk for overweight in early adolescence in a sample of Caucasian origin subjects, in Cyprus.

SUBJECTS

A total of 357 subjects (178 males) with baseline age 11.5+/-0.4 y were re-evaluated after a mean of 1.6+/-0.5 y.

MEASUREMENTS

Body weight and height, calculated body mass index (BMI), and blood pressure at baseline and follow-up. Serum lipids were determined at baseline. Obesity and overweight were defined at baseline and follow-up, according to the International Obesity Task Force data set. Socioeconomic class was determined. Self-reported parental weight and height were used to calculate the parental BMI. BMI tracking and changes in BMI categories were calculated (with 95% confidence interval (CI)). The future risk of overweight in baseline normal weight subjects was predicted using logistic regression analyses, where only normal weight subjects at baseline were included.

RESULTS

More males remained in the overweight or obese category than females: 86.7% (95% CI: 73.2, 94.9) vs 71.8% (95% CI: 55.1, 85.0), respectively, P=0.03. The identified predictors for future overweight were paternal obesity, odds ratio (OR): 7.1 (95% CI: 1.3, 38.0), systolic blood pressure >95th percentile, OR: 8.9 (95% CI: 1.9, 41.7), high triglyceride levels, OR: 4.2 (95% CI: 1.0, 16.9) and low HDL-cholesterol levels, OR: 7.6 (95% CI: 1.7, 34.3).

CONCLUSIONS

Triglycerides and HDL-cholesterol levels have been proved predictors for overweight in early adolescence for the first time. The different sex pattern in BMI tracking observed, and also the different environmental influences on future overweight risk compared to other studies, indicate that local circumstances should be considered when implementing national intervention strategies for the prevention of obesity.

Effect of enalaprilat on postoperative hypertension after surgical repair of coarctation of the aorta

OBJECTIVE

Hypertension in pediatric patients after surgical repair of coarctation of the aorta can be difficult to control and may lead to morbidity. The renin-angiotensin system mediates at least part of this hypertension. Enalaprilat, the only intravenous angiotensin-converting enzyme inhibitor, is used to treat hypertension in pediatric patients in other settings. However, its effect on postoperative hypertension during the early postoperative period in patients undergoing surgical repair of coarctation of the aorta is unknown.

DESIGN

Prospective, randomized, double-blind study.

SETTING

Operating room and the pediatric intensive care unit.

PATIENTS

Fourteen consecutive pediatric patients between the ages of 1 and 18 yrs scheduled to undergo surgical repair of coarctation of the aorta.

INTERVENTIONS

Patients were randomized to receive enalaprilat or saline placebo. Infusions were begun intraoperatively within 15 mins of aortic repair and repeated every 6 hrs.

MEASUREMENTS AND MAIN RESULTS

Plasma renin activity was measured at baseline and on postoperative day 1. Blood pressure was determined at 30 mins and at 2, 4, and 6 hrs after infusion and scored relative to the preoperative blood pressure. The blood pressure in the enalaprilat group was consistently lower at 30 mins, 2 hrs, and 4 hrs after infusion (p <.05), but not at 6 hrs. Plasma renin activity was significantly lower in the placebo group on postoperative day 1. Length of stay in the pediatric intensive care unit trended shorter in the treated group.

CONCLUSIONS

Conclusions are limited by a small cohort. Angiotensin-converting enzyme inhibitor therapy resulted in improved blood pressure control after coarctation repair. Further improvement of blood pressure control may be achievable by use of a larger dose of enalaprilat or a 4-hr enalaprilat-dosing interval.

Ambulatory blood pressure, left ventricular mass, and conduit artery function late after successful repair of coarctation of the aorta

OBJECTIVES

We sought to evaluate the determinants of hypertension during daily life and left ventricular (LV) hypertrophy in patients with successfully repaired coarctation of the aorta (CoA), as well as their relationship to abnormalities of arterial function.

BACKGROUND

Arterial hypertension may recur late after repair of CoA, which is related to a more adverse outcome. Furthermore, patients with normal resting blood pressure (BP) may have hypertension during daily life and LV hypertrophy. The determinants of these two adverse prognostic factors have not been investigated.

METHODS

We studied 72 patients (9 to 58 years of age) who underwent coarctation repair at age 0.1 to 480 months (42 [60%] at <1 year) and had been followed up for 155 +/- 76 months. They underwent ambulatory BP monitoring, echocardiography for LV mass, studies of brachial artery responses to flow (i.e., flow-mediated dilation [FMD]) and glyceryl trinitrate (GTN), and determination of pulse wave velocity (PWV) and measures of arterial reactivity and stiffness. Findings were compared with those of 53 healthy volunteers.

RESULTS

Patients had higher 24-h systolic BP and LV mass than controls. Both endothelium-dependent FMD and the response to the smooth muscle dilator GTN were reduced, and PWV was increased. There was a negative independent correlation between GTN response and 24-h systolic BP in both patients and control subjects. Systolic BP at 24 h was an independent predictor of LV mass, having an accentuated impact in coarctation subjects as compared with controls.

CONCLUSIONS

In patients with repaired coarctation, reduced vascular reactivity is associated with hypertension during daily life and with increased LV mass, both of which are important predictors for late morbidity and mortality.

Increased blood pressure in adolescents of low socioeconomic status with short stature

The nutritional programming hypothesis, which has been studied since the 1970s, proposes that intrauterine undernutrition continuing during the first years of life causes permanent metabolic disorders. These alterations are amplified with time, depending on the quality of the diet and on environmental factors. The aim of this cross-sectional study was to detect blood pressure alterations in teenagers with nutritional deficit. The study sample consisted of 53 adolescents living in shantytowns of São Paulo City, Brazil; 27 boys and 26 girls ranging in age from 11 to 16 years were studied. Weight, height, skinfold thickness, and blood pressure were measured during a medical visit. Anthropometric data were compared with the reference values of the National Center for Health Statistics and Frisancho, and arterial pressure data were compared with the reference values of the 1996 Task Force. The adolescents studied are among the 10% poorest stratum of the Brazilian population, with a per capita income of U.S. $45/month. The anthropometric results revealed nutritional deficiencies for the entire sample. The major marker of malnutrition was height, with a mean height deficit of 7 cm among boys and of 5 cm among girls. The overall prevalence of arterial (diastolic) hypertension for the sample was 21% (95% confidence interval 10%-32%). No significant difference was observed between sexes. The prevalence of cases with a systolic or diastolic arterial pressure above the 90th percentile, adjusted for height, was 51% ( n=27) (95% confidence interval 37%-65%); 6% ( n=3) of these individuals had simultaneous systolic and diastolic arterial hypertension. In conclusion, the prevalence of arterial hypertension was elevated among malnourished adolescents. The mechanisms involved in the genesis of hypertension seem to be related to malnutrition during an early phase of life, supporting the programming hypothesis.

Casual blood pressure and ambulatory blood pressure measurement in children

Some epidemiological studies on blood pressure among children and adolescents have revealed that blood pressure levels in childhood are the strongest predictors of adult blood pressure levels. In the adult population, hypertension causes a two to threefold increase in an individual's risk of cardiovascular morbidity. Cardiovascular risk depends on blood pressure itself, coexistent risk factors and whether there is hypertensive end-organ damage. Therefore, accuracy in determining blood pressure is essential and a standardized protocol should be considered for blood pressure measurement, which would make the comparison of results obtained by different studies in different countries possible. This article reviews the main determinants of accuracy for casual and ambulatory blood pressure measurements in children.

