Pulmonary arterial hypertension is a common clinical condition with complex causes, and depending on the cause, patients may visit different departments. The common causes of pulmonary arterial hypertension include the following. The first type is venous pulmonary hypertension, which is caused by diseases of the left heart system. Patients with this condition need to visit the department of cardiology, mainly to control heart failure. The second type is chronic thromboembolic pulmonary hypertension. The main reasons include thromboembolism in the proximal or distal pulmonary arteries, or due to tumors, parasites, foreign bodies, etc., leading to pulmonary embolism. Diseases of this type require visits to the respiratory department. Additionally, chronic pulmonary heart disease, such as heart failure caused by chronic obstructive pulmonary disease, interstitial lung disease, sleep breathing disorders, and hypoventilation lesions, also lead to pulmonary arterial hypertension and should be treated in the respiratory department. Furthermore, some rheumatic immune diseases and congenital heart diseases can also cause pulmonary arterial hypertension. As pulmonary arterial hypertension has gradually received more attention, some hospitals have established specialized outpatient clinics for pulmonary arterial hypertension.