Effect of Simvastatin on Cardiac Function

It is well know that statins have been used to low cholesterol to prevent and treat coronary artery disease for many years. It was also reported that statins could protect endothelial function and cardiac function during coronary artery bypass graft. However, some results were controversial. Also, there is no clinical data available on statin cardiac protection during surgery in China where rheumatic heart disease is prevalent. Thus, the investigators are trying to see whether statins can protect heart injury during cardiac surgery in Chinese. Part of patients will receive statin treatment and part of will not before surgery in the study. Both patients\' heart function will be measured and compared after surgery to determine whether statins can protect heart injury during heart surgery.