Where do mycotic (fungal) aneurysms occur in a patient with infective endocarditis?

From the Guidelines

Mycotic aneurysms in patients with infective endocarditis most commonly occur in the intracranial arteries, particularly the branches of the middle cerebral artery, with a reported frequency of 2-4%. These aneurysms can also develop in other locations including the aorta, visceral arteries (such as splenic, superior mesenteric, and renal arteries), and peripheral vessels 1. The formation of mycotic aneurysms results from septic emboli that lodge in the vasa vasorum or lumen of arteries, causing local infection, inflammation, and weakening of the arterial wall. The infectious process damages the vessel wall through direct bacterial invasion and inflammatory mediators, leading to aneurysm formation. Patients with left-sided endocarditis are at higher risk for mycotic aneurysms due to the systemic distribution of emboli.

Some key points to consider in the management of mycotic aneurysms include:

• Early detection and treatment of infectious aneurysms is essential given the high morbidity and mortality rate secondary to rupture 1
• Imaging should be systematically performed to detect intracranial infectious aneurysms in any case of IE with neurological symptoms, using techniques such as cerebral CT scan or MRI 1
• Management typically involves appropriate antimicrobial therapy for the underlying endocarditis, with surgical or endovascular intervention considered for aneurysms at high risk of rupture or those that have already ruptured 1
• The decision to intervene should be made on a case-by-case basis, taking into account the risk of rupture and the patient's overall clinical condition 1

It is also important to note that the true incidence of mycotic aneurysms may be higher than reported, as many cases may be subclinical 1. Therefore, a high index of suspicion and regular imaging may be necessary to detect these aneurysms early and prevent complications. In general, the management of mycotic aneurysms should prioritize the prevention of rupture and the reduction of morbidity and mortality, with a multidisciplinary approach involving cardiology, neurology, and neurosurgery.

From the Research

Locations of Mycotic Aneurysms

Mycotic aneurysms in patients with infective endocarditis can occur in various locations, including:

• Intracranial locations 2, 3, 4, 5
• Extracranial locations, such as limbs, liver, and heart 6, 2, 3

Specific Locations and Frequencies

• Intracranial mycotic aneurysms are more common, accounting for approximately 54.1% of cases 3
• Extracranial mycotic aneurysms account for around 45.9% of cases 3
• In one study, 12 out of 18 symptomatic peripheral mycotic aneurysms were intracranial, while 6 were extracranial 2

Clinical Implications

• The location of mycotic aneurysms is important for determining the best course of treatment and predicting patient outcomes 2, 3, 4
• Rupture of mycotic aneurysms, particularly intracranial ones, is associated with high mortality and poor prognosis 2, 3, 5