Melioidosis presenting as an infected intrathoracic subclavian artery pseudoaneurysm treated with femoral vein interposition graft☆☆☆
Article Outline
Abstract
We present the first case of in situ replacement of an infected subclavian artery using superficial femoral vein and the fourth reported case of an infected arterial pseudoaneurysm caused by pseudomonas pseudomallei. Sepsis and hoarseness developed in a 58-year-old man after recent travel to Borneo, Indonesia. Indirect laryngoscopy revealed a paralyzed right vocal cord. Computed tomography and arteriography revealed a 6.5-cm pseudoaneurysm of the proximal right subclavian artery. Blood cultures grew pseudomonas pseudomallei. An abnormal cardiac stress test prompted a coronary angiography, which revealed severe coronary artery disease. The patient underwent coronary artery bypass and in situ replacement of the infected subclavian artery pseudoaneurysm with a superficial femoral vein, along with placement of a pectoralis major muscle flap to cover the vein graft. Operative cultures of the pseudoaneurysm grew pseudomonas pseudomallei. The patient was treated with a 6-week course of intravenous ceftazidime and oral doxycycline and then continued on oral amoxicillin-clavulanate. One week after discontinuing intravenous antibiotics, the patient presented to the emergency department with a rapidly expanding, pulsatile mass in the right supraclavicular space. He was taken emergently to the operating room. After hypothermic circulatory arrest was accomplished, the disrupted vein graft and aneurysm cavity were resected and the subclavian artery was oversewn proximally and distally. Parenteral ceftazidime was continued for 3 months and oral amoxicillin-clavulanate (augmentin) was continued indefinitely. There was no evidence of infection clinically or by computed tomographic scan 2 years later. Although autogenous vein replacement of infected arteries and grafts may be successful in the majority of cases, this strategy should probably be avoided when particularly virulent bacteria such as the organism in this case are present. (J Vasc Surg 2002;35:569-72.)
Primary aneurysms of the intrathoracic subclavian artery are extremely rare, as our group and other authors have reported.1 Infected true and false aneurysms of the subclavian artery are even rarer and are usually caused by Staphylococcus , Salmonella , or syphilis. We report the case of a patient who had an infected proximal subclavian artery pseudoaneurysm caused by Burkholderia pseudomallei , the causative organism of melioidosis. To our knowledge, only three other cases of infected pseudoaneurysms caused by this bacterium have been reported.2, 3, 4 We report our management of this challenging problem, which is the first reported case of in situ replacement of an infected subclavian artery with a superficial femoral vein, and the devastating nature of infection caused by this virulent organism.
Case report
A 58-year-old man came to the hospital with a 4-week history of low-grade fever, hoarseness, malaise, and anorexia. The patient worked as a management consultant and reported work-related travel to rural Indonesia within the previous 7 months. On admission to the hospital, his temperature was 100.6°F orally. The right neck and chest were mildly erythematous, but the results of a physical examination were otherwise normal. He was hoarse, and right vocal cord paralysis was revealed by means of indirect laryngoscopy. His white blood cell count was elevated at 15.7/mL. A right superior mediastinal mass was revealed by means of a chest radiograph (Fig 1).
Fig. 1.
Admitting chest radiograph showing right upper mediastinal mass (arrow ).
Fig. 2.
CT scan demonstrating 6.5-cm proximal right subclavian artery pseudoaneurysm (most proximal, upper left ; next, upper right ; next, lower left ; most distal, lower right ).
Fig. 3.
Aortic arch arteriogram demonstrating proximal right subclavian artery pseudoaneurysm.
Fig. 4.
Selective catheterization of right subclavian artery shows spurting of dye into pseudoaneurysm arising from proximal right subclavian artery (A ) and filling of the pseudoaneurysm (B ).
The patient was brought to the operating room, and a coronary artery bypass grafting procedure and pseudoaneurysm repair were performed concomitantly. His severe coronary artery disease precluded repairing the pseudoaneurysm alone. Problems associated with performing the coronary artery bypass grafting procedure included the patient being septic, so we did not want to wait several weeks for him to recover, and the extension of the pseudoaneurysm almost to the sternum, which would make a repeat sternotomy difficult. Exposure was obtained via a median sternotomy with right surpraclavicular extension. The cardiac surgery team performed coronary artery bypass grafting procedures of two vessels. The aneurysmal coronary arteries may have occurred because of the infectious process, but they were not excised because of the associated bleeding expected with this treatment. Proximal control of the innominate artery was then obtained, as was distal control of the right subclavian, common carotid, and vertebral arteries. The infected pseudoaneurysm originated from the proximal subclavian artery and was resected. A large cavity was identified in the superomedial right chest. A superficial femoral vein graft was anastomosed to the origin of the right subclavian artery and to the subclavian artery immediately proximal to the right vertebral artery. The plastic surgery team placed a pectoralis major muscle flap to cover the vein graft and fill the right chest cavity. The patient tolerated the procedure well and was discharged home on the eighth postoperative day. Operative cultures of the pseudoaneurysm grew B pseudomallei . The patient was treated with a 6-week course of intravenous ceftazidime and oral doxycycline and then switched to oral amoxicillin-clavulanate.
