Ann Thorac Surg 2008;86:287-289. doi:10.1016/j.athoracsur.2008.01.086
© 2008 The Society of Thoracic Surgeons
Case Reports
Successful Treatment of Infected Ascending Aortic Prosthesis by Omental Wrapping Without Graft Removal
Gordan Samoukovic, MD,
Pierre-Luc Bernier, MD,
Kevin Lachapelle, MD*
Division of Cardiothoracic Surgery, Department of Surgery, McGill University Health Center, Montreal, Quebec, Canada
Accepted for publication January 28, 2008.
* Address correspondence to Dr Lachapelle, Division of Cardiothoracic Surgery, Department of Surgery, McGill University Health Center, 687 Pine Ave West, Room S-8.44, Montreal, Quebec, H3A 1A1, Canada (Email: kevin.lachapelle{at}muhc.mcgill.ca).
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Abstract
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A deep wound infection after a midline sternotomy is a very serious complication. The severity of it can be increased by the presence of prosthetic material. We present a case of a 76-year-old man who had an infection of an ascending aortic graft develop after a Bentall procedure. Rather than following the "traditional" surgical therapy of graft explantation and debridement, we chose to preserve the graft and protect it by omental translocation. The relative merits of this therapeutic approach are outlined and discussed. The patient was discharged on the postoperative day 6 after an uneventful postoperative course.
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Introduction
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Prosthetic aortic grafts have been used to treat aneurysms of both the thoracic and abdominal aortas. Graft infections after surgery of the thoracic aorta occur at a rate of 0.9% to 2% [1] and are associated with a mortality ranging from 25% to 75% [2, 3]. Although gram-negative bacilli, Enterococcus species, fungi, anaerobes, and polymicrobial flora are frequently recovered from the sites of these infections, the most commonly implicated causative vectors are Staphylococcus aureus and Staphylococcus epidermidis [4]. The majority of patients with an infected aortic graft present with fever and leukocytosis with or without chest pain. Although imaging modalities, including chest roentgenogram and computed tomography are nonspecific in the early postoperative stage and often show mediastinal fluid collection associated with surrounding tissue edema, definitive diagnosis usually depends on aspiration of the fluid. The mainstay of modern treatment of infected aortic grafts relies heavily on principles described by Hargrove and Edmunds [5] almost a quarter of a century ago; these include explantation and replacement of the infected material, extensive irrigation and tissue debridement, broad-spectrum antibiotic therapy and obliteration of dead space by autologous tissue, frequently of the greater omentum.
A 76-year-old man was referred to our center for preoperative workup of an enlarging ascending aortic aneurysm. The ascending aorta and the aortic root were enlarged to 4.8 cm and 5.0 cm, respectively, in the context of otherwise unremarkable computed tomographic imaging of the chest and abdomen. During diagnostic coronary angiography, the patient suffered an acute Stanford type A dissection involving the take-off of the left common carotid and subclavian arteries with preservation of the coronary artery perfusion and extending from the root of the aorta to the diaphragm. The patient was emergently transferred to the intensive care unit and subsequently to the operating room. Intraoperative findings revealed a calcified three-leaflet aortic valve with extensive degenerative changes along with a dilated thin-walled aorta without frank rupture. A decision was made to perform a Bentall procedure using a No. 25 Freestyle aortic valve (Medtronic Inc, Minneapolis, MN) and a replacement of the ascending aorta and hemi-arch with a No. 30 Hemashield graft (Boston, Scientific, Natick, MA) under deep hypothermic circulatory arrest and selective antegrade cerebral perfusion.
Antegrade cerebral perfusion was delivered through an axillary artery cannulation. The postoperative course was unremarkable; the patient was promptly extubated, transferred from the intensive care unit to the ward and was discharged on postoperative day 8.
