Pediatric Hypertension

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Pediatric Hypertension

• Morning Report
• January 8, 2004

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Why Worry?

• Atherosclerotic heart disease remains the leading
  cause of death and disability in North America.
• Pathologic studies have shown that both the
  presence and extent of atherosclerotic lesions at
  autopsy in children and young adults correlate
  with certain established risk factors LDL, TGs,
  systolic/diastolic blood pressure (BP), BMI, and
  tobacco use.

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Why Worry?

• Additionally, in adults, hypertension has been
  shown to be a risk factor for the development of
  renal disease.

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Background

• The 1987 Report of the Second Task Force on BP
  control in childhood resulted in
• The provision of BP norms for children and
  adolescents, and
• The standardization of BP measurement.
• The task force recommended that all children 3
  years and older have their BP recorded during HCM
  and urgent visits.

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Background (contd)

• In 1996, new BP tables were published that
  reanalyzed data from the 1987 task force report.
• These tables, adjusted for height and age, alter
  the BP percentile estimates of boys and girls of
  all ages.

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Neonates and Infants

• The average systolic BP at 1 day of age in term
  infants is 70 mmHg BP increases to 85 mmHg by 1
  month of age.
• In a large cohort of premature infants studied
  during the first 3 to 6 hours of life, the limits
  of systolic and diastolic BP were independent of
  birth weight and gestational age but tended to
  correlate with low apgar scores and maternal
  hypertension.

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Neonates and Infants (contd)

• Studies of older premature infants found
  significant correlation between systolic BP and
  length and weight.
• In children younger that 1 year, systolic BP has
  been used to define hypertension.

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Girls

• Boys

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Racial Variances

• Although blood pressure has been shown to be
  higher in black versus white children, the
  differences are not believed to be clinically
  significant.
• Therefore current reference standards do not
  distinguish between racial and ethnic groups.

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Predispositions

• Approximately 25 of the adult population in the
  United States has hypertension, with 90
  classified as having essential aka primary
  hypertension.
• Familial and longitudinal studies have shown that
  there is a link between genetic and environmental
  influences on BP during childhood and the
  development of primary hypertension.

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Predispositions

• Other factors contribute to the risks for primary
  hypertension, aside from genetic predisposition.
  These include reactivity of vascular smooth
  muscle, the kidney and the interaction of the
  RAS, cardiac index, obesity, and hormonal and
  environmental factors.

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Predispositions

• A direct relationship between weight and BP has
  been observed at as early as age 5 and is even
  more prominent in the 2nd decade.
• Genetic factors that impact sodium, potassium,
  and calcium regulation may also influence BP in
  young populations.

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Technical Issues

• The right arm is preferred for consistency and
  comparison with the standard tables.
• If 2 cuffs are close in size to the measured
  width of the arm, go with the larger cuff so as
  not to give falsely elevated readings.

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Technical Issues (contd)

• BP should be measured in a controlled environment
  after 3 to 5 minutes of rest in the seated
  position with the cubital fossa supported at
  heart level.
• The cuff should be inflated to a pressure of
  20-30 mm above systolic pressure with a deflation
  rate of 2-3mm/sec.
• Automated devices are acceptable in newborns and
  infants, but true diastolic pressure is not
  accurately assessed by the indirect methods used
  by these devices.

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Technical Issues (contd)

• Systolic pressure is determined by the onset of
  the tapping Korotkoff sounds.
• The definition of the diastolic pressure has been
  modified and is now described as the
  disappearance of the sounds (the 5th Korotkoff
  sound).
• In some children, Korotkoff sounds can be heard
  to 0 mm Hg. This occurrence excludes diastolic
  hypertension.

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Diagnosis

• Normal is a systolic and diastolic pressure less
  than 90th percentile.
• High normal is an average systolic or diastolic
  pressure greater than or equal to the 90th
  percentile, but less than 95th percentile.
• Hypertension is an average systolic or diastolic
  pressure of greater than or equal to the 95th
  percentile, and measured on at least 3 separate
  occasions.

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Diagnosis

• BP varies widely throughout the day in the
  context of normal diurnal fluctuation, changes in
  physical activity, emotional stress and other
  factors, making diagnosis difficult.
• Only 1 of children are found to have significant
  hypertension as defined by the task force
  recommendations.

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Diagnosis

• Ambulatory BP monitoring (ABPM) has become a
  valuable tool in evaluating hypertensive adults
  for diagnosis and ongoing care.
• In children ABPM is well tolerated and
  reproducible and seems to be a useful tool in the
  diagnosis of borderline hypertension.

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History

• A hypertension-oriented history should be
  elicited with emphasis on the following factors
• symptoms referable to hypertension,
• neonatal course (? umbilical lines),
• growth pattern,
• history of renal/urologic problems,
• medications (OCPs, decongestants, stimulants,
  NSAIDS, steroids),
• symptoms of endocrine etiology,
• and a family history of primary
  hypertension/genetic disorders known to be
  associated with secondary hypertension.

