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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Clinical features: fever, new valvular regurgitation, embolization, immune complexes, predisposing condition.

  • ≥ Two positive blood cultures with a typical microbe

  • Characteristic cardiac lesions on echocardiography or histology

GENERAL CONSIDERATIONS

  • Infective endocarditis represents an endothelial infection that usually occurs at sites of endothelial damage in blood vessels and is rare

  • Infection of cardiac valve endocardium is not rare and can afflict normal valves, but preexisting valve disease as a substrate is more common.

  • Valve infection probably begins with minor trauma, which would explain the observation that the valves with the highest force necessary to close the valve are the most commonly affected; in rank order: mitral, aortic, tricuspid, pulmonic. Also, infection usually starts at the closure line of the valves

  • Minor trauma may form a microscopic thrombus on the leaflet surface, which forms the nidus for infection

  • For the nidus to become infected, bacteria must enter the bloodstream in sufficient numbers from a break in the epidermal or mucosal surfaces of the body

  • As the vegetation grows, regurgitation of the affected valve almost always occurs due to destruction, scarring, or retraction of the leaflet

  • Occasionally, chordal involvement results in rupture or erosion of the leaflet to perforation, both of which can cause sudden severe atrioventricular valve regurgitation

  • Very large vegetations rarely can obstruct the valve orifice

  • Embolization of vegetations can result in damage to other organs from ischemia or remote infection

  • Invasion of the valve annulus by the organisms can lead to abscesses and fistulas

  • Infection of arterial walls due to vegetation embolization can lead to aneurysm formation and rupture, which can be devastating in the central nervous system

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Common symptoms: fever, chills, weakness, dyspnea

  • Less common symptoms: diaphoresis, weight loss, cough, stroke, rash, nausea/vomiting, headache, chest pain, myalgias/arthralgias

  • Unusual symptoms: abdominal pain, delirium/coma, hemoptysis, back pain

PHYSICAL EXAM FINDINGS

  • Common findings: fever, heart murmur, skin lesions or emboli, petechiae

  • Less common findings: Osler’s node, Janeway lesion, splinter hemorrhages, splenomegaly, stroke, heart failure, pneumonia, meningitis

  • Unusual findings: new or changing murmur, retinal lesions (Roth spots), renal failure, blue toe syndrome

  • Splenomegaly

DIFFERENTIAL DIAGNOSIS

  • Fever due to other causes

  • Sepsis not due to infective endocarditis

  • Valvular lesions on echocardiography that resemble infective vegetations: myxomatous valves, Libman-Sacks vegetations, marantic vegetations, papillary fibroelastomas, Lambl excrescences, nodules of Arantius (aortic valve)

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • Blood cultures: 3 from separate venipunctures over 24 hours

  • Serologic testing for organisms such as Histoplasma, Q fever, Brucella, Bartonella

  • Rheumatoid factor may be falsely positive

  • Leukocytosis, elevated gamma globulins, elevated erythrocyte sedimentation rate, anemia

ELECTROCARDIOGRAPHY

  • Sinus tachycardia

  • Aortic valve abscess formation can lead to first-, second-, ...

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