Discussion

In the current transcatheter device closure era for ostium secundum defects, surgical patch closure is done mainly for large defects or defects with inadequate rims and other complex CHDs. Patch closure is done using pericardium, either autologous or bovine and prosthetic material. Prosthetic materials like Dacron and Polytetrafluoroethylene carry a risk of endocarditis and thrombus formation. ^{Reference Okwulehie, Dharmapuram, Swain, Ramdoss, Sundararaghavan and Kona4} Autologous pericardial patch being easily available, sterile, and non-immunoreactive is the most commonly preferred material. ^{Reference Okwulehie, Dharmapuram, Swain, Ramdoss, Sundararaghavan and Kona4} However, it has a rough surface with a tendency to curl at the edges, leading to difficult handling and suturing. Treatment with 0.6% glutaraldehyde improves its handling qualities by cross-linking collagen, thereby reducing elasticity and enhancing shape fixation. Hence, glutaraldehyde fixed autologous pericardium is preferred, more so for repair of complex heart defects. ^{Reference Liava'a and Kalfa5}

The presence of a shunt across the patch of a surgically closed atrial septal defect is uncommon. There may be a persistent defect at the end of surgery termed as residual defect. Defects developing later in time after initial successful surgical closure are termed as recurrent defects. Evidence has been sparse in definition, diagnosis, and management of these conditions. They have mainly been attributed to two pathological processes namely suture dehiscence and patch degeneration. Suture dehiscence which usually occurs in the early postoperative period is seen at the suture site and is caused by excessive tension, trauma, and kinking stresses at knots. Suture dehiscence is commonly associated with closures involving complex CHDs with abnormal geometry of the defect or associated structures. In contrast, patch degeneration which usually occurs a few years later refers to shrinkage, retraction, calcification, aneurysmal dilatation, or degradation of the patch. Glutaraldehyde treatment of autologous pericardium has been shown to accelerate degenerative process. Unlike dehiscence which occurs primarily at suture lines, patch degradation may be located anywhere leading to eccentric shunts. ^{Reference Atik, Afiune and Caneo6,Reference Mohanty and Kumar7} The precise timing of development of recurrent ASD in our patient is difficult to predict, and could have variably progressed anywhere from immediate post-operative period to 6 months prior to index hospitalisation. Both possibilities of patch degeneration and late suture dehiscence were considered. A consensus of possible patch degeneration was arrived at after the heart team discussion, considering the slow progressive dyspnoea, absence of dehiscence flap near the retro aortic region, and the rarity of late suture dehiscence presenting 10 years after the initial surgery. Further imaging was limited due to logistic reasons. Obviously, this consensus represents an educated speculation.

Device closure of recurrent defects follow the same technique and selection criteria as for native secundum atrial septal defects. TEE has been the conventional method to assess the adequacy of the patch rims and device sizing. In future, newer modalities like intracardiac echocardiography or 3D printing may yield more information regarding patch thickness in this particular subset of patients. Percutaneous closure is less invasive, cost-effective with lesser complication rates compared to redo-surgery. ^{Reference Mohanty and Kumar7–Reference Chessa, Butera, Giamberti, Bini and Carminati10} This case highlights the importance of long-term clinical and echocardiographic surveillance in patients after surgical atrial septal defect closure. There should be a low threshold for transesophageal echocardiogram in the event of any suspicious findings on transthoracic echocardiogram along with a change in the patient’s clinical status.

Transcatheter closure is an excellent, feasible treatment modality compared to redo surgery is select cases of recurrent atrial septal defect.