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).