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Hepatobiliary Disease, Portal Hypertension & Syndromes of Liver Damage

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1. Normal Hepatic Physiology

• Synthetic functions: coagulation factors (II, V, VII, IX, X, XI, XII, fibrinogen), albumin, acute-phase proteins
• Metabolic functions: gluconeogenesis, lipid metabolism, drug/toxin biotransformation, ammonia detoxification (urea cycle)
• Excretory functions: bilirubin conjugation and secretion into bile, bile salt synthesis
• Immune/clearance functions: Kupffer cell phagocytosis; removal of activated coagulation factors from circulation

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2. Etiology of Hepatobiliary Disease

Infectious

Toxic / Drug-Induced

• Acetaminophen accounts for ~50% of acute liver failure in the United States (zone 3 perivenular necrosis via N-acetyl-p-benzoquinone imine — NAPQI)
• Alcohol: steatohepatitis → cirrhosis
• Valproate, tetracycline, methotrexate (idiosyncratic or dose-related)

Metabolic / Genetic

Biliary/Vascular

• Primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC)
• Budd-Chiari syndrome (hepatic vein outflow obstruction)
• Right-sided heart failure → congestive hepatopathy

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3. Pathology of Liver Damage

Cellular Response to Injury

1. Steatosis (fat accumulation) — macro- or microvesicular
2. Ballooning degeneration (hydropic change)
3. Apoptosis → acidophil/Councilman bodies
4. Necrosis: zone-specific (zone 3 in ischemia/acetaminophen; zone 1 in yellow fever); bridging necrosis spans portal tracts to central veins; pan-acinar necrosis in massive failure

Fibrosis and Cirrhosis

• Normally stores vitamin A (lipid droplets) in the Space of Disse
• When activated by TGF-β, PDGF, TNF-α, ROS → differentiates into fibrogenic myofibroblasts → collagen deposition
• Collagen in the Space of Disse causes "capillarization" of sinusoids (defenestration), disrupting hepatocyte-plasma exchange

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4. Portal Hypertension

Definition & Normal Threshold

• HVPG ≥10 mmHg: varices begin to form
• HVPG ≥12 mmHg: variceal hemorrhage and ascites risk

Etiology — Classification by Level

• Portal vein thrombosis / structural narrowing
• Massive splenomegaly with ↑ splenic blood flow

• Cirrhosis (all causes) — dominant cause worldwide
• Nodular regenerative hyperplasia
• Primary biliary cholangitis
• Schistosomiasis (periportal fibrosis)
• Massive fatty change, sarcoidosis, amyloidosis
• Infiltrative malignancy (primary or metastatic)
• HCC with portal vein invasion

• Severe right-sided heart failure
• Constrictive pericarditis
• Budd-Chiari syndrome (hepatic vein outflow obstruction)

Pathophysiology / Mechanism

1. Increased sinusoidal resistance (fixed + functional):
   • Fixed: fibrosis, regenerative nodules compress sinusoids
   • Functional: intrahepatic vasoconstriction due to ↓ NO production by sinusoidal endothelium + ↑ endothelin-1, angiotensinogen, eicosanoids → stellate cell/myofibroblast contraction
2. Increased portal venous inflow (hyperdynamic circulation):
   • Splanchnic arterial vasodilation (principal mediator: NO from excessive systemic production)
   • ↑ splanchnic blood flow → ↑ portal venous efflux
   • Systemic vasodilation → ↓ effective arterial blood volume → activation of RAAS + sympathetic NS → Na⁺ and water retention → plasma volume expansion → further ↑ portal inflow

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5. Four Major Consequences of Portal Hypertension

(A) Varices & Variceal Hemorrhage

• Portosystemic collaterals form when coronary/gastric veins reverse flow
• Gastroesophageal varices are clinically most important
• Rupture risk proportional to variceal diameter and intravariceal pressure
• Mortality from first bleed: ~20–30%

(B) Ascites

• Accumulation of fluid in the peritoneal cavity; cirrhosis accounts for 85% of cases
• Requires HVPG ≥12 mmHg
• Mechanism: sinusoidal hypertension + Na⁺ retention (RAAS activation)
• Advanced: refractory ascites, hyponatremia (water retention), hepatorenal syndrome

(C) Portosystemic Venous Shunts

• Esophageal varices, hemorrhoidal varices, caput medusae (periumbilical), retroperitoneal collaterals
• Bypass hepatic Kupffer cells → toxins/bacteria reach systemic circulation → encephalopathy risk

(D) Congestive Splenomegaly

• Passive congestion → splenomegaly → hypersplenism: thrombocytopenia, leukopenia, anemia

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6. Syndromes of Liver Damage / Hepatic Failure

Acute Liver Failure (Fulminant Hepatic Failure)

• Acetaminophen overdose (~50% of US cases)
• Autoimmune hepatitis, other drugs/toxins
• Viral: HAV, HBV, HEV (Asia)
• Rare: Budd-Chiari, Wilson disease, lymphoma/leukemia

1. Nausea, vomiting, jaundice → transaminases markedly elevated
2. Encephalopathy (asterixis, confusion → coma)
3. Coagulopathy (easy bruisability → intracranial bleeding)
4. Cholestasis (↑ bilirubin, bile stasis)
5. Multi-organ failure

Chronic Liver Failure / Decompensated Cirrhosis

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7. Physical Examination Signs

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8. Diagnostic Evaluation

Liver Function Tests

Serologic Markers

• HBsAg: active HBV infection
• Anti-HBs: recovery/immunity
• HBeAg: high replicative state of HBV
• Anti-HCV: exposure; confirmed by HCV RNA
• Anti-HAV IgM: acute HAV infection
• AMA (anti-mitochondrial Ab): primary biliary cholangitis
• ANA, anti-smooth muscle Ab: autoimmune hepatitis
• Ceruloplasmin ↓, urine copper ↑: Wilson disease
• Ferritin, transferrin saturation ↑: hemochromatosis

