Hypertensive Emergencies

Hypertensive Emergencies is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • An acute elevation of blood pressure (BP) with evidence of rapid and progressive end-organ damage, particularly in the cardiovascular, renal, and CNS. Examples include acute renal injury, acute myocardial infarction (MI), acute stroke, acute heart failure. Severe hypertension (HTN) without evidence of end-organ damage (even in the presence of symptoms) is referred to as hypertensive urgency.
  • Severe HTN or hypertensive crisis is defined as a diastolic BP of ≥120 mm Hg or systolic BP ≥180 mm Hg (1).
  • System(s) affected: cardiovascular; nervous; pulmonary; renal
  • Synonym(s): hypertensive crisis; severe HTN; malignant HTN; accelerated HTN

Epidemiology

Incidence
Incidence of hypertensive emergency: 1–2% of patients with HTN annually in the United States (2)

Prevalence
  • ~1/3 of U.S. adults (>20 years) has HTN (2).
  • Predominant age: elderly

Etiology and Pathophysiology

  • Increased sympathetic tone leads to increased BP.
  • Angiotensin II has multiple effects contributing to HTN and end-organ damage.
    • Stimulates sympathetic tone, aldosterone release, and antidiuretic hormone release
    • Chronic HTN induces vascular thickening and sclerosis.
    • Central effects include enhanced resorption of salt and water.
    • Chronic HTN shifts autoregulation of BP and cerebral blood flow.
  • Renal disease
  • Abrupt withdrawal from antihypertensives, especially clonidine
  • Withdrawal from CNS depressants
  • Medications: SSRIs, decongestants, appetite suppressants, steroids (including oral contraceptives), MAOI interaction with certain foods or drugs, drugs of abuse (cocaine, amphetamine)
  • Eclampsia/preeclampsia
  • Thrombotic thrombocytopenic purpura
  • Pheochromocytoma
  • Severe burns
  • Postoperative HTN

Genetics
  • Genetics: Risk of hypertensive emergency is higher in African Americans.
  • Predominant sex: male > female

Risk Factors

  • History of poorly controlled HTN
  • Drug abuse
  • Noncompliance with medications; abruptly stopping antihypertensive medication without supervision

General Prevention

Treat HTN and counsel patients on importance of compliance with antihypertensive treatment and dangers of stopping medications abruptly.

Commonly Associated Conditions

  • Chronic renal failure
  • Renovascular HTN
  • Acute glomerulonephritis
  • Renal vasculitis

Geriatric Considerations
Elderly patients may experience isolated systolic HTN due to decreased baroreceptor sensitivity.

Pediatric Considerations
  • Usually associated with renal disease
  • May present with abdominal pain
  • Preferred agents for children include labetalol, nicardipine, and nitroprusside.
Pregnancy Considerations
  • Labetalol, nicardipine, or hydralazine is preferred. Nitroprusside decreases placental blood flow, and cyanide metabolite crosses the placenta; may result in fetal toxicity with prolonged exposure
  • Treat preeclampsia.

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