The objective of the study is to make up the technique blind spots of the bipolar radiofrequency ablation in the surgical treatment of atrial fibrillation with rheumatic heart disease by using argon beam coagulator. And to improve the rates of cardioversion of atrial fibrillation after surgery, to decrease the long-term recurrence rate of atrial fibrillation and to compare the early term and long term outcomes of bipolar radiofrequency ablation and bipolar radiofrequency plus argon beam coagulator ablation.

Atrial fibrillation(AF) is the most common sustained arrhythmia. It can cause reduced heart function and increase the risk of thromboembolism. About 60% of patients with rheumatic heart disease have persistent AF.AF surgery is an effective intervention for patients with all types of AF undergoing concomitant cardiac surgery. AF surgery can reduce the risks of heart of stroke and heart failure and promote longer survival. Bipolar radiofrequency ablation is one of the most effective ways. But in the investigators' early study we find that there are technique blind spots in the left atrial ablation and right atrial ablation. In the bipolar left atrial linear ablation performed along the lower edge of interatrial groove incision up to the mitral annulus, there is a gap between the ends of the ablation line to the mitral annulus. And if the investigators use bipolar radiofrequency pliers it may injure the lcx left circumflex artery and left ventricular. In the bipolar right atrial radiofrequency ablation, the linear ablation performed along the lower edge of the coronary sinus ostium up to the inferoseptal commissure and the linear performed through the vertical incision on anterior wall of the right atrium up to the tricuspid annulus, there is also a gap between the end of the end of the ablation line and the tricuspid annulus. These gaps are one of factors of the recurrence of AF.

Argon beam coagulator is one of the most common hemostasis tools in heart surgery. It can also cause coagulation necrosis of the myocardium and do not do harm to the nearly myocardium the same as bipolar radiofrequency ablation. In the investigators' early study the investigators use the coagulation de plasma argon to burn the endocardium. And in the investigators' 6 mouth follow up, the rate of cardioversion is 90%. In this study the investigators plan to use argon beam coagulator to ablate these gaps.

The objective of the study is to make up the technique blind spots of the bipolar radiofrequency ablation in the surgical treatment of atrial fibrillation with rheumatic heart disease by using argon beam coagulator. And to improve the rates of cardioversion of atrial fibrillation after surgery, to decrease the long-term recurrence rate of atrial fibrillation and to compare the early term and long term outcomes of bipolar radiofrequency ablation and bipolar radiofrequency plusargon beam coagulator ablation.

Inclusion Criteria:

• The patients got atrial fibrillation with rheumatic heart disease need surgical radiofrequency ablation treatment

Exclusion Criteria:

• left atrial diameter>65mm，
• sick sinus syndrome，
• atrioventricular block，
• ventricular tachycardia，
• reoperation patients，
• implantation of permanent pacemaker，
• NYHA(New York Heart Association) class IV，
• Malignant tumor, or other serious diseases which life expectancy < 1 year，
• Heating temperature above 38 degrees or active infection.