Table 1 The wide spectrum of PAH-CHD

A. Eisenmenger syndrome

Includes all systemic-to-pulmonary shunts due to large defects leading to a severe increase in pulmonary vascular resistance (PVR) and reversal of the shunt, which becomes pulmonary-to-systemic or bidirectional. Cyanosis, erythrocytosis, and multiple organ involvement are common.

B. Pulmonary arterial hypertension associated with systemic-to-pulmonary shunts

Patients with moderate to large defects, in which the increase in PVR is mild to moderate, left-right shunt is still present and there is no cyanosis at rest.

C. Pulmonary arterial hypertension with small defects

Patients with small (coexistent) defects and a clinical picture very similar to idiopathic PAH. Includes:

 • ventricular septal defects <1 cm in diameter

 • atrial septal defects <2 cm in diameter

D. Pulmonary arterial hypertension after corrective cardiac surgery

Congenital heart disease has been corrected but PAH has persisted after surgery, or has developed several months or years after surgery in the absence of a significant residual defect.

 Segmental pulmonary arterial hypertension

Segments of the lung vasculature develop pulmonary vascular disease, while other parts may be normally perfused, hyper or hypoperfused. This is now included in group 5 after Nice 2013 [6]

 Pulmonary vascular disease in Fontan patients

A rise in PVR may occur in patients with a Fontan-type circulation and low pulmonary blood flow, despite low pulmonary arterial pressures.