Isabel Torro

Prevalence, Persistence, and Clinical Significance of Masked Hypertension in Youth

Masked hypertension, an elevated daytime ambulatory blood pressure in the presence of a normal office blood pressure, confers an increased cardiovascular risk to adults. We investigated the prevalence, persistence, and clinical significance of masked hypertension in children and adolescents. We enrolled 592 youths (6 to 18 years old). Youths with masked hypertension (n=34) and a random sample of the normotensive participants (n=200) were followed-up. In a nested case-control study, we compared echocardiographic left ventricular mass among cases with persistent masked hypertension and normotensive controls. At baseline, mean age was 10.2 years; 535 youths were normotensive on office and daytime ambulatory blood pressure measurement (90.4%), and 45 had masked hypertension (7.6%). Compared with normotensive controls, participants with masked hypertension had a higher ambulatory pulse rate, were more obese, and were 2.5-times more likely to have a parental history of hypertension. Among 34 patients with masked hypertension (median follow-up 37 months), 18 became normotensive, 13 had persistent masked hypertension, and 3 had sustained hypertension. Patients with persistent masked hypertension (n=17) or who progressed from masked to sustained hypertension (n=3) had a higher left ventricular mass index (34.9 versus 29.6 g/m2.7; P=0.023) and a higher percentage with left ventricular mass index above the 95th percentile (30% versus 0%; P=0.014) than normotensive controls. In children and adolescents, masked hypertension is a precursor of sustained hypertension and left ventricular hypertrophy. This condition warrants follow-up and, once it becomes persistent, is an indication for blood pressure-lowering treatment.

The impact of obesity and body fat distribution on ambulatory blood pressure in children and adolescents.

To assess the relationship between obesity, body fat distribution, and blood pressure in children and adolescents, various measures of obesity and the waist-to-hip circumference ratio were related to casual and ambulatory blood pressure as measured using a SpaceLabs 90207 monitor during a regular school day. Seventy obese and 70 nonobese children aged 6 to 16 years were included in the study. Regardless of the time period analyzed (24 h, daytime, or nighttime), ambulatory blood pressure and casual blood pressure were significantly higher among the obese children. The differences in systolic blood pressure observed between the groups were attributable to the presence of obesity as estimated by the ponderal index and by skinfold thickness. Similarly, systolic and diastolic loads, as an assessment of high blood pressure values over 24 h, were significantly higher in the obese children when compared to the loads for the nonobese children. Waist-to-hip circumference ratio was independently associated, (in multiple regression analysis) with systolic blood pressure, whether during 24 h, daytime, or nighttime periods, after controlling for age, sex, current height, ponderal index, and tricipital skinfold thickness. This study demonstrates that obesity is a determinant of ambulatory and casual blood pressure. Since obese children with a predominantly abdominal fat mass show higher blood pressure values, evaluation of body fat distribution in children may help to identify subjects more susceptible to developing hypertension later in life.

Added Impact of Obesity and Insulin Resistance in Nocturnal Blood Pressure Elevation in Children and Adolescents

The aim of the present study was to analyze the relationship between insulin resistance and the ambulatory blood pressure components in obese children and adolescents. Eighty-seven overweight and obese white children and adolescents of both sexes, of European origin from 6 to 18 years of age (mean age: 10.9±2.7 years), were selected. Obesity was defined on the basis of a threshold body mass index z score >2 (Coles least mean square method) and overweight with a body mass index from the 85th to 97th percentile. A validated oscillometric method was used to measure ambulatory BP (Spacelabs 90207) during 24 hours. Fasting glucose and insulin were measured, and the homeostasis model assessment index was calculated. Subjects were grouped into tertiles of homeostasis model assessment index. No significant differences in terms of age, sex, and body mass index z score distribution were observed among groups. When adjusted by age, sex, and height, nocturnal systolic blood pressure and heart rate were significantly higher in subjects in the highest homeostasis model assessment index tertile (>4.7) as compared with those of the other groups, whereas no differences were observed for awake systolic blood pressure or heart rate. Whereas body mass index z score was more closely related with blood pressure and heart rate values, waist circumference was strongly related with insulin resistance. Moreover, both waist circumference and insulin resistance were mainly associated with higher nocturnal but not with awake blood pressure. The early increment of nocturnal blood pressure and heart rate associated with hyperinsulinemia may be a harbinger of hypertension-related insulin resistance and may contribute to heightened cardiovascular risk associated with this condition.

