AbstractPulmonary arterial hypertension (PAH) is a vascular disorder associated with significant morbidity and mortality. The pathophysiology of PAH remains controversial, but the only currently available therapies for PAH are pharmacological pulmonary artery vasodilation, decreasing right ventricular (RV) afterload, and relieving symptoms. By now, there is no therapy being able to minimize vascular remodeling processes and thus to reverse or delay the natural history of the disease. It has been generally thought that reduction of RV preload was detrimental, which deteriorated the systemic hemodynamics. In the present study, however, we repetitively and briefly occluded (RBO) both superior vena cava and inferior vena cava by ligation (occlusion for less than 5 seconds then re-open for 30 seconds and repeated 5 cycles as one sequence, 1 sequence every 6 hours) to intermittently restrict RV preload, for continuous 24 hours, total 5 sequences, in the Sugen 5416 (VEGF receptor blocker) and hypoxia induced PAH rat models and we found this strategy was beneficial for lowering pulmonary vascular resistance (PVR).