Table 1. Types of pulmonary arterial hypertension (PAH) in congenital heart disease
A. Eisenmenger syndrome
    Includes all systemic-to-pulmonary shunts due to large defects leading to a severe increase in PVR and a reversed (pulmonary-to-systemic) or bidirectional shunt. Cyanosis, erythrocytosis, and multiple organ involvement are present
B. PAH associated with systemic-to-pulmonary shunts
    Patients with moderate-to-large defects, in which the increase in PVR is mild-to-moderate, left-to-right shunt is still largely present and no cyanosis is present at rest
C. PAH with small defects
    Patients with a clinical picture very similar to idiopathic PAH, who have (coincidental?) small cardiac defects: a ventricular septal defect <1 cm and an atrial septal defect <2 cm
D. PAH after corrective cardiac surgery
    Congenital heart disease has been corrected but PAH is still present immediately after surgery, or has recurred several months or years after surgery in the absence of significant post-operative residual congenital lesions or defects that originate as sequelae of previous surgery
  • PVR: pulmonary vascular resistance. Reproduced with modification from [2].