What is the definition of a hypertensive crisis?

Definition of Hypertensive Crisis

A hypertensive crisis is defined as a severe blood pressure elevation (>180/120 mmHg) that is further classified as either a hypertensive emergency when accompanied by evidence of new or worsening target organ damage, or a hypertensive urgency when severe blood pressure elevation occurs without acute target organ damage. 1

Types of Hypertensive Crisis

1. Hypertensive Emergency

• Definition: Severe BP elevation (>180/120 mmHg) with evidence of new or worsening acute hypertension-mediated organ damage 1
• Mortality: If left untreated, has a 1-year death rate >79% with median survival of only 10.4 months 1
• Examples of target organ damage:
  • Hypertensive encephalopathy
  • Intracranial hemorrhage
  • Acute ischemic stroke
  • Acute myocardial infarction
  • Acute left ventricular failure with pulmonary edema
  • Unstable angina pectoris
  • Dissecting aortic aneurysm
  • Acute renal failure
  • Eclampsia 1

2. Hypertensive Urgency

• Definition: Severe BP elevation (>180/120 mmHg) without progressive target organ dysfunction 1
• Presentation: Often occurs in non-compliant or inadequately treated hypertensive patients 1
• Symptoms: May include severe headache, shortness of breath, epistaxis, or severe anxiety 1

Special Classifications

Malignant Hypertension

• Characterized by severe BP elevation (usually >200/120 mmHg) with advanced bilateral retinopathy
• Retinal findings include flame-shaped hemorrhages, cotton wool spots, or papilledema 1

Hypertensive Encephalopathy

• Severe hypertension with neurological manifestations (seizures, lethargy, cortical blindness, coma)
• May lack advanced retinopathy in up to one-third of patients 1, 2

Thrombotic Microangiopathy

• Severe BP elevation with Coombs-negative hemolysis and thrombocytopenia
• Improves with BP-lowering therapy 1, 2

Management Principles

Hypertensive Emergency

1. Admission: Immediate admission to intensive care unit for continuous BP monitoring 1
2. Treatment: Parenteral administration of titratable short-acting IV antihypertensive agents 1, 3
3. BP Reduction Targets:
   • For compelling conditions (aortic dissection, severe preeclampsia/eclampsia, pheochromocytoma crisis):
     • Reduce SBP to <140 mmHg during first hour
     • For aortic dissection, reduce to <120 mmHg 1
   • For other conditions:
     • Reduce SBP by no more than 25% within first hour
     • If stable, reduce to 160/100 mmHg within next 2-6 hours
     • Cautiously reduce to normal during following 24-48 hours 1

Hypertensive Urgency

• Oral antihypertensive therapy is appropriate 3, 4
• BP reduction should occur gradually over 24-48 hours 5
• Avoid rapid BP reduction which can precipitate ischemia due to altered autoregulation 1

Important Considerations

• The actual BP level may not be as important as the rate of BP rise; patients with chronic hypertension often tolerate higher BP levels than previously normotensive individuals 1
• Short-acting nifedipine is no longer considered acceptable in the initial treatment of hypertensive emergencies or urgencies due to risk of excessive BP reduction 1
• Sodium nitroprusside should be used with caution due to its toxicity profile 3, 4
• Secondary causes should be investigated, particularly in malignant hypertension where they occur in 20-40% of cases 2

Common Pitfalls

1. Failing to distinguish between hypertensive emergency and urgency, leading to inappropriate management
2. Reducing BP too rapidly, which can cause cerebral, renal, or coronary ischemia
3. Using inappropriate medications (e.g., short-acting nifedipine)
4. Not investigating for secondary causes of hypertension
5. Inadequate follow-up after a hypertensive crisis, contributing to recurrence 6