Teaching Case

Chest pain and dyspnea in patient with a history of recent valvular replacement with aortic root Bentall-type rebuilding.

The patient was admitted for the recent onset of oppressive thoracic pain and increasing dyspnea. He had a history of recent (two months earlier) valvular replacement with aortic root Bentall-type rebuilding. Chest-X ray examination showed enlarged heart and mediastinum (Fig. 1). Emergency chest CT showed the presence in the ascending periaortic space of an heterogenous mass extending from the root up to the aortic arch with small air bubbles and peripheral enhancement at post-contrast scanning (Fig. 2). In addition, the mass appeared in continuity with the sternal suture, partially dehiscent, and was associated to partial displacement of the pulmonary trunk (Fig. 3). Submitted to surgical revision with mediastinal drainage and
washing, the material, mainly hemorrhagic, was sent to laboratory for bacteriologic culture. About 20 days after the surgical revision, the patient was readmitted for the newer occurrence of chest pain associated with mediastinal widening at chest-X ray. A new chest CT showed the recurrence of the above mentioned mediastinal mass with the same features and the presence of an ascending aorta leakage of contrast medium immediately above the left sinus of Valsalva (Fig. 4-5). The bacteriologic culture turned positive for Staphylococcus epidermidis.

Postoperative mediastinitis is a severe complication which occurs in approximately 2% of the patients who undergo surgical procedures requiring sternotomy or thoracotomy, and it is associated with approximately 12% operative mortality. Between the various risk factors associate with this complication, one of the most important is the presence of sternal instability with dehiscence of the surgical wound. The diagnosis of mediastinitis is based on clinical data and some associated variable CT signs, such as increase in the attenuation of the mediastinal fat, fluid collections especially if heterogenous and associated with mass-effect, air bubbles, pleural effusion, pericardic effusion, mediastinal lymphadenopathies, etc. The CT sensitivity and specificity for mediastinitis are very high (100% and 90%, respectively) if these signs are evident after 17° postoperative day, i.e. after the time necessary for recovery of surgical-related mediastinal anomalies. This severe postoperative complication requires an early diagnosis for a prompt treatment. CT is today not only the diagnostic method of choice, but also it allows to define the extension of the disease and its relationship with mediastinal structures.