Pulmonary arterial hypertension in paediatric and adult patients with congenital heart disease

Pulmonary arterial hypertension (PAH) commonly arises in patients with congenital heart disease (CHD). Greater numbers of patients with PAH associated with CHD (PAH-CHD) are now surviving into adulthood, many with increasingly complex cardiac defects. Patients with cardiac defects which result in left-to-right shunting are at risk of developing PAH, owing to the increased shear stress and circumferential stretch induced by increased pulmonary blood flow, which leads to endothelial dysfunction and progressive vascular remodelling and, thus, increased pulmonary vascular resistance. Although PAH-CHD shares similar lung histology with idiopathic PAH, differences do exist between these aetiologies. Management of PAH-CHD can involve surgical correction of the cardiac defect and/or treatment of the PAH, depending on the underlying cardiac defect and status of disease progression. Transplantation surgery can be curative but is not without limitations. The timing of intervention in patients with PAH-CHD is important, but the optimums are sometimes difficult to define, with limited robust data to inform management decisions. Uncontrolled studies suggest that prostacyclin analogues and phosphodiesterase type-5 inhibitors may have benefits in advanced pulmonary vascular disease. In the only randomised controlled trial dedicated to end-stage PAH-CHD, bosentan significantly reduced pulmonary vascular resistance and significantly increased 6-minute walk distance without compromising peripheral oxygen saturation, in patients with Eisenmenger syndrome. These data suggest that targeted therapies are beneficial in the PAH-CHD population, and warrant further research.