DISCUSSION
The incidence of prosthetic graft infection after aortic replacement has been reported to range from 0.5 to 9% and with mortality rate of 25-88%.3 In patients with graft infection and mediastinitis, effective and urgent treatment is crucial to prevent recurrence of infection and complications. The ideal treatment has not been clearly defined so far. Most of the studies include retrospective and relatively small patient cohort.
The most effective treatment of TAGI is the removal of the foreign material.3,4 However, removal and replacement of infected aortic grafts has high mortality and morbidity risks.1,3,4 As a less invasive approach graft-sparing strategies are advantageous for high-risk patients. Graft-sparing strategies comprise debridement, irrigation, closed continuous irrigation, VAC therapy and tissue flap coverage. Using VAC treatment instead of closed continuous irrigation in mediastinitis treatment seems to have better outcomes.5 The most preferred tissue flap for TAGI is omentum.3,4 Pectoralis major, rectus abdominis, latismus dorsi muscles has also been used.1,4,5
Umminger et al2 compared 11 TAGI cases of graft replacement and 14 TAGI cases of graft-sparing techniques. Their graft-sparing technique included aggressive debridement, extensive irrigation with a povidone–iodine solution and/or octenidine dihydrochloride followed by continuous mediastinal irrigation with antibiotic solutions in combination with systemic application of antibiotics for 2 weeks without omental or muscle flap usage. Their in-hospital mortality was 18% in the graft replacement group and 14% in the graft preserved group which was not statistically significant. They reported 14% (2 patients) reoperation rate after graft preservation technique due to recurrent graft infection at a median follow-up of 1.5 years who were eventually required graft replacement and one of them died on early postoperative period.
In another recent study by Uchino et al6 17 patients who underwent graft-sparing surgery for TAGI were analyzed. Hospital mortality was 29.4% which was relatively high. Their graft-sparing technique included local debridement of surrounding tissue with saline irrigation and drainage. They performed omental transfer only if the intraoperative gram stain was positive (in 5 patients). They did not encounter recurrence of infection after discharge requiring reintervention at a median follow-up of 18 months.
In the last two mentioned studies, they did not to use VAC therapy. Also Umminger et al2 did not use omental coverage while Uchino et al6 used in some patients. However, we prefered to use both VAC and omental coverage in staged surgery. The advantage of our approach was that we were able to achieve negative mediastinal culture after VAC therapy prior to omental transposition and sternal closure which enabled more secure environment to avoid future recurrent infection.
Only a few cases have been reported in the literature that included a combination of VAC and omental flap for TAGI treatment.4,7,8 Saiki et. al. (8) treated 5 patients with mediastinitis after aortic arch replacement using a combination of VAC therapy and omental transfer. Four of the five patients survived to discharge and have been reported to be free from mediastinal or graft infection at a mean follow-up period of 36,2 months.
In conclusion, we have successfully treated aortic graft infection by thoroughly debridement of all the infected tissues, followed by VAC therapy, and finally covering the infected aortic graft and mediastinum with omental flap. Combining VAC with omental transfer seems to be effective in TAGI treatment and should be taken into consideration in such cases.