Asian Cardiovasc Thorac Ann 2006;14:247-249
© 2006 Asia Publishing EXchange Ltd
Graft Replacement and Muscle Wrap for Infected Aneurysm of Thoracic Aorta
Masayuki Sakaki, MD,
Hiroshi Takano, MD,
Yuji Miyamoto, MD,
Yoshiki Sawa, MD,
Goro Matsumiya, MD,
Hikaru Matsuda, MD
Department of Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
For reprint information contact: Masayuki Sakaki, MD Tel: 81 6 6771 6051 Fax: 81 6 6775 2889 Email: msakaki{at}oph.gr.jp, Department of Cardiovascular Surgery, Osaka Police Hospital, 10-31 Kitayamachou, Tennouji, Osaka 543-0035, Japan.
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ABSTRACT
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A 68-year-old man was admitted with high fever and enlargement of the distal aortic arch on chest radiography. Computed tomography showed a huge proximal descending thoracic aortic aneurysm. Graft replacement of the proximal descending thoracic aorta was performed on an emergency basis, and a pectoralis major muscle flap was wrapped around the graft. Salmonella enteritidis was detected in the resected tissue. The patient recovered well, with no signs of infection.
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INTRODUCTION
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Infected aneurysm of the aorta is a rare but life-threatening condition requiring surgical repair. We describe a case of infected aneurysm of the proximal descending thoracic aorta, which was treated by in situ graft replacement and wrapping with a pectoralis major muscle flap.
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CASE REPORT
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A 68-year-old man with diabetes mellitus was admitted with a high fever. Enlargement of the distal aortic arch was noted on chest radiography, and computed tomography (CT) showed a huge proximal descending thoracic aortic aneurysm. He was transferred to our department for surgical treatment. On admission, his body temperature was 39.7°C. Laboratory examinations showed elevated serum C-reactive protein of 40.1 mg·dL–1 and a white blood cell count of 15,770/mm3. Serum creatinine and blood urea nitrogen levels were also elevated to 4.2 mg·dL–1 and 51 mg·dL–1, respectively. No bacteria were detected in a blood culture. Enhanced CT of the chest showed a huge sacciform aneurysm (70 x 75 mm) in the proximal descending thoracic aorta (Figure 1
). As an infected aneurysm was strongly suspected, imipenem/cilastatin and vancomycin hydrochloride were administrated immediately to control the infection. However, when the aneurysm was found to be expanding rapidly, on chest radiography and CT the following day, an emergency operation was carried out.
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Figure 1. Preoperative chest computed tomography scans showing the huge (70 x 75 mm) proximal descending thoracic aortic aneurysm (arrowed).
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Through a thoracotomy in the 4th intercostal space, a hematoma was observed in the subadventitial area of the aneurysm, indicating a sealed rupture. Cardiopulmonary bypass was established with drainage from the left femoral vein and pulmonary artery, and arterial return to the left axillary artery and left femoral artery. Circulatory arrest was induced at 20°C, the aneurysm was opened, and the clot was removed. The inflamed aortic wall was completely resected. Proximal anastomosis with a woven Dacron vascular graft, 28 mm in diameter (Hemashield; Meadox Medical, Oakland, NJ, USA), was carried out via an open proximal approach. Although there was no abscess formation in the aneurysmal wall, it was decided to transplant pectoralis major muscle to fill the dead space in the chest. A large flap of the left pectoralis major muscle was completely mobilized, preserving its artery, vein, and nerve as a pedicle. The mobilized muscle with pedicle was transferred into the pleural cavity through a window created in the 2nd intercostal space, and wrapped around the graft (Figure 2). Postoperatively, Salmonella enteritidis was detected on tissue culture of the aneurysmal wall. Intensive care including intravenous administration of sulfamethoxazole/trimethoprim and ceftazidime for 8 weeks, and infusion of immunoglobulin for several days, was provided postoperatively. The serum C-reactive protein level gradually decreased and the hemodynamics stabilized. The patient is now doing well after taking oral antibiotics for a year, with no signs of any recurrence of infection.
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Figure 2. The mobilized muscle was transferred into the chest and wrapped around the graft through a window created in the 2nd intercostal space.
