1 Department of Cardiology, Gansu Provincial Hospital, Lanzhou University, Lanzhou 730000, P. R. China.
2 FuWai Hospital & Key Laboratory of Pulmonary Vascular Medicine, State Key Laboratory of Cardiovascular Disease, National Centre for Cardiovascular Disease, Chinese Academy Medical Sciences & Peking Union Medical College, Beijing 100037, P. R. China.
3 Department of Radiology, Gansu Provincial Hospital, Lanzhou University, Lanzhou 730000, P. R. China.