Inclusion Criteria:  VSD diameter <6mm Significant left-to-right shunt Left atrial and ventricular enlargement detected by echocardiography or calculation of Qp/Qs ratio above 1.5 in the catheterization laboratory (Qp/Qs>1.5)  Exclusion Criteria:  Patients with arrhythmia after the procedure Young patients who may be inconsistent during Holter records