HypertensionBasics

DESCRIPTION

Hypertension is average systolic and/or diastolic BPs above the 95th percentile for age, gender, and height percentile on at

least 3 separate occasions as defined by the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Prehypertension: BP between the 90th percentile and 95th percentile or BP >120/80

in adolescents. Primary (essential) hypertension: Hypertension for which there is no underlying cause. Secondary hypertension: Hypertension for which an underlying cause can be identified. White Coat Hypertension: Elevated BP

readings in a medical setting with normal actual blood pressures.

GENERAL PREVENTION

Avoidance of excess weight gain and regular physical activity can prevent obesity-related hypertension.

EPIDEMIOLOGY

• Secondary hypertension is more common in children than in adults.

• Primary hypertension is now identifiable in children and adolescents, and is associated with overweight, the

metabolic syndrome and family history of hypertension.

BASICS-EPIDEMIOLOGY-Prevalence

• Hypertension in the pediatric population is estimated between 1% and 2%.

• 30% of children with BMI >95% have hypertension.

• Primary hypertension in blacks is twice that of whites.

RISK FACTORS

• Primary hypertension: Obesity, sedentary lifestyle, low birth weight, smoking, alcohol, hyperlipidemia, family history, stress, sodium intake, sleep apnea

• Secondary hypertension: Umbilical artery catheterization, UTI, genetic disease

Genetics

Primary hypertension is more likely to develop in individuals when there is a strong family history. The genetics of

secondary causes depend on the condition (e.g., polycystic kidney disease: Autosomal dominant, autosomal recessive; neurofibromatosis: Autosomal dominant; glucocorticoid-remediable aldosteronism: Autosomal dominant).

PATHOPHYSIOLOGY

• Many different mechanisms play a role in primary hypertension: Volume overload (sodium retention, excess sodium intake), volume distribution (sympathetic and renin overactivity, stress), and increased peripheral resistance

(renin and sympathetic activity, insulin, endothelins)

• Secondary causes, with examples, include:

1. Renal: Acute glomerulonephritis, chronic renal failure, polycystic kidney disease, reflux nephropathy

2. Renovascular: Fibromuscular dysplasia, neurofibromatosis, vasculitis

3. Cardiac: Coarctation of the aorta

4. Endocrine: Pheochromocytoma, neuroblastoma, glucocorticoid-remediable aldosteronism, Conn’s syndrome, apparent mineralocorticoid excess, Liddle’s and Gordon’s syndrome

5. Neurologic: Increased intracranial pressure

6. Drugs: corticosteroids, oral contraceptives, sympathomimetics, illicit drugs (cocaine, phencyclidine)

7. Other: Pain, burns, traction

Diagnosis

SIGNS AND SYMPTOMS

• Hypertensive emergency: Severely elevated BP with evidence of target organ injury (encephalopathy, seizures,

renal damage)

• Hypertensive urgency: Severely elevated BP with no evidence of secondary organ damage

History

• Headache, blurry vision, epistaxis, unusual weight gain or loss, chest pain, flushing

• UTIs can be associated with reflux nephropathy and hypertension.

• Gross hematuria, edema, fatigue may suggest renal disease.

• Birth history: Umbilical artery catheterization

• Medications: Corticosteroids, cold preparations, oral contraceptives, illicit drugs

• Family history: Hypertension, diabetes, obesity, familial endocrinopathies, renal disease

• Trauma: Arteriovenous (AV) fistula, traction

• Review of symptoms: Sleep apnea, obesity

Physical Exam

• BP:

1. Children >3 years old should have their BP measured during a health care episode

2. Child should be seated quietly for 5 minutes, feet on the floor with the right arm supported at the level of the heart. Routine BPs pressures are measured in the arm.

3. Use the proper cuff size. The inflatable bladder should completely encircle the arm and cover ~80–100% of the upper arm. A cuff that is inappropriately small will artificially increase the measurement.

4. Elevated BPs obtained by oscillometric devices should be repeated by auscultation.

5. When hypertension is confirmed, BP should be measured in both arms and in a leg. Normally, BP is 10–20

mm Hg higher in the legs. If leg BP is lower than arm, consider coarctation of the aorta.

• Tachycardia in hyperthyroidism, pheochromocytoma

• Body habitus: Thin, obese, growth failure, virilized, stigmata of Turner, or Williams syndrome

• Skin: Café au lait spots, neurofibromas, rashes, acanthosis, malar rash

• Head/Neck: Moon facies, thyromegaly

• Eyes: Funduscopic changes, proptosis

• Lungs: Rales

• Heart: Rub, gallop, murmur

• Abdomen: Mass, hepatosplenomegaly, bruit

• Genitalia: Ambiguous, virilized, femoral pulses

• Neurologic: Bell palsy

TESTS

Ambulatory BP monitoring may be helpful in cases where the diagnosis of hypertension is uncertain (white coat

hypertension, labile hypertension).

LABORATORY

The laboratory evaluation to determine the cause of hypertension should proceed in a stepwise fashion:

• Patients should have the following: Urinalysis, urine culture; serum electrolytes, blood urea nitrogen, creatinine, calcium, cholesterol; CBC; ECG (the most sensitive study to monitor end organ changes); renal ultrasound; retinal

exam.

