DISCUSSION
Infections of the aortic grafts are rare postoperative complications of aortic surgeries. They could happen in the early postoperative course or, as in our case, later years after surgery. Although the incidence varies between 1-5% based on center and surgeon expertise, the condition can be challenging and associated with a high mortality rate[1, 2]. Due to its complexity and rarity, the predisposing factors for aortic graft infection are yet to be extensively identified by studies [3]. Although the source of graft infection following the cardiac surgery procedure remains unknown, skin flora is considered the most common source of infection [3]. Early postoperative infections are considered from direct skin flora contamination, whereas delayed infection might be due to hemostatic agents, nosocomial septicemia, and immunocompromised states [4]. In our case the most likely predisposing factor for the patient was the immunocompromised state secondary to the treatment of prostate cancer.
Symptoms of aortic graft infection are often vague, and this requires a high degree of suspicion from the clinician when treating patients with pre-existing aortic grafts. It could present as a myriad of vague symptoms, including: fever, malaise, weight loss, back pain, leukocytosis, or abdominal pain. Computerized tomography (CT) with contrast enhancement is the diagnostic modality of choice in aortic graft infections [5].
The EuroScore is a simple and quick way to assess patients’ risk of mortality. Our patient had a score of 15%, which directly correlates to a 15% chance of postoperative death. Our patient also had multiple risk factors such as advanced age, urgent nature of procedure and history of previous cardiac surgery and anemia. Although anemia is not part of the EuroScore, studies have noted an increased mortality associated with pre-operative anemia especially in the setting of open heart surgery[6]. Our patient was managed in a hybrid operating room setting, where the patient first underwent drainage of their peri-aortic abscesses in a surgery that carries a mortality risk ranging between 19 to 25%. Subsequently, they underwent a TAVR. Post-operatively, the patient was transferred to Cardiovascular ICU and managed in the standard fashion.
The surgical management of acute graft infection depends on the degree and extent of infection. The general belief is that if the graft and autologous tissue were still surrounded by healthy tissue, the survival rate was higher if the vascular prosthesis was not removed[3, 7]. In our case, the graft was not infected, there were no signs of endocarditis and existing prosthetic grafts could be salvaged, so only local debridement was performed followed by placement of antibiotic beads around the graft site.
As previously mentioned, TAVR has become a game changer in the field of aortic valve surgery and thanks to this approach we were able to successfully treat a critically ill patient in a multi-disciplinary setting.