Pulmonary arterial hypertension (PAH) is a severe, progressive disease leading to right ventricular failure and finally death. Lung transplantation is recommended for PAH patients who do not respond to targeted drug combination therapy or World Health Organization functional class (WHO FC) Ⅲ or Ⅳ. However, only 3% of PAH patients can recieve the lung transplantation. A novel implantable interatrial shunt device (ISD) can create a relatively fixed right-to-left shunt established by balloon atrial septostomy (BAS). The device may decompress the right sided chambers, facilitate left heart filling, improve organ perfusion and reduce the likelihood of syncope, acute pulmonary hypertensive crisis and death. The systemic oxygen transport improves despite hypoxemia. Implantation is simple, feasible and safe, and the X-ray time and operation time are short. There is no severe complication or thrombosis during the mid-term follow-up of the clinical studies and the device remained patent. The syncope symptoms, six-minute walk distance, cardiac index and systemic oxygen transport improve significantly in the patients. ISD may be currently the last alternative treatment to improve symptoms and prolong survival in currently drug-resistant patients with severe PAH.