Case of the Month November 2016

Constant Chest Pain

Submitted by Brian Lee, MD, and Thomas J. Learch, MD.

A 43-year-old male with history of tertiary syphilis with syphilitic aortitis and aortic valve replacement is transferred to your hospital for management of aspergillus fungemia and presumed prosthetic valve fungal endocarditis diagnosed at an outside hospital. At the time of transfer, the patient complains of constant chest pain. Review of systems also reveals fevers and visual changes for the past four to five months. Given the visual symptoms and risk for embolic vegetations, a CT scan of the brain was performed. The following is a noncontrast CT image of the brain:

For a larger image, please click on Lee 1 .

The above image shows an intraparenchymal hematoma in the left parieto-occipital lobe with surrounding cerebral edema. A small amount of subarachnoid hemorrhage is also seen adjacent to the hematoma.

Given the patient’s clinical history of endocarditis and the finding of intra-parenchymal hemorrhage, a CT angiogram of the brain was performed. The following are several images from that study:

For a larger images, please click on Lee 2 . and Lee 3 .

The above images show two small round lesions at the high left parietal and low right frontal convexities with an enhancement pattern similar to that of blood vessels. Notably, the left parietal lesion is seen immediately adjacent to the previously seen hematoma and is most likely the source of the hemorrhage. Given the clinical history and imaging characteristics, these lesions were diagnosed as mycotic aneurysms.

Due to the risk for additional hemorrhages, the interventional neuroradiology service performed a cerebral angiogram and embolization procedure targeting the two mycotic aneurysms. The following images from the cerebral angiogram show the high left parietal aneurysm, appearing as an abnormal blush of contrast:

For larger images, please click on  Lee 4 and  Lee 5 .

And the following image shows the right frontal aneurysm:

For a larger image, please click on Lee 6 .

After the cerebral mycotic aneurysms were embolized, there was concern for additional mycotic aneurysms elsewhere in the body. As a result, an angiogram of the chest, abdomen, and pelvis was performed.

The following abnormalities were discovered in this study:

For larger images, please click on Lee 7 , Lee 8   and Lee 9 .

The above images show several aneurysms in the bilateral renal arteries and in the right gluteal muscles.

While the term mycotic is associated with fungus, most mycotic aneurysms are caused by bacterial infections. While typical aneurysms are most commonly associated with chronic risk factors such as high blood pressure and often occur in classic locations such as the infrarenal aorta or at the anterior communicating artery in the brain, mycotic aneurysms are secondarily caused by degeneration of the arterial wall caused by bacteremia or septic emboli, with infected cardiac valves being a primary etiology. These aneurysms can occur in smaller terminal vessels in locations that are not typical for regular aneurysms, as those seen in this case in the distal cerebral vessels and renal arteries. As a result, in a patient with endocarditis and spontaneous hemorrhage in an atypical location, CT angiography plays a primary role in identifying the source of the hemorrhage and in identifying additional sites of potential hemorrhage. Conversely if an aneurysm in an atypical location is suspected to be mycotic in nature, blood cultures may be high yield, as cultures are positive in 50 to 85 percent of cases of mycotic aneurysms.

Management of such aneurysms can be complex and may involve a combination of surgery and endovascular embolization, particularly for high-risk lesions such as in the brain. Antibiotics are a mainstay of treatment of mycotic aneurysm due to their association with bacteremia, though there is no standardized treatment duration or type. In particular, any infected prostheses (such as an infected bioprosthetic valve as in this case) may need to be surgically removed to avoid continued infectious seeding and creation of additional mycotic aneurysms.

References

https://www.uptodate.com/contents/overview-of-infected-mycotic-arterial-aneurysm

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