Portal Hypertension

Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Most individuals are asymptomatic until complications arise, including esophageal varices, portal hypertensive gastropathy, ascites, and hypersplenism. The diagnosis is clinical, but it can be supported by ultrasound findings (and hepatic venous pressure gradient measurement in unclear cases). Management requires treating the underlying etiology and managing the complications. This can include nonselective beta blockers to prevent bleeding from varices, diuretics and sodium restriction for ascites, and transjugular intrahepatic portosystemic shunt for refractory complications.

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Etiology and Pathophysiology

Etiology

The etiologies of portal hypertension can be classified based on the location of increased resistance to blood flow through the liver.

Prehepatic etiologies:

  • Portal vein thrombosis
  • Splenic vein thrombosis
  • Massive splenomegaly
  • Splanchnic arteriovenous fistula

Hepatic etiologies:

  • Presinusoidal:
    • Schistosomiasis
    • Early primary biliary cholangitis
    • Granulomatous disease (e.g., sarcoidosis)
    • Congenital hepatic fibrosis
    • Polycystic liver disease
    • Idiopathic noncirrhotic portal hypertension
  • Sinusoidal:
    • Cirrhosis (most common cause in Western countries)
    • Acute alcoholic hepatitis
    • Viral hepatitis
    • Vitamin A intoxication
  • Postsinusoidal: hepatic veno-occlusive disease

Posthepatic etiologies:

  • Cardiac:
    • Right-sided heart failure
    • Severe tricuspid regurgitation
    • Constrictive pericarditis
    • Restrictive cardiomyopathy
  • Noncardiac: Budd-Chiari syndrome

Pathophysiology

Anatomy:

  • Blood supply: the liver has a special dual blood supply that provides a mix of oxygenated and deoxygenated (but nutrient-rich) blood. 
    • Hepatic artery proper: 
      • Supplies 25% of the liver’s blood supply
      • Carries oxygenated blood
    • Portal vein: 
      • Supplies 75% of blood supply
      • Formed most commonly by the union of the splenic and superior mesenteric veins
      • Carries oxygen-poor, nutrient-rich blood drained from the abdominal organs
  • Venous drainage: sinusoids → central vein of each lobule → hepatic veins → inferior vena cava (IVC)
  • Portosystemic anastomoses: 
    • Alternative routes of circulation ensure venous drainage of the abdominal organs even if a blockage occurs in the portal system.
    • Anastomoses include:
      • Left gastric veins and lower esophageal veins 
      • Superior rectal veins and inferior and middle rectal veins
      • Paraumbilical veins and small epigastric veins
      • Intraparenchymal hepatic branches of right division of portal vein and retroperitoneal veins 
      • Omental and colonic veins with retroperitoneal veins 
      • Ductus venosus and the IVC

Portal hypertension:

  • Pathologically elevated pressure of the portal venous system (> 5 mm Hg higher than the IVC)
  • ↑ Venous resistance (e.g., liver disease, vascular obstruction) → ↑ portal venous pressure → complications:
    • Varices: ↑ collateral blood flow through the portosystemic anastomoses 
    • Ascites: 
      • ↑ Hydrostatic pressure in the downstream hepatic vessels →  fluid shift from intravascular space to peritoneal cavity
      • ↑ Splanchnic vasodilation and blood pooling → ↓ arterial volume → ↓ renal blood flow → RAAS activation → sodium and water retention
    • Hypersplenism: ↑ splenic vein pressure
Esophageal varices, splenomegaly, and rectal varices in portal hypertension

Esophageal varices, splenomegaly, and rectal varices resulting from backup of blood flow due to elevated pressures within the portal vein

Image by Lecturio.

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Clinical Presentation

Portal hypertension itself usually has no symptoms. Clinical manifestations arise as a result of the underlying etiology and/or complications.

