Hypertension

Hypertension is a common condition that affects one in every three adults in the United States. The ACC/AHA 2017 guidelines define it as a blood pressure of ≥ 130/80 mm Hg and the JNC 8 criteria as ≥ 140/90 mm Hg. Hypertension can be classified as either primary (essential) or secondary. Primary hypertension accounts for approx. 95% of cases of hypertension and has no detectable cause, whereas secondary hypertension is due to a specific underlying condition. Typical underlying conditions include renal, endocrine, or vascular diseases (e.g., renal failure, primary hyperaldosteronism, or coarctation of the aorta). Clinically, hypertension is usually asymptomatic until organ damage occurs, which then commonly affects the brain, heart, kidneys, or eyes (e.g., retinopathy, myocardial infarction, stroke). Common early symptoms of hypertension include headache, dizziness, tinnitus, and chest discomfort. Hypertension is diagnosed if blood pressure is persistently elevated on two or more separate measurements. Further diagnostic measures include evaluation of possible organ damage (e.g., kidney function tests) and additional tests if an underlying disease is suspected. Treatment of primary hypertension includes lifestyle changes (e.g., diet, weight loss, exercise) and pharmacotherapy. Commonly prescribed antihypertensive medications include ACE inhibitors, angiotensin receptor blockers, thiazide diuretics, and calcium channel blockers. Management of pediatric patients and pregnant women differs from that of nonpregnant adults because some of these drugs are contraindicated in these patient groups. To treat secondary hypertension, the underlying cause needs to be addressed.

See also “Hypertensive crisis.”

• Definition of hypertension in adults: persistent systolic blood pressure of ≥ 140 mm Hg and/or diastolic blood pressure ≥ 90 mm Hg
• ACC/AHA 2017 definition ^[1]

• JNC 8 definition: persistent systolic blood pressure of ≥ 140 mm Hg and/or diastolic blood pressure ≥ 90 mm Hg
• Definition of hypertension in children < 13 years: blood pressure ≥ 95^thpercentile to < 95^thpercentile + 12 mm Hg OR systolic blood pressure ≥ 130 mm Hg and/or diastolic blood pressure ≥ 80 mm Hg (whichever is lower) ^[2][3]

• Prevalence
  • One in three adults in the US is affected. ^[4]
  • Prevalence increases with age (65% of men and 75% of women develop hypertension by the age of ≥ 70 years). ^[5]
  • Rates are highest in African Americans and lowest in Asian Americans, with white individuals falling in the middle. ^[6][7]
  • 60–75% of obese and overweight patients are affected. ^[8]
• Sex ^[9]
  • ♂ > ♀ below 45 years of age
  • The sex ratio is almost balanced at > 45 years of age (i.e., after menopause)

Epidemiological data refers to the US, unless otherwise specified.

Primary (essential) hypertension

• Epidemiology
  • Accounts for 85–95% of cases of hypertension in adults
  • Accounts for 15–20% of cases of hypertension in children < 12 years of age
  • Age at onset: 25–55 years (prevalence is increasing in adolescents)
• Etiology
  • No specific cause known
  • Multifactorial etiology including epigenetic/genetic and environmental factors
  • Directly related to total peripheral resistance and cardiac output
• Risk factors
  • Nonmodifiable risk factors
    • Positive family history
    • Ethnicity
    • Advanced age
  • Modifiable risk factors
    • Obesity
    • Diabetes
    • Smoking, excessive alcohol or caffeine intake
    • Diet high in sodium, low in potassium
    • Physical inactivity
    • Psychological stress

Secondary hypertension ^[10][11]

• Epidemiology
  • Accounts for 5–10% of cases of hypertension in adults ^[12]
  • Accounts for 70–85% of cases of hypertension in children < 12 years of age
  • Age at onset < 25 years or > 55 years
• Etiology: caused by an identifiable underlying condition
  • Renal hypertension
    • Renovascular hypertension (the most common cause of secondary hypertension) can be due to:
      • Renal artery stenosis
      • Polyarteritis nodosa
      • Fibromuscular dysplasia of the renal arteries
    • Polycystic kidney disease (ADPKD)
    • Renal failure (renal parenchymal hypertension)
    • Glomerulonephritis
    • Systemic lupus erythematosus
    • Renal tumors
    • Atrophic kidney
  • Endocrine hypertension
    • Primary hyperaldosteronism
    • Hypercortisolism (Cushing syndrome)
    • Hyperthyroidism
    • Pheochromocytoma
    • Primary hyperparathyroidism
    • Acromegaly
    • Congenital adrenal hyperplasia
  • Other
    • Coarctation of the aorta
    • Obstructive sleep apnea
  • Medication: sympathomimetic drugs, corticosteroids, NSAIDs, oral contraceptives
  • Recreational drug use: amphetamines, cocaine, phencyclidine
  • Isolated systolic hypertension: See “Subtypes and variants” below.

