Intraoperative management and postoperative course
Surgical inspection revealed thick and pervasive, green-yellow membranes covering the entire heart, great vessels, diaphragm, both lungs as well as the entire chest wall (Fig. 1). The turf also covered contained ruptures of aorto-aortic anastomosis and the previously constructed end-to-side anastomosis of the LVAD arterial return to the native ascending aorta.
Remains of the vascular prosthesis were removed and the aorto-aortic anastomosis could be re-sutured due to sufficient length of the ascending aorta. Extensive debridement of all anatomical structures of the thoracic cavity was performed and \souta Negative Pressure Wound Therapy (NPWT) was applied.
Histopathological examination (Fig. 2), cultures as well as genomic sequencing of all specimens including pleural fluid uniformly revealedA. fumigatus . Galactomannan test was positive (EIA index 0.1), but bacterial fungal as well as blood cultures revealed no other microorganisms. CT-scan revealed no other organ involvement by invasive aspergillosis.
In lack of a literature report on any similar case with such extensiveAspergillus mediastinitis we empirically decided to pursue the following treatment. Surgical wound re-opening every third day, sharp and blunt mechanical scrubbing and cleaning of the fungal turf, topical application of voriconazole and chlorhexidine 2%, 20-fold diluted (resulting in chlorhexidine 0.01%), dunking the entire thoracic cavity for 40 minutes with each drug (Fig. 3) and an open chest treatment with NPWT between the re-explorations. Pre-emptive systemic antifungal therapy with a combination of caspofungin and voriconazole was started. Following susceptibility testing and determination of minimal inhibitory concentration (MIC 0.125mg/l), voriconazole was continued at a serum concentration of 4-6mg/l. The immunosuppressive regimen was tailored and potential organ rejection surveyed by echocardiography. Debridement and topical therapy was performed eight times. As by visible involvement of the sternal bone tissue, 5mm of each sternal side was removed, histopathology confirming A. fumigatus .
After the fourth surgical session, consistent with marked visible decrease of the fungal turf overspreading the mediastinal organs, repeated microscopic and microbiological examinations were found to be sterile with regard A.fumigatus. However, colonization with multi-drug resistant Acinetobacter baumannii susceptible only to polymyxin B (MIC 0.5mg/l) was detected in the sixth session. Hence, a diluted colistin-solution was applied topically to the thoracic cavity and infected structures and colistin was administered intravenously for one week. The postoperative course between each surgical session was uneventful, the patient remaining isolated but fully mobilized on the regular ward.
After eight surgical revisions revealing clean intrathoracic tissues on gross examination and negative microbiological findings with respect toA. fumigatus , definite wound closure was achieved 26 days after the first revision with a latissimus dorsi muscle flap plasty to fill the persistent left-sided thoracic cavity. Sternal refixation and wound closure were performed according to our infection-prevention protocol (sternal wound irrigation with vancomycin wax and gentamycin solution). Careful reversal of immunosuppression allowed a stable cardiovascular course without any signs of rejection checked by repeated endomyocardial biopsy and echocardiography. The patient was discharged 47 days after our first surgical intervention with uneventful postoperative recovery and wound healing. Oral voriconazole with regular monitoring of liver function was continued for 12 months, cardiac medication and immunosuppression are continued corresponding to state-of-the-art. One year after wound closure, no findings suspicious for persistent or recurrent fungal infection on chest X-ray and CT-scan and negative serum galactomannan were reported. The patient is in excellent condition with good functional capacity, normal biventricular function, normal coronary angiography and no signs of cardiac rejection, seven years after this episode of mediastinitis.