Because it is known that PAH is accompanied with increasing the expression of the fetal genes, such as Nppa (natriuretic peptide A; also known as ANF (atrial natriuretic factor)), Nppb (natriuretic peptide B; also known as BNP (brain natriuretic factor)), and Myh7 (myosin heavy chain; also known as β-MHC) [15,18], we measured the expression of fetal genes, using qRT-PCR. Here, NPPB is linked to pulmonary arterial hypertension.