CASE
A 72 year-old-female was admitted to the emergency department with severe chest pain. Computed tomography angiography (CTA) showed Stanford type A acute aortic dissection. She had history of hypertension, morbid obesity and current smoking. The patient underwent emergent surgery. Ascending aorta and hemiarch replacement was performed using a 28 mm Dacron tube graft (Hemashield, Medox Medical INC., Oakland, NJ, USA) under selective cerebral perfusion. The patient was easily weaned from the cardiopulmonary bypass. The sternum was closed with steel wires in standard fashion.
The patient was extubated on the first postoperative day. Persistent serous drainage between 300 to 400 ml per day from the mediastinal chest tube had continued until the 10th postoperative day. However, the serous drainage changed into purulent character on the 11th postoperative day. Therefore, the patient underwent urgent surgery due to suspicion of mediastinitis. Meropenem and vancomycin was empirically initiated after cultures were taken. Following re-sternotomy the aortic graft was exposed. Dacron graft had been covered by purulent discharge. All the infected tissue including soft tissue and sternal edges were debrided (Figure 1a).
After meticulous debridement and irrigation with diluted povidone iodine. The silver impregnated foam (KCI-Acelity, San Antonio, TX, USA) was cut to fill the mediastinal cavity and placed over the infected graft, sternum and the subcutaneous tissues and VAC therapy was initiated. Irrigation and foam replacement were performed per three days and swab cultures from mediastinum were taken at each dressing change. Streptococcus viridans and methicillin resistant Staphylococcus epidermidis was isolated from the mediastinal culture. The cultures became negative after 26th day of VAC initiation.
As the cultures turned negative and the necrotic tissues were replaced with healthy granulation tissues, the patient underwent omental transposition for aortic graft, mediastinal and sternal coverage. Omental flap was harvested through an upper midline laparotomy incision. A 2 cm part of skin and subcutaneous tissue was left intact between median sternotomy and laparotomy incision. Omental flap was passed through a small diaphragmatic incision anterior to the pericardium into the mediastinum and the Dacron graft was covered (Figure 1b). Re-wiring of the sternum was not possible because of insufficient sternal bone tissue, therefore bilateral pedicled pectoralis muscle flaps were used to close the median sternotomy. The patient was extubated on the second postoperative day. The patient was discharged home on the 15th postoperative day in good condition. Antibiotic treatment with oral linezolid was continued for 3 months. Until now the patient has been followed up for 36 months with annual CTA imaging and she has been symptom and infection free (Figure 1c).