Endovascular treatment of perigraft seroma in patient with prior hybrid thoracoabdominal repair using visceral bypass to relieve duodenal obstruction

Perigraft seroma (PS) is a postoperative complication occurring after prosthesis placement. A 48-year-old man who had previously undergone visceral debranching bypass surgery as a part of hybrid thoracoabdominal aortic repair was referred to our hospital because of vomiting. Contrast-enhanced computed tomography revealed a duodenal obstruction resulting from compression by a PS located around the bypass graft and extending to the right renal artery. Endovascular relining of the visceral bypass graft using a covered stent was performed, resulting in immediate resolution of the duodenal obstruction and shrinkage of the PS. Endovascular repair can be considered as an effective option for treating a PS.

Perigraft seroma (PS) is a rare postoperative complication occurring after vascular prosthesis placement, with an estimated incidence of 1.2% to 1.3% following open aortic reconstruction. 1 The most effective treatment has been reported to be graft replacement and resection of the seroma, 2 although such redo surgery will often be highly invasive. 1 In the present report, we have described a rare case of duodenal obstruction caused by PS development after visceral bypass surgery for a thoracoabdominal aneurysm that was successfully treated with an endovascular procedure.

CASE REPORT
A 48-year-old man with Marfan syndrome had been referred to our hospital because of vomiting. He had a history of multiple aortic surgical procedures, including aortic root and total arch replacement for acute type A aortic dissection 13 years before and hybrid endovascular repair 8 years earlier for a residual thoracoabdominal dissecting aneurysm. During the latter operation, bilateral renal arteries (RAs) and the superior mesenteric artery were translocated using cross-shaped bypass, 12-mm woven Visceral bypass surgery procedure. Cross-shaped bypass grafts were created with 12-mm woven (red arrow) and 8-mm expanded polytetrafluorethylene (ePTFE; blue arrow) grafts. First, the abdominal aorta and bilateral iliac arteries were replaced with woven grafts (black arrow). Next, the bilateral renal arteries (RAs) and superior mesenteric artery (SMA) were reconstructed using cross-shaped bypass grafts, which were finally attached to the replaced abdominal aorta woven graft. Lt, Left; Rt, right.   3-month follow-up examination, the seroma size had decreased to 40 Â 35 mm (Fig 4). The patient provided written informed consent for the report of his case details and imaging studies.

DISCUSSION
Serous ultrafiltrate extravasation through the graft wall can eventually result in a PS. Effective treatments include replacement of the affected graft, external surface sealing by application of fibrin glue components, and wrapping the graft with the saphenous vein, providing coverage for the pores outside the graft. 2,4,5 However, those will require repeat laparotomy, an invasive procedure. Endovascular repair methods that do not require repeat laparotomy and are minimally invasive for covering pores inside the graft have been recently developed, with seven cases that had used AneuRx (Medtronic, Minneapolis, MN) and Excluder and Viabahn (W.L. Gore & Associates) devices reported 2,6-9 (Table). In those cases, repeat laparotomy was considered difficult because of the elderly age of the patient or a history of multiple laparotomies. The symptoms due to gastrointestinal compression caused by PS were improved by endovascular repair alone in each patient within 1 or 2 days (Table). Moreover, none of those studies, which had had a mean follow-up period of 19 months, had reported any recurrence or additional intervention needed, including drainage.
Endovascular repair of a PS is a local procedure, with only the stent graft site receiving treatment; thus, identification of the affected graft and information regarding the PS site and graft material are necessary. It has been reported that a seroma will generally form around an affected graft, with ePTFE grafts more frequently involved than Dacron grafts. 10 In the present patient, the PS was localized around the right RA ePTFE graft and, thus, was suspected to be the causative factor. Because of the site and graft material, stent relining for that alone was considered achievable. Also, Lachat et al 7 reported two cases of endovascular repair for PS after visceral bypass surgery, for which stent relining was performed only for the affected graft because of the PS location and graft material. For cases of PS after visceral bypass surgery, the affected graft can be determined by the PS location and graft material composition, allowing for use of a minimally invasive intervention method.
The pathogenesis of PS formation remains unclear, although graft porosity, inadequate tissue incorporation, and improper manipulation before implantation are possible factors. 11 For the prevention of PS, gentle manipulation of the graft is required. However, identification in a clinical setting is difficult, and the condition has remained a diagnosis of exclusion. Measurement of CT attenuation of perigraft fluid has been considered to have diagnostic value, although various criteria for PS shown by CT attenuation have been reported. [10][11][12] In two large case series of PS development after aortic reconstruction, the interval from the initial procedure to seroma detection had a wide range from 3 to 156 months 10,11 (Table).
Exclusion of possible graft infection is crucial for the correct diagnosis of PS. Physical findings, inflammatory markers (eg, C-reactive protein, white blood cell count), and negative CT findings related to a graft infection, such as gas formation or perigraft soft tissue abnormalities, are helpful. 18 F-fluorodeoxyglucose positron emission tomography/CT can also help to exclude the possibility of graft infection. 13 If a safe procedure is possible, aspiration of perigraft fluid for microbiologic analysis is an important option for the final diagnosis and should be considered.

CONCLUSIONS
We have reported the successful endovascular repair of a PS that had developed around a visceral bypass graft after a hybrid thoracoabdominal aortic repair procedure. Relining of the visceral bypass graft with a covered stent resulted in immediate recovery of the duodenal obstruction as a seroma-related complication, indicating that endovascular repair can be an effective treatment option for PSs.