The operability of congenital heart disease with left to right shunt depends on the severity of the pulmonary vascular disease induced by the increased pulmonary blood flow. Although some recommendations exist regarding operative indications according to pathological, hemodynamic, and epidemiological factors, the evidence underlying these recommendations is not conclusive. Recently, oral pulmonary vasodilator therapy has been reported to improve outcomes in patients with idiopathic pulmonary arterial hypertension, and this therapy also appears to be effective in patients with congenital heart disease and pulmonary arterial hypertension, including those with postoperative pulmonary hypertension and Eisenmenger syndrome. It is expected that the availability of novel pulmonary vasodilator therapy will expand the operative indications in patients with congenital heart disease with left to right shunt, but there is currently insufficient evidence to definitively determine this. A multicenter double-blind study should be conducted to further examine this issue.