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Noninfective
endocarditis (nonbacterial thrombotic endocarditis) refers to formation
of sterile platelet and fibrin thrombi on cardiac valves and adjacent
endocardium in response to trauma, circulating immune complexes,
vasculitis, or a hypercoagulable state. Symptoms are those of systemic arterial
embolism. Diagnosis is by echocardiography and negative blood cultures.
Treatment consists of anticoagulants.
Etiology
and Pathophysiology
Vegetations are caused by physical trauma, not infection. They may be clinically undetectable or become a nidus for infection (leading to infective endocarditis), produce emboli, or impair valvular function.
Catheters passed through the right side of the heart may injure the tricuspid and pulmonic valves, resulting in platelet and fibrin attachment at the site of injury. In disorders such as SLE, circulating immune complexes may result in friable platelet and fibrin vegetations along a valve leaflet closure (Libman-Sacks lesions). These lesions do not usually cause significant valvular obstruction or regurgitation. Antiphospholipid syndrome (lupus anticoagulants, recurrent venous thrombosis, stroke, spontaneous abortions, livdo reticularis) also can lead to sterile endocardial vegetations and systemic emboli. Rarely, Wegener's granulomatosis leads to noninfective endocarditis.
Marantic
endocarditis:
In patients with chronic wasting diseases, disseminated intravascular coagulation, mucin-producing metastatic carcinomas (of lung, stomach, or pancreas), or chronic infections (eg, TB, pneumonia, osteomyelitis), large thrombotic vegetations may form on valves and produce significant emboli to the brain, kidneys, spleen, mesentery, extremities, and coronary arteries. These vegetations tend to form on congenitally abnormal cardiac valves or those damaged by rheumatic fever.
Symptoms,
Signs, and Diagnosis
Vegetations themselves do not cause symptoms. Symptoms result from embolization and depend on the organ affected (eg, brain, kidney, spleen). Fever and a heart murmur are sometimes present.
Noninfective endocarditis should be suspected when chronically ill patients develop symptoms suggesting arterial embolism. Serial blood cultures (see Endocarditis: Diagnosis) and echocardiography should be done. Negative blood cultures and valvular vegetations (but not atrial myxoma) suggest the diagnosis. Examination of embolic fragments after embolectomy can help make the diagnosis. Differentiation from culture-negative infective endocarditis may be difficult but is important. An anticoagulant is often needed in noninfective endocarditis but is contraindicated in infective endocarditis.
Prognosis
and Treatment
Prognosis is generally poor, more because of the seriousness of predisposing disorders than the cardiac lesion. Treatment consists of anticoagulation with heparin or warfarin , although results of such treatment have not been evaluated. Predisposing disorders should be treated whenever possible.
Last full review/revision November 2006 by Lawrence L. Pelletier, Jr., MD
Content last modified November 2006
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