Pulmonary arterial hypertension (PAH) is a group of clinicopathophysiological syndromes characterized by persistent increases in pulmonary vascular resistance caused by heterogenous diseases and different pathogenetic mechanisms [1]. PAH is characterized by a progressive increase in pulmonary vascular resistance and pulmonary artery pressure due to pulmonary artery obstruction, accompanied by irreversible pulmonary vascular remodeling, leading to right heart failure and death. The common pathophysiological features of PAH include vasoconstriction, in situ thrombosis and pulmonary vessel wall remodeling, with pulmonary artery occlusion due to vessel wall proliferation and remodeling considered to be the hallmark of PAH pathogenesis. Pulmonary vascular wall remodeling is an important feature of PAH and is manifested by vessel wall thickening. This vessel wall thickening results from hypertrophy and proliferation of one or more cell types and an increase in extracellular matrix components, involving almost all cell layers of the inner, middle and outer membranes of the vessel wall. Pulmonary vascular wall remodeling mainly includes the following four types: (1) myelination of the distal non-myelinated microarteries; (2) increased myelination of myelinated arteries; (3) formation of neointima; and (4) formation of plexiform lesions. This is an important feature of patients with severe PAH, and approximately 80% of patients with IPAH develop this lesion to varying degrees, mainly due to endothelial cell proliferation disorders. Excessive pulmonary vasoconstriction is another important feature of PAH. This excessive vasoconstriction is associated with malfunction of potassium channels and endothelial tissues, for example, endothelial malfunction leads to a decrease in the synthesis and secretion of the vasodilatory factors nitric oxide (NO) and prostacyclin (PGI2), and a significant increase in the secretion of the vasoconstrictor endothelin-1 (ET-1), triggering abnormal pulmonary vasoconstriction. According to the study, pulmonary vasoconstriction occurs early in the course of PAH. The third feature of PAH is in situ thrombosis. Its formation is related to endothelial damage: collagen fibers in the subendothelial layer are exposed due to endothelial damage, which in turn interact with platelets, causing them to adhere to the platelets, while platelets release large amounts of thromboxane (TXA2), platelet-activating factor and 5-hydroxytryptamine (5-HT), further promoting platelet aggregation and forming in situ thrombi. Traditional drugs for PAH treatment include anticoagulants, diuretics, and calcium channel blockers [7]. Although this treatment improves the symptoms of PAH patients, it does not slow down the progression of PAH. over the past 20 years, new therapeutic drugs have emerged, resulting in a significant improvement in the prognosis of PAH patients. Among the drugs that have been marketed, epoprostenol is the drug of choice for patients with severe PAH, but its expensive price, serious adverse effects, and complicated dosing regimen limit its use. A growing number of clinical studies have shown that ET-1 receptor antagonists are safer and more effective, and their oral administration is more desirable than that of prostacyclins. However, it is undeniable that the multiple adverse effects of this class of drugs also limit their use. Another class of PDE-5 inhibitors, which are easy to administer, have mild adverse effects, require no clinical monitoring, and are less expensive than prostacyclins and ET-1 receptor antagonists, are not available for patients with severe PAH in class IV cardiac function.