Extra-Anatomical Bypass Grafting and Latissimus Dorsi Myocutaneous Flap Reconstruction for Post-sternotomy Mediastinitis With Prosthetic Aortic Graft Infection

Abstract

Extra-anatomical bypass grafting is a surgical method used to remove an infected aortic graft and promote revascularization with a new graft in the non-infected area. Here, we report a case of intractable post-sternotomy mediastinitis (PSM) with aortic graft infection which was treated with extra-anatomical bypass grafting. A 56-year-old woman with a history of multiple aortic dissection and prosthetic graft replacement in the thoracoabdominal area developed PSM with aortic arch graft infection. Bacterial culture of the exposed prosthetic graft tissue yielded multidrug-resistant Pseudomonas aeruginosa. Meticulous debridement of the wound and management by negative pressure wound therapy with continuous irrigation was performed. However, the infection of the prosthetic graft could not be controlled. Extra-anatomical bypass was performed between the left common carotid artery and right subclavian artery via the right common carotid artery. Then, the infected graft was removed. After the resolution of infection, the mediastinal wound was reconstructed with a pedicled latissimus dorsi myocutaneous flap, which was harvested from the right dorsum. No recurrence of infection occurred in the nine-month follow-up period. Debridement and removal of exposed artificial graft are considered the gold standard for treating wound infection. In situ replacement of infected aortic grafts carries a risk of re-infection due to residual bacterial contamination of the periprosthetic tissue. Extra-anatomical bypass would be a useful option for reducing the risk of re-infection in patients with intractable PSM and prosthetic aortic graft infection. Further studies are warranted to evaluate the risks and benefits of this operative method.

Keywords: aortic arch graft infection; extra-anatomical bypass grafting; negative pressure wound therapy with continuous irrigation; pedicled latissimus dorsi myocutaneous flap; post-sternotomy mediastinitis.

Figure 1. On admission.

(a) Computed tomography angiography of the aorta. The arrow shows the replaced prosthetic graft during the last operation. (b) The infected prosthetic graft was exposed within the mediastinal wound without the sternal bone.

Figure 2. Removal of the infected graft.

(a) The exposed prosthetic graft was removed. (b) Gram staining of the periprosthetic tissues confirmed phagocytosis of bacteria by neutrophils (arrow).

Figure 3. After the extra-anatomical bypass operation.

(a) Postoperative computed tomography angiography demonstrated a new prosthetic graft that connected the left common carotid artery and right subclavicular artery (yellow arrowhead) via the right common carotid artery (yellow arrow). (b, c) Postoperative angiography of the ascending aorta revealed anterograde blood flow in the new graft (yellow arrow and arrowhead). The white arrow indicates the right thoracodorsal artery.

Figure 4. Latissimus dorsi myocutaneous flap reconstruction.

(a) Healthy granulation tissue formation suggesting that the removal of the infected prosthetic graft promoted mediastinal wound healing. The arrow indicates the stump of the ascending aorta. (b) The sternal wound was reconstructed using a pedicled latissimus dorsi myocutaneous flap, which was perfused by the right thoracodorsal artery. (c) The flap survived completely. There were no signs of infection recurrence nine months postoperatively.