Fever, subungual splinter hemorrhages (in image A), and history of IV drug abuse raise concern for infective endocarditis. An echocardiogram will likely confirm the diagnosis by demonstrating a valvular vegetation.
Splinter hemorrhages in infective endocarditis are the result of microemboli from valvular vegetations. Splinter hemorrhages appear as red to black small thin longitudinal lines under the nail plate. They represent rupture of the longitudinally oriented nail bed capillaries. The most common causes of splinter hemorrhages are trauma and nail psoriasis. However, splinter hemorrhages may be associated with other chronic dermatoses involving the nail (e.g. lichen plans) and, more rarely, with systemic illness such as infective endocarditis.
Pierce et al. note that risk factors for infective endocarditis. Prominent risk factors include congenital or structural heart disease, prosthetic heart valve IV drug use and recent invasive procedure. Preexisting structural heart abnormalities are present in up to 75% of patients diagnosed with infective endocarditis.
Brusch and Weinstein note that left-sided endocarditis is far more common than right-sided. Most cases of right-sided endocarditis occur on the tricuspid valve in persons who use injection drugs.
Figure A shows subungual splinter hemorrhages.
Illustration A shows Duke classification of infective endocarditis.
Illustration B shows Duke criteria used in classification.
Illustration C shows parasternal long axis view from 2-D echocardiogram with close-up of aortic valve shows large vegetations of both leaflets as a result of bacterial endocarditis.
Illustration D shows petechiae in bacterial endocarditis.
Illustration E shows Osler nodes.
Illustration F shows Janeway lesions.
2. Chest X-Ray can occasionally reveal important diagnostic clues (e.g. septic pulmonary emboli) but would not show a valve vegetation, which indicates active endocarditis.
3. Pulmonary function tests would help diagnose asthma, but not infective endocarditis.
4. EKGs rarely reveal diagnostic findings of infective endocarditis, but may help determine the presence of emboli to the coronary circulation if there are ischemic changes.
5. CT pulmonary angiography would help diagnose pulmonary embolus (PE), but not infective endocarditis. Sometimes PE is a complication of infective endocarditis, but unlikely in the patient in this scenario.
Pierce D, Calkins BC, Thornton K. Infectious endocarditis: diagnosis and treatment. Am Fam Physician. 2012 May 15;85(10):981-6.
PMID:22612050 (Link to Abstract)
Brusch JL, Weinstein WL. Infective Endocarditis. New York, NY: Oxford University Press; 1996.
USMLE World Step 1 QBank Question #228. Copyright © USMLEWorld, LLC 2012