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Physical Exam

• Exam should focus on
• evidence of hypertensive encephalopathy, Bells
  Palsy, retinopathy
• neurofibromas, café-au-lait spots, Von
  Hippel-Lindau disease, lesions of tuberous
  sclerosis
• hirsutism, moon facies, buffalo hump, truncal
  obesity, striae, thyromegaly
• cutaneous findings of SLE or HSP
• evidence of BPD, pulmonary edema,
• CHF, bruits, edema, diminished pulses,
• pregnancy,
• Turner syndrome, William syndrome,
• enlarged kidneys, abdominal masses.

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Etiologies

• The likelihood of identifying a secondary cause
  of hypertension is directly related to the degree
  of BP elevation and inversely related to the age
  of the child.

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Newborns

• Renal artery thrombosis
• Renal artery stenosis
• Renal venous thrombosis
• Congenital renal abnormalities
• Coarctation of the aorta
• Bronchopulmonary dysplasia (less common)
• Patent ductus arteriosus (less common)
• Intraventricular hemorrhage (less common)

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First Year of Life

• Coarctation of the aorta
• Renovascular disease
• Renal parenchymal disease

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Age 1 to 6 Years

• Renal parenchymal disease
• Renovascular disease
• Coarctation of the aorta
• Endocrine causes (less common)
• Primary hypertension (less common)

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Age 6 to 12 Years

• Renal parenchymal disease
• Renovascular disease
• Primary hypertension
• Coarctation of the aorta
• Endocrine causes (less common)
• Iatrogenic (less common)

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Age 12 to 18 Years

• Primary hypertension
• Iatrogenic
• Renal parenchymal disease
• Renovascular disease (less common)
• Endocrine causes (less common)
• Coarctation of the aorta (less common)

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The Percentages
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Evaluation

• Phase 1
• CBC
• UA
• Urine culture
• BUN, CR, electrolytes, calcium, uric acid
• Lipid panel
• Renal ultrasound
• Echocardiogram

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Evaluation

• Phase 2
• Renal scan with angiotensin-converting enzyme
  inhibitor
• Renin profiling
• Urine collection for catecholamines
• Plasma and urinary steroids

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Evaluation

• Phase 3
• Renal artery imaging
• Mataiodobenzguanidine (MIBG) scan of adrenals
• Caval sampling for catecholamines

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Evaluation

• In the first year of life, virtually all
  hypertension is secondary, and even in infants in
  whom no cause was found secondary disease must
  still be suspected.
• Given the low prevalence of secondary disease in
  the adolescent population with mild hypertension,
  only minimal studies are warranted.

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Evaluation

• Whenever a young child is found to be
  hypertensive, renovascular disease should be
  strongly suspected, and the initial evaluation
  should entail assessment of the renal anatomy and
  blood flow.
• Echocardiography is more sensitive than ECG for
  detecting early left ventricular hypertrophy.

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Nonpharmacologic Measures

• Generally, management should begin with smoking
  cessation, weight loss, aerobic exercise, and
  dietary modifications.
• Although demonstrated in adults, the limitation
  of sodium intake and its positive impact on BP is
  less clear in children.
• Despite the lack of large scale trials
  demonstrating the effectiveness of such
  interventions, it is reasonable to recommend them
  given the benefits observed in the adult
  population.

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Indications for Pharmacologic Therapy

• Absolute
• Symptomatic hypertension
• Target organ damage (LVH, retinopathy,
  microalbuminuria)
• Secondary hypertension
• Persistent hypertension despite nonpharmacologic
  measures

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Indications for Pharmacologic Therapy

• Relative
• Sustained or nocturnal hypertension on ambulatory
  monitoring
• Presence of other cardiovascular risk factors
  (smoking, elevated lipids)
• Obesity related hypertension
• Family history of hypertension

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Pharmacotherapy

• The goal of treatment is to achieve a decrease in
  BP to below the 90 to 95th percentile and prevent
  long term sequelae of persistent hypertension.
• The majority of children with secondary
  hypertension require pharmacotherapy and
  frequently more than one medication.
• Patients with high-renin hypertension as with
  chronic renal disease and renovascular disease as
  well as those patients with diabetes would likely
  benefit more from ACE inhibitors.

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Summary

• When discovered, elevated BP should be
  appropriately investigated with the evaluation
  tailored to the age of the child and the severity
  of the BP elevation.
• Despite the absence of clear links between
  childhood hypertension and adult cardiovascular
  disease, it seems logical to suppose that the
  treatment of childhood hypertension would reduce
  cardiovascular and renal morbidity risk in
  adulthood.

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Bibliography

• Bartosh S, Aronson A Childhood Hypertension An
  update of Etiology, Diagnosis, and Treatment.
  Pediatric Clinics of North America 46235, 1999.
• Flynn Joseph Recognizing and Managing the
  Hypertensive Child. Contemporary Pediatrics
  2038, 2003
• Kay J, Sinaiko A, et al Pediatric Hypertension.
  American Heart Journal Sept422, 2001.