Abstract:ObjectiveTo acquire a knowledge of various kinds of circumstances when sinus bradycardia patients (the average heart rate<55 bpm) are taking dynamic electrocardiogram (ECG) examination.Methods Select 100 cases of outpatients and inpatients from January 2012 to January 2013 who were diagnosed by routine ECG examination with sinus bradycardia.Results When obvious sinus bradycardia attacks and long RR interval longer than 2.0 seconds appears, the usual causes include coronary heart disease, hypertension and myocardial infarction. From primary to secondary, the reasons for ECG changes of long RR interval are as follows that obvious sinus bradycardia complicated with arrhythmia accout for 43%(43/100), nonconducted atrial extrasystoles accout for 21%(21/100), Ⅱ° atrioventricular block 17%(17/100), Ⅱ° sinoatrial block 10%(10/100) and sinus arrest 9%(9/100).Conclusion The dynamic ECG proves to be safe and effective in the examination of obvious sinus bradycardia, causes analysis of long RR interval as well as diagnosis of a variety of ECG changes, which help to promote the diagnostic accuracy and cure rate clinically.