Increasing myocardial contraction and blood pressure in C57BL/6 mice during early postnatal development

Knowledge of the developmental changes of cardiovascular parameters in the genetic background of a mouse strain is important for understanding phenotypic changes in transgenic or knockout mouse models for heart disease. We studied arterial blood pressure and myocardial contractility in mice of the common background strain C57BL/6, aged 21 days [postnatal day 21 (P21)] to 580 days. Heart rate increased during maturation from 396 beats/min at P21 to 551 beats/min at postnatal day 50 (P50), and mean arterial blood pressure increased in parallel from 86 to 110 mmHg and remained constant afterward. Echocardiographically determined left ventricular myocardial wall dimensions (R = 0.79, P < 0.0001) and left ventricular mass calculated using the area-length algorithm correlated strongly with histomorphometrical measurements (R = 0.93, P < 0.001). Sarcomere shortening records from isolated ventricular myocytes used as a measure for myocardial contractility revealed a negative shortening-frequency relation under a pacing frequency of 2 Hz and a positive relation above 2 Hz. Shortening amplitudes recorded from P21 myocytes were smaller, and the shortening-frequency relation was less steep than in adult myocytes. A stimulation pause was followed by a negative "staircase" at pacing frequency of < or =6 Hz and a positive staircase at > or =6 Hz. P21 myocytes developed positive staircases at 8 and 10 Hz, and adult myocytes also developed them at 6 Hz. Blood pressure increase during maturation until P50 may originate from increasing single cardiomyocyte contractility.

Blood pressure distribution in a Hungarian adolescent population: comparison with normal values in the USA

OBJECTIVES

To describe the blood pressure characteristics and distribution of all adolescent high school students (aged 15-18 years) in Debrecen (total population 230 000), Hungary. To define threshold values for normal blood pressure by age-, sex- and height-specific groups. To compare our data with results from a USA meta-analysis, which forms the basis of current guidelines.

PARTICIPANTS AND METHODS

All young people attending high school in Debrecen (final sample = 10 359) participated in the study. After they had rested for 10 min, three blood pressure measurements were taken from the right upper arm, separated by 5 min intervals. All measurements were obtained by a validated, automated, digital Omron M4 device.

RESULTS

The 50th, 90th and 95th percentile values of blood pressure were defined by dividing the adolescent population into age-, sex- and height-specific subgroups. In comparison with USA guidelines, in our sample the systolic blood pressure of boys in the different subgroups was 6-11 mmHg greater, whereas this difference was less marked for girls (1-5 mmHg). There were no marked differences in diastolic blood pressure, but our values were slightly lower.

CONCLUSIONS

Our findings demonstrate the influence of geographical and ethnic variations on blood pressure. Acceptance and use of non-population-specific blood pressure distributions may lead to under- or overdiagnosis of adolescent hypertension. The use of geographically more relevant data should be encouraged.

Total peripheral vascular resistance in pediatric renal transplant patients

BACKGROUND

Abnormal cardiovascular reactivity at rest and during physical exercise may be a risk factor for left ventricular hypertrophy (LVH) in pediatric renal transplanted (Tx) patients. Data on total peripheral vascular resistance (TPR) are not available.

METHODS

Eleven renal Tx patients treated with cyclosporine (7 females and 4 males; mean age 14.6 +/- 3.3 years; mean time since transplantation 43 +/- 35 months) were evaluated for 24-hour blood pressure (BP), TPR and echocardiographic left ventricular mass (LVM). TPR values of patients were compared with data of a group of 11 healthy controls matched for sex and age.

RESULTS

Twenty-four-hour ambulatory blood pressure monitoring showed that all but one patient had normal daytime BP values and six patients showed a reduced or inverse nocturnal dip. LVH was found in 72% of the patients. In comparison with healthy controls, patients showed significantly elevated TPR at rest and during exercise suggesting an increased vascular tone. The degree of LVH in these patients is severe and appears disproportionate to the BP values.

CONCLUSION

The high incidence of LVH can reflect an augmented cardiovascular reactivity associated with a disturbed circadian pattern. The increase in TPR and the reduction of the nocturnal fall of BP also might contribute to the development of LVH in young renal Tx patients.

Ambulatory blood pressure monitoring (ABPM) in normotensive adolescents with type 1 diabetes

OBJECTIVE

To evaluate 24-h ambulatory blood pressure monitoring (ABPM) for early detection of hypertension in adolescents with type 1 diabetes mellitus (DM1).

DESIGN

Patients underwent fundoscopy, albuminuria determinations, two repeated autonomic cardiovascular tests, heart rate (HR) variation during deep breathing and blood pressure (BP) variation during sustained handgrip. Twenty-four hour BP measurements were taken automatically by an oscillometric portable monitor.

SETTING

A specialty pediatric diabetes clinic and subjects' homes.

PARTICIPANTS

Eighteen children aged 10-17 yr with 2+ yr of DM1, without long-term complications, and 34 controls.

RESULTS

Higher ambulatory HR during the day than at night did not differ between DM1 subjects and controls. Mean systolic (s) and diastolic (d) BP in patients during the daytime were not significantly different from the control values. During the night, both sBP and dBP mean values in patients differed from those of controls. Statistical analysis of day and night HR and BP measurements were not different in both groups. The percentage decrease during the night in sBP and dBP was significantly smaller in patients than in controls. There were no differences by gender or duration of diabetes > or < 5 yr or by HbA1 above and below 10%. No difference in nocturnal sBP or dBP decline was observed between patients with or without abnormal autonomic test results.

CONCLUSION

ABPM is more reliable than casual BP measurement in detecting early BP alterations during the night, before the appearance of microalbuminuria, in young patients with DM1.

Low body weight is a risk factor for proteinuria in multiracial Southeast Asian pediatric population

We examined the impact of low birth weight and low current body weight on proteinuria in a cohort of children participating in the pilot study of a nationwide screening program. Two thousand eighty-three children underwent screening examinations, including birth history, anthropometric measures, blood pressure measurements, and urinalysis. On this study, children with proteinuria were found to have significantly lower mean body weights compared with children without proteinuria (38.7 +/- 7.6 versus 42.8 +/- 11.0 kg; P < 0.001). Progressively decreasing body weights were associated with increasing degrees of proteinuria (42.8 +/- 11.0, 38.9 +/- 7.6, and 37.2 +/- 8.5 kg for 0, 30, and 100 mg/dL of protein, respectively; P = 0.05). When examined by multiple logistic regression, low body weight was associated with a 1.8-fold greater risk (95% confidence interval, 1.27 to 2.64; P = 0.0019) for proteinuria after adjusting for potential confounders. There were trends for lower birth weights in children with proteinuria (3,047.6 +/- 445.2 versus 3,175.0 +/- 608.6 g for proteinuric and nonproteinuric groups, respectively; P = 0.275) and a greater prevalence of children with birth weights less than the 25th percentile (31.3% versus 25.0%; P = 0.786). The relationship between low current body weight and proteinuria was not explained by differences in blood pressure. In conclusion, low current body weight had a stronger relationship with proteinuria than low birth weight in this pediatric population. We hypothesize that the effect of low birth weight on renal disease may be significantly enhanced by environmental factors that result in a low current body weight.

Linear catch-up growth does not increase the risk of elevated blood pressure and reduces the risk of overweight in males

OBJECTIVES

To analyse if size at birth is associated with blood pressure and body mass index (BMI) at conscription in males, and if linear catch-up growth in height modifies these associations.

DESIGN

A population-based cohort study of 276 033 single-born males aged 17-24. Information from the Swedish Birth Register was individually linked to the Swedish Conscript Register. Systolic blood pressure was standardized for final height.

RESULTS

Compared to males not being small for gestational age at birth, males being light for gestational age [<-2 standard deviation scores (SDS)] were at increased risk of high systolic blood pressure [odds ratio (OR) 1.33; 95% confidence intervals (CI) 1.20-1.46], and a short adult stature was associated with a further increased risk [OR 1.65 (CI 1.13-2.40)]. Being born short for gestational age (<-2 SDS) was associated with a slightly increased risk of high systolic blood pressure [OR 1.16 (CI 1.04-1.29)], and linear catch-up growth in height did not increase this risk. Males born short for gestational age, who also were short at conscription, had an increased risk of a high BMI [OR 1.65 (CI 1.25-2.19)].

CONCLUSIONS

Males born light for gestational age have an increased risk of high systolic blood pressure, especially if they end up with short adult stature. Being born short for gestational age is associated with a slightly increased risk of high systolic blood pressure, and catch-up growth is not associated with a further risk. Lack of catch-up growth is, among males born short for gestational age, associated with an increased risk of overweight.

Screening for eligibility in the study of antihypertensive medication in children: experience from the Ziac Pediatric Hypertension Study

BACKGROUND

The FDA Modernization Act has resulted in an increase in pediatric trials of antihypertensive medications. As experience is limited in children to guide the planning of these studies, we reviewed data from the Ziac Pediatric Hypertension Study to determine patterns of early study termination to help future studies.

