Late Infectious Complication After Exclusion of Popliteal Artery Aneurysm by Ligation and Venous Bypass
Article Outline
We present a case of a late infection of a popliteal artery aneurysm (PAA) 8 years after ligation and repair with a venous bypass graft. The patient presented with fever and a progressive painful swelling in the popliteal fossa. CT-angiography and MRI showed a large abscess in the region of the excluded PAA. Bacterial culture showed a Streptococcus Milleri. Repeated drainage and prolonged antibiotic therapy were necessary to cure the infection. On final exploration the abscess corresponded with the ligated aneurysm which was still fed by small vessels in the aneurysm wall, suggesting the thrombus in the aneurysm was infected via a bacteremia. The patient's recovery after repeated drainage of the infection and complete exclusion of the aneurysm was complicated by a transient superficial peroneal nerve paralysis.
Keywords: Popliteal aneurysm, Complications, Surgical treatment, Infection
Introduction
Ligation and bypass is one of the treatment options for popliteal artery aneurysm (PAA). Ligation and bypass does not always stop blood flow in the sac of a PAA. Excluded aneurysms can be filled with blood by persistent flow through collateral arteries, resulting in aneurysm growth and rupture.1 This may be a drawback of conventional open repair as well as endovascular treatment. Therefore some authors have recommended aneurysm excision.1, 2 We present a case of a late infectious complication after open surgical repair of a PAA, in which the aneurysm was not excluded completely.
Case
A 53-year old man presented at our emergency department 8 years after a PAA had been excluded by ligation and venous bypass graft in his right leg. On presentation he had a temperature of 39 degrees Celsius and a red and painful swelling just above the knee fold. Laboratory evaluation showed a C-reactive protein (CRP) of 155
mg/L and a WBC of 7.7×109/L. Ultrasonography showed a thrombosis of the popliteal vein and a fluid collection in the knee fold. MRI and CT-angiography confirmed the presence of an abscess with possible filling with blood (Fig. 1). Culture of the fluid, obtained by needle aspiration showed a Streptococcus Milleri. The fluid collection was drained surgically and antibiotic treatment with penicillin and clindamycin was started. Cardiac ultrasonography, an x-ray of thorax and sinuses could not locate an alternative focus of a bacteraemia. The patient was discharged with continuation of clindamycin for six weeks. CRP dropped to 0.6mg/L.
Fig. 1
A transversal CTA image through the popliteal aneurysm. This image clearly demonstrates the distorted anatomy by compression by the aneurysm.
Drainage of the abscess was performed four times in total. The patient was readmitted three times for surgical drainage to control the infection when the antibiotics were stopped because symptoms had disappeared and the laboratory infection parameters had normalized. Both packing with wet gauges and leaving a drain was attempted to control the infection. One such operation was complicated by a transient injury of the superficial peroneal nerve. At the final admission Streptoccus Milleri was isolated from both the blood and fluid collection in the popliteal fossa. Based upon this information a definitive surgical intervention was planned consisting of resection of the dorsal wall of the aneurysm which at operation was found still to be fed by small branches and remove as much as possible of the infected thrombus. All feeding branches were underrun. After this operation the patients was treated with Linezolid for two months because of allergic reactions to all other antibiotics. After this the symptoms resolved, CRP and ESR normalized and ultrasonography and MRI revealed no more fluid collections, with subsequent complete recovery of the patient.
Discussion
Elective treatment of a PAA to prevent thrombosis or rupture can be performed by several surgical techniques. There have been reports on secondary aneurysm growth after surgical intervention.1, 2, 3 Some authors have therefore stressed the need for complete resection of the aneurysm as standard treatment.1, 2 This is in contrast with endovascular repair, in which type II endoleak can result in aneurysm growth.
Asymptomatic aneurysm enlargement after ligation and bypass on its self has little clinical relevance. However, as in the presented case, persistent flow into the aneurysm sac largely filled with thrombus can be an excellent medium for bacterial growth. Colonization was most likely caused by an asymptomatic bacteraemia. Colonization of the aneurysm was extremely persistent in our patient, in spite of several weeks of antibiotic therapy, after each drainage of the pus pocket. Cure from the infection could only be achieved by removing as much as possible of the aneurysm sac.
The presented case demonstrates a very rare but serious complication of incomplete exclusion of a popliteal artery aneurysm. This may be another argument for standard treatment of PAA by underrunning all feeding vessels of the aneurysm before bypassing or making an interposition graft.1, 2 Simple ligation and bypass or endovascular repair carry by nature the risk of secondary aneurysm growth or an infection. Moreover, reintervention because of aneurysm growth or infection can be hazardous concerning peroneal nerve lesion since the anatomy can be distorted and obscure.
References
- . Fate of excluded popliteal artery aneurysms. J Vasc Surg. 2003;37:954–959
- . Late complications after ligation and bypass for popliteal aneurysm. Br J Surg. 2004;91:174–177
- Outcome of popliteal artery aneurysms after exclusion and bypass: significance of residual patent branches mimicking type II endoleaks. J Vasc Surg. 2004;40:886–890
PII: S1533-3167(06)00075-6
doi:10.1016/j.ejvsextra.2006.08.002
© 2006 Elsevier Ltd. All rights reserved.
Refers to article:
- Late Infectious Complication after Exclusion of Popliteal Artery Aneurysm by Ligation and Venous Bypass , 13 November 2006
