Abstract: To investigate the electrical and geometric changes of heart after percutaneous closure of atrial septal defect (ASD). Methods: A total of 100 patients received percutaneous closure of ASD, and were measured standard 12lead electrocardiography (ECG) and transthoracic echocardiography(TTE) before closure, 24 hours, 1 month and 3months after closure. The items of ECG included PR interval, QRS duration, PII and RV1+SV5, and that of TTE included the diastolic diameter of right ventricle(RVDD) and left ventricle(LVDD), RVDD/LVDD ratio, the lateral diameter of left atrial (LALD) , the lateral diameter of right atrial (RALD), RALD/ LALD ratio and ejection fraction(EF) of LV. Results: In all patients, the PR interval, RVDD, RALD, RVDD/LVDD and RALD/ LALD ratio decreased and LVDD, LALD, EF increased significantly after closure, but QRS duration, PII and

Key words: Atrial septal defect, Percutaneous closure, Electrocardiography, Transthoracic echocardiography