METHODS

For inclusion, subjects aged 6 to 17 years were required to have an average systolic blood pressure (SBP) or diastolic blood pressure (DBP) above the 95th percentile at the last of three visits during 2 weeks of single-blind placebo screening. Early study termination was defined as early termination for any reason. Screening termination was defined as normalization of blood pressure (BP) during the placebo screening phase.

RESULTS

Early study termination rate was 27% (38 of 140 subjects). The most common reason was screening termination due to normalization of BP, accounting for 63% of all early study terminations. Among screening termination subjects who completed three screening visits, SBP was higher (P < .001) at visit 1 (129+/-8 mm Hg) than at visit 2 (123+/-7 mm Hg) or visit 3 (121+/-8 mm Hg), but did not differ between visits 2 and 3. Screening termination occurred in 15% with isolated SBP hypertension, and 21% with isolated DBP hypertension. At randomization, 83% had SBP hypertension and 53% had DBP hypertension.

CONCLUSIONS

These data suggest that SBP hypertension should be part of inclusion criteria to increase enrollment and reduce the rate of screening termination, and that 1-week placebo screening is necessary and sufficient to minimize inclusion of transiently hypertensive subjects.

Tracking of blood pressure in Australian children

OBJECTIVE

Tracking of blood pressure (BP) from childhood occurs in populations but, for individuals, prediction of adult BP from childhood levels is poor. We examined factors that may influence tracking of BP to identify better predictors of higher BP in early adult life.

DESIGN

A prospective study of children recruited at the age of 9 years by random sampling of Perth metropolitan schools stratified by socio-economic status.

SETTING

Community based with re-surveys 3-yearly for 9 years.

PARTICIPANTS

A total of 516 boys and 520 girls at 9 years; 680 boys and 630 girls at 12 years; 318 boys and 300 girls at 15 years; 330 men and 326 women at 18 years.

MAIN OUTCOME MEASURES

Systolic (SBP) and diastolic (DBP) BP.

RESULTS

Persistence in the highest quartile for SBP between surveys was seen in 34-48% of subjects and in 37% between the ages of 9 and 18 years. The proportion increased to around 60% in those in the highest quartile for body mass index (BMI), to 70% in those in the highest quartile for change in BMI and to 60% if there was a family history of hypertension. In log-linear models, persistence in a quartile for SBP was significantly related to a family history of hypertension, previous SBP, BMI and change in BMI. Relationships were similar for DBP.

CONCLUSIONS

Excessive weight gain in adolescence and a family history of hypertension substantially increase the risk of higher BP persisting into early adult life. Recognition of children at risk would allow early intervention emphasizing weight control with potential long-term benefits.

Anger expression, body fat, and blood pressure in adolescents: Project HeartBeat!

This study explores the potential influence of growth, body/composition, and sexual maturity on the relation of anger expression and blood pressure in adolescents. Baseline data from Project HeartBeat! (82 boys and 85 girls, 14 years of age) examined the ability of anger expression (STAXI scale) to predict blood pressure, after controlling for the effects of ethnicity (African-American/ non-African-American), height, weight, percentage body fat, and sexual maturity. Blood pressures were unrelated to anger expression in models that included the above developmental variables. However, girls scoring high on healthy anger expression ("anger-control") had significantly lower levels of percentage body fat (P = 0.015) independent of the above factors. The literature suggests that body fat or body mass is often, though not unanimously, associated with unhealthy forms of anger expression in adolescents. Research is required into the biological, social, and behavioral origins of the association between body fat and anger expression. Height and sexual maturity, virtually ignored in this literature, should be included in future research.

The use of short-acting nifedipine in pediatric patients with hypertension

OBJECTIVE

To evaluate the use of short-acting nifedipine for treatment of severe hypertension in children.

STUDY DESIGN

A retrospective chart review of 520 nifedipine doses given for severe hypertension in 117 pediatric patients was completed. Nifedipine dose, systolic and diastolic blood pressures before and within 2 hours of the dose, and side effects were recorded. Pre- and post-dose mean arterial pressure (MAP) and percent reductions in MAP and systolic and diastolic blood pressure were calculated. Age, dose, primary diagnosis, and use of other antihypertensive agents were examined with respect to blood pressure reduction.

RESULTS

Of the doses received, 35% were associated with > or =25% reduction in MAP, a degree of MAP reduction previously associated with hypertension treatment complications. MAP percent reduction was correlated with nifedipine dose adjusted for weight (r = 0.24, P<.001). Mean nifedipine doses per kilogram were larger in patients who had > or =25% MAP reduction compared with those who had <25% MAP reduction (0.26 +/- 0.12 mg/kg vs. 0.21 +/- 0.11 mg/kg, F = 29.01, P <.001). Adolescents received lower nifedipine doses per kilogram and had lower percent reduction in blood pressure compared with younger children. No clinically significant side effects were noted after administration of nifedipine.

CONCLUSION

Precipitous reductions in blood pressure are ameliorated by decreasing the initial nifedipine dose to < or =0.25 mg/kg in pediatric patients. Short-acting nifedipine use in pediatric patients with hypertension in a hospital setting is safe.

The measurement of blood pressure and the detection of hypertension in children and adolescents

Despite the publication of several expert committee guidelines for the measurement of blood pressure (BP) and the diagnosis of hypertension in children and adolescents, it was our perception and clinical experience that there still appeared to be a general lack of standardisation of BP measurement techniques and little consensus on the criteria for diagnosing hypertension. To investigate this further, we have conducted a postal survey of consultant-grade paediatricians who were members of the British Paediatric Association (BPA). A total of 1500 questionnaires were sent out and 708 analysable replies were received (47.1%). This showed that 68.6% of paediatricians routinely measured BP, at least on one occasion, in children or adolescents attending their outpatient clinics, 17.7% started at or soon after birth, 12.3% started at the age of 1 year, 20.0% at 3 years, 12.0% from 7 years of age and 3.5% from the age of 13. Only 60.5% reported that they had a choice of four or more different cuff sizes in their clinic. Forty-one percent of respondents reported that the BP was always or sometimes measured by nurses. Fifty-one percent of respondents measured diastolic BP at the phase of muffling of sound (Korotkoff phase IV), 31.9% used the disappearance of sound (phase V) whilst 15.9% claimed that they measured both end-points. The criteria for diagnosing a child as being hypertensive varied greatly; 17.9% reported that they responded to the systolic BP alone, 13.5% to the diastolic BP alone, 65.9% relied on both pressures, and 2.7% responded to either the systolic or diastolic pressure if it was raised. Furthermore, 12.9% diagnosed hypertension if the BP exceeded the 90th percentile in relation to age and 41.8% used the 95th percentile. However 45.3% of respondents employed a higher dividing line. In hospitalised children, leg blood pressures were measured routinely by 30.3%, although a further 44.0% would do so if aortic coarctation or other vascular diseases were suspected. Despite considerable variation in clinical practice, techniques and criteria, only 11.4% of clinicians would manage the patients themselves, with the remainder referring the child on to the appropriate specialist. The survey suggests a general lack of standardisation of BP measurement techniques and little consensus on the criteria for diagnosing hypertension amongst paediatricians. Simplified, shortened and updated guidelines on hypertension in paediatric practice and research are needed.

Blood pressure and sexual maturity in adolescents: the Heartfelt Study

This study investigates sexual maturity as a predictor of resting blood pressures independent of other known predictors, in 179 boys and 204 girls 11-16 years of age from the Heartfelt Study. The sample included youth of African (n = 140), Mexican (n = 117), and European and "other" (n = 126) backgrounds. Sexual maturity was assessed during clinical examination of three standard indicators for each sex. Systolic and diastolic blood pressures were higher in children of maturity stages IV and V, compared to stages I-III, in each gender/ethnic group (P < 0.01 in almost all groups). Boys and girls advanced in sexual maturity for their age group, had significantly higher systolic blood pressures (but not diastolic) than the less advanced in linear models that included height, body mass index (BMI), ethnicity, and age as co-predictors. Diastolic blood pressures were predicted by height in boys and by age and the BMI in girls. This analysis, using a very conservative approach, suggests that sexual maturity provides important and independent information on systolic blood pressure in adolescents. Further investigation of its role in 24-hr blood pressures and in blood pressures taken during physical and emotional stress, is recommended.

