creation date: 2025-10-16 23:16
tags: Pathologies
Hypertensive Crisis
Background
Definitions
Hypertensive crisis is defined as SBP ≥180 mmHg or DBP ≤120 mmHg.
Hypertensive urgency refers to a crisis without acute target organ damage.
Hypertensive emergency refers to a crisis with life-threatening complications such as stroke, myocardial infarction, acute kidney injury, or aortic dissection.
Etiology
The etiology of crisis is multifactorial. Common etiologies and/or precipitating factors include:
Medication-related
- Medication nonadherence
- Withdrawal of antihypertensive medications
- Drug interactions or overdose (Eg. MAOi with tyramine-rich foods, sympathomimetic drugs)
Renal causes - Renovascular diseases (eg. polyarteritis)
- Renal parenchymal disease (eg. glomerulonephritis, tubulointerstitial nephritis)
Endocrine disorder - Pheochromcytoma
- Cushing disease
- Primary hyperaldosteronism
- Renin-secreting tumour
Cardiovascular abnormalities - Coarctation of the aorta
Central nervous system disorders - Head injury
- Cerebral infarction
- Intracerebral hemorrhage
Substance use and withdrawal - Illicit drug use (eg. cocaine, phencyclidine, amphetamines)
- Excessive alcohol consumption
Psychosocial and physiologic stress - Severe emotional stress
- Acute pain
- Anxiety
Pathogenesis
The manifestations of hypertensive emergencies arise when blood pressure increases rapidly and significantly over a short period.
The mechanism behind the organ damage is complex and involves vascular, neurohormonal, and endothelial dysfunction. The major mechanism resulting in symptoms is the mechanical stress on the vasculature caused by the raise in BP.
Some other key factors include:
- Increased systemic vascular resistance (from RAAS activation)
- Pressure natriuresis
- Tissue hypoperfusion
- Ischemia
Endothelial dysfunction
Elevated blood pressure causes shear stress on endothelial cells. This disrupts the balance between vasodilation and vasoconstriction, promoting vascular permeability and inflammatory response.
Elevated BP also stimulates vascular smooth muscle contraction with further exacerbates the crisis.
Disruption of autoregulation of blood flow
Many organs, especially the brain and kidney, possess autoregulation mechanisms that maintain stable blood flow regardless of blood pressure fluctuations.
This can precipitate rupture of blood vessels, cerebral edema, or cause acute kidney injury.
Neurohumoral activation
In response to hypertension, the body activates neurohormonal systems such as:
- Sympathetic nervous system
- RAAS
- Release of endothelin-1
These mechanisms contribute to oxidative stress, vasoconstriction, vasospasms, and other cardiovascular strain.
Micro and macroangiopathy
Hypertension causes damage to the small and large blood vessels which can result in various conditions and syndromes based on where the vessels are.
Activation of inflammatory and coagulation pathways
Activation of coagulation cascade increases the risk of thrombosis and microthrombi formation. Thrombotic obliteration of small vessels and disseminated intravascular coagulation can compromise tissue perfusion, contributing organ damage.
Clinical Presentation
Signs & Symptoms
Common manifestations of hypertension-mediated organ damage in emergencies include:
- Encephalopathy
- Intracerebral hemorrhage
- Acute ischemic stroke
- Acute myocardial infarction
- Acute left ventricular failure with pulmonary edema
- Unstable angina pectoris
- Dissecting aortic aneurysm
- Acute kidney failure
- Eclampsia
Nonspecific symptoms may headaches, visual disturbances, chest pain, and shortness of breath. Encephalopathy may present with dizziness, lethargy, visual symptoms, seizures, and unconsciousness.
Retinopathy may manifest with:
- Flame-shaped hemorrhages
- Cotton wool spots
- Papilledema
History & Physical Exam
As hypertensive urgency is often asymptomatic and would be found incidentally. Hypertensive emergency, however, may manifest with a variety of symptoms based on the involved organs.
Assessment of blood pressure should be done on both arms as significant difference between the two arms may suggest aortic dissection involving the subclavian artery. Radio-radial or radio-femoral delay in pulse may also suggest dissection.
Fundoscopy should be included as retinopathy is a significant finding in hypertensive emergencies.
In patients with suspected encephalopathy, neurological exam should be used to rule out other neurological conditions.
Other aspects to evaluate for include:
- Acute head injury or trauma
- Generalized or focal neurological symptoms
- Nausea and vomiting
- Chest discomfort or pain (suspecting myocardial ischemia or aortic dissection)
- Acute, severe back pain (dissection)
- Dyspnea (pulmonary edema)
- Drug use
Risk factors
Diagnosis
Criteria
Diagnosis of hypertensive crisis is made with either systolic blood pressure ≥180 mmHg or diastolic blood pressure ≥120 mmHg.
However, clinicians should still evaluate a patient even if the presenting BP is less if there was a severely elevated blood pressure from baseline.
Work-up
Clinical findings should guide investigations with the goal of confirming the extent of organ damage. This may include:
- Electrocardiography
- Chest radiography
- Urinanalysis and pregnancy test
- Serum electrolytes and creatinine
- Cardiac biomarkers (if ACS is suspected)
- CT head
- Contrast-enhanced CT for aorta
Differential
A number of diagnoses may be concurrently present or contribute to hypertension-mediated dysfunction. These include:
- Aortic coarctation
- Aortic dissection
- Chronic kidney disease
- Eclampsia
- Hypercalcemia
- Hyperthyroidism
- Pheochromocytoma
- Renal artery stenosis
- Subarachnoid hemorrhage
Red Flags / Complications
The prognosis of untreated hypertensive crisis is poor and timely management is important for outcomes. Complications, even following treatment, include:
- Long-term cardiovascular and renal complications
- Increased risk of stroke, vision loss, kidney damage, adverse cardiac events
Management
Hypertensive urgency (no symptoms)
In patients without acute or worsening hypertension-mediated organ damage, hospital admission is typically not required.
Management consists of adjustment of existing antihypertensive therapy or adding additional oral agents.
The goal is to decrease BP over days to weeks.
Note that there is an increased risk of developing hypertensive emergency and thus timely follow-up is crucial to confirm adequate blood pressure control.
Hypertensive emergency
The goal of treating hypertensive emergencies is to minimize organ damage through controlled reduction of blood pressure. A rapid or excessive reduction is not recommended as the body may have adapted to the chronically elevated pressures and doing so can lead to ischemic injury. The underlying condition should be treated.
Generally, targets are:
- Reduce by <25% in first hour
- Graduate reduction to normal levels over next 24-48 hours
In certain conditions, more rapid treatment may be necessary due to life-threatening complications. These conditions are:
- Acute ischemic stroke
- Acute aortic dissection
- Acute intracerebral hemorrhage
- Acute myocardial infarction
- Pheochromocytoma crisis
- Preeclampsia and eclampsia
Choice of antihypertensive can vary based on severity and affected organs but is administered via IV. Options include:
- Nitrates (nitroprusside, nitroglycerin)
- Calcium channel blockers (clevidipine, nicardipine)
- Dopamine-1 agonist (fenoldopam)
- Adrenergic-blocker (labetalol, esmolol)
- Others (hydralazine, enalaprilat, phentolamine)
In cases where IV antihypertensives are not available or if the organ damage is not serious, oral options may be used but will decreased blood pressure at a slower rate.