What is portal hypertension?

Portal Hypertension

Portal hypertension is defined as a pathological increase in portal pressure with a hepatic venous pressure gradient (HVPG) above 5 mmHg, with clinically significant portal hypertension (CSPH) occurring at HVPG ≥10 mmHg. 1, 2

Pathophysiology

• Portal hypertension develops through a combination of increased intrahepatic resistance and increased portal blood flow, following the hydraulic equivalent of Ohm's law where "Pressure = Resistance × Flow" 1

• The increased intrahepatic resistance has two components:

  • Structural component (70%): Due to fibrous tissue, vascular distortion from regenerative nodules, and microthrombi 1
  • Functional component (30%): Due to endothelial dysfunction resulting from reduced nitric oxide bioavailability 1

• As portal pressure increases, collateral circulation develops, including esophageal and gastric varices, which serve as drainage veins to reduce portal pressure 3

Classification

Portal hypertension can be classified based on anatomical location 2:

• Prehepatic: Obstruction before the liver (e.g., extrahepatic portal vein obstruction)
• Intrahepatic: Within the liver (most common, typically from cirrhosis)
• Posthepatic: After the liver (e.g., Budd-Chiari syndrome)

Clinical Manifestations

• Clinical signs of portal hypertension include 1:
  • Splenomegaly/hypersplenism
  • Esophageal and gastric varices
  • Ascites (non-malignant)
  • Portovenous collaterals
  • Hepatic encephalopathy
  • Hepatorenal syndrome

Diagnosis

• The gold standard for diagnosing and quantifying portal hypertension is measurement of the hepatic venous pressure gradient (HVPG) 1

  • Normal HVPG: 1-5 mmHg
  • Portal hypertension: HVPG >5 mmHg
  • Clinically significant portal hypertension (CSPH): HVPG ≥10 mmHg

• Non-invasive assessment methods 1:

  • Imaging-based tests:
    • Transient elastography (TE): At 15 kPa, sensitivity 90-96%, specificity 48-50%
    • At 25 kPa, sensitivity 57-85%, specificity 82-93%
  • Blood-based tests (less accurate):
    • APRI: 56% sensitivity, 68% specificity
    • FIB-4: 54% sensitivity, 73% specificity

• First-line investigation for extrahepatic portal vein obstruction is Doppler ultrasound, with CT for confirmation 1

Prognostic Significance

• HVPG ≥10 mmHg is associated with higher risk of clinical decompensation 1
• HVPG ≥16 mmHg is strongly associated with increased mortality 1, 2
• In compensated cirrhosis, HVPG reduction of ≥10% after therapy is associated with decreased risk of first variceal hemorrhage 1

Management Approach

• Treatment strategy depends on the stage of portal hypertension 2:

  • Mild portal hypertension (HVPG >5 but <10 mmHg): Focus on treating underlying cause
  • CSPH without varices (HVPG ≥10 mmHg): Focus on preventing clinical decompensation

• For variceal bleeding 2:

  • Acute management: Vasoactive agents and endoscopic therapy
  • Transjugular intrahepatic portosystemic shunt (TIPS) for refractory bleeding

• For ascites (most common complication) 2:

  • Survival decreases from 80% at 5 years in compensated cirrhosis to 50% when ascites develops

• Liver transplantation should be considered for all patients with decompensated cirrhosis 2

Special Considerations

• Consider screening for extrahepatic portal vein obstruction in patients with myeloproliferative disease and antiphospholipid syndrome 1

• Idiopathic non-cirrhotic portal hypertension (INCPH) should be diagnosed only after excluding other causes of portal hypertension 1

• In patients with extrahepatic portal vein obstruction, once prophylaxis for gastrointestinal bleeding has been implemented, treat underlying prothrombotic conditions 1