Andersons pediatric cardiology 1606

Familial Clustering The tendency for parents and children and siblings to have similar blood pressures is well recognized among adults This clustering is also apparent in children, with a correlation between siblings of 0.33 at the age of 2 to 14 years.139 Significant, though less strong, correlations have been found between mothers and infants as young as 1 week.140 There is convincing evidence that blood pressure is heritable, with both office (systolic and diastolic BP) and ambulatory blood pressure (nighttime) levels for both systolic and diastolic being shown to be influenced by genetic factors.141,142 Overall, blood pressure is thought to be a complex polygenic trait, but, as discussed later, there are distinct monogenic forms of hypertension.143 Newer gene analyses techniques, including genome-wide association and exome sequencing studies, have resulted in improved understanding of both the genetics of blood pressure regulation and hypertension.144,145 Studies on adopted children, compared with other members of the family, including nonadopted siblings, have shown no correlation between the blood pressure of adopted children and other members of the family The blood pressure of the parents and the nonadopted children, in contrast, correlated significantly.140 This implies that, at least in children, inheritance is more important than environment in determining blood pressure Environment is not without influence, however, and the duration of adoption rather than age at adoption, as well as resemblance in body weight, was linked to the small positive aggregation of blood pressure observed in adoptees living in the same home.140,146 Interestingly, more recent data from a large follow-up study from Italy over 25 years suggest genetic influences to be more prevalent than environmental factors when evaluating the variation of both systolic and diastolic blood pressure.147 Exercise, Traction, and Hypertension Isometric rather than dynamic exercise is associated with a greater rise in diastolic pressure.148 The Task Force Group29 expressed doubt concerning the advisability of isometric exercise, such as weight lifting, body building, and so on, in hypertensive children No dangerous rise in either diastolic or systolic pressure was demonstrated, however, during either dynamic or isometric exercise in hypertensive adolescents,149 with some150 concluding that maximal exercise testing was safe in hypertensive adolescents Although the exercise performance of this cohort was normal, systolic and diastolic pressures were higher than in children with labile hypertension This finding might indicate caution in allowing full participation in physical activity such as competitive sports With this caveat, exercise is recommended for hypertension because it is associated with a useful reduction in peripheral vascular resistance and blood pressure.151 Children with insufficient exercise are more likely to have hypertension,152 with recent meta-analysis showing improvement in blood pressure but not at significant levels following short-term exercise.153 The impact of moderate to vigorous physical exercise was shown recently, with higher levels of physical activity associated with lower BP, and results suggested that the volume of activity may be more important than the intensity.154 Physical exercise during adolescence and young adulthood has also been shown to associate with reduced incidence of hypertension as adults.155 Children undergoing orthopedic immobilization with plaster casts, and those in traction, have a fourfold greater incidence of hypertension.156 The rise in blood pressure, averaging 33 mm Hg in one study, was maximal on the fourth day of treatment, but resolved when the treatment was stopped.157 The cause is not known, but it has been related to increased sympathetic activity from stretching of the sciatic nerve, to retention of salt and water from immobilization, and to increased production of catecholamines causing increased output of renin from the kidney.157 Obesity and Hypertension The dramatic increase in childhood obesity and overweight in most developed countries has been an alarming phenomenon over the past 2 to 3 decades.158–161 This phenomenon has been reported worldwide, with recognition that these trends are likely to have major consequences for public health.162 One major consequence is the development of the metabolic syndrome—this being the association of obesity, hypertension, dyslipidemia, and diabetes mellitus with aggregation of risk factors in the same patient as shown in the recent study by Lurbe and colleagues.163 Population-based studies have shown that obese and overweight children have much higher rates of hypertension than those who are not overweight.161,164–167 As discussed, levels of blood pressure track from childhood to adulthood Hypertension, along with other components of the metabolic syndrome, has been shown to lead to the development of early atherosclerosis.168–171 Lean mass and total body fat mass independently and positively correlate with increased pressures.172 A positive correlation with blood pressure in this latter cohort was observed across a range of bodily habitus, and not just for overweight or obese children Others173 have suggested that loss of weight would help reduce risks of developing hypertension in later life Recent evidence from large cohort studies has highlighted this association of childhood adiposity and adult adiposity with adverse cardiovascular outcomes including blood pressure as young adults.174 When evaluating patients with high blood pressure, therefore, note should be taken of the presence of comorbid features, such as overweight, obesity, and dyslipidemia Measures to lose weight should remain an active part of the plan for management of an overweight or obese child with hypertension Sodium Intake There is broad recognition that much of the hypertension found in adults relates to the dietary intake of salt The relation between the prevalence of hypertension in a population and the cultural preference for salt in the diet is well established.175 Processed food accounts for 80% of the salt in the average Western diet, and it is argued that the manufacturers of this processed food should reduce this content.176 A meta-analysis177 of 10 trials looking at the effect of reducing intake of salt on pressures in infants, children, and adolescents showed that a modest reduction led to an immediate and significant fall in blood pressure High sodium intake and overweight and/or obesity are recognized as risk factors for hypertension in children.36 Recent data from the NHANES study cohort demonstrated that sodium intake was positively associated with systolic blood pressure and risk for elevated blood pressure among US children, with the highest blood pressure levels in those with excess weight and sodium intake.178