Abstract:Objective To discuss the ECG characteristics of atrial flutter complicating alternating Wenckebach phenomenon and corresponding clinical significance. Methods Retrospective analysis was performed on clinical data of 13 patients with atrial flutter complicating alternating Wenckebach phenomenon. According to ECG manifestations, the research objects can be classified into type A and B. Results Ten out of 13 cases were patients with organic heart disease and 3 were nonorganicheartdisease one. Among the 10 organicheartdisease patients, first degree atrioventricular block(AVB) or second degree typed Ⅰ AVB still remained in 7 cases after conversion to sinus rhythm with amiodarone or propafenone. It implied that alternating Wenckebach phenomenon in the 7 cases were mainly pathological block. Two (patients with pneumonia and traumatic brain injury) out of the 3 patients without organic heart disease restored to sinus rhythm and no AVB was found, suggesting functional block. All the 13 patients were clinically cured, or improved and discharged from hospital. Conclusion Atrial flutter complicating alternating Wenckebach phenomenon is actually double layer block of atrioventricular node, and type B is slightly more than type A. If the phenomenon is seen in patients with organic heart disease, AVB mostly exists after conversion to sinus rhythm, suggesting a possibility of pathological block. If it is, the dose of antiarrhythmic drugs should be reduced adequately to avoid high or third degree AVB.