Perceived stress and blood pressure in early adolescent children

The objective of this investigation was to determine the individual contributions of perceived daily, major, and total stressors to blood pressure in early adolescent children. Toward this goal, cardiovascular risk factors were assessed in 74 6th-grade students. Height and body weight, measured in standard fashion, were used to calculate body mass index (BMI). Waist and hip circumferences and triceps and calf skinfolds were taken to determine the distribution and percentage of body fat, respectively. Seated resting blood pressure was obtained using a mercury sphygmomanometer. The dietary sodium-to-potassium ratio was calculated from a food intake questionnaire. Family history of hypertension was self-reported by participant's parents, and physical activity and perceived stress levels were determined by questionnaire. When added to the hierarchical regression models, the perceived stress variables did not significantly predict any additional variance in systolic or diastolic blood pressure in this early adolescent sample. Additionally, bivariate correlations between the stress variables and blood pressure were nonsignificant. The nonpsychological hypertension risk factors accounted for 25%-35% of the total variance in systolic and diastolic blood pressure. Further, regression analyses revealed that with the exception of BMI and the sodium-to-potassium ratio, no other risk factors were independent predictors of systolic or diastolic blood pressure. Further identification and understanding of environmental precursors of childhood hypertension is recommended.

Obesity in the pediatric patient: cardiovascular complications

The prevalence and severity of obesity are increasing in children and adolescents. This raises concerns about the accompanying cardiovascular complications. Such complications include hypertension, dyslipidemia, type II diabetes which may accelerate vascular disease, left ventricular hypertrophy and pulmonary hypertension due to obstructive sleep apnea. The evaluation of an obese child or adolescent should include careful consideration of these possible cardiovascular complications. If they are present, treatment should be directed at both obesity and the risk factor abnormality. This treatment may be important for prevention of future cardiovascular morbidity and mortality. In addition, research is necessary to better understand the mechanisms by which obesity increases the risk of cardiovascular disease.

Combining annual blood pressure measurements in childhood to improve prediction of young adult blood pressure

Tracking correlations of blood pressure (BP) have been reported between levels measured in a single year during both childhood and adulthood. Because of the variability of BP, these correlations increase with the number of visits and measurements per visit in each year. It remains unclear, however, whether such correlations would improve further by combining BP data collected over several years. From 1978-1981, BP was measured annually in a cohort of 339 children in East Boston, MA, at four visits one week apart with three measurements per visit. Of this cohort, then aged 18-26 years, 316 were re-examined in 1989-1990 at three visits one week apart with three measures per visit. Tracking correlations were estimated from levels measured in a single year as well as means averaged over several years in childhood, adjusting for age, year of measurement, as well as smoking, alcohol and oral contraceptive use. Multivariate models were fit to estimate tracking correlations from childhood to young adulthood adjusting for within-person variability. Using a single year in childhood, these were 0.49 in boys and 0.59 in girls for systolic BP and 0.39 and 0.48 for diastolic BP (all p<0.001). Using the long-term average in childhood and adjusting for variability across years, these values were 0.55 in boys and 0.66 in girls for systolic BP and 0.47 and 0.57 for diastolic BP (all p<0.001). We observed concomitant increases in the predictive value of childhood BP for young adult BP. These results suggest that averaging BP over at least two years during childhood increases tracking correlations and improves the prediction of adult values from childhood levels.

Comparison between casual blood pressure and ambulatory blood pressure monitoring parameters in healthy and hypertensive adolescents

Casual blood pressure measurements were compared with mean ambulatory blood pressure values during wakefulness and sleep in 45 normotensive and 30 hypertensive adolescents of both sexes aged 10-18 years. Two sets of auscultatory casual blood pressure were obtained, one in a pediatric office setting (office blood pressure), performed by the physician, and one in the ambulatory blood pressure monitoring (ABPM) unit, performed by a trained nurse, prior to the initiation of ABPM (pre-ABPM blood pressure). In normotensive and hypertensive subjects of both sexes, the mean office systolic blood pressure (SBP) was lower than the mean pre-ABPM SBP, and the mean office diastolic blood pressure (DBP) was lower than the mean pre-ABPM DBP. In normotensive participants, the mean pre-ABPM SBP/DBP was lower than the mean ABPM SBP/DBP while awake, the mean ABPM SBP/DBP during sleep being lower than the mean ABPM SBP/DBP values while awake and the mean pre-ABPM SBP/DBP. No statistical difference was demonstrated between the mean office SBP and the mean ABPM SBP during sleep, the mean ABPM DBP during sleep being lower than the mean office DBP. The hypertensive adolescents presented a blood pressure profile similar to that of the normotensive group, albeit shifted upwards, with no significant difference between the mean pre-ABPM SBP and the mean ABPM SBP while awake but a higher mean pre-ABPM DBP than mean ABPM DBP while awake. This study suggests that, by evaluating the casual blood pressure in different environment/observer situations, the power of casual blood pressure to predict inadequate blood pressure control, manifested as abnormal ABPM parameters, can be enhanced. Our data indicate ABPM to be the method of choice for the early diagnosis and adequate follow-up of adolescent hypertension.

White coat hypertension in children with elevated casual blood pressure

OBJECTIVE

We reviewed our experience using ambulatory blood pressure monitoring (ABPM) in children referred to a hypertension clinic to determine the frequency of pediatric white coat hypertension (WCH).

STUDY DESIGN

WCH was defined by 3 different diagnostic criteria: (1) mean 24-hour blood pressure (BP) less than Task Force-defined 95th percentile, (2) mean 24-hour BP less than 95th percentile from pediatric normative ABPM data, and (3) mean 24-hour BP less than ABPM 95th percentile and BP load (percentage of BP readings during 24-hour period exceeding the 95th percentile) less than 25%.

RESULTS

Clinic BP values were available in 67 otherwise healthy children who underwent ABPM; 51 had confirmed clinic hypertension by Task Force criteria. WCH frequency in these 51 patients with the stated criteria was 53%, 45%, and 22%, respectively. Elevated BP load was found in 52% (12/23) of patients with normal mean BP.

CONCLUSION

These results suggest that many children referred for casual BP elevation have WCH even by strict diagnostic criteria. ABPM may help differentiate WCH from persistent hypertension, thereby avoiding unnecessary diagnostic evaluation and identifying children most likely to benefit from early intervention.

Relationship of cerebral perfusion pressure and survival in pediatric brain-injured patients

BACKGROUND

Adult brain injury studies recommend maintaining cerebral perfusion pressure (CPP) above 70 mm Hg. We evaluated CPP and outcome in brain-injured children.

METHODS

We retrospectively reviewed the hospital courses of children at two Level I trauma centers who required insertion of intracranial pressure (ICP) monitors for management of traumatic brain injury. ICP, CPP, and mean arterial pressure were evaluated hourly, and means were calculated for the first 48 hours after injury.

RESULTS

Of 188 brain-injured children, 118 had ICP monitors placed within 24 hours of injury. They suffered severe brain injury, with average admitting Glasgow Coma Scale scores of 6 +/- 3. Overall mortality rate was 28%. No patient with mean CPP less than 40 mm Hg survived. Among patients with mean CPP in deciles of 40 to 49, 50 to 59, 60 to 69, or 70 mm Hg, no significant difference in Glasgow Outcome Scale distribution existed.

CONCLUSION

Low mean CPP was lethal. In children with survivable brain injury (mean CPP > 40 mm Hg), CPP did not stratify patients for risk of adverse outcome.

