Zhi-Wei Zhang1, Tian-Xiang Gu2. 1. Department of Cardiovascular Surgery, 1st Affiliated Hospital of China Medical University, 155 Nanjing St, Shenyang, China. Electronic address: neoart@163.com. 2. Department of Cardiovascular Surgery, 1st Affiliated Hospital of China Medical University, 155 Nanjing St, Shenyang, China.