Pediatric preventive cardiology has increased in importance over the past several years due to the increasing number of children with obesity, hypertension, and dyslipidemia. In adults, elevated blood pressure, abdominal obesity, atherogenic dyslipidemia, and elevated plasma glucose levels are collectively known as the metabolic syndrome. The metabolic syndrome is associated with significantly increased risk of developing premature cardiovascular disease. Although there is currently no agreed upon definition of metabolic syndrome in children and adolescents, we do know that the extent of atherosclerotic progression is significantly correlated with several cardiovascular risk factors found in childhood, including elevated total cholesterol and low-density lipoprotein cholesterol, low levels of high-density lipoprotein cholesterol, obesity, high blood pressure, and smoking. Identifying children at a young age is beneficial because it allows for early implementation of dietary and lifestyle changes that may help delay the onset or progression of atherosclerosis. Indeed, in 2011, integrated cardiovascular risk reduction guidelines were published, specifically focusing on the promotion of cardiovascular health in children and adolescents as well as the identification and management of certain cardiovascular risk factors.1 This chapter will focus on 3 main areas of preventive cardiology: obesity, hypertension, and dyslipidemia.

Definition

Over the past 2 decades, the labels and definitions for overweight and obesity have changed2 and are demonstrated in Table 15-1. Not included in Table 15-1 are definitions for healthy weight (5th-84th percentile) and underweight (<5th percentile) children. The body mass index (BMI = body weight in kilograms/height in meters squared) category classifications are defined using the 2000 Centers for Disease Control and Prevention growth charts.2 The BMI value used to plot on the growth curves can be obtained in a variety of ways, including calculators and formulas, nomograms, and tables and wheels. Over the past few years, many practitioners calculate the BMI using personal electronic data assistant programs, smart phone applications, electronic healthcare record software, or Internet calculators. Although most of these applications will provide output in BMI percentiles, in most instances, these values still need to be manually plotted on a curve in order to track trends over time. For children less than 2 years of age, the practitioner should plot weight for height values over time.3

Although BMI is a widely used and inexpensive method for assessment of body fat, it does have limitations. These limitations are in some part due to the fact that body fat is typically higher among older individuals as well as females. In the older adolescent population, it can be particularly troublesome because the classification of obese versus overweight may be different using the adult versus pediatric definitions given the same BMI in the same patient. In addition, the scale cannot differentiate between lean muscle mass and fat; therefore, an athletic child who is very muscular may fall into the overweight or obese category when he or she has a larger percentage of muscle mass making up his or her body weight.

Alternative methods for assessing body fat such as skinfold thickness or waist and/or thigh circumferences may be more accurate for assessing overweight and obesity. However, they are more labor intensive and have more subjective variability when making measurements. More research is necessary using these methods in the pediatric population before recommending them for use in everyday practice.

Epidemiology

As shown in Figure 15-1, the past 3 decades have seen a dramatic increase in obesity in the United States, with the rate of obesity doubling in adults and the rates among children tripling.4 According to the statistics reported by the Department of Health and Human Services Expert Committee, obesity prevalence in U.S. children has increased from approximately 5% in 1963 to 1970 to 17% in 2003 to 2004.3

Data from the National Health and Nutrition Examination Survey (NHANES) showed significant differences over the past 25 years in prevalence rates of obesity by race, sex, and poverty level (Figure 15-2). For example, minority groups had a significantly higher prevalence of severe obesity than the Caucasian population. Additionally, there were significant differences by poverty–income ratio, with the most affluent (poverty–income ratio >3) demonstrating the lowest prevalence of severe obesity. In select BMI percentiles, there were significant differences by age groups, with the greatest prevalence of high BMI in the older age groups. The prevalence of those with a BMI ≥99th percentile was found to be significantly higher in boys compared with girls.5 In addition, data from the Early Childhood Longitudinal Study birth cohort demonstrated that the highest prevalence of obesity among 4-year-old children in the United States was in American Indian/Native Alaskan children.6

Clinical Presentation

Most children will present with only an elevated BMI noted during routine physical examination. Other children with more extreme obesity may present with a spectrum of physical findings associated with obesity itself and/or secondary to other associated comorbid conditions. In addition to elevated BMI, some examples of presenting clinical signs on physical examination may include truncal/central adipose deposition, striae, acanthosis nigricans (Figure 15-3), acne, or hirsutism (Figure 15-4).

