Erping Xi1, Jian Zhu1, Ming Yan1, Yu Zhang1, Shuibo Zhu2. 1. Department of Thoracic Cardiovascular Surgery, Wuhan General Hospital of Guangzhou Command, Wuhan, Hubei 430070, China. 2. Department of Thoracic Cardiovascular Surgery, Wuhan General Hospital of Guangzhou Command, Wuhan, Hubei 430070, China. Email: zhudandan2008@163.com.