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

Definition and 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

Diagnosis

• The gold standard for diagnosing and quantifying portal hypertension is measurement of the hepatic venous pressure gradient (HVPG) 1, 2

• Classification of portal pressure:

  • Normal HVPG: 1-5 mmHg
  • Portal hypertension: HVPG >5 mmHg
  • Clinically significant portal hypertension (CSPH): HVPG ≥10 mmHg 1, 3

• Non-invasive assessment methods include:

  • Imaging-based tests: transient elastography (TE) with sensitivity 90-96% and specificity 48-50% at 15 kPa 1
  • Blood-based tests: APRI with 56% sensitivity and 68% specificity 1
  • First-line investigation for extrahepatic portal vein obstruction is Doppler ultrasound, with CT for confirmation 1

Clinical Manifestations

• Gastrointestinal bleeding related to portal hypertension is the most frequent life-threatening complication 2
• Ascites is the most common complication, reducing 5-year survival from 80% to 50% 2, 3
• Other manifestations include:
  • Splenomegaly and hypersplenism leading to reduced blood cell counts 2
  • Gastroesophageal varices and portal hypertensive gastropathy 2
  • Portosystemic collaterals detectable on abdominal imaging 2
  • Hepatic hydrothorax/pleural effusion in 0%-8% of cases 2

Prognostic Significance

• HVPG ≥10 mmHg is associated with higher risk of clinical decompensation 1
• HVPG ≥16 mmHg is strongly associated with increased mortality 1, 3
• In compensated cirrhosis, HVPG reduction of ≥10% after therapy is associated with decreased risk of first variceal hemorrhage 1, 2
• Previous gastrointestinal bleeding and size of esophageal varices predict future gastrointestinal bleeding 2

Management Approach

• Treatment strategy depends on the stage of portal hypertension:

  • Mild portal hypertension (HVPG >5 but <10 mmHg): focus on treating the underlying cause 1, 3
  • CSPH without varices (HVPG ≥10 mmHg): focus on preventing clinical decompensation 1, 3

• For variceal bleeding:

  • Acute management includes vasoactive agents and endoscopic therapy 1, 3
  • Combination of endoscopic therapy and pharmacological treatment improves hemostasis and reduces mortality 2, 3

• For ascites:

  • Survival decreases from 80% at 5 years in compensated cirrhosis to 50% when ascites develops 1, 2
  • TIPS (transjugular intrahepatic portosystemic shunt) is recommended for refractory ascites 2, 3

• Liver transplantation should be considered for all patients with decompensated cirrhosis as definitive treatment 1, 2, 3

Special Considerations

• Screening for extrahepatic portal vein obstruction should be considered 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, underlying prothrombotic conditions should be treated 1

Common Pitfalls and Caveats

• Non-selective beta-blockers (NSBBs) are ineffective in mild portal hypertension (HVPG >5 but <10 mmHg) 2, 3
• NSBBs, including carvedilol, should be considered for CSPH (HVPG ≥10 mmHg) even without varices 2
• Diagnostic paracentesis with measurement of ascitic fluid albumin/protein, neutrophil count, culture, and amylase is essential when ascites is present 2