Screening and Prevention

In the current era of increasing prevalence of childhood obesity, it is essential that primary care providers screen patients for the development of obesity as well as for environmental and genetic risk factors that place them at a higher risk for developing obesity. The difficulty of behavioral weight-loss therapy and the often life-long struggle with weight maintenance in the obese population or, alternatively, the potential expense and dangers of medication use and surgical treatment highlight the importance of prevention strategies in this population. Primary care providers are accustomed to providing prevention counseling for a number of entities beginning in the newborn period through adolescence; in the face of the increasing prevalence of childhood obesity, counseling to aid in prevention of obesity should now be included.

In 2007, a report was published regarding the prevention, assessment, and treatment of childhood obesity. The recommendations were subsequently endorsed by many organizations, including the American Academy of Pediatrics. The report emphasizes that obesity prevention should include all children beginning from the time of birth. As shown in Figure 15-5, in addition to the routine measurement of height, weight, and growth curves and BMI assessment, additional information should be obtained regarding environment and lifestyle. A detailed history of dietary intake (including beverages) and physical activity is important for all patients, regardless of the presence of obesity. Providers should counsel patients and their families to adopt and maintain a spectrum of healthy behaviors focused on improving physical activity and eating habits and decreasing sedentary behaviors. Some specific examples include limiting sugar-sweetened beverages, encouraging fruit and vegetable consumption, limiting screen time (including television, video games, computers, and other electronic devices) to less than 2 hours daily, eating breakfast, limiting eating at restaurants, encouraging family meals, and limiting portion sizes. In patients with overweight and obesity, these are opportunities for dietary and activity changes to help with either weight loss or weight stabilization. In those with a normal BMI, at-risk diet and activity behaviors can be identified early to provide counseling and early intervention in efforts to prevent the development of obesity. Because children who have parents and/or siblings who are obese are at a higher risk of developing obesity, those patients should be identified, and the family should be counseled as early as possible. The challenge for the provider is not in the provision of this prevention counseling, but rather the process of providing this information and support in such a way as to influence the family to alter behaviors influenced by long-standing traditions, habits, culture, and physical environment. As a guide to implement this plan for prevention, the report also details a 15-minute “Obesity Prevention Protocol.”3

Diagnosis and Evaluation

According to the 2007 recommendations, a BMI under the 5th percentile is defined as underweight, BMI in the 5th to 84th percentile is defined as a healthy weight, BMI in the 85th to 94th percentile is defined as overweight, and BMI in the 95th percentile or higher is defined as obese.

Children with elevated BMI levels face more than just the risk of persistent or future obesity. A BMI level in the 85th percentile or higher places a child at risk for other medical problems affecting multiple organ systems. An evaluation of these other associated conditions must be included in the evaluation of a child with obesity. Some examples of weight-related problems include sleep disturbances, respiratory problems, gastrointestinal problems, orthopedic issues, psychiatric and nervous system problems, skin problems, and cardiovascular disorders. Table 15-2 illustrates the signs, symptoms, and physical examination findings in children with obesity and the respective possible causes for each.

Although a detailed history and physical examination with an exhaustive review of systems can elicit many of the associated comorbid conditions, there are some conditions that require screening with other modalities, as illustrated in Table 15-3. For example, it is recommended that all children ages 2 years and older with a BMI in the 85th percentile or higher have a fasting lipid panel. In addition, if additional risk factors are identified, liver function tests and a fasting glucose should be evaluated every 2 years beginning at age 10 years. For those with BMI >95th percentile, these tests should be completed every 2 years regardless of additional risk factors. Abnormal elevation of liver enzymes on 2 occasions may indicate the need for further evaluation including the assistance of gastrointestinal specialists. Abnormalities revealed from initial history, review of systems, physical examination, and laboratory testing may prompt further testing to evaluate for additional comorbidities, as outlined in Table 15-3.

