• Clinical science

Hypertension

Summary

Hypertension is a common condition that affects one in every three adults in the United States. The AHA/ACC guidelines define it as a blood pressure of ≥ 130/80 mm Hg and by 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 crises.

Definition

References:[3][4][5]

Epidemiology

  • Prevalence
    • One in three adults in the US is affected.
    • Prevalence increases with age (∼ 65% among those ≥ 60 years of age).
    • African Americans are more commonly affected than Asian American or white individuals.
    • 60–75% of obese and overweight patients are affected.
  • Sex: > below age of 45; ; the sex ratio is almost balanced at > 45 years of age (i.e., after menopause)
  • Most common risk factor for cardiovascular disease

References:[6][7][3][8][9][10][11][12]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Primary (essential) hypertension

  • No specific cause; multifactorial etiology including epigenetic/genetic and environmental factors
  • 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)

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

  • Caused by an identifiable underlying condition
  • Accounts for 5–15% of cases of hypertension in adults
  • Accounts for 70–85% of cases of hypertension in children < 12 years of age
  • Age at onset < 25 years or > 55 years

Causes

RECENT can help you remember the causes of secondary hypertension: R = Renal (e.g., renal artery stenosis, glomerulonephritis), E = Endocrine (e.g., Cushing syndrome, hyperthyroidism, Conn syndrome), C = Coarctation of aorta, E = Estrogen (oral contraceptives), N = Neurologic (raised intracranial pressure, psychostimulants use), T = Treatment (e.g., glucocorticoids, NSAIDs).

References:[13][13][14][3][15][16][17][18][19]

Clinical features

  • 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 below)
  • 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!

References:[7][19]

Subtypes and variants

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: 24-hour blood pressure monitoring

Isolated systolic hypertension (ISH)

References:[6][13][14][20][21][22][23][24][25][26][27][28][29][30][31][32][5][33][34][1][35]

Diagnostics

General approach

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” for the basic approach to measurement.
AHA/ACC 2017 BP categories
BP category Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg)
Normal blood pressure < 120 and < 80
Elevated 120–129 and < 80
Stage 1 hypertension 130–139 or 80–89
Stage 2 hypertension ≥ 140 or ≥ 90
JNC 8 BP categories
BP category Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg)
Normal blood pressure < 120 and < 80
Prehypertension 120–139 or 80–89
Stage 1 hypertension 140–159 or 90–99
Stage 2 hypertension ≥ 160 or ≥ 100

Initial evaluation of newly diagnosed hypertensive patients

Approach to diagnosing secondary hypertension

  • 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 learning cards.)
Diagnostic findings Underlying condition
Hypokalemia
Metabolic alkalosis and aldosterone-to-renin ratio
Difference in blood pressure In both arms
Of upper and lower limbs

Daytime sleepiness (Epworth scale, Berlin questionnaire)

Nondipping in 24-hour blood pressure monitoring

Increased 24-hour urinary metanephrines
↑ Serum calcium, PTH level, ↓ serum phosphates
↑ Serum cortisol
TSH, ↑ free T4

Screening for hypertension (USPSTF recommendations) [36]

  • 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.

References:[37][14][20][3][19][38][5][39][40][41][42]

Treatment

Nonpharmacological measures (lifestyle changes for managing hypertension)

Intervention (in order of effectiveness) Target Approximate systolic BP reduction in hypertensive patients
Weight loss
  • Ideal body weight
1 mm Hg per kg reduction in body weight in overweight individuals
DASH diet
  • Diet rich in fruits, vegetables, and whole grains; low in saturated and trans fats
11 mm Hg
Decrease dietary sodium
  • Daily sodium intake < 1500 mg/day
5–6 mm Hg
Exercise Aerobic
  • 90–150 minutes per week
  • 65–75% of maximum heart rate (e.g., brisk walk)
5–8 mm Hg
Dynamic resistance (e.g., weight training)
  • 50–80% of maximum strength
  • 6 exercises with 3 sets per exercise and 10 repetitions per set
  • 90–150 minutes per week
4 mm Hg
Isometric resistance (e.g., hand grip exercise)
  • 30–40% of maximum strength
  • 4 repetitions/session, 3 sessions/week for 8–10 weeks
5 mm Hg
Increase dietary potassium
  • Daily potassium intake 3.5–5 g
4–5 mm Hg
Decreased alcohol intake
  • : ≤ 2 drink daily
  • : ≤ 1 drink daily
4 mm Hg
Smoking cessation
  • Completely quit smoking

3–5 mm Hg after 1 year; 6–7 mm Hg after 3 years [43]

Nonpharmacological measures should be pursued in any patient with a systolic BP > 120 mm Hg or a diastolic BP > 80 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

Guideline Indication for pharmacological therapy Treatment goal
AHA/ACC 2017
  • Age < 65: BP < 130/80 mm Hg
  • Age ≥ 65: systolic BP < 130 mm Hg
    • For patients with significant comorbidities or limited life expectancy, the BP goal is determined based on clinical judgment and the patient's preference.
JNC 8
  • BP less than threshold for initiating pharmacological therapy
  • Initiation of treatment
  • Follow-up
    • Reassess within one month of initiating or changing pharmacological therapy.
      • 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.
      • If blood pressure is controlled: Reassess after 3–6 months and annually thereafter.

Overview of antihypertensive drugs

Drug class Comments Side effects
First-line drugs
ACE inhibitors (e.g., lisinopril, captopril, enalapril)
Angiotensin-receptor blockers (ARB) (e.g., losartan, valsartan)
Thiazide diuretics (e.g., hydrochlorothiazide, chlorthalidone)
Calcium channel blockers Dihydropyridines (e.g., nifedipine, amlodipine)
Nondihydropyridines (e.g., diltiazem, verapamil)
Second-line drugs
Beta blockers (e.g., propranolol, metoprolol, labetalol)
Loop diuretics (e.g. furosemide, torsemide)
Aldosterone antagonists (e.g., eplerenone, spironolactone)
Direct renin inhibitors (e.g., aliskiren)
  • Should not be used in combination with ACEi or ARBs
  • ↑ K+
Alpha-1 blockers (e.g., prazosin, doxazosin)
Alpha-2 agonists (e.g., clonidine)
  • Rarely used
  • CNS depression
  • Bradycardia
  • Rebound hypertension
Direct arteriolar vasodilators (e.g., hydralazine)

Treatment of hypertension in pregnancy

Treatment of hypertension in children

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!

References:[37][13][14][3][15][38][44][45][46][5][1][2][47]

Complications

  • Arterial hypertension leads to changes in the vascular endothelium, particularly of the small vessels, and can therefore affect any organ system.
  • See also hypertensive crises.

Cardiovascular system

Brain

  • Stroke , TIA
  • Cognitive changes such as memory loss

Kidneys

Eyes

Local treatment of the eye is not possible; therefore, systemic reduction of blood pressure is critical!

Classification system according to Keith-Wagener-Barker Findings Symptoms
Grade I Vessel diameter variation: arteriolar constriction and tortuosity Usually asymptomatic
Grade II Gunn sign and marked constriction of vessels and sclerosis of arterioles
Grade III Cotton-wool exudates, hard exudates, retinal hemorrhage, retinal edema, macular star formation Decreased and/or blurred vision, headaches
Grade IV Papilledema, optic atrophy

References:[13][14][21][22][3][19][23][24][25][26][27][28][29][30][48][49][50][51][31][32][5][33][34][52][53]

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