Four days later, the patient returned to the emergency room with a primary complaint of mild chest pain, fever, and generalized malaise. Routine laboratory investigations revealed a leukocytosis of 26 x 109 cells/L. Computed tomographic imaging showed right-sided pericardial and retrosternal fluid collections containing bubbles (Fig 1). The patient was diagnosed with mediastinitis and was admitted to the hospital. Treatment with broad-spectrum antibiotics (intravenous vancomycin adjusted according to creatinine clearance for a therapeutic serum level and ciprofloxacin [500 mg orally twice daily]) was initiated. Eventually, blood cultures grew S. epidermidis. Despite the antibiotic therapy, the patient remained febrile and leukocytic. Consequently, 7 days later the patient was taken to the operating room for re-exploration. Intraoperative findings revealed extensive inflammation of the mediastinal tissue as well as pus around the right atrium and the graft itself. The area was copiously irrigated and aggressive debridement (including resection of the sternum) was performed. Due to the fragility of the surrounding tissue we chose not to explant the graft, but to protect it with autologous tissue. For this purpose, we opened the abdomen and mobilized the omentum, which was fairly large and mobile as should be expected in a virgin abdomen. We detached it from the colon, preserving the middle colic artery, and from the gastric vessels, basing it on the gastroduodenal artery. This allowed for development of three distinct omental processes. The mobilized omentum was translocated into the thoracic cavity through a substernal diaphragmatic window. Although one of the omental processes was used to complete a 360-degree wrap around the graft, the rest of it filled the mediastinum. The omentum was long enough to reach the aortic arch and fill the manubrial portion of the defect. The pectoralis muscles were not mobilized. Retention sutures were used to reapproximate the created skin flaps. The patient weighted 86 kg and measured 180 cm for a body surface area of 2.1 m2 according to Mosteller's [6] formula.
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Fig 1. Computed tomographic image suggestive of mediastinitis with retrosternal fluid collection and air bubbles.
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The patient's postoperative course was unremarkable. He was extubated in the intensive care unit the following day and transferred to the ward. Postoperative irrigation of the mediastinum was not used, but antibiotics were continued for 4 weeks after the re-exploration (rifampin, 600 mg orally once a day and intravenous vancomycin adjusted according to creatinine clearance for a therapeutic serum level). He was discharged on postoperative day 6. Nine months later, he was being followed-up regularly, and was asymptomatic in the context of computed tomographic imaging suggestive of a normal healing process without evidence of reinfection or aneurysmal formation (Fig 2). The patient will be seen in follow-up every 6 months with yearly computed tomographic imaging of his thorax.
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Fig 2. Follow-up (1 month) computed tomographic image showing the omental wrapping without evidence of fluid collection.
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Comment
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This article demonstrates a successful case of infected ascending aortic graft treatment using omental translocation and wrapping without graft removal.
Omental translocation is widely used and undoubtedly effective in the treatment of postoperative mediastinitis. The filling potential of the omentum, its vascularity, and its ease for translocation make it a great tool. However, the presence of an infected graft complicates matters and increases the risk of anastomotic rupture and late pseudoaneurysm formation in cases of mediastinal infections. Unfortunately, the accepted treatment of such a complication (ie, debridement and removal of the graft), constitutes a major undertaking and is associated with a significant mortality risk. In some instances, the characteristics of the patient make this reoperation prohibitively risky. In such circumstances, the option previously presented is interesting. Obviously, careful follow-up involving frequent imaging is required to detect late complications.
In summary, omental translocation without graft removal should be considered as a treatment alternative for infected aortic prosthesis in cases in which graft replacement is judged to be overly risky. Patients who undergo this intervention should be vigilantly followed.
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References
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- Seeger JM. Management of patients with prosthetic graft infection Am Surg 2000;66:166.[Medline]
- Svensson LG, Crawford ES, Hess KR, et al. Experience with 1509 patients undergoing thoracoabdominal aortic operations J Vasc Surg 1993;17:357.[Medline]
- Hargrove 3rd WC, Edmunds Jr LH. Management of infected thoracic aortic prosthetic grafts Ann Thorac Surg 1984;37:72.[Abstract/Free Full Text]
- Sharp WJ, Hobballah JJ, Mohan CR, et al. The management of the infected aortic prosthesis: a current decade of experience J Vasc Surg 1994;16:844.
- Coselli JS, Koksoy C, LeMaire SA. Management of thoracic aortic graft infections Ann Thorac Surg 1999;67:1990.[Abstract/Free Full Text]
- Mosteller RD. Simplified calculation of body-surface area N Engl J Med 1987;317:1098.[Medline]
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Abstract
Introduction
