Discussion
The majority of the mycotic aortic aneurysms (MAA) develop as result of
a bacteraemia in a patient with a pre-existing atherosclerotic aortic
aneurysm1. This may be due to seeding of disrupted
aortic intima or mural thrombus, infection in related organs,
penetrating trauma or bacterial endocarditis, causing an aggressive
local infection with rapid expansion of the arterial wall and a high
risk of rupture1.
Mycotic thoracic aortic aneurysms (MTAA) account for less than 1% of
all aneurysm repairs in the USA compared to up to 3% of all aneurysm
repairs in Asia1,2,8. Symptoms are often nonspecific
such as fever, sepsis and less frequently chest- or shoulder
pain3. Tracheal compression due to a TAA is very
rare9. Rupture or impending rupture occurs in
50-85%2,9. Diagnosis remains difficult with
nonspecific laboratory findings such as leucocytosis in 65-85% or
elevated C-reactive protein in 75-80%9. Blood
cultures are positive in 50-90% but become negative in up to 25-50%
after starting antibiotic treatment9. In the Western
world the most common pathogens are streptococcal and staphylococcal
species, gram negative bacteria such as Salmonella or tuberculosis have
a high prevalence in Asia2,8. On CTA scan a saccular
aneurysm with an irregular contour in absence of extensive
atherosclerosis is suggestive of a mycotic aneurysm9.
Periaortic findings such as soft tissue inflammation may also be
present9.
Historically, surgical debridement, intravenous antibiotic treatment and
open aorta repair is considered the treatment of choice. However, recent
studies, i.e. an European multicentre study on mycotic aortic aneurysms
showed durable outcome of endovascular treatment with 91% survival at
30 days, 19% fatal infection-related complications and 55% 5-year
survival rate5. Nevertheless, in patients with a
ruptured aneurysm, fever, tracheal- or oesophageal fistula with or
without uncontrolled bleeding at time of surgery, endovascular repair
should be considered a bridge to definite surgical
repair10.
In this case report, emergency TEVAR was regarded as designated
treatment over open repair given the expertise in thoracic stent
grafting at our institute and patient characteristics, in line with
recent literature5,10. The clinical deterioration
after primary intervention was considered the result of ongoing
infection and progressive dilatation of the aneurysm, resulting in a new
or, at completion angiography undiagnosed, type Ib endoleak. After
primary airway management a second vascular intervention was considered.
While, open aneurysm repair lacked patient compliance, endovascular
extension of the stent was performed. Even though, the patient initially
recovered after the endovascular stent extension and tracheal stent
placement a new episode of respiratory insufficiency developed. Removing
the tracheal stents to restore the trachea and thereby restoring the
cough reflex and cilia function was considered. However, because of the
prolonged and long anticipated hospitalization the patient wished no
further invasive treatment. This severe course following unsuccessful
endovascular treatment of a MTAA has not been described before and was
lethal in the presented case.