Location of the ventricular septal defect as described in the preoperative investigation
| Location | n | TTE | Invasive study | TTE and invasive study |
| Perimembranous | 221 (85%) | 108 | 41 | 72 |
| With extension to the inflow septum | 11 | 4 | 0 | 7 |
| With extension to the outflow septum | 101 | 66 | 0 | 35 |
| Extension not specified | 109 | 38 | 41 | 30 |
| Gerbode defect | 1 (0.4%) | 0 | 1 | 0 |
| Muscular | 25 (10%) | 7 | 6 | 12 |
| Subpulmonary | 9 | 4 | 1 | 4 |
| Central | 2 | 0 | 0 | 2 |
| Apical | 2 | 0 | 1 | 1 |
| Not specified | 12 | 3 | 4 | 5 |
| Location not specified | 13 (5%) | 3 | 8 | 2 |
| Multiple defects in the ventricular septum | 15 (5.5%) | 7 | 3 | 5 |
One ventricular septal defect was found at primary surgery for mitral regurgitation and one at surgery for aneurysm of the sinus of Valsalva with leakage to the right ventricle (these are not included in the table) (n = 275). TTE, transthoracic echocardiography.