Portal Hypertension

Definition

• Portal HTN:
  • Results from increased resistance or increased portal blood flow
  • When caused by sinusoidal damage from liver disease, defined as an increase in the pressure gradient between the portal vein and the hepatic vein
  • Key consequence of cirrhosis and can result in life-threatening complications

Pathophysiology

• Normal portal circulation

  • Portal venous system: delivers blood directly to the liver from the organs in nutrient digestion

  • Portal vein: formed by the confluence of the splenic vein and the superior mesenteric vein

  • High compliance, low-resistance system: allows large volume flow without changes in portal venous pressure

  • The hepatic artery converges with the portal vein to flow into the hepatic sinusoids and constitutes 30% of cardiac output (dual-supply)

• Hemodynamic changes

  • Portal HTN results from :

    • Increased portal resistance

    • Increased portal blood flow

  • In cirrhosis:

    • Increased intrahepatic resistance

      • Fixed component

        • Distortion of the intrahepatic microcirculation by sinusoidal fibrosis and compression by regenerative nodules

      • Functional components

        • Intrahepatic vasoconstriction due to contraction of hepatic stellate cells and myofibroblasts

        • Increased production of vasoconstrictors (endothelins)

        • Reduced production of vasodilator (nitrous oxide)

    • Increased portal blood flow

      • Increased portal pressures induce overproduction of NO in splanchnic endothelial cells

      • Progressive splanchnic vasodilation and increased portal flow

  • Hyperdynamic circulatory syndrome

    • Decreased SVR, decreased MAP, increased cardiac index

  • Decreased pressure detected by baroreceptors (carotid and renal)

    • Activation of RAAS and ADH

    • Increased sodium and water retention

    • May lead to ascites and hepatorenal syndrome

  • Portosystemic collaterals develop to decompress the increased portal HTN

    • Hemorrhage from gastroesophageal varices

• Classification and Causes of Portal HTN

  • NA and Europe: most common cause is cirrhosis

  • Other causes:

    • Extrahepatic portal vein thrombosis

    • Schistosomiasis

• Measurement of portal pressure

  • HVPG is a measurement of portal pressure

    • Independent measure of variceal hemorrhage and death

    • Measurement: transjugular/femoral approach

    • Normal range: 3-5 mmHg

    • Portal HTN is defined as HVPG >6 mmHg

Variceal Hemorrhage

• Definition

  • Present in 50% of patients with cirrhosis

  • Presence corresponds to severity of liver disease

  • Aggressive and early management is essential (mortality is 15-20%)

• Pathophysiology

  • Portosystemic collaterals open to decompress the increased portal HTN

    • Opening of preexisting vessels or by angiogenesis

    • Reversal of preexisting flow

  • Variceal wall tension is the main factor determining the risk of variceal hemorrhage and correlates with vessel diameter and pressure within the vessel

    • Hemorrhage possible when HVPG >= 12 mmHg

• Clinical and Laboratory Findings

  • Presentation

    • Large-volume hematemesis and/or melena

    • Stigmata of chronic liver disease and GI hemorrhage

    • Hypovolemic shock

  • Laboratory findings

    • Chronic liver disease and portal HTN:

      • Prolonged PT, thrombocytopenia, hypoalbuminemia

• Diagnosis

  • EDG (esophagogastroduodenoscopy)

    • Reveals gastric or esophageal varices

    • Identification of active bleeding and/or stigmata of high hemorrhage risk

      • Pigmented "cherry red" spots

      • Longitudinal "red wale" streaks/signs

• Treatment

  • Acute variceal bleeding

    • ICU + hemodynamic stabilization

    • Symptomatic transfusions

  • Pharmacologic therapy

    • Octreotide (somatostatin analogue)

      • Splanchnic vasoconstriction and reduction of portal blood flow

      • Adjunct to endoscopic therapy

    • Antibiotic

      • Reduction of bacterial infection risk including spontaneous bacterial peritonitis

      • Ceftriaxone or fluoroquinolone (5-7 days)

  • Endoscopic therapy

    • ASAP when hemodynamically stable

    • Endoscopy variceal ligation (EVL) w/ "rubber band" strangulation of the varix

  • Balloon tamponade

    • Used for hemorrhaging varices secondary to EVL

    • Short-term hemostasis

    • Inflation of gastric and esophageal balloon sequentially

    • Is not a definite treatment

  • Transjugular intrahepatic portosystemic shunt (TIPS)

    • Considered for uncontrolled esophageal variceal hemorrhage after failed pharmacologic and endoscopic therapy

    • Creation of a communication between the hepatic vein and an intrahepatic branch of the portal vein

    • Reduction of portal pressure

• Prevention of Variceal Hemorrhage

  • Primary prophylaxis:

    • Nonselective beta blockers (NSBB) (decreases portal venous inflow via unopposed vasoconstriction in the mesenteric arterioles); or

    • EVL to decrease risk of hemorrhage

  • Secondary prophylaxis:

    • Combination therapy: NSBB + serial EVL

    • TIPS