Hypertensive Crisis Disease Background

Last updated: 12 December 2025
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Introduction

The clinical differentiation between hypertensive emergency and acute severe hypertension is dependent on the presence of target organ damage (TOD) rather than the level of blood pressure (BP).  For successful management of patients, it is necessary to differentiate hypertensive emergency from acute severe hypertension.

Hypertensive Emergency

Hypertensive emergency is severely elevated BP (systolic BP [SBP] >180 mmHg and/or diastolic BP [DBP] >120 mmHg) that is complicated by progressive or worsening TOD of the central nervous system (CNS), heart, kidneys, lungs, large arteries, retina, or the gravid uterus. There is no definite BP threshold for the diagnosis of hypertensive emergency.  Most target organ damage happens with DBP ≥130 mmHg.

Clinical Conditions or Associated Target Organ Damage that Meet the Diagnostic Criteria for Hypertensive Emergency

  • Acute left ventricular (LV) failure with pulmonary edema
  • Acute coronary syndrome
  • Acute renal failure
  • Crisis associated with pheochromocytoma
  • Dissecting aortic aneurysm
  • Hypertensive encephalopathy
  • Intracranial hemorrhage or cerebrovascular accident (CVA)
  • Illicit drug use (eg amphetamines, cocaine)
  • Perioperative hypertension
  • Severe preeclampsia/eclampsia
  • Symptomatic microangiopathic hemolytic anemia
  • Malignant hypertension with or without thrombotic microangiopathy or acute renal failure

 

Acute Severe Hypertension

Acute severe hypertension refers to patients with severely elevated BP (>180 mmHg/120 mmHg) but with no evidence of acute end-organ damage, usually asymptomatic with a mild headache. Frequently associated with non-compliance with or discontinuing or decreasing treatment, as well as anxiety, acute pain, emotional stress, or non-adherence to a low-sodium diet. 

Epidemiology

Hypertension affects approximately 1.3 billion individuals worldwide, yet only about 17-20% achieve adequate blood pressure control.  It is estimated that approximately 1-2% of individuals with hypertension will experience a hypertensive crisis because of untreated or inadequately controlled blood pressure.  Findings regarding gender differences among patients with hypertensive emergencies have been inconsistent. Most published studies report a higher prevalence of hypertensive crisis among women; however, many of these studies included patients with eclampsia. Other studies indicate that men account for a slightly higher proportion of hypertensive emergency cases than women.

Black patients comprise the largest proportion of hospital admissions for hypertensive emergency, followed by White and Hispanic patients. The prevalence of hypertensive emergencies in Asia differed across countries and regions and was lower compared to Western countries. Cross-sectional and retrospective studies in South and Southeast Asia report that hypertensive emergencies in emergency departments occur in approximately 0.1–0.5% of cases.

Pathophysiology

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Chronic uncontrolled hypertension causes long-term endothelial injury characterized by oxidative stress and reduced nitric oxide production. Progressive arteriolar thickening and atherosclerosis result in vascular narrowing and decreased arterial compliance, including within the cerebral circulation. Hypertensive emergency is thought to occur when vascular autoregulation fails, leading to a sudden increase in systemic vascular resistance. This triggers microvascular injury, activation of the renin–angiotensin system, vasoconstriction, pressure-induced natriuresis, and volume depletion, creating a self-perpetuating cycle that further accelerates blood pressure elevation.

Risk Factors

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Risk factors for hypertensive crisis largely overlap with those of cardiovascular disease, including chronic kidney disease, renovascular hypertension, coronary artery disease, heart failure, prior stroke, alcohol consumption, and recreational drug use. Hypertensive emergencies are also commonly associated with comorbid conditions such as diabetes, hyperlipidemia, and chronic kidney disease. Among patients with acute severe hypertension, the presence of advanced age (>60 years old), male sex, chronic kidney disease, and proteinuria are risk factors necessitating close monitoring, though management can be done in an outpatient setting. Nonadherence to antihypertensive medications was also recognized as a significant risk factor for developing hypertensive crises. In rare instances, disorders such as pheochromocytoma or inflammatory vascular diseases may precipitate a hypertensive crisis.