Dominant and recessive inheritance of morbid obesity associated with melanocortin 4 receptor deficiency

Over 20 severely obese subjects in 11 independent kindreds have been reported to have pathogenic heterozygous mutations in the gene encoding the melanocortin 4 receptor (MC4R), making this the most common known monogenic cause of human obesity. To date, the detailed clinical phenotype of this dominantly inherited disorder has not been defined, and no homozygous subjects have been described. We determined the nucleotide sequence of the entire coding region of the MC4R gene in 243 subjects with severe, early-onset obesity. A novel two-base pair GT insertion in codon 279 was found in two unrelated subjects, and four novel missense mutations, N62S, R165Q, V253I, C271Y, and one mutation (T112M) reported previously were found in five subjects. N62S was found in homozygous form in five children with severe obesity from a consanguineous pedigree. All four heterozygous carriers were nonobese. Several features of the phenotype, e.g. hyperphagia, tendency toward tall stature, hyperinsulinemia, and preserved reproductive function, closely resemble those reported previously in Mc4r knock-out mice. In addition, a marked increase in bone mineral density was seen in all affected subjects. In transient transfection assays, the N62S mutant receptor showed a responsiveness to alphaMSH that was intermediate between the wild-type receptor and mutant receptors carrying nonsense and missense mutations associated with dominantly inherited obesity. Thus MC4R mutations result in a syndrome of hyperphagic obesity in humans that can present with either dominant or recessive patterns of inheritance.

Predicting heart growth during puberty: The Muscatine Study

OBJECTIVES

During childhood, heart growth is closely associated with somatic growth including increases in body weight, fat-free body mass (FFM), and height. However, with age, greater variability in heart size in relationship to body size is observed, presumably attributable to the increased effect of cardiac workload. At this time, little is known as to what functional attributes (eg, aerobic fitness) contribute to cardiac workload and the relative contribution of these attributes to heart growth during childhood and adolescence. In this article, we report cross-sectional and longitudinal relationships among aerobic fitness, body size, blood pressure (BP), and left ventricular mass (LVM) through puberty including the predictors of heart growth during puberty and the tracking of LVM from pre-puberty to late and post-puberty. Describing the predictors of heart size and heart growth and establishing the likelihood that a large heart, relative to peers, may (or may not) remain a large heart should aid pediatricians in discerning between normal developmental increases in LVM and increases in LVM suggestive of excessive heart growth (left ventricular hypertrophy).

METHODOLOGY

Using a repeated-measures design, we assessed aerobic fitness, FFM, fatness, weight, height, sexual maturation, resting BP, peak exercise BP, and LVM in 125 healthy children (mean baseline age: 10.5 years) for a period of 5 years. All subjects were either in prepuberty or early puberty at the beginning of the study. At follow-up, 110 subjects attempted all research procedures (87% of the initial cohort). Using anthropometry and bioelectrical impedance, we measured FFM, fatness, weight, and height quarterly (once every 3 months) for a total of 20 examinations. Resting BP and LVM (2-dimensional echocardiography) were also assessed quarterly. Aerobic fitness, peak exercise BP, and sexual maturation (staging of secondary sex characteristics and, for boys, serum testosterone) were measured annually (5 examinations). The same field staff conducted all examinations. Statistical methods included Spearman rank correlation coefficients (r(s)) calculated to estimate how well the year 5 LVM was predicted by LVM at earlier years. We also categorized the LVM data into tertiles and reported the percentage who remained in the extreme tertiles in year 5, given they began in that tertile in year 1. Gender-specific stepwise multivariate analysis was used to evaluate predictors of follow-up LVM and predictors of changes in LVM. The latter model examined whether the variability in the changes in LVM, as quantified by subject-specific slopes, could be explained by changes in predictor variables, also quantified by subject-specific slopes.

RESULTS

At baseline and at follow-up, boys tended to be taller, leaner, more aerobically fit, and had greater LVM than girls. Rate of change for these variables was also greater in boys than girls. For example, LVM increased 62% in boys and 48% in girls. At year 5, subjects had advanced at least 1 stage in genital or breast development and over 80% of the subjects were in late- or post-puberty. Significant and strong tracking of heart size (r(s) =.65-.87) was observed. The likelihood that a subject would be in an extreme tertile for heart size at follow-up was approximately doubled if he or she started there at baseline. In boys, baseline FFM explained 54% of the variability in follow-up LVM. Change in aerobic fitness and change in FFM explained 55% of the variability in change in LVM. In girls, baseline aerobic fitness and fatness explained 45% of the variability in follow-up LVM. Because FFM did not enter in this model, we constructed an alternative model in which baseline aerobic fitness adjusted for FFM was entered. Using this approach, 43% of the variability in follow-up LVM was explained by baseline FFM, fatness, and adjusted aerobic fitness. Change in FFM explained 58% of the variability in change in LVM. (ABSTRACT TRUNCATED)

Sex and race differences in cardiovascular disease risk factor changes in schoolchildren, 1975-1990: the Princeton School Study

OBJECTIVES

This study was done to assess changes in obesity and risk factors for cardiovascular disease (CVD) in Black and White children from 1975 through 1990.

METHODS

A cross-sectional study of body composition and CVD risk factors conducted in a school district as part of the Lipid Research Clinics (LRC) Program Prevalence Study (1973-1975) was compared with a later study (1989-1990) conducted in the same school district, which remained demographically stable. The studies included 1456 third- and fifth-grade students and 300 LRC subjects within the same age ranges.

RESULTS

Students in the 1989-1990 study had a significantly higher mean body mass index (BMI), total blood cholesterol concentration, and systolic and diastolic blood pressures and marginally higher resting heart rates than those in the earlier study. The prevalence of obesity increased from 12.5% to 25.3%, and of hypercholesterolemia from 8.0% to 14.8%. Black females had the largest increase in BMI and resting heart rate and the highest prevalence of elevated total cholesterol in the 1989-1990 study.

CONCLUSIONS

The results of this study suggest a secular trend toward increased obesity in children and portend the potential development of a public health problem that could reverse the recent decline in morbidity from CVD.

The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study

BACKGROUND

Although overweight and obesity in childhood are related to dyslipidemia, hyperinsulinemia, and hypertension, most studies have examined levels of these risk factors individually or have used internal cutpoints (eg, quintiles) to classify overweight and risk factors.

OBJECTIVE

We used cutpoints derived from several national studies to examine the relation of overweight (Quetelet index, >95th percentile) to adverse risk factor levels and risk factor clustering.

DESIGN

The sample consisted of 9167 5- to 17-year-olds examined in seven cross-sectional studies conducted by the Bogalusa Heart Study between 1973 and 1994.

RESULTS

About 11% of examined schoolchildren were considered overweight. Although adverse lipid, insulin, and blood pressure levels did not vary substantially with the Quetelet index at levels <85th percentile, risk factor prevalences increased greatly at higher levels of the Quetelet index. Overweight schoolchildren were 2.4 times as likely as children with a Quetelet index <85th percentile to have an elevated level of total cholesterol. Odds ratios for other associations were 2.4 (diastolic blood pressure), 3.0 (low-density lipoprotein cholesterol), 3.4 (high-density lipoprotein cholesterol), 4.5 (systolic blood pressure), 7.1 (triglycerides), and 12.6 (fasting insulin). Several of these associations differed between whites and blacks, and by age. Of the 813 overweight schoolchildren, 475 (58%) were found to have at least one risk factor. Furthermore, the use of overweight as a screening tool could identify 50% of schoolchildren who had two or more risk factors.

CONCLUSIONS

Because overweight is associated with various risk factors even among young children, it is possible that the successful prevention and treatment of obesity in childhood could reduce the adult incidence of cardiovascular disease.

Childhood hypertension. An update on etiology, diagnosis, and treatment

In the general population, an estimated 70% or more of premature morbidity can be attributed to tobacco use, undertreatment of hypertension, and obesity. From a public health perspective, health-related behaviors that reduce the risk for cardiovascular disease should be encouraged for all children and their families. Pediatricians are obligated to accurately and frequently monitor patients' blood pressures. When discovered, elevated blood pressure should be appropriately investigated, with the evaluation being tailored to the age of the child and to the severity of the blood pressure elevation. Investigation should focus on not only a search for a cause but also target organ effects. Timely recognition of abnormal blood pressure and appropriate interventions are necessary to affect the future development of cardiovascular and renal morbidity and mortality.

