HepatoPulmonary Syndrome

πŸ”· HEPATOPULMONARY SYNDROME (HPS)

πŸ“Œ Definition (AASLD Criteria)

HPS is a triad of:

  1. Chronic liver disease and/or portal hypertension
  2. Arterial hypoxemia (PaOβ‚‚ <80 mmHg or A–a gradient >15 mmHg)
  3. Intrapulmonary vascular dilatations (IPVDs)


πŸ”¬ Pathophysiology

Mechanism

Effect

Portal hypertension β†’ NO overproduction

Systemic and pulmonary vasodilation

Pulmonary capillary dilation

↑ Capillary diameter β†’ ↓ oxygen diffusion

Right-to-left intrapulmonary shunt

Bypasses alveolar oxygenation

Ventilation-Perfusion (V/Q) mismatch

Leads to hypoxemia

↓ Hypoxic pulmonary vasoconstriction

Contributes to shunt physiology


πŸ”‘ Key mediators: Nitric oxide, endothelin-1, carbon monoxide, angiogenesis (VEGF)


πŸ”¬ Histopathology

  • Dilated pulmonary capillaries (20–500 Β΅m)
  • Normal alveolar architecture
  • Capillary remodeling without inflammation


πŸ” Clinical Features

Feature

Notes

Platypnea

Dyspnea worsens in upright position

Orthodeoxia

↓ PaOβ‚‚ β‰₯5% or β‰₯4 mmHg on standing

Dyspnea, fatigue

Progressive

Clubbing, cyanosis

In advanced stages

Spider nevi

Indicator of hyperdynamic circulation



πŸ§ͺ Diagnostic Work-up

Test

Findings

ABG

↓ PaOβ‚‚, ↑ A–a gradient

Pulse oximetry

↓ SpOβ‚‚ on standing

Contrast-enhanced TTE

Bubbles appear in left atrium after 3–6 beats (vs. <3 beats in PFO)

99mTc-MAA scan

Uptake in brain/kidneys β†’ intrapulmonary shunt

CT Chest

Shows diffuse vascular dilations

Liver function tests

Often deranged



πŸ”Ž Severity Classification (by PaOβ‚‚)

Severity

PaOβ‚‚ (mmHg)

Mild

β‰₯80

Moderate

60–79

Severe

50–59

Very severe

<50



πŸ’‰ Management

🧬 Medical

Option

Remarks

Oxygen therapy

Mainstay for symptom relief

NO inhibitors (methylene blue)

Temporary benefit

Pentoxifylline

TNF-Ξ± blocker

Garlic extract

Vasomodulator

Somatostatin analogs

In trials


πŸ“Œ No medical therapy reverses disease long-term.

🩺 Liver Transplantation

  • Only definitive therapy
  • ~85% resolution post-transplant (within 6–12 months)
  • High MELD exception score allowed for HPS

πŸ›‘ Contraindications

  • PaOβ‚‚ <50 mmHg may be a relative contraindication to transplantation due to increased perioperative mortality.


πŸ“š Key Points for Exams

  • Triad: Liver disease + IPVD + hypoxemia
  • Diagnostic test of choice: Contrast-enhanced transthoracic echo (bubble study)
  • Definitive treatment: Liver transplantation
  • Differentiator from PoPH: HPS has low PVR, normal/low PAP


πŸ”· PORTOPULMONARY HYPERTENSION (PoPH)

πŸ“Œ Definition (as per 6th WSPH)

PoPH = Pulmonary arterial hypertension (PAH) + portal hypertension, defined by:

Hemodynamic Parameter

Threshold

mPAP

>20 mmHg

PVR

>2 Wood units

PAWP

≀15 mmHg

Portal hypertension

Clinically evident (with/without cirrhosis)



πŸ”¬ Pathophysiology

Mechanism

Role

Shear stress from hyperdynamic circulation

Endothelial injury

Imbalance: ↑ vasoconstrictors (endothelin-1), ↓ vasodilators (NO)

Vasoconstriction, remodeling

Smooth muscle hypertrophy

↑ PVR

Intimal fibrosis

Fixed PAH


⚠️ Distinct from HPS, which is vasodilation dominant.


πŸ” Clinical Features

Feature

Notes

Dyspnea

On exertion, then at rest

Fatigue

Common early symptom

Syncope

Indicates severe disease

Signs of RV failure

JVP, ascites, edema

Loud P2

Pulmonary hypertension sign



πŸ§ͺ Diagnosis

πŸ“‰ Echocardiography

  • RV hypertrophy/dilation
  • Elevated RV systolic pressure

πŸ“ Right Heart Catheterization (Definitive)

Parameter

Threshold

mPAP

>20 mmHg

PAWP

≀15 mmHg

PVR

>2 WU


πŸ“ˆ Additional Tests

  • NT-proBNP: Elevated in RV strain
  • LFTs: For MELD
  • V/Q scan: Rule out CTEPH
  • CXR: Enlarged PA, pruning
  • CT: Enlarged main PA (>29 mm), RV enlargement


πŸ’Š Treatment

🚨 General

  • Avoid volume overload
  • Sodium restriction, diuretics
  • Oβ‚‚ for hypoxemia
  • Avoid hepatotoxic or cardiodepressive drugs

πŸ’‰ Specific PAH Therapy

Class

Drugs

Endothelin antagonists

Bosentan, Ambrisentan

PDE-5 inhibitors

Sildenafil, Tadalafil

Prostacyclins

Epoprostenol, Iloprost


⚠️ Bosentan can cause hepatotoxicity β†’ monitor LFTs!


πŸ₯ Liver Transplant Considerations

Severity

mPAP

Implications

Mild

25–35 mmHg

Usually acceptable for transplant

Moderate

35–50 mmHg

Increased perioperative risk

Severe

>50 mmHg

Contraindication to transplant unless optimized with PAH therapy


πŸ“Œ PAH therapy β†’ mPAP <35 mmHg β†’ reconsider for transplant


πŸ“ Key Differences: HPS vs. PoPH

Feature

HPS

PoPH

Pathophysiology

Vasodilation (NO-mediated)

Vasoconstriction + remodeling

Pulmonary pressure

Normal/low

Elevated (>20 mmHg)

PVR

Low

High (>2 WU)

PaOβ‚‚

Decreased

Normal/low

Hypoxemia cause

IPVD/shunt

↑ PVR β†’ RVF

Treatment

Liver transplant

PAH drugs Β± transplant



πŸ” Viva/MCQ Pearls

  • HPS: Diagnosis via bubble echo
  • PoPH: Right heart catheterization is gold standard
  • HPS: Orthodeoxia, platypnea
  • PoPH: May contraindicate liver transplant
  • HPS: ↓ PVR, PoPH: ↑ PVR
  • Drug of choice in PoPH: Sildenafil