A 38-year-old man with a history of rheumatic mitral stenosis presents with fever, new cardiac murmur, and splinter hemorrhages. Blood cultures grow Streptococcus viridans. Regarding the pathophysiology and clinical features of infective endocarditis, all of the following are true EXCEPT:

Explanation

## Distinguishing Peripheral Manifestations of Infective Endocarditis ### Correct Answer Analysis **Option B is FALSE:** Vegetations in left-sided infective endocarditis form on the **ventricular surface** of the mitral valve leaflets — NOT the atrial surface. This is because the regurgitant jet (from the left ventricle back toward the left atrium) creates turbulent flow and endothelial damage on the ventricular (upstream) aspect of the valve. The damaged endothelium becomes a nidus for platelet-fibrin thrombus formation, upon which bacteria adhere and proliferate. This is a well-established principle in IE pathophysiology (Robbins & Cotran Pathologic Basis of Disease, 10th ed.). ### Peripheral Stigmata of IE — Correct Features | Finding | Pathophysiology | Timing | Clinical Appearance | |---------|-----------------|--------|---------------------| | **Osler nodes** | Immune complex deposition in small vessels | Late (weeks) | Tender, painful nodules on fingertip pads | | **Janeway lesions** | Septic microemboli with vasculitis | Early-mid | Painless erythematous macules, palms/soles | | **Splinter hemorrhages** | Linear hemorrhages under nails | Variable | Flame-shaped, linear streaks | | **Roth spots** | Retinal hemorrhage + immune/inflammatory aggregates | Late | White-centered retinal hemorrhage | **Key Point:** Vegetations in left-sided IE form on the **ventricular surface** of the mitral valve (and the atrial surface of the aortic valve), corresponding to the low-pressure side downstream of the regurgitant jet — this is the classic "jet lesion" concept from Harrison's Principles of Internal Medicine. **Clinical Pearl:** The distinction between Osler nodes (immune-mediated, painful, late) and Janeway lesions (embolic, painless, early-acute) is a high-yield exam topic. Option C (Osler nodes) and Option D (Janeway lesions) are both correctly described. **High-Yield:** Option A (Roth spots) — while the pathophysiology is mixed (immune + hemorrhagic, not purely septic emboli), the description of "white-centered retinal hemorrhage" is broadly accepted. Option B contains a clear anatomical error that makes it the best "false" statement in this EXCEPT question. ### Vegetation Characteristics 1. **Location:** Vegetations form on the **ventricular surface** of the AV valves (mitral, tricuspid) and the **atrial surface** of the semilunar valves (aortic, pulmonary). 2. **Streptococcus viridans:** Typically causes subacute endocarditis on previously abnormal valves (rheumatic disease, MVP). 3. **Embolic phenomena:** Result from septic emboli breaking off vegetations and lodging in small vessels (brain, spleen, kidneys, retina).