Although this study included a very small number of cases, we found that transcatheter closure of postoperative VSD can be performed safely and effectively using various devices. The postoperative VSDs in our series not only resulted from residual leaks, but also from fenestration and Gerbode shunt.
Patients 3 years old and over with hemodynamically significant perimembranous VSD that is adequately separated from the aortic and tricuspid valves are ideal candidates for a transcatheter approach. In cases of a muscular VSD, transcatheter closure is also considered suitable for children weighing ≥5 kg . However, on review of the literature, we did not find any mention of transcatheter closure of postoperative VSDs. It is generally accepted that most postoperative VSDs can be safely closed using such a device. However, the location of the VSD, and the reasons for its development must be considered to identify good candidates for this type of closure. It is sometimes difficult to determine the precise location of postoperative VSDs. Therefore, a comprehensive understanding of the prior surgery is critical. For instance, if the post-operative VSD is located at the center of a patch of a previous VSD (that was closed with fenestration), the risk of aortic valve injury, tricuspid valve injury, or heart block should be minimal. Otherwise, the most important factor is the VSD’s distance from the aortic valve.
Most cases of postoperative VSD result from leakage following VSD closure. Most residual defects < 2 mm in size will close spontaneously, while those > 2 mm will not [7, 8]. Volume overload and infective endocarditis are two reasons that a postoperative VSD requires intervention. We described three patients with leakage of the VSD and evidence of volume overload who were successfully treated.
We also report one patient with a Gerbode defect involving a left ventricular to right atrial communication after DORV total correction. Acquired Gerbode shunts are thought to result from endocarditis, trauma, myocardial infarct, and as a complication of cardiac surgery [9, 10]. The percutaneous closure of Gerbode shunts has previously been described by Song et al.  Due to its proximity to the atrioventricular node and the tricuspid valve, close monitoring is necessary both during and after percutaneous closure of a Gerbode shunt.
Two patients in this study had residual VSDs due to fenestrated patch closures. In these circumstances, VSD closure is performed using a fenestrated or valved patch to reduce the risk of right heart decompensation [12, 13]. After postoperative stabilization and further interventional management of hypoplastic or stenotic pulmonary arteries, VSD closure may be necessary at a later date. Transcatheter closure of these VSDs remains challenging. It is particularly difficult due to the extremely flat anatomy of the patch material, and the short distance to the aortic valve .
Most patients had evidence of volume overload. However, it was difficult to measure Qp/Qs given the patients’ condition during the procedure. Two patients not only had postoperative VSD, but also pulmonary stenosis. We corrected the pulmonary stenosis and VSD simultaneously, because a VSD shunt might increase in intensity after relief of pulmonary stenosis alone. Therefore, postoperative VSDs should be evaluated in consideration of the patient’s overall cardiac condition.
We used various devices in the closure procedures. The Amplatzer muscular VSD occluders, perimembranous VSD occluders, ADOs, and septal occluders have previously been used to close VSDs percutaneously [14, 15]. We had good results when the postoperative VSD was closed using a cocoon membranous VSD occlude. There were no complications during follow-up in these cases. In general, several complications have been reported after percutaneous closure of a postoperative VSD. These include death, device embolization, heart block, new valvular regurgitation, hemolysis requiring blood transfusion, and the need for subsequent surgical or percutaneous interventions [1,2,3,4]. The most serious complication is complete atrioventricular block (cAVB), especially after transcatheter closure of a perimembranous VSD. The incidence of cAVB ranges 0–5.7% . The occurrence of cAVB is related to proximity of the conduction system to the margins of the VSD. Fibrosis or scar formation can occur in the margins of the VSD after a previous operation. Therefore, we suspected that the abovementioned subsequent negative influence of the occluder might decrease, reducing the occurrence of cAVB after closure of postoperative residual VSD . In addition, we used the femoral arteriovenous loop for all cases. However, in some cases, only the femoral vein or artery approach is possible. Therefore, it depends on the location of the VSD and the device. Devices with symmetric retention discs can be implanted through the femoral artery.
Based on our experience, we can recommend transcatheter closure of postoperative VSDs in patients with symptoms of failure. Most postoperative VSDs can be closed using various device types. Transcatheter closure can only be safely performed in patients > 7 kg. In particular, fenestrated VSDs can be safely and effectively closed if the fenestration is no longer necessary. However, surgical closure should be considered if combined lesion also requires surgical repair.
Our study has several limitations. This was a retrospective study based on a small series of cases from a single tertiary center. It also had a short follow-up period. Therefore, the study design itself may have introduced bias. We were unable to measure necessary objective data before and after the intervention, including the Qp/Qs and pulmonary pressures. Therefore, no definitive conclusions should be drawn from our findings.