A 52-year-old man with alcoholic cirrhosis presents with hematemesis. Upper endoscopy confirms variceal bleeding. Regarding the pathophysiology and management of portal hypertension in cirrhosis, all of the following are true EXCEPT:

Explanation

## Pathophysiology of Portal Hypertension in Cirrhosis **Key Point:** Portal hypertension in cirrhosis results from two main mechanisms: (1) increased intrahepatic resistance due to architectural distortion and fibrosis, and (2) splanchnic vasodilation with increased blood flow. ### Mechanisms of Portal Hypertension | Mechanism | Pathophysiology | Clinical Relevance | |-----------|-----------------|--------------------| | **Intrahepatic resistance** | Cirrhotic nodules, fibrosis, and loss of sinusoidal fenestration obstruct blood flow | Primary driver (~70% of pressure gradient) | | **Splanchnic vasodilation** | Increased NO, prostacyclin, and other vasodilators in splanchnic bed | Increases portal blood flow, worsens hypertension | | **Decreased systemic vascular resistance** | Compensatory response to portal hypertension | Leads to hyperdynamic circulation | **High-Yield:** The question tests understanding of what does NOT cause portal hypertension in cirrhosis. Increased splanchnic *arterial resistance* is incorrect — the problem is splanchnic *vasodilation* (decreased resistance) with increased flow, not increased resistance. ### Why Option 3 is Correct Portal hypertension in cirrhosis is **NOT** caused by increased splanchnic arterial resistance. In fact, the opposite occurs: splanchnic arteries are vasodilated due to increased nitric oxide and other vasodilators. This vasodilation increases splanchnic blood flow, which compounds the pressure gradient created by intrahepatic obstruction. ### Mechanism of Beta-Blocker Action Beta-blockers (propranolol, carvedilol, nadolol) reduce portal pressure by: 1. Decreasing cardiac output (β₁ blockade) 2. Reducing splanchnic blood flow (β₂ blockade of splanchnic vasodilation) 3. Net result: reduced portal blood flow and pressure gradient **Clinical Pearl:** Carvedilol is superior to propranolol because it has additional α-blocking properties that further reduce splanchnic resistance, making it more effective at lowering portal pressure. [cite:Harrison 21e Ch 297] ## Summary Table: Cirrhosis-Related Portal Hypertension | Feature | True | False | |---------|------|-------| | Intrahepatic resistance ↑ | ✓ | — | | Splanchnic vasodilation | ✓ | — | | Splanchnic arterial resistance ↑ | — | ✓ | | NO-mediated vasodilation | ✓ | — | | Beta-blockers ↓ cardiac output | ✓ | — |