investigate the sinus and atrioventricular node functions in patients with rheumatic heart disease combined with chronic atrial fibrillation (AF).Methods:Thirty rheumatic heart disease patients with chronic AF underwent epicardial mapping during valvular operation.The sinus and atrioventricular node functions were assessed after cardioversion.Results:Twenty-eight patients had their sinus rhythm restored after undergoing electrical cardioversion.The success rate was 94%.None of the 28 patients showed sinus and atrioventricular node hypofunction.The mean SNRT was (840.7±199.1) ms;mean SNRTc was (231.8±103.1) ms,all the atrioventricular Wenckebach points were over 130 min-1 with a mean value of (327.1±37.1) ms,all the atrioventricular conduction 2∶1 block were over 150 min-1.Conclusion:After the electrical cardioversion,the sinus and atrioventricular node functions of most rheumatic heart disease patients with chronic AF stay within the normal range.The results suggested that these patients should be given the opportunity to undergo cardioversion promptly.