In PH pathophysiology: BNP is elevated in several forms of PAH, including idiopathic PAH (IPAH) (32), PAH associated with connective tissue diseases (CTD-PAH) (33), congenital systemic-pulmonary shunts (34), PH associated with lung diseases (35), PH with chronic obstructive pulmonary disease (COPD) (28), chronic thromboembolic PH (CTEPH) (29) and PH associated with acute pulmonary embolism (36). Here, NPPB is linked to chronic obstructive pulmonary disease.