Makindo Medical Notes

Related Subjects: |Chronic liver disease |Cirrhosis |Alkaline phosphatase (ALP) |Liver Function Tests |Ascites Assessment and Management |Budd-Chiari syndrome |Autoimmune Hepatitis |Primary Biliary Cirrhosis |Primary Sclerosing Cholangitis |Wilson disease |Hereditary Haemochromatosis |Alpha-1 Antitrypsin (AAT) deficiency |Non alcoholic steatohepatitis (NASH) |Spontaneous Bacterial Peritonitis |Alcoholism and Alcoholic Liver Disease |Liver Transplantation

About Portal Hypertension

• Portal hypertension is defined by an increase in portal pressure above normal levels.
• The normal portal pressure ranges from 2-5 mmHg
• Portal hypertension occurs when this pressure rises to 12 mmHg or higher .

Anatomy of the Portal System

The portal system consists of the venous drainage from the gastrointestinal (GI) tract, converging to form the portal vein which enters the liver. Key anatomical connections include:

• The inferior mesenteric vein joins the splenic vein .
• The splenic vein then joins the superior mesenteric vein to form the portal vein .
• The portal vein enters the liver and flows into the liver sinusoids, providing venous blood to the liver.
• From the liver, blood exits through the hepatic vein into the inferior vena cava (IVC) .
• The usual gradient across the liver venous outflow (from the portal vein to the hepatic vein) is about 3 mmHg , known as the wedged hepatic venous pressure.
• Portal hypertension can lead to bleeding if the pressure exceeds 12 mmHg .

Causes of Portal Hypertension

Additional Information

• Pre-Sinusoidal Causes: These involve obstruction before blood enters the liver sinusoids, primarily affecting the portal vein and its branches.
• Intrahepatic Pre-Sinusoidal Causes: Conditions within the liver that obstruct portal blood flow before it reaches the sinusoids.
• Sinusoidal Causes: Direct involvement of the liver sinusoids, leading to increased resistance to blood flow.
• Post-Sinusoidal Causes: Obstructions after the sinusoids, affecting hepatic veins and inferior vena cava.

Pathophysiology

• Portal hypertension results from increased resistance to portal blood flow, which can occur at various anatomical levels.
• Increased pressure within the portal system leads to the development of collateral circulation, varices, and complications like ascites and hepatic encephalopathy.

Aetiology and Pathophysiology

• Portal pressure is proportional to the product of flow and resistance.
• In portal hypertension, the primary factor is increased resistance within the portal system.
• A compensatory portosystemic circulation develops, redirecting much of the portal blood flow directly into systemic circulation.
• Globally, the most common cause of portal hypertension is schistosomiasis , which leads to increased portal pressure withoutcausing liver failure.

Clinical Presentation

• Splenomegaly is a classic finding and is almost universally present in portal hypertension. It can be diagnosed clinically and confirmed via ultrasound.
• Cruveilhier-Baumgarten Disease : Characterized by a patent umbilical vein that serves as a portosystemic shunt in patients with cirrhosis, producing a venous hum over the liver or at the xiphisternum.
• The venous hum is known as the Cruveilhier-Baumgarten sign . Interestingly, ascites is not typically present in this syndrome.
• Varices commonly develop in the lower esophagus and anus in portal hypertension and may be mistaken for hemorrhoids.

Investigations

• Accurate diagnosis and evaluation of portal hypertension require a range of investigations:
• Complete Blood Count (CBC) : May reveal hypersplenism with thrombocytopenia (platelet count typically between 50-100 x 10⁹/L) and mild leukopenia.
• Liver Function Tests (LFTs) : Abnormal in cases of liver disease (e.g., elevated bilirubin, ALT, and AST in cirrhosis).
• Coagulation Profile : Prolonged PT and INR in advanced liver disease due to reduced production of clotting factors.
• Ultrasound (US) : First-line imaging to assess liver and spleen size, presence of ascites, and portal vein diameter.
• Doppler Ultrasound : Evaluates blood flow in the portal vein, hepatic artery, and hepatic veins.
• CT or MRI : Provides a more detailed view, especially useful for identifying structural causes like thrombosis or tumours.
• Esophagogastroduodenoscopy (EGD) : Essential for detecting and assessing oesophageal and gastric varices, which are common in portal hypertension.

Hepatic Venous Pressure Gradient (HVPG)

• Directly measures the gradient between portal vein and hepatic vein pressures. A gradient over 10 mmHg indicates significant portal hypertension, and a gradient >12 mmHg predicts variceal bleeding risk.

Management of Portal Hypertension

• Non-selective Beta-Blockers (e.g., propranolol, nadolol): Reduce portal pressure and are used to prevent variceal bleeding.
• Diuretics (e.g., spironolactone and furosemide): Manage ascites by reducing fluid buildup.
• Vasopressors (e.g., terlipressin, somatostatin): Used during acute variceal bleeding episodes to reduce splanchnic blood flow and portal pressure.
• Endoscopic Variceal Ligation (EVL) : Periodic banding to prevent or manage variceal bleeding.

Surgical and Interventional Management

• Transjugular Intrahepatic Portosystemic Shunt (TIPS) : Creates a shunt within the liver to reduce portal pressure and prevent recurrent variceal bleeding. Often used in refractory cases.
• Liver Transplantation : Considered for patients with liver failure secondary to portal hypertension, particularly in cases of decompensated cirrhosis.

Lifestyle and Supportive Measures

• Dietary Modifications : Salt restriction and fluid management to control ascites.
• Avoidance of Alcohol : Crucial for patients with cirrhosis or other liver diseases contributing to portal hypertension.
• Regular Monitoring : Surveillance for varices and routine liver function assessments.