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.