Causes of Ischemic Hepatitis (Shock Liver)
Primary Etiology
Ischemic hepatitis results from acute hepatic hypoperfusion in the setting of pre-existing cardiac disease, particularly right-sided heart failure with hepatic congestion, which sensitizes the liver to subsequent circulatory collapse. 1
The "Two-Hit" Mechanism
- Approximately 50% of ischemic hepatitis cases occur without documented hypotension, indicating that hepatic congestion alone creates vulnerability to even modest perfusion deficits. 1, 2
- The pathogenesis follows a two-hit model: first, chronic hepatic congestion from right-sided heart failure compromises baseline hepatic oxygenation; second, a superimposed hypoperfusion event (even without frank shock) triggers massive centrilobular necrosis. 3, 4
- All patients with ischemic hepatitis in landmark studies had underlying organic heart disease, and 94% had right-sided heart failure with passive hepatic congestion. 4
Cardiovascular Causes (Most Common)
Low Cardiac Output States
- Severe congestive heart failure (especially right-sided failure with hepatic venous congestion) is the predominant predisposing condition. 1, 3, 4
- Cardiogenic shock from acute myocardial infarction, decompensated cardiomyopathy, or acute valvular dysfunction. 1, 2
- Cardiac arrest with prolonged resuscitation. 1
Arrhythmias
- Rapid atrial fibrillation or other tachyarrhythmias causing acute hemodynamic decompensation. 5
- Severe bradyarrhythmias leading to inadequate cardiac output. 3
Vascular Causes
- Celiac artery stenosis combined with systemic hypotension can precipitate hepatic artery steal syndrome, though this is rare because hepatic collaterals are typically robust. 6
- Hepatic artery thrombosis (though this typically causes focal rather than diffuse injury). 6
Circulatory Failure
Septic Shock
- Septic shock is a major contributor, often in combination with underlying cardiac disease. 3, 7
- The combination of systemic vasodilation, increased metabolic demand, and microcirculatory dysfunction creates profound hepatic hypoperfusion. 7
Hypovolemic Shock
- Severe hemorrhage (though trauma patients with isolated hypotension rarely develop ischemic hepatitis unless pre-existing cardiac disease is present). 4
- Profound dehydration or third-spacing in critical illness. 7
Respiratory Failure
- Severe hypoxemia from acute respiratory distress syndrome (ARDS), pneumonia, or pulmonary embolism reduces hepatic oxygen delivery. 3, 7
- Respiratory failure often coexists with cardiac dysfunction, creating a synergistic insult. 7
Critical Clinical Context
Vasopressor Requirement
- Patients requiring vasopressor therapy have significantly higher mortality risk, as vasopressors indicate severe underlying circulatory failure. 7
Multifactorial Etiology
- The majority of ischemic hepatitis cases have multifactorial causes, typically combining cardiac disease, hypotension, and respiratory or renal dysfunction. 7, 4
Concurrent Organ Injury
- Acute kidney injury and rhabdomyolysis frequently accompany ischemic hepatitis, reflecting systemic hypoperfusion. 1, 2
Key Pathophysiologic Insight
Systemic hypotension or shock alone does not cause ischemic hepatitis in patients without underlying cardiac disease. In a controlled study of trauma patients with documented systolic blood pressure <75 mmHg for ≥15 minutes, zero patients developed ischemic hepatitis (mean peak AST only 78 IU/L), whereas all patients with ischemic hepatitis had severe underlying cardiac disease. 4 This confirms that hepatic venous congestion from right-sided heart failure is the critical predisposing factor that renders the liver vulnerable to hypoperfusion. 4
Clinical Pitfalls
- Do not require documented hypotension to diagnose ischemic hepatitis—half of cases arise without recorded shock episodes because chronic congestion alone can precipitate injury during modest perfusion decrements. 1, 2
- Do not assume isolated hypotension will cause ischemic hepatitis—the liver tolerates transient hypotension remarkably well unless pre-existing cardiac disease with congestion is present. 4
- Recognize that vasopressor use signals both the severity of circulatory failure and independently predicts mortality. 7