RECENT: Renal (e.g., renal artery stenosis, glomerulonephritis), Endocrine (e.g., Cushing syndrome, hyperthyroidism, Conn syndrome), Coarctation of the aorta, Estrogen (oral contraceptives), Neurologic (raised intracranial pressure, psychostimulants use), Treatment (e.g., glucocorticoids, NSAIDs) are the causes of secondary hypertension.

• Hypertension is usually asymptomatic until:
  • Complications of end-organ damage arise (see “Complications” below)
  • Or an acute increase in blood pressure occurs (see “Hypertensive crisis”)
• Secondary hypertension usually manifests with symptoms of the underlying disease (e.g., abdominal bruit in renovascular disease, edema in CKD, daytime sleepiness in obstructive sleep apnea).
• Nonspecific symptoms of hypertension
  • Headaches, esp. early morning or waking headache
  • Dizziness, tinnitus, blurred vision
  • Flushed appearance
  • Epistaxis
  • Chest discomfort, palpitations
  • Strong, bounding pulse on palpation
  • Nervousness
  • Fatigue, sleep disturbances

Since hypertension is often asymptomatic, regular screening is necessary to prevent end-organ damage.

White coat hypertension (white coat effect)

• Definition: arterial hypertension detected only in clinical settings or during blood pressure measurement at a physician's practice
• Etiology: anxiety experienced by the patient
• Clinical features: consistently normal blood pressure measurements and normalization of elevated blood pressure outside of a clinical setting
• Diagnostics
  • Take different blood pressure measurements several minutes apart (after the patient had time to relax)
  • Take blood pressure measurements on several visits (at least 2)

Isolated systolic hypertension (ISH) ^[13]

• Definition: increase in systolic blood pressure (≥ 140 mm Hg) with diastolic BP within normal limits (≤ 90 mm Hg)
• Etiology
  • ISH in elderly: decreased arterial elasticity and increased stiffness → decreased arterial compliance
  • ISH secondary to increased cardiac output
    • Anemia
    • Hyperthyroidism
    • Chronic aortic regurgitation
    • AV fistula
• Clinical features:
  • Often asymptomatic
  • Signs of increased pulse pressure: e.g., head pounding, rhythmic nodding, bobbing of the head in synchrony with heartbeats
  • Symptoms of hypertension (see “Clinical features” above)
• Diagnostics: See “Diagnosis of hypertension” below.
• Treatment: thiazide diuretics OR dihydropyridine calcium antagonists
• Prognosis: high risk of cardiovascular events (MI, stroke, renal dysfunction)

General approach ^[11][14][15]

Blood pressure monitoring

• Repeated measurements on both arms; : Hypertension is diagnosed if the average blood pressure on at least two readings obtained on at least two separate visits is elevated.
• Long-term measurement of blood pressure (24 hours)
• See “Blood pressure measurement.”

Initial evaluation of newly diagnosed hypertensive patients

• Stratification of cardiovascular risk: : fasting blood glucose, lipid profile (HDL, LDL, and triglycerides levels)
• Evaluation of end-organ damage and underlying causes
  • Complete blood count
  • Renal function tests: serum creatinine and eGFR
  • Serum Na⁺, K⁺, and Ca²⁺
  • Urinalysis
  • TSH
  • Electrocardiogram (ECG)

Approach to diagnosing secondary hypertension ^[11][14][15]

• General indicators of secondary hypertension
  • Young age (< 30 years) at onset of hypertension
  • Onset of diastolic hypertension at an older age (> 55 years)
  • Abrupt onset of hypertension
  • End-organ damage that is disproportionate to the degree of hypertension
  • Recurrent hypertensive crises
  • Resistant hypertension: hypertension that is resistant to treatment with at least three antihypertensives of different classes including a diuretic
• Specific indicators (For details regarding individual diagnostic procedures, see the individual articles.)

Screening for hypertension (USPSTF recommendations) ^[16]

• Individuals 18–39 years of age with normal blood pressure (< 130/85 mm Hg) and without other risk factors: Screen every 3–5 years.
• Individuals > 40 years of age or who are at increased risk for high blood pressure : Screen every year.

Nonpharmacological measures (lifestyle changes for managing hypertension)

Nonpharmacological measures should be pursued in any patient with a systolic BP > 130 mm Hg or a diastolic BP > 90 mm Hg.
Patients should be taught to measure their own blood pressure to allow for long-term monitoring and assessment of treatment efficiency.

Pharmacologic treatment ^{[12][14][15][18]}

• Initiation of treatment
  • Number of antihypertensives
    • Newly diagnosed hypertension with BP < 150/90 mm Hg: Begin therapy with one primary antihypertensive.
    • Newly diagnosed hypertension with BP > 150/90 mm Hg: Begin therapy with two primary antihypertensives.
  • Choice of antihypertensive drug
    • Non-African American patients (including individuals with diabetes): thiazide-type diuretic, calcium channel blocker (CCB), angiotensin-converting enzyme inhibitor (ACEI), or angiotensin receptor blocker (ARB)
    • African American patients (including individuals with diabetes): thiazide-type diuretic or CCB
    • In adults with chronic kidney disease: initial (or add-on) treatment should include an ACEI OR ARB to improve kidney outcome.

