Although recent advance in treatment of PAH, including prostacyclin analogs (e.g., prostaglandin I2, PGI2), endothelin-1 (ET-1) receptor blockades, and phosphodiesterase type 5 (PDE-5) inhibitors, improved prognosis of PAH patients, RVH and contractile dysfunction of RV are major determinants of prognosis in PAH and the mortality of PAH patients still remains high [1]–[3]. Here, PDE5A is linked to pulmonary arterial hypertension.