Pulmonary arterial hypertension associated with tetralogy of Fallot.

Pulmonary arterial hypertension (PAH) is a common postoperative complication in patients with congenital heart disease (CHD). Although the recent clinical classification of pulmonary hypertension divided PAH associated with CHD (PAH-CHD) into several subclasses, the anatomical and hemodynamic features of postoperative PAH-CHD vary enormously. Therefore, it is still difficult to obtain clinical evidence supporting the indication of pulmonary vasodilators for PAH-CHD. We often encounter patients with PAH occurring after surgical treatment of tetralogy of Fallot (TOF), especially patients with major aortopulmonary collateral arteries (MAPCAs). PAH might be caused by pulmonary agenesis, hypoplasia and/or thrombosis, inadequate closure of the ventricular septal defect, relief of the pulmonic stenosis, or an excessively large prior systemic-to-pulmonary shunt. Moreover, patients with TOF and MAPCAs who are diagnosed as inoperable because of the presence of PAH show similar hemodynamic and clinical features to patients with Eisenmenger syndrome. The MAPCAs in these patients usually show hypoplastic and abnormal arborization. Based on our experience, we believe that PAH-targeted therapies are effective in some patients with PAH occurring after surgical treatment of TOF and MAPCAs, especially as an adjunct to percutaneous pulmonary angioplasty. To help classify patients with PAH associated with TOF, especially with MAPCAs, we propose several new subclassifications: "PAH due to hypoplastic pulmonary arterial beds", "PAH due to abnormal pulmonary arborization", or "segmental PAH associated with CHD." A multicenter registry of patients using a unified protocol is essential to explore the indications and efficacy of pulmonary vasodilators for postoperative PAH-CHD.