Mediastinitis and pseudoaneurysm of brachiocephalic artery long after the resection of invasive thymoma and postoperative irradiation

Abstract

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, an dlow-densit yarea si nth emediastinu m(Figur e1) .A cultur eof the suppuration grew Pseudomonas aeruginosa. Arteriography showe da sacra laneurys mo fth ebrachiocephali carter y(Figur e2). 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