Mycotic Ascending Aortic Pseudoaneurysm at Aortic Cannulation Site
Gökçe 
irin, MD,
O
uz Yilmaz, MD,
Ergun Demirsoy, MD,
Servet Alan, MD1,
Nerime Soybir, MD2,
Bingür Sönmez, MD1
Department of Cardiovascular Surgery
1 Department of Infectious Diseases
2 Department of Anesthesiology, Istanbul Memorial Hospital Istanbul, Turkey
Gökçe irin, MD, Tel: +90 505 3108500, Fax: +90 212 3146644, Email: drgsirin{at}yahoo.com, Istanbul Memorial Hospital, Department of Cardiovascular Surgery, A Blok Kat:2 Piyale Pa
a Bulvar
34385 Okmeydan, ili, 
stanbul, Turkey.
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ABSTRACT
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Mycotic aneurysm of the aorta is a rare but highly fatal complication of coronary bypass surgery. A 49-year-old man developed mycotic pseudoaneurysm in the ascending aorta after coronary bypass in another hospital. Computed tomography showed the pseudoaneurysm originated from the previous aortic cannulation site. The defect was successfully repaired with pericardial-pledgeted sutures.
Key Words: Aneurysm • False • Ascending Aorta • Coronary Artery Bypass • Mediastinitis
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INTRODUCTION
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Pseudoaneurysm of the ascending aorta is a rare but very serious complication after coronary artery bypass grafting. There are only a few case reports of mycotic aneurysms of the ascending aorta.1–8 Despite the introduction of novel antibiotics, surgery in such cases still incurs high rates of morbidity and mortality.1
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CASE REPORT
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A 49-year-old man presented with a nonpulsatile mass over the upper 3rd of the sternum. He had undergone double coronary artery bypass grafting 6 months earlier in another medical center, and was treated for persistent sternal drainage afterwards. His C-reactive protein level, erythrocyte sedimentation rate, and leukocyte count were elevated. Multislice computed tomography revealed a 90.6 x 45.8-mm retrosternal pseudoaneurysm originating from the ascending aorta, eroding the posterior border of the sternum, and extending as a second 38.5 x 52.8-mm mass anterior to the sternum (Figure 1
). Cardiopulmonary bypass was commenced via femor-ofemoral cannulation, and the patient was cooled to 20°C. An incision over the sternal mass revealed a pouch filled with infected hematoma. A sternotomy was performed, and under total circulatory arrest, the retrosternal aneurysmal pouch was incised to reveal a 1.5 x 1.5-cm circular defect on the anterior ascending aorta, corresponding to the previous cannulation site. The Teflon-pledgeted sutures closing the cannulation site had become totally detached. A 10F Foley catheter balloon was inflated in the defect to control bleeding and permit restarting body perfusion. The defect in the aorta was repaired primarily with pericardial-pledgeted sutures. The mediastinum was debrided, cultures were taken, and 2 latex drains were positioned mediastinally and subcutaneously. Methicillin-sensitive staphylococcus epidermidis grew in tissue cultures; parenteral teicoplanin and piperacillin/tazobactam were administered for 6 weeks. The drains were gradually pulled out and shortened, then totally withdrawn at the end of the 2nd week. Cultures from drained areas and blood were negative. The patient was discharged on the 20th postoperative day. Antibiotic therapy totalled 3 months. Computed tomography angiography was performed after 6 months (Figure 2), at which time the infection parameters were all within normal limits.
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Figure 1. Preoperative multislice computed tomography showing the pseudoaneurysm originating from the ascending aorta, and the extension of the mass anterior to the sternum.
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Figure 2. Postoperative multislice computed tomography of the same patient after 6 months, showing a completely normal ascending aorta.
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DISCUSSION
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Mycotic ascending aortic aneurysm is a very rare complication of open heart surgery. Although it is more frequent after coronary artery bypass, such cases have also been reported in immunosuppressed heart or heart-lung transplant recipients.1–3 The most frequently isolated pathogen is staphylococcus aureus.4–6 Pseudoaneurysms of the ascending aorta usually originate from the proximal anastomosis, suture lines, or cannulation sites.1,4,5,7,8 Synthetic materials, such as Dacron or Teflon pledgets, may facilitate infection. Any concomitant mediastinal infection may predispose to pseudoaneurysm formation.7 In this case, the pseudoaneurysm originated from the previous aortic cannulation site, and the Teflon-pledgeted sutures had become totally detached.
Because the aneurysm usually adheres to the sternum, repeat sternotomy carries a high risk of fatal hemorrhage. Therefore, commencing cardiopulmonary bypass via femoral cannulation before sternotomy would be a safer technique.1,4 There are reports of successful use of moderate systemic hypothermia with low flow or deep hypothermic circulatory arrest.4–6 We carried out mediastinal exploration during deep hypothermia with low flow, and the aortic repair was performed under circulatory arrest to increase the margin of safety.
When surgical repair is planned, any proposed patch should be minimally reactive, such as autologous or porcine pericardium.1,5 Use of synthetic materials facilitates the colonization of microorganisms predisposing to recurrent or permanent infections. That is why we preferred to use pericardial-pledgeted sutures to repair the defect in the aortic wall. Such cases can also be treated successfully with novel endovascular stent-grafting techniques.3,8 Placing synthetic materials in an already infected area is not advised; indeed, one patient was lost due to sepsis after a technically successful procedure.7 However, we believe endovascular stent-grafting may be advantageous, but with concomitant long-term antibiotic therapy.
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REFERENCES
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Asian Cardiovasc Thorac Ann 2009;
17:417-418
© 2009 by SAGE Publications
DOI: 10.1177/0218492309338095
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ABSTRACT
INTRODUCTION