Evidence of common complications

  • Collateral portosystemic blood flow and varices:
    • Caput medusae (engorged paraumbilical veins)
    • Hematemesis and/or melena due to:
      • Esophageal varices (potentially life-threatening)
      • Portal hypertensive gastropathy (gastric mucosal vascular congestion)
    • Bleeding from rectal varices
  • Hypersplenism:
    • Splenomegaly
    • Pancytopenia
  • Ascites:
    • Abdominal distention
    • Fluid wave
    • Shifting dullness

Evidence of common etiologies

  • Cirrhosis:
    • Jaundice
    • Pruritus
    • Gynecomastia
    • Palmar erythema
    • Spider angiomata
    • Asterixis
  • Right-sided congestive heart failure
    • Peripheral edema
    • Elevated jugular venous pressure
    • Shortness of breath
    • Paroxysmal nocturnal dyspnea

Diagnosis

Diagnostic evaluation

The diagnosis of portal hypertension is generally based on clinical evaluation, but it may be supported by:

  • Ultrasonography:
    • Should be performed with Doppler flow
    • Can support the diagnosis, but not sensitive
    • Potential findings suggesting portal hypertension:
      • Reversed blood flow in the portal vein
      • Portosystemic collaterals
      • Enlarged portal vein diameter
      • Ascites
      • Splenomegaly
    • Evaluates for potential etiologies:
      • Nodular/cirrhotic liver
      • Venous thrombosis
  • Hepatic venous pressure gradient measurement (HVPG)
    • Usually done only if the diagnosis is unclear
    • Approximates the pressure gradient between the portal vein and IVC by using a transjugular catheter
    • HVPG ≥ 6 mm Hg is diagnostic.
Ultrasound of the liver identifies a large portal vein consistent with portal hypertension

Ultrasound of the liver identifies a large portal vein, consistent with portal hypertension.

Image: “Ultrasound abdomen: ultrasound of liver identifies a patent portal vein, 158 mm in diameter, indicative of portal hypertension in this noncirrhotic patient.” by Ratnayake S. et al. License: CC BY 3.0

Additional evaluation

Additional studies may be performed based on the clinical presentation and presence of complications.

  • Cirrhosis:
    • Liver enzymes (↑ bilirubin, AST, and ALT are common)
    • ↑ Coagulation studies
    • ↓ Albumin
    • ↑ Ammonia 
  • Hypersplenism: CBC → evaluate for anemia, thrombocytopenia
  • Ascites: 
    • Paracentesis can be considered.
    • Serum–ascites albumin gradient (SAAG): > 1.1 g/dL indicates portal hypertension
    • Ascites total protein:
      • > 2.5 g/dL, consider cardiac causes and Budd-Chiari syndrome
      • < 2.5 g/dL, consider cirrhosis
  • Varices: EGD: 
    • Can be performed to screen for esophageal varices
    • Diagnostic and therapeutic for acute bleeding from esophageal varices
Esophageal varices cirrhosis

Endoscopic view of the esophageal varices:
The red patches indicate a recent bleed.

Image: “Gastroscopy image of esophageal varices with prominent red wale spots” by Samir. License: Public Domain

Management

The focus of therapy is to prevent and treat the complications of portal vein thrombosis. It is also important to treat the underlying etiology (when possible).

Varices and portal hypertensive gastropathy management

  • Nonselective β-blockers (propranolol, nadolol): 
    • Cause splanchnic vasoconstriction and  ↓ portal inflow
    • ↓ Risk of bleeding from varices or gastropathy
  • Management for acute bleeding:
    • IV fluid resuscitation
    • Blood transfusion, as needed
    • Octreotide: causes splanchnic vasoconstriction → ↓ portal pressure
    • Antibiotic prophylaxis (ceftriaxone): ↓ risk of spontaneous bacterial peritonitis
    • Endoscopic interventions: endoscopic band ligation or sclerotherapy for varices
  • Transjugular intrahepatic portosystemic shunt: 
    • May be used for recurrent or refractory bleeding
    • Creates and stents a connection between the portal and hepatic vein → ↓ pressure in the portal vein