Ascites Evaluation: SAAG

• SAAG (serum-ascites albumin gradient) ≥1.1 g/dL → portal hypertension cause
• PMN count in ascitic fluid >250/μL → spontaneous bacterial peritonitis (SBP)

Hepatic Venous Pressure Gradient (HVPG)

• Gold standard to quantify portal hypertension
• HVPG >10 mmHg: clinically significant portal hypertension

MELD Score

MELD = [0.957 × ln(Cr) + 0.378 × ln(Bil) + 1.12 × ln(INR) + 0.643] × 10

Imaging

• Ultrasound: first-line; detects nodularity, ascites, splenomegaly, portal vein dilation, Doppler flow reversal
• CT/MRI: staging, detection of HCC, vascular anatomy
• Elastography (FibroScan): non-invasive fibrosis quantification
• Liver biopsy: gold standard for fibrosis staging, hepatitis grading, storage disease diagnosis

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9. Complications and Related Syndromes

Spontaneous Bacterial Peritonitis (SBP)

• Infection of ascitic fluid without secondary cause
• Mechanism: bacterial translocation from gut lumen → mesenteric lymph nodes → transient bacteremia → colonizes ascitic fluid (low complement, low opsonic activity)
• Organisms: gram-negative enteric (E. coli, Klebsiella) predominantly; increasing multidrug-resistant organisms with prophylaxis use
• Diagnosis: PMN >250/μL in ascitic fluid
• Treatment: 3rd-generation cephalosporins (cefotaxime); albumin IV to prevent hepatorenal syndrome
• Prophylaxis: norfloxacin or trimethoprim-sulfamethoxazole in high-risk patients (prior SBP, low protein ascites)

Hepatorenal Syndrome (HRS)

• Prerenal kidney injury in cirrhosis from maximal splanchnic vasodilation → renal vasoconstriction
• HRS-AKI (Type 1): rapidly progressive, creatinine doubles within 2 weeks; triggered by SBP, hemorrhage
• HRS-non-AKI (Type 2): slower, associated with refractory ascites
• Treatment: vasoconstrictor (terlipressin or norepinephrine) + albumin; liver transplantation is definitive

Hepatic Encephalopathy (HE)

• Neuropsychiatric manifestation caused by ammonia (from gut bacteria + enterocytes) bypassing hepatic detoxification
• Ammonia → astrocyte swelling (glutamine as osmolyte) → cerebral edema
• Grades:
  • Grade 1: sleep-wake inversion, forgetfulness
  • Grade 2: confusion, bizarre behavior, disorientation
  • Grade 3: lethargy, profound disorientation
  • Grade 4: coma
• Hallmark sign: asterixis (flapping tremor)
• Treatment: lactulose (reduces ammonia production/absorption), rifaximin (non-absorbable antibiotic), dietary protein restriction (avoid excess)
• Precipitants: GI bleed, infection, constipation, hypokalemia, sedatives

Hepatopulmonary Syndrome

• Intrapulmonary vascular dilatations → V/Q mismatch and shunting → hypoxemia
• Diagnosis: PaO₂ <80 mmHg + positive contrast echocardiography (microbubbles in left heart)
• Signs: platypnea (dyspnea worsening upright), orthodeoxia, clubbing, cyanosis
• Present in 5–10% of liver transplant candidates; resolves post-transplant

Portopulmonary Hypertension

• Pulmonary arterial hypertension in the setting of portal hypertension
• Diagnosis: mean PAP >25 mmHg on right heart catheterization + PCWP <15 mmHg

Coagulopathy of Liver Disease

• Liver synthesizes factors II, V, VII, IX, X, XI, XII, fibrinogen + anticoagulants (protein C, S, antithrombin)
• Paradoxically "rebalanced" coagulopathy — bleeding AND thrombosis risk
• PT/INR prolonged; thrombocytopenia from hypersplenism

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10. Treatment Overview

Treating the Underlying Cause

Reducing Portal Pressure

• Non-selective beta-blockers (propranolol, carvedilol): reduce cardiac output AND splanchnic vasodilation; primary and secondary prophylaxis against variceal hemorrhage and decompensation
• Endoscopic band ligation (EBL): acute variceal bleeding and secondary prophylaxis
• Endoscopic sclerotherapy: alternative to EBL
• TIPS (Transjugular Intrahepatic Portosystemic Shunt): refractory bleeding, refractory ascites; creates intrahepatic porto-systemic shunt; risk: worsening encephalopathy

Managing Ascites

• Na⁺ restriction (<2 g/day), fluid restriction (if hyponatremic)
• Spironolactone (first-line diuretic; blocks aldosterone) ± furosemide
• Large-volume paracentesis + albumin replacement (8 g per liter removed) for tense ascites
• TIPS for refractory ascites

Hepatic Encephalopathy

• Identify and treat precipitants
• Lactulose: cathartic; acidifies colon → traps NH₃ as NH₄⁺; target 2–3 soft stools/day
• Rifaximin: poorly absorbed antibiotic; reduces gut ammonia-producing bacteria; maintenance therapy

Liver Transplantation

• Definitive therapy for end-stage liver disease
• Indicated when MELD-Na ≥15 or decompensating events occur
• Corrects both liver failure and portal hypertension
• HCC within Milan criteria is a transplant indication
• Post-transplant: lifelong immunosuppression (calcineurin inhibitors ± mycophenolate)

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Summary Table: Syndromes of Liver Damage

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