The prognosis of pulmonary hypertension depends on the function of the right heart. The main symptoms in the final stage of pulmonary hypertension are those of right heart failure. At this time, the patient mainly shows symptoms such as swelling of the lower limbs, oliguria, and abdominal distension. The difficulty in breathing may be slightly less severe than in the early stages. These symptoms are mainly caused by venous congestion in the systemic circulation, which prevents blood from returning from the lower limbs, leading to edema or ascites in the lower parts of the body.