Comparison of key distinguishing features between pulmonary arterial hypertension (PAH) and pulmonary veno-occlusive disease (PVOD)

 Main gene mutationBMPR2, ACVRL1, ENG, KCNK3, CAV-1, SMAD9EIF2AK4
 Genetic transmissionAutosomal dominantAutosomal recessive
 Estimated prevalence15 cases per million1–2 cases per million
 Sex ratioFemale predominance (∼2:1)No sex predominance
 SmokingPossible associationMore prevalent than idiopathic PAH
 Occupational exposureAbsentOrganic solvent (trichloroethylene)
Risk factors
 Drugs and toxinsAnorexigens (aminorex, fenfluramine derivatives, benfluorex), dasatanib, interferonChemotherapy (alkylating agents)
 Associated conditionsConnective tissue disease, congenital heart disease, HIV infection, portal hypertensionConnective tissue disease particularly in systemic sclerosis
Clinical examination
 Auscultatory cracklesAbsentRare, except in presence of pulmonary oedema
 Pleural effusionsPossiblePossible
Right heart catheterisation
 mPAP, PAWP, PVRIncreased mPAP, normal PAWP, increased PVRIncreased mPAP, normal PAWP, increased PVR
 Acute vasoreactivity testing∼10% in idiopathic PAH (predicts long-term CCB response)∼10% (not a predictor of CCB response)
Pulmonary function
 FEV1, FVC, TLCNormal (possible mild reduction)Normal (possible mild reduction)
DLCO, DLCO/VANormal or mildly reducedSevere reduction
 Resting PaO2Normal or mildly reducedOften severe reduction
 Desaturation on exerciseOften presentOften severe reduction
  Chest HRCTUsually normal parenchymaCentrilobular ground-glass opacities, septal lines, mediastinal lymph node enlargement
V′/Q′ lung scanUsually normalUsually normal
 BALNormalPossible occult alveolar haemorrhage
 Targeted PAH therapyRCTs demonstrating improved haemodynamics, functional capacity and clinical outcomesRisk of pulmonary oedema
Conflicting data from small case series
  • mPAP: mean pulmonary artery pressure; PAWP: pulmonary artery wedge pressure; PVR: pulmonary vascular resistance; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; TLC: total lung capacity; DLCO: diffusing capacity of the lung for carbon monoxide; DLCO/VA: DLCO adjusted for alveolar volume; PaO2: arterial oxygen tension; HRCT: high-resolution computed tomography; V′/Q′: ventilation/perfusion; BAL: bronchoalveolar lavage; BMPR2: bone morphogenetic protein receptor type 2; ACVRL1: activin A receptor type II-like kinase 1; ENG: endoglin; KCNK3: potassium channel subfamily K member 3; CAV-1: caveolin 1; EIF2AK4: eukaryotic translation initiation factor 2 alpha kinase 4; CCB: calcium channel blocker; RCT: randomised controlled trial.