An asymmetric VSD closure device has a left ventricular disc with a narrower flange towards the aortic side to reduce the chance of impinging on the aortic valve. Amplatzer asymmetric ventricular septal defect occluder is the one which is used often (AAVSDO).1 The left ventricular disc is typically 5 millimeters towards the left ventricular apex while it is only 0.5 millimeters towards the aorta. The connecting waist is 1.5 millimeters long and the right ventricular disc is 4 millimeters larger than the waist. The asymmetric VSD closure device is made of nitinol mesh covered with dacron fabric to facilitate thrombogenesis so that the final occlusion of the defect is by thrombus formation in the mesh.2
Complete heart block is an important risk of device closure of perimembranous ventricular septal defect (VSD). This is because of pressure from the device damaging the atrioventricular (AV) conduction system which passes along the posterior border of the VSD. Other possibilities are trauma during the implant procedure leading to local hematoma formation, inflammatory response to the material of the device.
Potential complications of device closure of VSD
These include device migration, pericardial effusion, embolic episodes, delayed onset of conduction disturbances or even infective endocarditis. Fortunately, these complications are rare.
As with other intracardiac device closures, subjects are started on aspirin to prevent thrombus formation on the device, which is continued for six months which is the period required for endothelialization of the device surface.