Snapshot A 58-year-old man develops fever, tachycardia, and worsening chest pain 2 days after undergoing a coronary artery bypass surgery for coronary artery disease. On examination, his sternotomy wound is draining purulent fluid. A chest radiograph demonstrates mediastinal widening and a CT scan demonstrates mediastinal gas. Introduction Clinical definition inflammation of the mediastinum types of mediastinitis acute acute infection often due to complications following a sternotomy chronic fibrosis from chronic inflammatory conditions (e.g., granulomatous disease) Epidemiology Incidence 3% incidence of acute mediastinitis following sternotomy very low incidence of chronic mediastinitis Risk factors recent sternotomy Etiology Pathophysiology mechanism of injury acute contamination from esophageal or retropharyngeal regions post-surgical esophageal perforation chronic fibrosing inflammation of the mediastinal space in the setting of chronic infection granulomatous diseases tuberculosis sarcoidosis histoplasmosis other infectious causes dental infections - progress to involve the submandibular space then the mediastinum acute necrotizing ulcerative gingivitis (trench mouth) treatment antibiotics chlorhexidine mouthwash regular dental care pathoanatomy normal anatomy superior mediastinum vessels aortic arch superior vena cava nerves vagus nerves phrenic nerves sympathetic trunk other structures thymus trachea esophagus thoracic duct middle mediastinum vessels ascending aorta pulmonary trunk nerves cardiac plexus phrenic nerves other structures heart anterior mediastinum contains no major structures posterior mediastinum vessels descending aorta azygous venous system other structures esophagus thoracic duct Presentation Symptoms chest pain fever tachycardia Physical exam purulent discharge from the wound wound erythema sternal tenderness Imaging Radiographs indication should be obtained if mediastinitis is suspected findings mediastinal widening Computerized tomography (CT) indication should be obtained if mediastinitis is suspected findings mediastinal gas and fluid Differential Acute pericarditis distinguishing factor may present with pleuritic chest pain and a friction rub Cardiac tamponade distinguishing factor may present with Beck triad (hypotension, muffled heart sounds, and jugular venous distension) Treatment Operative surgical emergency debridement and broad-spectrum antibiotics Complications Death Prognosis Survival with treatment 40% acute mortality rate with treatment 10-year survival rate is 40%