Background Ventricular septal defect (VSD) is the most common type of congenital heart abnormality with perimembranous VSD (pmVSD) accounting for ∼70% of all VSD. Nowadays, transcatheter closure is the first choice for suitable pmVSD. However, there was no report about closing the large oval-shaped VSD percutaneously. Case summary A 34-year-old male with known VSD was referred for transcatheter closure after failed attempts in other hospital. Patient had been diagnosed with VSD at a young age, but he was lost to follow-up. He presented with shortness of breath due to heart failure and pulmonary hypertension. The initial measurement of the defect was 6–7 mm by transthoracic echocardiography (TTE), transoesophageal echocardiography (TEE), and LV angiography. However, re-measurement using TEE and 3D echocardiography revealed that the VSD is …