J Thorac Cardiovasc Surg 2005;130:918-919
© 2005 The American Association for Thoracic Surgery
Mediastinitis and pseudoaneurysm of brachiocephalic artery long after the resection of invasive thymoma and postoperative irradiation
Kenichi Okubo, MD
*
,
Jun Isobe, MD,
Jiro Kitamura, MD,
Yoichiro Ueno, MD
General Thoracic Surgery and Cardiac Surgery, National Hospital Organization, Nagara Medical Center, Gifu, Japan.
Received for publication March 14, 2005; accepted for publication May 3, 2005.
* Address for reprints: Kenichi Okubo, MD, General Thoracic Surgery, National Hospital Organization, Nagara Medical Center, 1300-7 Nagara, Gifu 502-0071, Japan (Email: okubo{at}nagara-lan.hosp.go.jp).
Mediastinitis is a complication after median sternotomy. We report a rare case of mediastinitis and mycotic pseudoaneurysm of the brachiocephalic artery that occurred long after the resection of invasive thymoma and postoperative irradiation and was treated with extensive procedures.
Clinical Summary
A 68-year-old woman was seen with skin ulceration and suppuration from the wound in the anterior chest wall. She had undergone resection of invasive thymoma through median sternotomy 65 months previously. This operative treatment included combined resection of pericardium, right lung, and superior vena cava, along with interposition of an artificial polytetrafluoroethylene graft between the brachiocephalic vein and the right atrium. The patient received adjuvant radiation therapy of 50 Gy to the mediastinum for pathologically diagnosed Masaoka stage III thymoma. Computed tomography of the chest showed a dilated branch of the aortic arch compressing the sternum posteriorly, an occluded artificial graft between the brachiocephalic vein and the right atrium, and low-density areas in the mediastinum (Figure 1). A culture of the suppuration grew Pseudomonas aeruginosa. Arteriography showed a sacral aneurysm of the brachiocephalic artery (Figure 2). The patient underwent excision of the aneurysm through median resternotomy and extended right collar incision for the diagnosis of mediastinitis and mycotic aneurysm of brachiocephalic artery. The implanted polytetrafluoroethylene graft was found to be filled with pus and was removed. After the sternum had been released from the aneurysm, the wall of which was found to be extremely thin, the aneurysm ruptured suddenly. Cardiopulmonary bypass was quickly instituted through the previously exposed cannulations of the femoral artery and vein, with the ruptured aneurysm compressed by the surgeon's finger. Selective cerebral perfusion was established with additional cannulations of the right axillary artery and the right atrium. The aneurysm of the brachiocephalic artery was excised under conditions of circulatory arrest with profound hypothermia. A Dacron polyester fabric graft was anastomosed with the tailored aortic arch at the origin of the brachiocephalic artery proximally. The distal anastomosis was at the bifurcation of common carotid artery and subclavian artery, with cardiopulmonary bypass restarted without axillary artery perfusion. Circulatory arrest time was 22 minutes, and the duration of cardiopulmonary bypass was 224 minutes. After the patient was weaned from cardiopulmonary bypass, necrotic sternum was resected and the infected mediastinum was irrigated with povidone iodine. Pedicled omentum was then transposed to cover the mediastinum and the Dacron graft through the extended upper abdominal approach. The skin and subcutaneous tissues were resutured, with the defect in the sternum left. After the operation, the patient required mechanical ventilation for respiratory failure for 8 days. After endotracheal extubation, she recovered well. She has been doing well for 28 months after the operation.
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Figure 1. Chest computed tomography showing a dilated aortic branch compressing the sternum and an occluded artificial graft.
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Comment
Pseudoaneurysm of the brachiocephalic artery has been reported from a variety of etiologies.
1
Traumatic injuries are the most frequently reported cause of this pseudoaneurysm. Blunt or stabbing injury
2,3
and medically introduced trauma,
4
such as catheterization, intravenous cannulation, and stenting, have occasionally been reported as causes. Infectious cause has infrequently been seen after cardiac surgery.
5
Cannulation sutures or artificial grafts have become the foci of mediastinitis and have caused mycotic pseudoaneurysm of adjacent arteries.
Our patient showed mediastinitis and pseudoaneurysm of the brachiocephalic artery long after the surgical treatment for invasive thymoma. Because of the extent of the mediastinitis and the pus formation in the implanted graft, the pseudoaneurysm of the brachiocephalic artery appeared to be of infectious origin. The chronic mediastinitis was associated with previous median sternotomy and postoperative irradiation, although more than 5 years had passed since the resection of invasive thymoma. Adjuvant irradiation would have caused poor vascularization in the postoperative mediastinum, with consequent failure of protection against transsternal infection. Such a mycotic pseudoaneurysm of brachiocephalic artery after combined surgery and irradiation has seldom been reported in the literature. Extensive procedures—including removal of infective foci, necrotic sternum, and artificial graft; excision of the pseudoaneurysm; surgical irrigation; and omentum transposition—appear to have been successful in treating this extended mediastinal infection.
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