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DISCUSSION
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Infected aneurysm of the thoracic aorta is relatively uncommon and difficult to diagnose. Preoperative diagnosis of aortic infection is generally achieved by CT findings of a sacral type of aneurysm. Lee and colleagues1 found that a CT scan was valuable in confirming the diagnosis of infected aneurysm, and its sensitivity and specificity were 100%. The important CT features are: irregularities and haziness of the aortic wall with abscess formation; thrombus formation, which is also common in dissecting aneurysms; vertebral destruction of the spinal column and paraspinal mass formation. In this case, the patient had been treated for fever of unknown origin for several days before enlargement of the aortic shadow was found on chest radiography, and chest CT revealed the aneurysm with thrombus formation in the proximal descending thoracic aorta.
The timing of surgery may be difficult to determine. Chan and colleagues2 recommended early operation within 24 hours of admission, without regard to the status of the infection, because of the potential for rapid expansion or rupture of the infected aneurysm. Cina and colleagues3 stated that prompt confirmation of infection was desirable for successful in situ repair with synthetic material. Due to the rapid growth of the aneurysm in this patient, we had to perform an emergency operation without confirmation of the bacteria. As a result, effective antibiotics could not be administered until the 3rd postoperative day.
For the infrarenal aorta and iliac arteries, ligation of the aorta and an extra-anatomic bypass graft have been considered as standard treatment for aortic sepsis, to avoid the use of grafts in a contaminated lesion. However, patency rates for long axillobifemoral bypass grafts are poor, and aortic stump bleeding has been reported.4,5 Chiba and colleagues6 found that an extra-anatomic bypass graft gave no absolute guarantee against graft infection. Meticulous debridement of all infected tissue, and covering the graft with a viable tissue flap when necessary, provided the best outcome.7,8 Graft coverage and closure of the dead space has been accomplished by mobilizing grossly uninfected local tissue including thymus, pericardial fat pads, muscle (pectoralis major, rectus abdominis, and latissimus dorsi), and greater omentum. Omental flaps based on the right gastroepiploic artery and vein are preferred when omentum is available in an adequate size, as in patients in a non-debilitated condition and those without a previous abdominal operation. However, we were uncertain whether sufficient volume of omentum for coverage of the graft could be mobilized to the site in this case, thus we used the pectoralis major muscle. Although there was no sign of infection, the patient was given oral antibiotics after discharge, and careful follow-up with frequent chest CT scans.
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REFERENCES
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- Lee MH, Chan P, Chiou HJ, Cheung WK. Diagnostic imaging of Salmonella-related mycotic aneurysm of aorta by CT. Clin Imaging 1996;20:26–30.[Medline]
- Chan FY, Crawford ES, Coselli JS, Safi HJ, Williams TW Jr. In situ prosthetic graft replacement for mycotic aneurysm of the aorta. Ann Thorac Surg 1989;47:193–203.[Abstract]
- Cina CS, Arena GO, Fiture AO, Clase CM, Doobay B. Ruptured mycotic thoracoabdominal aortic aneurysms: a report of three cases and a systematic review. J Vasc Surg 2001;33:861–7.[Medline]
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- Pasic M, Carrel T, Vogt M, von Segesser L, Turina M. Treatment of mycotic aneurysm of the aorta and its branches: the location determines the operative technique. Eur J Vasc Surg 1992;6:419–23.[Medline]
- Chiba Y, Muraoka R, Ihaya A, Kimura T, Morioka K, Nara M, et al. Surgical treatment of infected thoracic and abdominal aortic aneurysms. Cardiovasc Surg 1996;4:476–9.[Medline]
- Coselli JS, Crawford ES, Williams TW Jr, Bradshaw MW, Wiemer DR, Harris RL, et al. Treatment of postoperative infection of ascending aorta and transverse aortic arch, including use of viable omentum and muscle flaps. Ann Thorac Surg 1990;50:868–81.[Abstract]
- Hsu RB, Tsay YG, Wang SS, Chu SH. Surgical treatment for primary infected aneurysm of the descending thoracic aorta, abdominal aorta, and iliac arteries. J Vasc Surg 2002;36:746–50.[Medline]
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ABSTRACT
INTRODUCTION