Ascites management

  • Conservative management
    • Sodium restriction (< 2 g/day)
    • Diuretic therapy:
      • Furosemide
      • Spironolactone
  • Invasive management:
    • Therapeutic paracentesis:
      • Rapid symptom relief
      • Used if ascites is refractory to conservative measures
    • Transjugular intrahepatic portosystemic shunt for refractory ascites

Clinical Relevance

  • Cirrhosis: late stage of hepatic necrosis and scarring. In cirrhosis, chronic cellular damage causes extensive distortion of the normal hepatic architecture, which can lead to impairment of normal blood flow through the liver and portal hypertension. Signs and symptoms are often nonspecific (e.g., fatigue, anorexia, weight loss). Decompensation manifests as jaundice, ascites, and liver failure. Diagnosis often requires liver biopsy. Management is mostly supportive, with liver transplantation being the only curative treatment.
  • Budd-Chiari syndrome: hepatic venous outflow obstruction (from thrombosis, compression, or vascular invasion), which may affect the hepatic veins and/or IVC. Typical presentation is with hepatomegaly, ascites, and abdominal discomfort. The diagnosis is confirmed by Doppler ultrasonography. Treatment involves addressing the underlying condition that caused the venous occlusion.
  • Portal vein thrombosis: can occur from a number of causes (hypercoagulable state, surgery, inflammation, trauma, malignancy) and results in portal hypertension. Ultrasound with Doppler showing absent or diminished blood flow through the portal vein is usually diagnostic. Management includes anticoagulation, thrombolysis in specific cases, and management of complications of portal hypertension.
  • Schistosomiasis: infection by the trematode Schistosoma. Schistosomiasis occurs in developing countries with poor sanitation. The clinical presentation is a result of the host’s immune response to antigens from the eggs. Most individuals are asymptomatic, but others may develop acute schistosome dermatitis, acute schistosomiasis syndrome, or chronic schistosomiasis. The diagnosis can be made with microscopic evaluation of the urine or feces, serology, or PCR. The treatment for schistosomiasis is praziquantel.
  • Congestive hepatopathy: right-sided congestive heart failure can lead to severe venous congestion, including within the liver. This can progress to cirrhosis. Individuals can have evidence of both heart failure and cirrhosis, and the diagnosis is generally clinical. Management involves treating the underlying heart failure.

References

  1. Hou, W., Sanyal, A. J. (2009). Ascites: diagnosis and management. Med Clin North Am 93:801–817, vii. reference.medscape.com/medline/abstract/19577115
  2. Lubel, J. S., Angus, P. W. /2005). Modern management of portal hypertension. Intern Med J 35:45–49. reference.medscape.com/medline/abstract/15667468
  3. Bleibel, W., Chopra, S., Curry, M. P. (2021). Portal hypertension in adults. UpToDate. Retrieved October 3, 2021, from https://www.uptodate.com/contents/portal-hypertension-in-adults
  4. Garcia-Pagan, J. C., Pik Eu, J. C. (2021). Noncirrhotic portal hypertension. UpToDate. Retrieved October 3, 2021, from https://www.uptodate.com/contents/noncirrhotic-portal-hypertension
  5. Oliver, T. I., Sharma, B., John, S. (2021). Portal hypertension. StatPearls. Retrieved October 3, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK507718/
  6. Carale, J., Azer, S. A., Mekaroonkamol, P. (2017). Portal hypertension. Medscape. Retrieved October 3, 2021, from https://emedicine.medscape.com/article/182098-overview
  7. Tholey, D. (2021). Portal hypertension. MSD Manual Professional Version. Retrieved October 3, 2021, from https://www.msdmanuals.com/professional/hepatic-and-biliary-disorders/approach-to-the-patient-with-liver-disease/portal-hypertension

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