Fact-sheet: Infected arterial aneurysm
- Mycotic aneurysm
Updated on 04/18/2018 at 4:05 PM
View all RADEOS cases associated with this fact-sheet
Definition
Definition: aneurysm resulting from infection of the arterial wall, usually bacterial.
The term "mycotic" is historical (W. Osler) and is used to designate infected arterial aneurysms of any type.
Rare: 0.7-2.6% of aortic aneurysms.
Four pathophysiological mechanisms:
.Preexisting aneurysm - infectious vasa vasorum microemboli
.Pathological intimal infection (ulcerated atheroma) by a circulating infectious agent
.Contiguous arterial infectious involvement - infectious focus
.Direct arterial inoculation - traumatic or iatrogenic.
Pseudoaneurysm +++: contained rupture - adventitia
Microbiology:
>40% of the time
.Staphylococcus aureus
.Salmonella (the only organism capable of invading a healthy intima)
Other organisms
.Streptococci
.Gram-negative bacilli - E. coli
.Mycobacterium / fungal agents (Candida, Aspergillus) - very rare
.Syphilis: rare with antibiotics today. 0.5 to 1.3% of cases
Clinical features
Diagnostic delay frequent ++
>Clinical triad: fever, abdominal pain, pulsatile mass (20%)
Prolonged fever
Absence of symptoms in 7% of cases
Complications:
locoregional extension - septic shock
>Rupture: 53-75%
>Mortality rate: 16-40%
Laboratory findings
Biological inflammatory syndrome
Positive blood culture in 75% of cases
CT
Infected arterial aneurysm:
- Focal dilation, generally saccular, sometimes multilobulated, often eccentric
- Inflammatory involvement of the peri-aortic spaces: infiltration of the peri-aortic fat, inflammatory pseudo-tissue mass +/- abscess
- Possible aortic wall or peri-aortic air bubbles
- Lymphadenopathy
- No mural thrombus or calcifications of the aneurysmal walls.
Involves portions of the aorta usually spared by atherosclerotic aneurysms (thoracic and suprarenal aorta).
Rapid growth.
Management
Emergency surgical management due to rapid progression.
Associated antibiotic therapy.