Birth Weight Influences Blood Pressure Values and Variability in Children and Adolescents

The objective of the present study was to assess the relationships between birth weight and the values and variability of ambulatory blood pressure. Six hundred thirty healthy children (369 girls) age 4 to 18 years (mean, 9.9 years) born at term after a normotensive pregnancy were included. The subjects were divided into 5 groups according to birth weight. For each subject, a 24-hour ambulatory blood pressure monitoring was performed according to the protocol designed. Average and variability (estimated as the standard deviation) of ambulatory blood pressure and heart rate were calculated separately for 24-hour, daytime, and nighttime periods. When values were adjusted for gender, current age, weight, and height, children with the lowest birth weights had the highest ambulatory blood pressure values and variability, whereas no differences in heart rate were observed. Multiple regression analysis showed that although current weight was the strongest predictor for 24-hour systolic blood pressure (P <0.001), there was also an independent and significant inverse relationship for birth weight (P <0.002) after controlling for gender, current age, and height. Likewise, birth weight was independently and inversely correlated with 24-hour systolic blood pressure variability (P <0.03). In conclusion, children who had lower birth weights tended to have not only the highest blood pressure values but also the highest blood pressure variability, independent of the increases in ambulatory blood pressure values. Knowing that high blood pressure variability is at least partially independent of blood pressure values, the importance of this variability on further blood pressure rises and/or on vascular damage later in life needs to be assessed in future studies.

Blood Pressure and Obesity Exert Independent Influences on Pulse Wave Velocity in Youth

The objective was to analyze pulse wave velocity (PWV) in normotensive, high-normal, and hypertensive youths by using aortic-derived parameters from peripheral recordings. The impact of obesity on vascular phenotypes was also analyzed. A total of 501 whites from 8 to 18 years of age were included. The subjects were divided according to BP criteria: 424 (85%) were normotensive, 56 (11%) high-normal, and 21 (4%) hypertensive. Obesity was present in 284 (56%) and overweight in 138 (28%). Pulse wave analysis using a SphygmoCor device was performed to determine central blood pressure (BP), augmentation index, and measurement of PWV. Among the BP groups, differences appeared in age, sex, and height but not in body mass index. Significant differences in peripheral and central systolic and diastolic BPs and pulse pressures were observed within groups. A graded increase in PWV was present across the BP strata without differences in augmentation index. Using a multiple regression analysis, age, BP groups, and obesity status were independently associated with PWV. Older and hypertensive subjects had the highest PWV, whereas, from normal weight status to obesity, PWV decreased. Likewise, PWV was positively related to peripheral or central systolic BP and negatively related to body mass index z score. For 1 SD of peripheral systolic BP, PWV increased 0.329 m/s, and for 1 SD of body mass index z score PWV decreased 0.129 m/s. In conclusion, PWV is increased in hypertensive and even in high-normal children and adolescents. Furthermore, obesity, the factor most frequently related to essential hypertension in adolescents, blunted the expected increment in PWV of hypertensive and high-normal subjects.

Influence of Concurrent Obesity and Low Birth Weight on Blood Pressure Phenotype in Youth

The aim of this study was to assess the impact of obesity and low birth weight on both office and ambulatory blood pressure (BP) values, as well as on aortic-derived parameters in youths. A total of 422 white youths, from 10 to 18 years of age, were included. Subjects were divided into 4 groups according to the presence (234; 55%) or the absence (188; 45%) of obesity and according to low (114; 27%) or normal (308; 73%, birth weight. Spacelabs 90207 was used to measure ambulatory BP during a 24-hour period. SphygmoCor radial/aortic transform software was used to estimate aortic pressure waveform. Office, 24-hour, daytime, and nighttime systolic BP values were significantly higher in those subjects with low birth weight who became obese. The lowest BP values were present in nonobese subjects in the absence of low birth weight. In the middle, with similar BP values, were nonobese subjects with low birth weight and obese subjects in the absence of low birth weight. No interaction existed between obesity and low birth weight in the office (P=0.165) or ambulatory (P=0.603) systolic BP values. Augmentation index, an estimate of the pulse wave reflection, was significantly higher in the nonobese low birth weight group when compared with the other groups after controlling for height, heart rate, and diastolic BP. A significant interaction between low birth weight and obesity (P<0.005) existed. In conclusion, although the low birth weight children who become obese have the highest systolic BP values, the presence of obesity blunts the increment of the reflecting wave observed in low birth weight subjects.

The impact of the degree of obesity on the discrepancies between office and ambulatory blood pressure values in youth.

Objectives Obesity is an increasingly frequent problem among children and adolescents, and may lead to blood pressure (BP) increase. The aim of the present study was to assess the prevalence of hypertension, white-coat and masked hypertension in obese adolescents making systematic use of both office BP and 24-h ambulatory BP measurement. The impact of different degrees of obesity on BP and heart rate variability was also investigated. Methods Office and ambulatory BP were obtained in 285 overweight and obese Caucasian adolescents (11–18 years old) and in 180 age- and sex-matched controls. The extent of obesity was quantified using body mass index z score. Results A significant positive relationship between body mass index z score and both office and ambulatory systolic BP was found after adjusting for age and height in both boys and girls. Obese youths had not only higher BP levels, but also higher BP variability compared with controls. Among obese youths, 20.8% had abnormal BP conditions, 6.6% were white-coat hypertensives, 9.2% were masked hypertensives and 5% were sustained hypertensives. Conclusions The prevalence of these abnormal BP conditions, which can be identified thanks to ambulatory BP monitoring, further emphasizes the usefulness of this diagnostic tool in obese youths.