• Follow-up: Reassess within one month of initiating or changing pharmacological therapy.
  • If blood pressure is controlled: Reassess after 3–6 months and annually thereafter.
  • If the treatment goal is not reached with one drug, increase the dose of the initial drug or add a second drug.
  • If the treatment goal cannot be reached with two drugs:
    • Add a third drug.
    • Evaluate for secondary causes of hypertension.

Treatment according to subgroups ^{[12][14][15][18]}

• Primary hypertension: thiazide diuretics, ACEIs, ARBs, and/or dihydropyridine CCBs
• Patients with CHF
  • Diuretics, aldosterone antagonists, ACEIs, and ARBs
  • ARBs can be combined with sacubitril
  • Beta blockers
    • Safe to use in compensated CHF
    • Must be used cautiously in decompensated CHF
    • Contraindicated in cardiogenic shock
• Patients with diabetes mellitus
  • ACEIs, ARBs, CCBs, thiazide diuretics, beta blockers
  • ACEIs/ARBs are protective against diabetic nephropathy. Beta blockers can mask hypoglycemia symptoms.
• Patients with asthma
  • ARBs, CCB, thiazide diuretics, cardioselective beta blockers (nonselective beta blockers can cause bronchoconstriction)
  • Avoid ACEIs (can cause bradykinin-induced cough).
• Treatment of hypertension in pregnancy
  • First-line treatment: methyldopa, labetalol, hydralazine, and nifedipine
  • Second-line treatment: thiazides, clonidine
  • Contraindicated: furosemide, ACEI, ARB, renin inhibitors (e.g., aliskiren)
  • See “Treatment of gestational hypertension.”

Moms Love Healthy Newborns: Use Methyldopa, Labetalol, Hydralazine, or Nifedipine for hypertensive pregnant women.

• Treatment of hypertension in children ^[2][3]
  • Treat the underlying cause (e.g., surgical correction of coarctation of the aorta)
  • Lifestyle changes in children with elevated BP (see “Nonpharmacologic measures” in “Treatment” above)
  • Pharmacologic management is indicated for symptomatic hypertension, diabetes mellitus, CKD, and end-organ damage, as well as if there is an insufficient response or no response to lifestyle changes.
    • Goal: BP < 90^th percentile (BP < 50^th percentile in children with diabetes mellitus or CKD)
    • Drugs: ACEI, ARB, or CCB (in children with CKD or diabetes mellitus, ACEIs or ARBs are preferred)
  • Hypertensive emergency: labetalol, nicardipine, or sodium nitroprusside

Beta blockers are not recommended for initial treatment of hypertension in children due to their metabolic side effects (e.g., impaired glucose tolerance) and the fact that they exacerbate asthma!

• Arterial hypertension is the most common risk factor for cardiovascular disease
• It leads to changes in the vascular endothelium, particularly of the small vessels, and can therefore affect any organ system.
• See also “Hypertensive crisis.”

Cardiovascular system ^[11][19]

• Left ventricular hypertrophy, hypertrophic cardiomyopathy, dilated cardiomyopathy
• Congestive heart failure
• Coronary artery disease and myocardial infarction
• Atrial fibrillation
• Aortic aneurysm
• Aortic dissection
• Carotid artery stenosis
• Peripheral artery disease
• Atherosclerosis

Brain ^[11][19][20]

• Stroke , TIA
• Subcortical leukoencephalopathy
• Cognitive changes such as memory loss

Kidneys ^[19][21]

• Hypertensive nephrosclerosis: a renal vascular injury secondary to long-standing arterial hypertension
  • Pathophysiology: chronic hypertension → narrowing of afferent arterioles → reduction of glomerular blood flow → glomerular and tubular ischemia → arteriolonephrosclerosis and fibrosis (focal segmental glomerulosclerosis) → end-stage renal disease
  • Typical findings
    • Initially microalbuminuria and microhematuria
    • With disease progression, nephrosclerosis with macroalbuminuria (usually < 1 g/day) and progressive renal failure occur.
    • Biopsy: sclerosis in capillary tufts, arterial hyalinosis
• Chronic kidney disease

Eyes ^[11][19]

• Hypertensive retinopathy: arteriosclerotic and hypertension-related changes of the retinal vessels
  • Fundoscopic examination:
    • Cotton-wool spots
    • Retinal hemorrhages (i.e., flame-shaped hemorrhages)
    • Microaneurysms
    • Macular star (results from exudation into the macula)
    • Arteriovenous nicking: a tapering of a retinal venule at the point where a retinal arteriole crosses the retinal venule
      • Hourglass shape on fundoscopic exam
      • Associated with advanced hypertensive retinopathy.
    • Marked swelling and prominence of the optic disk with indistinct borders due to papilledema and optic atrophy (end-stage disease)
• Presence of papilledema in a hypertensive patient may indicate a hypertensive crisis and warrants urgent lowering of the blood pressure (see “Hypertensive crisis”)

Local treatment of retinopathy is not possible, therefore, systemic reduction of blood pressure is critical!

We list the most important complications. The selection is not exhaustive.

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