Ambulatory blood pressure monitoring and interdialytic weight gain in children receiving chronic hemodialysis

Volume overload appears to induce hypertension in hemodialysis patients, yet studies of the effect of hydration status on interdialytic blood pressure (BP) have yielded contradictory results. We measured interdialytic BP by ambulatory BP monitoring (ABPM) during inpatient fluid restriction in 12 children receiving chronic hemodialysis to describe the overall BP pattern and to determine the effect of weight gain on BP change. Weight was measured on admission and four times each day. For each weight, casual BP was measured and compared with the mean of 3 hours of ABPM surrounding the weight measurement. Sleep BP decreased from daytime BP by 6% for systolic BP (SBP) and 11% for diastolic BP (DBP). Sleep loads were greater than daytime loads (P < 0.01) for SBP (53% v 28%) and DBP (57% v 27%). Overall, 58% (7 of 12) of the patients had sleep SBP load greater than 50%, and 67% (8 of 12) of the patients had sleep DBP load greater than 50%. Casual and ABPM measurements of BP showed moderate correlations for SBP (r = 0.51) and DBP (r = 0.46) and mean differences between methods of 6.3 +/- 13.2 mm Hg and -1.4 +/- 12.6 mm Hg, respectively. Increases in interdialytic weight were positively associated with increases in SBP (r = 0.41; P < 0.001), and interdialytic BP changes varied closely with corresponding weight changes. We conclude that in children receiving chronic hemodialysis: (1) sleep BP decreases are attenuated and sleep BP loads are elevated, (2) casual BP correlates poorly with ABPM, and (3) interdialytic weight and BP are related.

Interaction between body size and cardiac workload: influence on left ventricular mass during body growth and adulthood

The development of the left ventricle parallels body growth. During infancy, the relation between body size and left ventricular (LV) mass is very close. With advancing age, variability of LV mass in relation to body size markedly increases. To test the hypothesis that the age-related increase in variability of LV mass is due to the progressive impact of hemodynamic stimuli on LV growth, quantitative M-mode echocardiograms were obtained in 766 normal-weight, normotensive individuals over a range of ages from 1 day to 85 years (330 female subjects, 373 subjects younger than 18 years). LV mass was linearly related to height2.7 (r2=.69). Prediction of values of LV mass by body size was more accurate at birth and progressively less precise with increasing age. Stroke work (stroke volume times systolic pressure) was closely related to LV mass (r2=.74). The explained variance of LV mass increased from 69% in the univariate regression with height2.7 to 82% in a multivariate model including height2.7, stroke work, and gender. In children and adolescents (younger than 18 years), height2.7 was the main determinant of LV mass, whereas during adulthood stroke work and gender were more important predictors of LV mass than height2.7. Thus (1) the influence of body growth on development of LV mass decreases after early infancy because of both the variability of hemodynamic load and the increasing effect of gender; (2) after adolescence, during adulthood, in normotensive, normal-weight individuals, the impact of hemodynamic load and male gender on LV mass is greater than the one of body size; and (3) an appreciable proportion of variability of LV mass remains unexplained with the studied models. This might be due to genotypic variations and/or measurement error.

Predictors of ambulatory blood pressure: identification of high-risk adolescents

Within a life span perspective on prevention, adolescence was conceptualized as a pivotal transition in the evolution of risk for hypertension and other cardiovascular morbidity. Resting blood pressure (BP), BP reactivity, and 24-hour ambulatory BP were measured in a multiethnic sample of 41 male and female adolescents aged 15 to 16 years old. Results were consistent with the hypothesis that BP levels during reactivity testing would be better predictors of ambulatory BP than levels of BP measured at rest using a standard protocol. Ethnic group differences in ambulatory BP were statistically significant. The findings warrant further study and may provide a means for early identification of adolescents at risk for developing high BP.

Percentiles for body mass index in U.S. children 5 to 17 years of age

OBJECTIVES

It has been recommended that body mass index (BMI) (weight in kilograms/height in meter2) be used routinely to evaluate obesity in children and adolescents. This report describes the distribution of BMI in children and adolescents in the United States.

METHODS

Standardized measurements of height and weight from 9 large epidemiologic studies including 66,772 children age 5 to 17 years were used to develop tables for the distributions of BMI that are age, race, and gender specific.

RESULTS

The mean BMI increases with age and is slightly higher for girls than boys. Mean BMI for black and Hispanic girls was noticeably higher than for white girls. The percentiles of BMI are consistently higher than those based on the NHANES I measures, particularly for the 95th percentile. The proportion of obese children compared with NHANES I standards is higher and is highest for Hispanic boys and black and Hispanic girls.

CONCLUSION

The tables and figures will allow pediatricians to determine the relative ranking of BMI for patients compared with values derived from a large sample of healthy children and adolescents. The identified gender and ethnic differences may be guides to understanding the cause and prevention of obesity.

Hypertension and pregnancy-related hypertension

Pregnant women with hypertension can be divided into two groups: normotensive women who develop the uniquely pregnancy-related syndrome of preeclampsia, which is characterized by hypertension, proteinuria, and edema; and women with chronic hypertension who become pregnant and are at increased risk for developing superimposed preeclampsia. Preeclampsia is a syndrome of generalized endothelial dysfunction initiated by abnormal placentation and consequent placental under-perfusion, release of cytokines and other toxins, and vasoconstriction and platelet activation. Preeclampsia is the major cause of both maternal and fetal morbidity and mortality and may be complicated by eclampsia (seizures) and hepatic and renal failure. The process is completely reversible by delivery of the fetus and placenta, but intrauterine growth retardation and premature delivery pose major threats to the fetus and may require care in tertiary care center. Treatment of preexisting or pregnancy-induced hypertension does not prevent or reverse the process, but is justified to prevent maternal cardiovascular complications, especially during labor and delivery.

Longitudinal correlates of change in blood pressure in adolescent girls

The objective of this study was to assess the longitudinal changes in blood pressure in black and white adolescent girls and evaluate potential determinants of changes in blood pressure, including sexual maturation and body size. A total of 1213 black and 1166 white girls, ages 9 or 10 years at study entry, were followed up through age 14 with annual measurements of height, weight, skinfold thickness, stage of sexual maturation, systolic and diastolic blood pressures, and other cardiovascular risk factors. Average blood pressures in black girls were generally 1 to 2 mm Hg higher than in white girls of similar age over the course of the study. Age, race, stage of sexual maturation, height, and body mass index (kg/m2) were all significant univariate predictors of systolic and diastolic blood pressures in longitudinal regression analyses. Black girls had a significantly smaller increase in blood pressure for a given increase in body mass index compared with white girls. The predicted increases in blood pressure per unit increase in body mass index (mm Hg per kg/m2) were as follows: systolic, 0.65+/-0.04 in whites and 0.52+/-0.04 in blacks (P<.001); diastolic fourth Korotkoff phase, 0.31+/-0.04 in whites and 0.15+/-0.03 in blacks (P<.001); and diastolic fifth Korotkoff phase, 0.31+/-0.05 in whites and 0.16+/-0.04 in blacks (P<.001). Understanding of the determinants of the racial differences in blood pressure could provide the rationale for future interventions to reduce the excess cardiovascular mortality in black compared with white women.

Evaluation of hematuria, proteinuria, and hypertension in adolescents

Signs or symptoms of renal disease in adolescents deserve prompt attention and appropriate evaluation. Adolescents are susceptible to a variety of urinary tract disorders. The key issue in the evaluation of hematuria or proteinuria in adolescents is the existence of concomitant signs of renal disease. For isolated hematuria or proteinuria, demonstration of persistence and a reasoned evaluation are in order. Hypertension in adolescents must be carefully documented and, when present, considered seriously. The fact that most teens with persistent elevated blood pressures have essential hypertension is still a great concern because for most of these adolescents the hypertension will be lifelong and, if left untreated, can be associated with significant morbidity and mortality in the adult years.

