【Abstract】Objective: The prognosis of patients with left-to-right shunt congenital heart disease associated pulmonary hypertension is significantly better than that of idiopathic pulmonary hypertension, but the specific mechanism is unclear. The purpose of this project is to make a rat model of idiopathic pulmonary hypertension and congenital heart disease with pulmonary hypertension, and compare the similarities and differences between the two models in pulmonary vascular remodeling and cardiac remodeling. Methods: Male SD rats were divided into three groups: control group (n=8), monocrotaline (MCT) group (50mg/kg) to simulate idiopathic pulmonary hypertension (n=8); Cervical arteriovenous shunt surgery monocrotaline (MCT) group (50mg/kg) simulated left to right shunt congenital heart disease with pulmonary hypertension (n=8). Three weeks after the establishment of the model, echocardiography, left and right cardiac catheter pressure measurement and lung histopathological staining were performed to compare the cardiac and pulmonary phenotypes of the rats. Results: Compared with the control group, there was no significant difference between the MCT group and the operation MCT group in the right ventricular hypertrophy, right ventricular dysfunction, mean pulmonary artery pressure, pulmonary vascular remodeling and other indicators 3 weeks after operation. But in many indexes related to left heart, the rats in the operation MCT group were significantly better than those in the simple MCT group. Compared with the control group, the left ventricular lumen diameter (LVID; d) and left ventricular ejection fraction (EF%) in the operation MCT group did not decrease in the diastolic period; The maximum rate of increase of right ventricular internal pressure (MAX dp/dt) and the maximum rate of decrease of left ventricular internal pressure (MIN dp/dt) in the operation MCT group were lower than those in the simple MCT group. Conclusion: Left to right shunt surgery can not change MCT-induced pulmonary hypertension and right heart remodeling, but can produce left heart compensation, which may be beneficial to the prognosis of patients. The animal model of this project establishes the basis for studying the different pathological mechanisms of idiopathic pulmonary hypertension and pulmonary hypertension associated with congenital heart disease.