Treatment

The goals for treatment of childhood obesity are to improve health and reduce long-term medical complications by introducing permanent healthy lifestyle changes. With more severe obesity, escalation to additional forms of therapy may be indicated. Individual patient characteristics may determine which therapies are likely to be successful. Younger patients and those with lower BMI percentiles should generally change weight more gradually than older patients and those with higher BMI percentiles. In accordance with these principles, a staged approach should be implemented for treatment of obesity in children and adolescents. This approach emphasizes healthy lifestyle changes regarding dietary habits and physical activity to promote slow sustained weight loss and continued practice of these new lifestyle changes. It allows for adjustment of treatment and escalation to other stages in light of differing patient characteristics or failed weight loss after 3 to 6 months in the current stage.3

When traditional weight-loss measures are unsuccessful, there are medications and surgical treatment options that are now available; however, these are reserved for only the most severe cases and in the older adolescent and adult population. Although the detailed discussion of these therapies is beyond the scope of this text, consideration for medication and/or bariatric surgery should only be considered after well-documented failure of lifestyle modifications. These patients should be referred to an obesity and/or bariatric medicine specialist for further evaluation and treatment.

Introduction

Hypertension in the pediatric population is an incredibly complex phenomenon, representing the end result of a wide variety of underlying pathologic processes. Although the most common cause of hypertension in childhood is essential hypertension, there are many renal, cardiovascular, endocrine, and metabolic conditions that predispose to or directly cause hypertension. To make the diagnosis, the blood pressure must be measured accurately, which can be challenging due to patient cooperation and proper cuff selection. Furthermore, the diagnosis of hypertension is not constant, with normal blood pressure values changing with age, sex, and height. When the diagnosis is made, initial treatment is often with lifestyle changes followed by medication therapy, usually with the assistance of subspecialty consultation.

Definition

Hypertension in children is classified as prehypertension, stage 1 hypertension, and stage 2 hypertension. These classifications are dependent on the degree of blood pressure elevation relative to normative values for age, sex, and height. Blood pressure should be measured in a standardized way. According to the American Academy of Pediatrics, patients should be in a seated position for 5 minutes, with both feet on the ground, back supported, and the right arm elevated and supported with the elbow at the level of the heart.7 A properly sized blood pressure cuff should be selected, with a bladder width of about 40% of the arm circumference midway between the acromion and the olecranon. The bladder length should cover 80% to 100% of the circumference of the arm, as shown in Figure 15-6. Failure to select the proper cuff size for patient size can cause spurious values to be measured, with cuffs that are too small causing artificially elevated blood pressure and cuffs that are too large causing artificially low blood pressure.

Blood pressure can be determined by either auscultatory measurement or oscillometric devices. The standard method for auscultation is to use a standard sphygmomanometer with the bell of the stethoscope placed over the brachial artery pulse. The systolic blood pressure is defined as the onset of the Korotkoff sounds (K1), and the diastolic blood pressure is defined as the disappearance of Korotkoff sounds (K5). In some children, Korotkoff sounds may be heard until virtually 0 mm Hg, in which case the diastolic blood pressure is identified at the muffling of sounds (K4). The average of 2 to 3 measurements should be used to determine the blood pressure value.

Although auscultation is considered to be the standard method for measuring blood pressure, many offices and hospital settings use oscillometric devices for rapidly measuring blood pressure. The advantage to these devices is that they are quick and easy to use and they minimize interobserver variability. These devices measure mean blood pressure and then use proprietary algorithms to calculate systolic and diastolic values. The principal uses for these devices are for serial in-hospital measurements where auscultation would be impractical, outpatient screening of infants and small children where auscultation is very difficult, and screening in an office setting. Blood pressure values greater than the 90th percentile for age, sex, and height should be repeated by auscultation.