First-year blood pressure increase steepest in low birthweight newborns

Aim The present research has been undertaken prospectively to study the impact of birthweight and growth pattern on blood pressure changes from birth through the first year of life. Methods Parents of newborns born at term (gestational age > 37 weeks) after uncomplicated pregnancies and in the absence of perinatal illness were randomly invited to allow their children to participate in the study. One hundred and forty-nine (84 male and 65 female) newborns were included in the present analysis. The newborns were divided into four groups according to birthweight: < 2500 g (n = 23); 2500–2999 g (n = 39); 3000–3500 g (n = 48); and > 3500 g (n = 39). Results At birth systolic and diastolic blood pressure were significantly lower and heart rate was significantly higher in those children with the lowest birthweight as compared to those in the other groups. During the first month of life a significant trend, inversely related to birthweight, was present for systolic as well as diastolic blood pressure. After the first month of life, at 3, 6, 9 and at 12 months, systolic and diastolic blood pressure were similar across birthweight groups. In a multiple regression analysis, birthweight was a positive independent determinant of systolic blood pressure at birth and an inverse independent determinant of the increment of systolic blood pressure during the first month of life and of the systolic blood pressure at the end of the first year. Conclusions In summary, the present study goes further towards understanding blood pressure changes in low birthweight babies. Beginning at birth, both blood pressure values, as well as changes in blood pressure, provide information about the impact of intrauterine life on the risk of developing hypertension later in life.

Exercise intervention in childhood obesity: a randomized controlled trial comparing hospital-versus home-based groups

OBJECTIVE The aim of this study was to compare the effect of a hospital clinic group- versus home-based combined exercise-diet program for the treatment of childhood obesity. METHODS One hundred ten overweight/obese Spanish children and adolescents (6-16 years) in 2 intervention groups (hospital clinic group-based [n = 45] and home-based [n = 41]) and a sex-age-matched control group (n = 24) were randomly assigned to participate in a 6-month combined exercise (aerobic and resistance training) and Mediterranean diet program. Anthropometric values (including body weight, height, body mass index, BMI-Z score, and waist circumference) were measured pre- and postintervention for all the participants. Percentage body fat was also determined with a body fat analyzer (TANITA TBF-410 M). RESULTS Our study showed a significant reduction in percentage body fat and body mass index Z-score among both intervention-group participants (4%, 0.16, hospital clinic group-based; 4.4%, 0.23, home-based; P < .0001). There was also a significant reduction in waist circumference in the home-based group (4.4 cm; P = .019). Attendance rates at intervention sessions were equivalent for both intervention groups (P = .805). CONCLUSIONS The study findings indicate that a simple home-based combined exercise and Mediterranean diet program may be effective among overweight and obese children and adolescents, because it improves body composition, is feasible and can be adopted on a large scale without substantial expenses.

Current and Birth Weights Exert Independent Influences on Nocturnal Pressure-Natriuresis Relationships in Normotensive Children

The objective was to study the impact of birth weight on the relationship between ambulatory blood pressure and urinary sodium excretion in children and adolescents. The study included 134 healthy children (61 boys), all Caucasians, who were born at term after a normotensive pregnancy. For each subject, a 24-hour ambulatory blood pressure monitoring and a complete urine collection were simultaneously performed according to the protocols designed. Average ambulatory blood pressure (BP) and the urinary excretion rates for sodium, potassium, and creatinine were calculated separately for 24-hour, awake, and sleep periods defined by a mini-diary. The excretion rate of sodium during sleep time was positively correlated with ambulatory systolic BP; such a positive relationship was not found for waking hours. Consequently, the impact of birth weight on the relationship between blood pressure and the urinary sodium excretion rate was analyzed during sleeping hours. Stepwise multiple regression analysis shows that although current weight was the strongest predictor for the sodium excretion rate during sleep (P<.001), there was also an independent significant direct relationship for birth weight (P<.04) after controlling for age, sex, and the average of systolic BP during sleep. Adjusted for current weight, a significant difference in the regression slopes relating urinary sodium excretion rate and systolic BP during sleep exists between children in the lowest (<3.100 kg) and the highest tertiles (>3.500 kg) of birth weight (P<.02). Differences in sodium excretion rates, adjusted for current weight, between the two extreme tertiles of birth weight became significant at the highest systolic BP (P<.04). The children who had the lowest birth weight tended to excrete less sodium during sleep. The results of the present study show a blunted pressure natriuresis curve in children and adolescents with the lowest birth weight. Whether this abnormal renal sodium handling may be present as an initial or as an intermediate mechanism leading to higher BP values must be assessed in additional studies.