Introduction and Background

Pulmonary arterial hypertension (PAH) is a devastating disease with significant morbidity and mortality [1]. Classified as a subgroup of pulmonary hypertension by the World Health Organization, it includes persistent hypertension of the newborn, hypertension secondary to congenital heart disease, and idiopathic PAH [2]. For all categories, survival rates are poor. Children with idiopathic PAH (comprising 50-60 % of those with PAH) have demonstrated 5-year survival rate of 75 % in both European studies as well as the US REVEAL (Registry to Evaluate Early and Long Term PAH Disease Manage-ment) study [3-5]. Research efforts are complicated by the multifactorial nature of the disease [6-14], involving maladaptive pul-monary wall remodeling and changes in the pulmonary arterial hemodynamic environment [2]. It is postulate