Blood pressure should be measured in every child 3 years of age and older at all visits to medical care. In addition, patients younger than 3 years of age meeting specific high-risk criteria should also be screened. These patients include those with a history of prematurity, congenital heart disease, recurrent urinary tract infections, known renal/urologic disease, malignancy, or solid organ transplantation. In addition, patients with a systemic disease or taking medications known to elevate the blood pressure should be screened at a young age. Importantly, any measurement of elevated blood pressure should be repeated several times in a single clinic visit and confirmed at follow-up visits. Results are compared to published normative values based on age, sex, and height.7 Normal values are considered to be less than the 90th percentile and should be repeated at the next medical evaluation. Patients with blood pressure measurements ≥90th percentile and less than the 95th percentile are considered to have prehypertension. In addition, adolescents with a blood pressure greater than 120/80 mm Hg but less than the 95th percentile are also considered to have prehypertension. Hypertension is defined as average systolic or diastolic blood pressure >95th percentile on 3 separate occasions. This can be further subdivided into stage 1 hypertension for blood pressures ranging from the 95th percentile to 5 mm Hg above the 99th percentile and stage 2 hypertension for blood pressures greater than 5 mm Hg above the 99th percentile for age, sex, and height.

Hypertensive urgency or emergency is when patients have severely elevated blood pressure and other risk factors, including symptomatic hypertension, underlying diabetes, or other serious medical conditions. A hypertensive emergency is defined as severe hypertension with evidence of end-organ dysfunction. Hypertensive urgency is defined as severe hypertension without evidence of end-organ dysfunction.8

White coat hypertension is defined as an average blood pressure greater than the 95th percentile when measured in the physician’s office but consistently less than the 90th percentile when measured in a nonmedical setting. Although initially thought to be harmless, there is some indication that these children may be at higher risk for developing hypertension later in life.

Clinical Presentation

The most common presentation of hypertension is measuring an elevated blood pressure in otherwise well-appearing children during routine medical evaluations. Generally, children who present with symptoms are those with a hypertensive urgency or emergency and who require immediate evaluation. During the initial evaluation, it is important to determine whether primary or secondary hypertension is present because the incidence of secondary hypertension is much higher in children than adults.

Primary Hypertension

Previously thought to be a disease of adulthood, primary hypertension is now recognized as a disease of childhood and adolescence. Characteristically, primary hypertension is stage 1 hypertension and is asymptomatic. It is typically found in older children and adolescents with a strong family history of primary hypertension. Younger children with more severe hypertension and without a family history of hypertension are at higher likelihood of having a secondary cause. As with adults, primary hypertension often presents with other comorbidities, including obesity, insulin resistance, hyperlipidemia, and obstructive sleep apnea. Together, these disorders increase the risk for each other and for long-term cardiovascular disease.

Many children with hypertension are found to be overweight, and the current increasing rise in obesity is thought to be a contributing factor to the increasing prevalence of hypertension. There is evidence to show that elevation of blood pressure is related to higher BMI, with the likelihood of having hypertension doubling for each 1-unit increase in the BMI z-score in school-aged children. Other data have shown increases in blood pressure in all age groups with increasing BMI.9-11

Secondary Hypertension

Compared to primary hypertension, which almost always presents asymptomatically during routine screening, secondary hypertension is far more likely to present with symptoms. These presenting symptoms may either be indications of the underlying disease process or a manifestation of the markedly elevated blood pressure. Cardiac and neurologic indicators of hypertension include headache, stroke, seizure, visual disturbances, chest pain, syncope, and shortness of breath. Although these presenting symptoms are not specific for any particular cause of secondary hypertension, patients presenting with symptoms are at a higher likelihood of having a secondary cause.

Some of the clinical signs of secondary causes of hypertension are summarized in Table 15-4. A careful and complete history and physical examination with specific attention for the common and uncommon findings of these underlying processes is vital to making a rapid diagnosis of the underlying cause of the secondary hypertension. Specific attention must be paid to screening for the signs and symptoms of the emergent conditions such as elevated intracranial pressure, coarctation of the aorta, and acute renal failure. In addition, there are numerous genetic syndromes, such as Williams and Turners syndromes, that have very characteristic physical examination findings.

Diagnosis

The diagnosis of hypertension is reliant on the careful measurement of blood pressure using proper technique, which is outlined earlier. All elevated blood pressure measurements should be confirmed on 3 separate occasions. The diagnostic algorithm is summarized in Figure 15-7. Patients with prehypertension and stage 1 hypertension can often be evaluated as outpatients over a time course of weeks or months. All patients with stage 2 and symptomatic hypertension should be evaluated very rapidly with the degree of urgency directly related to the amount of blood pressure elevation and the severity of the symptoms. Some of these patients may require referral to the emergency department and hospital admission for diagnosis and treatment.