Relations of left ventricular geometry and function to body composition in children with high casual blood pressure

To determine whether abnormal casual blood pressure (BP) is associated with left ventricular (LV) abnormalities in children, 190 6- to 11-year-old children (77 girls, 113 boys) were studied at a school site in Naples, Italy, by limited echocardiography and bioelectric impedance to calculate fat-free body mass (FFM). Single-visit BP measurements (defined as casual BP) were high (based on the Italian tables of BP) in 34 children (18%; 9 girls, 25 boys; 133+/-8/81+/-10 mm Hg) and obesity was present in 44 (23%; 15 girls, 29 boys). Sex- and age-independent risk of high casual BP value was 2.9-fold (odds ratio) greater in obese than in normal-weight children (95% confidence interval, 1.3 to 6.5; P<.01). LV mass (as both absolute value and normalized for height or FFM) was higher and relative wall thickness increased in children with high casual BP (all P<.01). Prevalence of LV hypertrophy was 21% among children with high casual BP (P<.004 versus 4.3% in normal group). Risk of LV hypertrophy was 5.5-fold higher in the presence of high casual BP (P<.004), whereas obesity, age, and sex did not have independent effects. Endocardial shortening was slightly higher in children with high casual BP (36.8+/-8.2%) than in children with normal BP (34.3+/-4.8%, P<.02), whereas midwall shortening was identical in the two groups (20%). Both endocardial shortening and midwall shortening were negatively related to end-systolic stress (r=-.62, SEE=3.8% and r=-.32, SEE=2.4% in normal children). Shortening as a percentage of predicted from wall stress was increased in children with high casual BP at the endocardial level (P<.001), whereas it was normal at the midwall. Therefore, (1) casual detection of high BP in school children is associated with LV geometric abnormalities similar to those found in adults with sustained hypertension (LV hypertrophy, concentric pattern); (2) similar to in adult hypertension, endocardial chamber function in children is supranormal; and (3) in contrast to findings in adults, midwall shortening is normal in children with high casual BP.

Age-related changes in total arterial capacitance from birth to maturity in a normotensive population

We evaluated the effect of body growth and aging on the ratio of echocardiographic (Teichholz) stroke volume to pulse pressure (SV/PP ratio) in 373 normal-weight, normotensive children to adolescents (1 day to 17 years old; 166 girls, 87 nonwhite) and 393 normal adults (17 to 85 years old; 164 women, 112 nonwhite). Stroke volume increased with age in children (r = .64, P < .0001) and was stable in adults; pulse pressure decreased slightly with age in children (r = -.10, P = .06) and increased in adults (r = .29, P < .0001). As a consequence, SV/PP ratio increased with age in children (r = .51, P < .0001) and decreased in adults (r = -.18, P = .0004). To control for changes in body size that influence the size of the arterial tree, we used ANCOVA to adjust SV/PP for body size. Body size-adjusted SV/PP ratio was no longer related to age in children, whereas the negative relation with aging in adults remained statistically significant (r = -.19, P < .0002). Heart rate was negatively related to SV/PP ratio in both children and adolescents and adults, but this relation did not influence the relation with age. In multivariate analysis, high SV/PP ratio was predicted by greater height (P < .002) and weight (P < .04) and nonwhite race (P < .001) in children and adolescents and by younger age (P < .0001), greater weight (P < .0001), and low heart rate (P < .001) in adults. Sex did not enter the regression models. Thus, (1) SV/PP ratio is a measure of increasing capacity of the arterial tree during growth, whereas it depends on arterial compliance during adulthood through old age; (2) arterial compliance decreases progressively with aging; (3) the apparent difference between males and females might be due to their different body sizes.

Prediction of young adult blood pressure from childhood blood pressure, height, and weight

To assess the ability of childhood blood pressure, height, and weight to predict young adult blood pressure, the authors examined data obtained over multiple visits for four years on 339 children aged 8-18 years in East Boston, Massachusetts. These subjects were again seen 8-12 years later when they were aged 20-26 years. Multivariate regression models were used to predict true blood pressure in young adulthood from observed childhood measurements closest to age 10 (n = 219), adjusting for within-person variability. Without adjusting for childhood blood pressure, childhood height, weight and body mass index were at least marginally associated with young adult systolic blood pressure in boys and girls, with similar coefficients for each gender. The strongest predictor was weight (beta = 0.6 mmHg/10 lbs for girls, and beta = 0.7 mmHg/10 lbs for boys), and height was no longer predictive with weight in the model. With childhood blood pressure included, neither childhood height nor weight were predictors of future systolic blood pressure. However, change in height and weight were predictors of future systolic blood pressure. Weight change was a stronger predictor in girls than boys with beta = 0.9 mmHg/10 lbs. For diastolic blood pressure, height and weight had limited predictive ability in these data. These models, which allow for both between- and within-person variability in young adulthood, may be used to estimate the predictive value for future high blood pressure of a child's current blood pressure, height and weight, as well as future change in height and weight. These data suggest that the effects of childhood height and weight on future blood pressure may be negligible given childhood blood pressure, but that later height and weight remain predictive.

Stroke volume and cardiac output in normotensive children and adults. Assessment of relations with body size and impact of overweight

BACKGROUND

Relations between organs and body size are not linear but rather follow allometric (growth) relations characterized by their powers (exponents).

METHODS AND RESULTS

Stroke volume (SV) by M-mode echocardiography was related to height, weight, body surface area (BSA), and ideal BSA (derived from ideal body weight for given height) in 970 normotensive individuals (1 day to 85 years old; 426 < 18 years old; 204 overweight to obese; 426 female). In normal-weight children, adults, and the entire population, SV was related by allometric relations to BSA (power = 0.82 to 1.19), body weight (power = 0.57 to 0.71), and height (power = 1.45 to 2.04) (all P < .0001). Relations of cardiac output to measures of body size had lower allometric powers than those for SV in the entire population (0.41 for body weight, 0.62 for BSA, and 1.16 for height). In overweight adults, observed SVs were 17% greater than predicted for ideal BSA, a difference that was approximated by normalization of SV for height to age-specific allometric powers. Similarly, observed cardiac output was 19% greater than predicted for ideal BSA, a difference that was accurately detected by use of cardiac output/height to age-specific allometric powers but not of BSA to the first power.

CONCLUSIONS

Indices of SV and cardiac output for BSA are pertinent when the effect of obesity needs to be removed, because these indices obscure the impact of obesity. To detect the effect of obesity on LV pump function, normalization of SV and cardiac output for ideal BSA or for height to its age-specific allometric power should be practiced.

Liddle's syndrome: prospective genetic screening and suppressed aldosterone secretion in an extended kindred

Liddle's syndrome is an autosomal dominant form of hypertension that resembles primary hyperaldosteronism, is characterized by the early onset of hypertension with hypokalemia and suppression of both PRA and aldosterone, and is caused by mutations in the carboxyl-terminus of the beta- or gamma-subunits of the renal epithelial sodium channel. We describe a kindred (K176) whose distinguishing clinical features were mild hypertension and decreased aldosterone secretion. The index case was a 16-yr-old girl with intermittent mild hypertension and hypokalemia and subnormal PRA, aldosterone, 18-hydroxy-corticosterone, and deoxycortisol levels, but normal cortisol/cortisone metabolite ratio and cortisol half-life. A frameshift mutation in the carboxyl-terminus of the beta-subunit of the epithelial sodium channel was identified in the index case, establishing the diagnosis of Liddle's syndrome. Sixteen at-risk relatives of the index case were tested. Seven new subjects were heterozygous for the mutation found in the index case, and two deceased obligate carriers were identified. All genetically affected adult subjects had a history of mild hypertension, and four had a history of hypokalemia. Basal and postcosyntropin plasma aldosterone and urinary aldosterone levels were significantly suppressed in those positive for the mutation. The family demonstrates variability in the severity of hypertension and hypokalemia in this disease, raising the possibility that this disease may be underdiagnosed among patients with essential hypertension.

