Infectious Endocarditis Vegetations

The Correct Answer is C

Small thrombi that develop on cardiac valves are termed vegetations. Vegetations may be seen in bacterial infection of the valves (bacterial endocarditis) also seen with IV drug users, systemic lupus erythematosus, and in chronic wasting states.

Please see Figure 1 (Figure 12-22 in Robbins 5^th edition).

This figure diagrammatically compares the lesions of the four major forms of vegetative endocarditis:
RHD (Rheumatic Heart Disease) – Notice what looks like a string of beads which are small verrucae or small vegetations, sterile deposits of fibrin tend toward a predilection for the closing margin of the valve (not the free edge). This is where the trauma is occurring as the valve closes.

IE (Infective Endocarditis) – The damage may start on the closing margin of the valve, particularly if the valve is already damaged. Unlike RHD, they tend to be larger and bulkier. Particularly with fungal infective endocarditis as compared to bacterial, the vegetations become very large. The larger they are, the greater the risk of breaking off and embolizing.

NBTE (non-bacterial thrombotic endocarditis) – tend to be localized and also tend to be at the closing margin. They can grow large enough to break off and embolize depending on the circumstances.

SLE (Libman-Sacks endocarditis) – Lesions also tend to occur at the closing margin. One of the distinctive features here is that the vegetations can be on either or both sides of the valve leaflets (notice how the artist shows the leaflet partially lifted to demonstrate the underside of the leaflet).

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