Despite the fact that remarkable improvements have been achieved in quality of life and survival through increasing number of specific medical treatment alternatives in severe pulmonary hypertension, many patients have resistance to medical treatment. Atrial septostomy is considered as a palliative procedure in severe pulmonary hypertension to relieve symptoms of severe pulmonary hypertension by reducing right ventricular preload and increasing systemic flow. Gradual balloon dilatation and blade balloon atrial septostomy are the most frequently used methods. If atrial septostomy is performed in experienced medical centers, it provides clinical improvement and even has tendency to extend life expectancy in patients with pulmonary hypertension resistant to medical treatment.