Portal Hypertension Flashcards
What causes portal HTN?
obstruction to blood flow somewhere in the portal circuit
3 areas in which increase in bloodflow resistance can occur?
- Sinusoidal (intrahepatic)
- Presinusoidal
- Postsinusoidal
What characteristics are used to measure portal vein pressures?
- Free hepatic vein pressure (FHVP)
- Wedged hepatic vein pressure (WHVP)
- Hepatic vein pressure gradient (HVPG)
HVPG = WHVP - FHVP
In a healthy liver, HVPG should be very small
In the western world, what is the greatest cause of intrahepatic resistance to blood flow?
Cirrhosis
What are some causes of presinusoidal HTN?
- Thrombotic occlusion
- Portal venule blockage
What are conditions that can lead to postsinusoidal portal HTN?
CHF or Budd-Chiari Syndrome
How can endothelial dysfn in cirrhosis lead to portal HTN?
Decreased amounts of nitric oxide results in vasoconstriction and hepatic portal HTN
What effects does portal HTN have on the mesenteric bloodflow?
Increased blood volume and sheer stress causes vasodilation of the mesenteric arteries. This results in decreased effective arterial blood volume and other manifestations such as ascites, hepatorenal syndrome, and hepatopulmonary syndrome
What is the major cause of intrahepatic portal HTN worldwide?
Schistosomiasis (S. mansoni and japonicum)
Typical cause of presinusoidal HTN?
Portal Vein Thrombosis
What is the name of the syndrome in which congestive disease of the liver caused by occlusion of the hepatic veins and their tributaries?
Budd-Chiari Syndrome
Prinicpal cause of Budd-Chiari Syndrome?
Thrombosis of hepatic vein
Variation of Budd-Chiari syndrome caused by occlusion of the central hepatic venules and small branches of the hepatic veins?
Hepatic-veno occlusive disease
What is the most common complication of portal HTN?
Esophageal varices
Why does splenomegaly occur in hepatic portal HTN?
Cell transit time increases and therefore RBCs, WBCs, and platelets are removed at a greater rate
What are the focal hemorrhages that cause fibrotic, iron-laden nodules in hypersplenism that occurs with hepatic portal HTN?
Gmna-Gandy bodies
What is ascites?
Accumulation of fluid in the peritoneal cavity
Describe the pathogenesis of ascites
Hydrostatic pressure forces fluid into the space of Disse. This fluid then spills into the peritoneal cavity as ascites
What is an important complication of cirrhosis and ascites?
Spontaneous bacterial peritonitis
What are the characteristics of heptorenal syndrome?
Renal hypoperfusion: Oliguria, azotemia, increased plasma creatinine
Describe the pathogenesis of hepatorenal syndrome?
In early portal HTN, renal glomerular filtration pressure is protected from systemic arteriolar vasodilation by intrarenal prostaglandins. With increasingly severe arteriolar vasodilation, these intrarenal factor sbecome ineffective, renal arterial vasoconstriction intensifies and GFR decreases.
What is hepatopulmonary syndrome?
AV shunts that are formed in the lungs in the presence of renal failure resulting in V/Q mismatch and hypoxemia
Pathogenesis of hepatic hydrothorax
Ascites fluid effuses across diaphragm into thorax
