Eur J Cardiothorac Surg 2007;31:941-943. doi:10.1016/j.ejcts.2007.01.032
Copyright © 2007, European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved
Descending thoracic aortic aneurysm complicated with severe vertebral erosion
Yosuke Takahashi*,
Yasuyuki Sasaki,
Toshihiko Shibata,
Shigefumi Suehiro
Department of Cardiovascular Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan
Received 8 November 2006;
received in revised form 9 January 2007;
accepted 15 January 2007.
* Corresponding author. Tel.: +81 6 6645 3980; fax: +81 6 6646 3071. (Email: ysk{at}msic.med.osaka-cu.ac.jp).
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Abstract
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We describe a case of successful surgical treatment for mycotic thoracic aortic aneurysm with vertebral erosion. A 70-year-old man presented with a 2 month history of back pain. Chest roentgenography and enhanced computed tomography showed a descending thoracic aortic aneurysm with destruction of T8–T10 vertebrae. We suspected that the formation of pseudoaneurysms was due to direct extension of tuberculous vertebral osteomyelitis. He was managed with a combination of surgery and antituberculous chemotherapy. No causative pathogen was identified from specimens obtained perioperatively. The postoperative course was uneventful and he remained well 2 years later.
Key Words: Thoracic aortic aneurysm • Tuberculosis • Vertebral erosion
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1. Introduction
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Thoracic aortic aneurysm with vertebral erosion is a very rare and potentially fatal condition. Most of these aneurysms are mycotic in nature, often tuberculous [1,2]. We report here a case of successful surgical treatment for a descending aortic pseudoaneurysm probably caused by direct extension of corresponding vertebral osteomyelitis.
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2. Case report
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A 70-year-old man presented to hospital with a two-month history of dull back pain. He had a history of pulmonary tuberculosis 50 years previously. Chest roentgenography (A) and magnetic resonance imaging (B) showed a descending thoracic aortic aneurysm with severe destruction of the eighth to tenth thoracic vertebral bodies (Fig. 1
). Enhanced computed tomography confirmed the saccular aneurysm and severe destruction of the vertebral bodies (Fig. 2
). On admission to hospital, physical examination and laboratory data were almost normal. No causative pathogens were cultured from blood or sputa. An aortogram demonstrated a 7 cm x 5 cm saccular aneurysm of the posterior wall of the middle to distal descending thoracic aorta. Since most thoracic aortic aneurysms with corresponding vertebral erosion are associated with mycotic infection, especially tuberculosis, we suspected this was a tuberculous aortic aneurysm and initiated antituberculous chemotherapy with rifampicin, ethambutol, and isoniazid.
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Fig. 1. (A) Preoperative chest roentogram showing destruction of the anterior bodies of T8–T10 vertebrae. (B) Preoperative magnetic resonance imaging showing destruction of the anterior bodies of T8–T10 vertebrae complicated with descending aortic aneurysm.
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Fig. 2. Preoperative chest computed tomography showing the descending aortic aneurysm with destruction of the vertebrae from T8 to T10.
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Thirteen days after admission, elective surgical repair was performed. The patient underwent a left posterolateral thoracotomy through the 6th intercostal space and cardiopulmonary bypass was established with arterial cannulation of the femoral artery and venous cannulation of the pulmonary artery. There was no abscess formation adjacent to the aneurysm and no active infectious findings. The aneurysm was protruding posteriorly and corresponding vertebral body was significantly destroyed. The anterior aortic wall and the aortic wall beyond the aneurysm were normal structure. When the aneurysm was opened and thrombus was removed, a fragment of vertebral body was visible within the lumen of the posterior aortic wall. After debridement of aneurismal wall and necrotic tissues around the defect of vertebral bodies, the aneurysm was replaced with a prosthetic graft, with reconstruction of the 10th intercostal artery. Cultures of the surgical sample did not grow acid-fast bacilli. Histopathologic examination demonstrated a pseudoaneurysm but could not confirm caseous necrosis.
The postoperative course was uneventful and the patient was discharged after 30 days of antituberculous chemotherapy. He remained well 24 months after the operation and computed tomography showed that there was no anastomotic aneurysm and no infectious sign.
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3. Discussion
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In 1984, Atlas et al. first reported thoracic aortic aneurysm (TAA) with vertebral erosion [3]. To date, 24 cases of TAA with vertebral lesions have been reported in the English literature and most of them are mycotic in nature. The most common organisms identified in aortic and vertebral lesions are Mycobacterium tuberculosis, Salmonella sp, Gram-positive cocci and Gram-negative bacilli excluding Salmonella
[1]. There are two main mechanisms leading to TAA complicated with vertebral erosion: direct extension of vertebral osteomyelitis to involve the aorta, and continuous pulsation of a TAA causing destruction of vertebral bodies.
Clinical symptoms of TAA with vertebral erosion include fatigue, weight loss, fever, localized chronic back pain and neurological deficits [1]. In contrast with other mycotic TAA, most cases of tuberculous TAA are diagnosed on the basis of histopathology without culture confirmation [1]. Choudhary et al. reported positive culture for Mycobacterium tuberculosis in only two of five cases of tuberculous TAA [4]. Although the surgical sample from our patient did not yield cultures or histopathological findings proving tuberculosis, we treated this as a tuberculous TAA because of his past history of pulmonary tuberculosis and operative findings of pseudoaneurysms complicated with vertebral destruction. In this case, severe destruction of the vertebral bodies was followed by the formation of a pseudoaneurysm within the defect of the vertebral bodies; therefore we suspect the cause of pseudoaneurysm formation to be direct extension of tuberculous vertebral osteomyelitis. One quarter of tuberculous vertebral osteomyelitis is complicated with aortic involvement, such as aortic aneurysm or aortitis, by contiguous extension from the spine [2]. A review by Long in 1999 identified that the majority of reported cases of tuberculous TAA (30 of 40 cases) are caused by direct extension of a contiguous focus such as lymph nodes or vertebral osteomyelitis [5].
Surgical procedures for TAA complicated with vertebral erosion consist of either in situ reconstruction, or resection of the aneurysm and extra-anatomic bypass [1]. If there is active infection, resection of the aorta and extra-anatomic bypass or homograft replacement is the appropriate procedure. Since there was no active infection around the aneurysm and both proximal and distal anastomotic aortic wall appeared to be normal findings in this case, we selected to perform in situ reconstruction with a prosthetic graft. Recently endovascular stent grafting has provided an alternative treatment for aortic aneurysm complicated with vertebral erosion [6]. In patients with mycotic aneurysms, despite placement of the stent graft at the site of primary infection, complications including bacteremia, reinfection, or delayed rupture have not been reported in mid term result [7]. However, there were no reports about long-term results of mycotic TAA after endovascular stentgraft procedure. Thus, we did favor open surgery, which facilitates complete debridement of the infected tissue. In a high risk patients such as old age or severe cardiac, renal, or pulmonary diseases, endovascualr stent grafting have implications for alternative new method. If there is marked collapse of vertebral bodies or narrowing of the spinal canal resulting in neurological deficit, a surgical procedure such as subtotal corporectomy of the corresponding vertebrae followed by orthopedic stabilization of the spine is recommended [8]. Although severe vertebral destruction was pointed out in this case, we did not perform orthopedic stabilization of the spine since there was no neurological finding and fixed stability of vertebrae was demonstrated preoperatively.
We experienced an exceedingly rare case of TAA with severe vertebral erosion, which may have been caused by direct extension of tuberculous vertebral osteomyelitis. Treatment with combined antituberculous chemotherapy and aortic reconstruction using a prosthetic graft was successful.
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References
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Abstract
1. Introduction
