Spotlight – Massive Prosthetic Aortic Abscess

Read this case report from McCann et al bcr-2019-230204.R2 – Massive prosthetic aortic abscess: an overarching plight 7 years post-Bentall’s procedure and test yourself on these two questions below:

Case Questions:

1) What are the clinical and biochemical characteristics of patients presenting with thoracic aortic graft infections?

Fever is present between 80-100% of patients with thoracic aortic graft infections.1, 2 Patients presenting with infections >1 year post-operatively have lower levels of C-reactive protein (169 vs 44 mg/L) and fewer cases of severe sepsis compared to early infections.2 Approximately 30% of patients have an embolic event at presentation.1, 2 Other symptoms include those related to abscess formation in the mediastinum, and fistula formation leading to bleeding.3 The presenting symptoms and clinical presentation of patients with thoracic aortic infections is diverse, especially in those in the late post-operative period. A high index of suspicion must be maintained of graft involvement in those with raised inflammatory markers and fever in the absence of a definitive source.

2) What is the role of 18-fluorodeoxyglucose positron emission tomography (18-FDG PET) in the diagnosis of prosthetic aortic graft infections?

The use of 18-FDG PET in vascular graft infections has been found to have a sensitivity, specificity and positive predictive value of 100%, 86% and 96% respectively in a recent study, which included thoracic aortic grafts.4 The negative predictive value was 100% in the same series of patients. 418-FDG PET has also been shown to be superior to computed tomography (CT) alone in some studies. 5 The use of 18-FDG PET has also been shown to improve the diagnostic performance of the Modified-Duke Criteria for diagnosing prosthetic valve endocarditis, which may be useful in patients with concomitant aortic valve prostheses.6 The diagnosis of thoracic aortic graft infections requires a combination of clinical, biochemical, microbiological and radiographic diagnostic data, including the use of echocardiography, CT and PET/CT.3, 7 18-FDG PET appears to be a highly sensitive and specific test in cases of suspected aortic graft infection where there is diagnostic uncertainty.

References:

  1. Machelart I, Greib C, Wirth G, et al.: Graft infection after a Bentall procedure: A case series and systematic review of the literature. Diagnostic Microbiology and Infectious Disease. 88:158-162, 2017.
  2. Ramos A, García-Montero C, Moreno A, et al.: Endocarditis in patients with ascending aortic prosthetic graft: a case series from a national multicentre registry. European Journal of Cardio-Thoracic Surgery. 50:1149-1157, 2016.
  3. Bianco V, Kilic A, Gleason TG, et al.: Management of thoracic aortic graft infections. Journal of cardiac surgery. 33:658-665, 2018.
  4. Sah BR, Husmann L, Mayer D, et al.: Diagnostic performance of 18F-FDG-PET/CT in vascular graft infections. European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery. 49:455-464, 2015.
  5. Bruggink JLM, Glaudemans AWJM, Saleem BR, et al.: Accuracy of FDG-PET–CT in the Diagnostic Work-up of Vascular Prosthetic Graft Infection. European Journal of Vascular and Endovascular Surgery. 40:348-354, 2010.
  6. Saby L, Laas O, Habib G, et al.: Positron Emission Tomography/Computed Tomography for Diagnosis of Prosthetic Valve Endocarditis: Increased Valvular 18F-Fluorodeoxyglucose Uptake as a Novel Major Criterion. Journal of the American College of Cardiology. 61:2374-2382, 2013.
  7. Wilson WR, Bower TC, Creager MA, et al.: Vascular Graft Infections, Mycotic Aneurysms, and Endovascular Infections: A Scientific Statement From the American Heart Association. Circulation. 134:e412-e460, 2016.