Nutrient intake and blood pressure in the Dietary Intervention Study in Children

Delineating the role that diet plays in blood pressure levels in children is important for guiding dietary recommendations for the prevention of hypertension. The purpose of this study was to investigate relationships between dietary nutrients and blood pressure in children. Data were analyzed from 662 participants in the Dietary Intervention Study in Children who had elevated low-density lipoprotein cholesterol and were aged 8 to 11 years at baseline. Three 24-hour dietary recalls, systolic pressure, diastolic pressure, height, and weight were obtained at baseline, 1 year, and 3 years. Nutrients analyzed were the micronutrients calcium, magnesium, and potassium; the macronutrients protein, carbohydrates, total fat, saturated fat, polyunsaturated fat, and monounsaturated fat; dietary cholesterol; and total dietary fiber. Baseline and 3-year longitudinal relationships were examined through multivariate models on diastolic and systolic pressures separately, controlling for height, weight, sex, and total caloric intake. The following associations were found in longitudinal analyses: analyzing each nutrient separately, for systolic pressure, inverse associations with calcium (P < .05); magnesium, potassium, and protein (all P < .01); and fiber (P < .05), and direct associations with total fat and monounsaturated fat (both P < .05); for diastolic pressure, inverse associations with calcium (P < .01); magnesium and potassium (both P < .05), protein (P < .01); and carbohydrates and fiber (both P < .05), and direct associations with polyunsaturated fat (P < .01) and monounsaturated fat (P < .05). Analyzing all nutrients simultaneously, for systolic pressure, direct association with total fat (P < .01); for diastolic pressure, inverse associations with calcium (P < .01) and fiber (P < .05), and direct association with total and monounsaturated fats (both P < .05). Results from this sample of children with elevated low-density lipoprotein cholesterol indicate that dietary calcium, fiber, and fat may be important determinants of blood pressure level in children.

Oscillometric twenty-four-hour ambulatory blood pressure values in healthy children and adolescents: a multicenter trial including 1141 subjects

Ambulatory blood pressure (ABP) monitoring is increasingly used to evaluate the blood pressure of children and adolescents. The upper normal ABP values in the pediatric age group are still unknown, because reference values based on a sufficiently high number of healthy children have not yet been published. In this multicenter trial, we pooled ABP records of 1141 healthy children and adolescents with a body height between 115 and 185 cm. The study was carried out by seven centers according to a common protocol. The 50th percentile for 24-hour systolic ABP increased moderately with height, from 103 to 113 mm Hg in girls and from 105 to 120 mm Hg in boys. The 50th percentile for diastolic 24-hour means was 66 +/- 1 mm Hg, irrespective of height or gender. Diastolic daytime means were 73 +/- 1 mm Hg, which is remarkably high compared with reference values for casual blood pressure. The mean nocturnal systolic and diastolic ABP (midnight to 6 AM) was 13% +/- 6% and 23% +/- 9% lower compared with the daytime means (8 AM to 8 PM), respectively. This multicenter study provides well-based limits of normal ABP in mid-European children.

Diagnosis and management of hypertension in childhood

Blood pressure measurements should be taken at intervals on all children. At the very least, blood pressure measurements should be recorded on school and hospital admission. Once obtained, the pressure should be compared to established normals. If the pressure is repeatedly high, hypertension may be diagnosed and a cause sought. Unfortunately, most hypertension is usually mild in childhood, treatment programs should be initiated using nonpharmacologic measures. If needed a number of effective antihypertensive medications are available. The step-care approach presented in this article may be helpful in guiding the pediatric practitioner in this therapy.

Prediction of resting cardiovascular functioning in youth with family histories of essential hypertension: a 5-year follow-up

Two hundred forty-six children (96 Whites, of whom 51 were males; 150 African- Americans, of whom 69 were males) with a familial history of essential hypertension (EH) were re-evaluated 5 years after an initial evaluation. During the initial visit anthropometric, demographic, and resting cardiovascular (CV) parameters (designated initial baseline levels) were assessed. These CV parameters (systolic and diastolic blood pressure [BP], heart rate, cardiac output index [CI], and total peripheral resistance index [TPRI] were also measured during postural challenge, a video game challenge, and a cold pressor task. At follow-up, resting CV parameters were again evaluated, and designated as follow-up resting levels. Moderate temporal stability (r range = .43-.56) was observed for all resting CV parameters. Mean stress responses for each CV parameter for all 3 stressors during the initial visit were positively related to the respective CV follow-up resting level. BP stress responses to postural change and video game challenge to be significant independent predictors of future resting BP after controlling for standard EH risk factors. Follow-up resting CI was not predicted by any stress responses, whereas follow-up resting TPRI was predicted by TPRI responses to the video game after controlling for standard Eh risk factors. These results contrast with those from an earlier 1-year follow-up, where stress responses for neither CI nor TPRI predicted follow-up resting levels. It appears that, as children get older, TPRI stress responses play a stronger role in vasoconstrictive function.

Sexual maturation and racial differences in blood pressure in girls: the National Heart, Lung, and Blood Institute Growth and Health Study

OBJECTIVE

To evaluate racial differences in blood pressure in girls aged 9 to 10 years in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS) and to evaluate the extent to which racial differences in blood pressure are explained by other factors, including sexual maturation and body size.

METHODS

The NGHS enrolled 539 black and 616 white girls aged 9 years, and 674 black and 550 white girls aged 10 years. Racial differences in blood pressure were examined. Relationships of stage of sexual maturation, height, and skinfold thickness with systolic and diastolic blood pressure were evaluated by multiple regression analysis.

RESULTS

The black girls had significantly higher systolic (102.0 +/- 8.90 vs 100.5 +/- 9.42 mm Hg, p <0.001) and diastolic (58.0 +/- 12.0 vs 56.5 +/- 12.51 mm Hg, p <0.01) blood pressures than the white girls. The black girls were also more advanced in sexual maturation and were taller (142.9 +/- 7.94 vs 139.6 +/- 7.05, p <0.001) and heavier (39.6 +/- 11.24 vs 35.3 +/- 8.73 kg, p <0.001) than the white girls. Both systolic and diastolic blood pressure were significantly correlated with level of maturation, height, weight, and sum of skinfolds. Stage of maturation was found to account for the difference in blood pressure between black girls and white girls. In a multiple regression analysis, controlling for height (for diastolic blood pressure) and for both height and sum of skinfolds (for systolic blood pressure) eliminated the effects of race and stage of maturation on blood pressure.

CONCLUSION

Racial differences in blood pressure were observed for 9- and 10-year-old girls and are explained by the fact that black girls were more mature than white girls. The effect of sexual maturation on blood pressure appears to operate through height and body fat. The effect of obesity may be more important for systolic than for diastolic blood pressure. Continuation of racial differences in blood pressure may result in a higher prevalence of hypertension for black women.

Correlates of the hemodynamic determinants of blood pressure

The purpose of this study was to investigate the association of sex, race, lean body mass, and fat mass with the hemodynamic determinants of blood pressure, including stroke volume, heart rate, and total peripheral vascular resistance. The study included 201 subjects aged 6 to 17 years, 105 of whom were male and 98 of whom were black. Lean body mass and fat mass were both significant (P < .05) independent determinants of stroke volume, cardiac output, and total peripheral vascular resistance. However, the direction of the effect of lean body mass was opposite for stroke volume and cardiac output compared with that of total peripheral vascular resistance. The direct relationship of lean body mass with systolic blood pressure (SBP) and diastolic blood pressure (DBP) (regression coefficients, 0.55 +/- 0.05 for SBP and 0.47 +/- 0.05 for DBP) indicates that the effect of lean body mass on cardiac output may predominate. Lean body mass explained substantially more of the variance of the hemodynamic variables than did fat mass. After control for the effects of body size, male subjects had higher heart rate and cardiac output, and female subjects had higher vascular resistance. White subjects had higher stroke volume and cardiac output, and black subjects had higher peripheral vascular resistance. This study demonstrates that lean body mass is a more important correlate of the hemodynamic determinants of blood pressure than is fat mass and that sex and race have significant independent relationships with the hemodynamic determinants of blood pressure in children and adolescents.

Hypertension in pediatric patients

The importance of hypertension in the pediatric population has not been as well-appreciated as in adults. This may be due in part to the much lower prevalence of hypertension in children. Nevertheless, hypertension is an important clinical problem in pediatrics, and the approach to its management differs from that in adults in several major respects. Compared with adults, a much greater percentage of hypertension in children is caused by secondary, potentially correctable, disease states. Elevated blood pressure in children may also represent the early expression of primary or essential hypertension. In addition, the technique of blood pressure measurement, the definitions of high blood pressure, and the classifications of blood pressure values in children are different than in adults. These factors dictate a pediatric approach to detection, evaluation, and management of hypertension in children and adolescents.