Remote ischaemic preconditioning has shown its cardiac protective effect during heart surgery including coronary artery bypass graft surgery, congenital heart disease and aneurysm. However, no data was reported on heart valve disease surgery. Rheumatic heart disease is one of the major heart diseases requiring surgery in China. Thus, the investigators chose heart valve disease as a focus to see whether remote ischaemic preconditioning also has cardiac protective effect during heart valve surgery.