Abstract
A patient who underwent multiple aortic operations suffered persistent infection of the ascending aorta and arch prosthesis and was finally treated with lifelong antibiotics. An 8-year follow-up with positron emission computed tomography is reported.
Infection of Dacron prosthesis after replacement of aortic aneurysm of the ascending aorta and aortic arch is a deleterious complication, which is normally treated surgically [1]. However, it has been observed that infection of well-functioning grafts can be controlled if the micro-organisms were sensitive to antibiotics [2]. We report on a patient who underwent multiple cardiosurgical operations and finally ended up with lifelong antibiotics. An 8-year follow-up with positron emission computed tomography (PET-CT) using 18F-fludeoxyglucose (2-deoxy-2-(18F)fluoro-D-glucose) is demonstrated.
CASE REPORT
A 57-year-old man presented with a pulsating mass in the jugulum in 2008. His medical history revealed replacement of the aortic valve with a mechanical prosthesis 3 years ago and replacement of the ascending aorta 2 years ago. The descending aorta had been provided with a stent following type B aortic dissection. CT demonstrated a huge partially thrombosed aneurysm adjacent to the ascending aorta, subcutaneously reaching the jugulum. The patient underwent immediate third-time surgery, where a ruptured distal suture line was found. The prosthesis of the ascending aorta was replaced during deep hypothermic circulatory arrest. The operative course was uneventful.
Two months later, a mediastinocutaneous fistula developed and a thoracic CT scan depicted accumulation of a liquid structure around the aortic prosthesis suspicious of graft infection. PET-CT using 18F-fludeoxyglucose confirmed the finding, but due to the incalculable risk for another operation an antibiotic treatment was initiated. The patient remained stable and the PET/CT findings did not worsen.
Eighteen months after the last operation (2009), the patient was again admitted with suspicion of another aortic rupture. A giant mediastinal haematoma compressed the superior caval vein, the right ventricle and the pulmonary artery. Emergency surgery revealed again rupture of the distal anastomotic site of the ascending aorta prosthesis. Assuming a widespread local infection, a rigorous debridement with a second redo replacement of the ascending aorta and a total arch replacement with elephant trunk were performed as a fourth time operation. The patient survived surgery and could be fully rehabilitated.
Another 6 months later, wound healing problems with abscess formation evolved again in the jugulum. A thoracic CT scan again demonstrated a small liquid around the aorta, but no mediastinal leaking of contrast medium. The wound was only revised.
The patient went on being treated with lifelong oral antibiotics (cefuroxime) and remained asymptomatic with a good quality of life until now.
Positron emission computed tomography using 18F-fludeoxyglucose
After the third operation, imaging demonstrated massive infectious involvement of the aortic arch and descending aorta as well as a mediastinocutaneous fistula. The control follow-up studies 6 and 12 months after the fourth operation showed a dramatic improvement with only mild activity around the ascending aorta.
Yearly PET-CT controls followed and demonstrated a further slow decline of inflammatory activity. Since 2013, only a small spot of the anterior aorta close to the sternum is involved (Fig. 1). The maximal standardized uptake values undulated in the range from 5.7 to 9.7.
Postoperative controls from 2012 to 2016 demonstrating a further decline of inflammatory activity.
DISCUSSION
This patient with his multiple complications demonstrates the complexity of treatment of prosthetic infection in aortic surgery. Following the third operation, the patient developed wound infection which during the later course could not be fully eradicated despite extensive redo surgery with additional aortic arch replacement.
The intriguing observation, however, was the ability to control the prosthetic and mediastinal infection with long-term antibiotic therapy. When a mediastinocutaneous fistula reaching to the aortic prosthesis was proved, PET-CT findings did not worsen and even improved, while the patient remained clinically well.
The yearly imaging controls readily prove that oral antibiotic treatment is successful. The maximal standardized uptake values are of only little help, as many factors influence the standardized uptake value measurements including patient weight, blood glucose level, post-injection uptake time, lesion size, motion artefacts as well as technical factors [3].
Unfortunately, no ready-to-use concept is available for these patients. Since most prosthetic infections are caused by Staphylococcus bacteria antibiotics sensitive to the former are commonly medicated. As cessation of drug therapy may cause reappearance of the disease, patient compliance remains crucial for long-term success [4]. An ongoing intravenous therapy does not seem to be necessary as suggested by others [5].
CONCLUSION
Patients with chronic infection of aortic prosthesis not amenable to curative surgery can be treated well with permanent oral antibiotics. PET-CT using 18F-fludeoxyglucose scans demonstrate inflammatory activity and provide a good surveillance tool during follow-up.
Conflict of interest: none declared.
