The Committee on Atherosclerosis, Hypertension, and Obesity in the Young (AHOY) of the Council on Cardiovascular Disease in the Young, American Heart Association (AHA), recently published a scientific statement on cardiovascular health in childhood. The full statement was published in the July 2, 2002 issue of Circulation.
Coronary heart disease is the leading cause of death in the United States, making it responsible for about 500,000 deaths each year. Pathologic data have shown that atherosclerosis begins in childhood and that the extent of atherosclerotic change in children and young adults can be correlated with the presence of the same risk factors identified in adults. The goal of the statement is to provide strategies for promoting cardiovascular health that can be integrated into the comprehensive care of children. The committee also reviewed physical activity, obesity, insulin resistance and type 2 diabetes, hypertension, high blood cholesterol levels, and cigarette smoking.
In children, benefits associated with a physically active lifestyle include weight control, lower blood pressure, improved psychologic well-being, and a predisposition to increased physical activity in adulthood. Children should participate in regular (four to five times a week) activities that generate energy expenditures significantly above the resting level and ideally at least 50 to 60 percent of maximal exertion.
Activity assessment should be tailored for each child beginning in preschool and continuing through adolescence. Factors to be considered include age, sex, race, level of sexual maturity, and physical and mental disabilities that may affect participation (e.g., chronic diseases or medical conditions). Other general areas for the physician to discuss include the following:
Number of hours per day spent watching television or playing video or computer games.
Time spent participating in age-appropriate organized sports or lessons.
Amount of time spent in school or day-care physical education that includes at least 30 minutes of coordinated large-muscle exercise.
Time spent doing household chores, or a family outing that involves walking, swimming, etc.
There have been dramatic increases in the past two decades in overweight children and adolescents, and rates of obesity have increased two- to fourfold. Obesity should be defined as a level of overweight that is associated with adverse physical or psychologic health problems. Body mass index (BMI) is the recommended measure of relative weight for clinical use. It is calculated as weight in kilograms divided by the square of height in meters. It is particularly important to calculate BMI for children and adolescents in the upper percentiles (75th percentile and above) for height and weight, because they are at greater risk of obesity. Patients above the 95th percentile for BMI are significantly more likely to remain overweight as adults and suffer health complications of obesity.
Physicians should counsel their patients to avoid fad diets or other programs that promise a quick fix to their weight problems. At best, they produce short-term weight loss, and some may cause serious harm. Currently, there are no pharmacologic agents available for weight control that are safe or effective for use in children and adolescents.
Insulin Resistance and Type 2 Diabetes
Recent reports indicate an increase in the incidence of type 2 diabetes in children. A direct association between obesity and insulin resistance also has been reported. Being overweight during childhood and adolescence is associated with high levels of fasting insulin, lipids, and blood pressure in young adulthood. Weight loss in these patients results in a decrease in insulin concentration and an increase in insulin sensitivity toward normal in adults and adolescents.
Clear recommendations for assessing and treating insulin resistance syndrome are not presently available. A thorough history is essential in detecting those who are at risk because of race or ethnicity or familial predisposition. Fasting plasma glucose testing also has been recommended. Emphasis on detection, assessment, prevention, and treatment of overweight and obesity is necessary because of the connection with insulin resistance.
High Blood Pressure
Elevated blood pressure may begin in childhood or adolescence and normally rises with age. According to the AHA, all children three years and older should have their blood pressure measured at routine checkups. In children, elevated blood pressure is defined as systolic or diastolic blood pressure persistently above the 95th percentile. Management for primary hypertension includes initiating non-pharmacologic therapies, such as active dietary counseling and physical activity prescriptions.
The goals of blood pressure control in children and adolescents are to prevent lifestyle factors that contribute to an excessive rise in blood pressure with increasing age and to identify patients with secondary hypertension and those with severe primary hypertension.
High Blood Cholesterol Levels
Cholesterol levels track over time, meaning that children with high levels of low-density lipoprotein (LDL) cholesterol are likely to become adults with high levels. The AHA recommendations emphasize a diet low in saturated fat (less than 10 percent of energy) and cholesterol (less than 300 mg per day) to lower blood cholesterol levels and promote cardiovascular health in all children older than two years. For children between two and 19 years of age, acceptable levels of total cholesterol and LDL cholesterol are less than 170 mg per dL (4.40 mmol per L) and less than 110 mg per dL (2.85 mmol per L), respectively; borderline levels are 170 to 199 mg per dL (4.40 to 5.14 mmol per L) and 110 to 129 mg per dL (2.85 to 3.34 mmol per L); and high levels are at least 200 mg per dL (5.15 mmol per L) and at least 130 mg per dL (3.35 mmol per L). In American children, 170 and 200 mg per dL approximate the 75th and 95th percentiles for total cholesterol levels, respectively. All children with an LDL cholesterol level of more than 130 mg per dL should receive targeted intervention and follow-up.
The onset of smoking is usually in adolescence, so a smoking history should be obtained in all children older than eight years during routine health assessments. Physicians should have patient information ready to distribute to parents and children that describes the hazards of smoking. The handouts should include specific information on smoking cessation methods and contact materials for community resources.
Family History of Cardiovascular Disease
Coronary artery disease (CAD) tends to cluster in families, so a family history should be documented early in childhood. A positive family history is defined as documented myocardial infarction, angiographic documentation of CAD, angina pectoris, or sudden cardiac death in a first- or second-degree relative who was 55 years or younger. The risk associated with any predictor is markedly affected by the intensity of coexisting risk factors. Family history, smoking history (including passive smoking), blood pressure percentiles, BMI percentile chart, serum cholesterol level, and level of fitness can be used to develop an estimate of CAD risk and direct management.