Department of Cardiovascular Surgery, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, P.R. China. Department of Cardiovascular Surgery, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, P.R. China. Department of Cardiovascular Surgery, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, P.R. China. Department of Cardiovascular Surgery, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, P.R. China. Department of Cardiovascular Surgery, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, P.R. China.