One week after stopping intravenous antibiotics, the patient came to the emergency room with a rapidly expanding, erythematous, pulsatile mass in the right supraclavicular space. The mass had appeared 1 day before and had enlarged overnight. The patient also had fever, chills, and confusion. An 11.5- by 11.5- by 21-cm pseudoaneurysm at the base of the innominate artery was revealed by means of an emergent enhanced CT scan. He was taken emergently to the operating room, and a femorofemoral bypass graft was performed. A median sternotomy was again performed, and hypothermic circulatory arrest was accomplished. The pseudoaneurysm was entered and was noted to be emanating from a large hole in the body of an otherwise intact vein graft. The vein graft and aneurysm cavity were resected, and the subclavian artery was oversewn proximally and distally. Omentum was mobilized on a vascularized pedicle to fill the large defect, and a Duval drain was placed in the cavity. Although the distal arm was mottled, and Doppler scanning signals were absent in the right radial and ulnar arteries immediately postoperatively, the appearance of the arm returned to normal, and Doppler scanning signals were present 12 hours later. Blood cultures taken at the time of hospital admission and intraoperative cultures of the pseudoaneurysm grew B pseudomallei . External drainage of the thoracic cavity and parenteral ceftazidime were continued for 3 months. He was then given oral amoxicillin-clavulanate, which he has continued taking for 24 months without evidence of residual infection clinically or by means of quarterly CT scans.
Discussion
Intracavitary infected pseudoaneurysms present a significant challenge. Traditional treatment has included resection of the aneurysm and extra-anatomic bypass grafting. In this case of an infected proximal right subclavian aneurysm, this strategy posed four problems. First, we were concerned that continuity could not be maintained between the innominate artery and the right common carotid artery if the distal innominate artery needed to be resected. If that proved to be the case, performance of an extra-anatomic bypass grafting procedure, such as axilloaxillary or femoroaxillary bypass grafting, would require revascularization of both the right subclavian and common carotid arteries, with another bypass grafting procedure from the subclavian artery to the common carotid artery. Second, we needed to enter the supraclavicular space to obtain distal control of the subclavian artery, making it difficult to perform an extra-anatomic bypass grafting procedure separate from the infected field. Third, severe upper-extremity ischemia has been reported after excision of the infected subclavian artery when revascularization was not performed.5, 6 Fourth, excision of the infected pseudoaneurysm and oversewing the proximal artery could potentially result in subclavian artery stump blow-out. For these reasons, we opted to replace the infected arterial segment with autogenous vein. Given the size of the proximal subclavian artery, we chose superficial femoral vein as the conduit. The use of this vessel has been well described by Clagget for in situ replacement of infected aortic aneurysms and infected aortic grafts.7 To our knowledge, its use in the subclavian position has not been described before.
B pseudomallei (formerly Pseudomonas pseudomallei ) is a small, gram-negative, motile, aerobic bacillus that is easily cultured with standard media. It is found in soil, stagnant streams, ponds, and rice paddies. The clinical disease known as melioidosis is seen in humans and animals and is endemic in areas within 20° latitude north and south of the equator, especially in Southeast Asia but also in Northeastern Australia and Central, Western, and Eastern Africa.8 Infection is transmitted by means of inhalation, ingestion, or direct contact with soil, water, food, and infected animals. Person-to-person transmission can occur, but is rare. Melioidosis may present as an acute or chronic infection and can have a latency period of many years before becoming clinically apparent. Mild or subclinical infection is fairly common; 1% to 2% of healthy, non-wounded Vietnam veterans were found to have positive serologies. Thirty-five American soldiers died of the illness during the Vietnam War.9
The most common clinical manifestations include acute, localized, suppurative skin infection, pulmonary infection, and septicemia. The mortality rate of patients with bacteremia and sepsis is approximately 40% and may be as high as 90%.10 Several antibiotics have proved effective for the treatment of melioidosis. For patients with bacteremia, ceftazidime has emerged as a drug of choice, along with imipenem and possibly meropenem. Oral amoxicillin-clavulanate is also active and useful for chronic infection. Trimethoprim-sulfamethoxisole, choramphenicol, and doxycylcine have proven less efficacious than in the past. Flouroquinolones do not have any efficacy against this organism.10
The three earlier reported cases of infected aneurysms or pseudoaneurysms caused by B pseudomallei were a thoracoabdominal aneurysm, an infrarenal abdominal aortic aneurysm, and a renal artery aneurysm.2, 3, 4 The clinical course of the thoracoabdominal aneurysm was one of fulminant sepsis and death caused by rupture.2 The abdominal aortic aneurysm was successfully treated with operative repair and prosthetic graft placement.3 The renal artery aneurysm was successfully treated with aneurysm excision and nephrectomy.4 This case represents, to our knowledge, the fourth such case of arterial pseudoaneurysm with B pseudomallei .
This case highlights the potential for life-threatening complications, in particular an infected intrathoracic pseudoaneurysm, with B pseudomallei , a bacterial infection rarely seen in the United States. It also portends the rising incidence of imported exotic diseases acquired in endemic areas, because worldwide travel continues to increase. Although autogenous vein replacement of infected arteries and grafts can be successful in most cases with more commonly encountered bacteria, this strategy should probably be avoided, when possible, for infected arterial pseudoaneurysms with this bacterium.
Acknowledgements
We thank Dr Gary Lum, Royal Darwin Hospital in Australia, and Dr Andrew H. J. Simpson, Wellcome-Mahidol University Oxford Tropical Medicine Research Programme in Bangkok, Thailand, for their invaluable advice and assistance in suggesting antimicrobial treatment of this patient.
References
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☆ Competition of interest: nil.
☆☆ Reprint requests: Keith D. Calligaro, MD, Section of Vascular Surgery, Pennsylvania Hospital, 700 Spruce St, Suite 101, Philadelphia, PA 19106.
PII: S0741-5214(02)01456-8
doi:10.1067/mva.2002.118592
© 2002 Society for Vascular Surgery and The American Association for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