• Further evaluation is based on history, physical examination, and/or to prove secondary causes: Voiding

cystourethrogram, DMSA renal scan, 3-D CT angiogram, MRA, urine or plasma for catecholamines and metanephrines, plasma renin activity, aldosterone levels

• More invasive studies include the following: Renal angiogram; renal vein renin concentrations; MIBG scan; renal biopsy; genetic studies to identify rare causes of hypertension

DIFFERENTIAL DIAGNOSIS

The initial objective after diagnosing hypertension in children is distinguishing primary from secondary causes. Generally, the younger the child and more elevated the BP measurements, the more likely the cause of hypertension is secondary.

Treatment

INITIAL STABILIZATION

• Hypertensive emergencies should be treated with intravenous blood pressure medications, aiming to decrease the BP by 25% over the 1st 8 hours and gradually normalizing BP over 24–48 hours.

• Hypertensive urgencies can be treated by either IV or PO antihypertensives depending on symptomatology.

GENERAL MEASURES

• If BP is >95th percentile, it should be repeated on 2 more occasions.

• If BP is >99th percentile plus 5 mm Hg, prompt referral for evaluation and therapy should be made.

• If the patient is symptomatic, immediate referral and treatment are indicated.

• Mild primary hypertension may be managed with nonpharmacologic treatment: Weight reduction, exercise, sodiumrestriction, avoidance of certain medications such as pseudoephedrine

• Pharmacologic therapy should be directed to the cause of secondary hypertension when this is known or for severe,sustained hypertension. Medications may be needed in children with mild-to-moderate hypertension if

nonpharmacologic therapy has failed or if end organ changes are present.

DIET

• Dietary increase in fresh vegetables, fresh fruits, fiber, and nonfat dairy

• Restriction of sodium and calories

ACTIVITY

• Regular aerobic physical activity (30–60 minutes several days a week).

• Limitation of sedentary activities to <2 hours per day.

SPECIAL THERAPY

Dialysis may be needed for hypertension in chronic renal failure.

MEDICATIONS

• Classes of antihypertensive agents include α- and β-blockers, diuretics, vasodilators (direct and calcium channel

blockers), ACE inhibitors, and angiotensin receptor blockers (ARB):

• Therapy should be initiated with a single drug.

1. Avoid multiple medications with the same mechanism of action.

2. Elicit a history of adverse effects and adjust medications accordingly.

3. Specific classes should be used with concurrent medical conditions: ACE inhibitors or ARBs in children with diabetes and microalbuminuria or proteinuric renal diseases; beta blockers or calcium channel

blockers with migraine headaches.

4. Certain classes of medication should be avoided in patients with specific conditions, such as asthma and

diabetes (beta-blockers) and bilateral renal artery stenosis (ACE inhibitors).

• ACE inhibitors are associated with congenital malformations and are contraindicated during pregnancy; calcium

channel blockers and beta blockers are alternatives.

SURGERY

Surgical correction of renovascular hypertension and coarctation of the aorta. Percutaneous transluminal angioplasty has

been used for renal artery stenosis.

Follow-up Recommendations

DISPOSITION

Admission Criteria

• Hypertensive emergencies should be admitted to the ICU if indicated.

• Hypertenisive urgencies should be admitted to the hospital.

EXPECTED COURSE/PROGNOSIS

The patient’s prognosis depends on the underlying cause of the hypertension. It is excellent if the BP is well controlled.

POSSIBLE COMPLICATIONS

• CHF

• Renal failure

• Encephalopathy

• Retinopathy

PATIENT MONITORING

The reduction of BP with medication should be gradual to avoid side effects. The medications themselves cause adverse

effects, such as exercise intolerance (beta-blockers), headaches (vasodilators), renal insufficiency or hyperkalemia(ACE inhibitors), or hypokalemia (diuretics).

Patient Teaching Medication

DIET

• Increase in fresh vegetables, fresh fruits, fiber, and nonfat dairy

• Restriction of sodium and calories

ACTIVITY

• Regular aerobic physical activity (30–60 minutes several days a week)

• Limitation of sedentary activities to <2 hours per day

PREVENTION

Avoidance of excess weight gain, smoking, and alcohol; regular physical activity

Frequently Asked Questions

• Q: What is the value of ambulatory BP monitoring?

• A: This device is similar to a Holter monitorand measures BPs over a 24-hour period while the patient is awake andasleep. By reviewing the BPs, one can determine if a significant proportion of readings are elevated and whether or

not the normal dip in pressures during sleep is seen. Thus conditions such as “white coat hypertension” can be verified or discounted.

• Q: What are the indications for invasive studies such as angiography?

• A: This decision should be individualized and based on the severity of the hypertension, response to medication,

the clinical presentation (e.g., neurofibromatosis), and results of other studies. In general, young children and all children with severe, unexplained hypertension should be completely evaluated.

• Q: Can adolescents with elevated BP compete in sports?

• A: Adolescents with hypertension should be encouraged to participate in athletics if their BP is well controlled. The

use of stress testing in this population is controversial.

• Q: Do I need to worry about isolated systolic hypertension?

• A: Studies in adults have shown that sustained systolic hypertension may be just as important as diastolic hypertension.