In pediatric patients with congenital heart disease associated with pulmonary arterial hypertension (PAH-CHD), deciding about surgery may be difficult depending on the diagnostic scenario. Most patients with communications between the cardiac chambers or the great arteries can now be operated on quite safely, with excellent results. Pulmonary hypertension accounts for complications in less than 10% of cases. In general, it has been considered that early assignment to surgery is the best strategy to avoid complications. This is unquestionable. However, late referral is still a problem in developing countries and underserved areas. Furthermore, it must be acknowledged that severe pulmonary vasculopathy may be present early in life, leading to the speculation that vascular lesions may develop from birth, or even before. Moderate to severe pulmonary vascular abnormalities limit the success of the repair of cardiac anomalies. First, the so-called postoperative pulmonary hypertensive crises are relatively infrequent in the present era, but still associated with high mortality rates (>20%). Patient management requires sophisticated armamentarium for life support, sometimes extracorporeal membrane oxygenation (ECMO). Second, patients surviving the immediate postoperative period may remain at risk of persistent postoperative PAH, which is associated with poor outcome compared to other etiologies of pediatric PAH. Therefore, while becoming aware of these complications, clinicians and surgeons need to get together and plan the best therapeutic strategy on an individual basis.

For a long time, cardiac catheterization (with the acute pulmonary vasodilation test, AVT) has been considered as a gold-standard assessment of PAH-CHD. In most tertiary centers indeed, catheterization data occupy a high hierarchical position in the decision to operate on PAH-CHD patients. Also, subclassifications of PAH-CHD according to disease severity are based on hemodynamic parameters. However, obtainment and interpretation of catheterization data are not easy tasks, especially in the pediatric population, for several reasons:

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