Infective Endocarditis

Introduction

Infective endocarditis is a form of endocarditis, or inflammation, of the inner tissue of the heart (such as its valves) caused by infectious pathogens. The agents are usually bacterial, but other organisms can also be responsible.

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http://diseasespictures.com/endocarditis/

Epidemiology:

  • Incidence of endocarditis estimated as 2-6 cases/100,000 person years
  • 90% of endocarditis occurs in patients with pre-existing heart disease
  • Worldwide, condition that most predisposes individuals to endocarditis is rheumatic heart disease; nationwide, it is mitral valve prolapse
  • Endocarditis continues to have a high mortality, estimated at 10-20% among hospitalized patients
  • Greatest morbidity occurs among those with recent cardiac prostheses, status-post heart transplant, or prior endocarditis

 

Pathogenesis

  • Step 1: Formation of non-bacterial thrombotic embolus (vegetation)
    • Turbulent flow from acquired or congenital heart disease traumatizes endothelium
    • Traumitized endothelium serves as a nidus for fibrin and platelet deposition
  • Step 2: Pathogen seeds blood
    • Gernerally occurs via trauma to a mucosal surface from such daily activities as teeth brushing or chewing, or invasive activities like dental, GI, or GU procedures
  • Step 3: Pathogen adheres to fibrin-laden endothelium or device
    • Gram-positive cocci (Staph, Strep) most common pathogens
    • Gram-negative bacteria (HACEK organisms) and fungi (Candida, Aspergillus) can also adhere
  • Step 4: Pathogen promotes fibrin deposition
    • Micro-organism stimulates more fibrin deposition on pre-exisiting aseptic vegetation
    • Creates secluded area within which pathogen can proliferate

 

Sequelae

  • Valvular damage: Pathogen destroys valves - cause regurgitation and possibly even heart failure
  • Emboli: Septic emboli travel to lung, brain, kidney, or extremities and cause local infection and ischemia/infarction
  • Immune-mediated: Circulating immune complexes can possibly mediate glomerulonephritis or vasculitis

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mitral valve vegetation caused by bacterial endocarditis. - http://en.wikipedia.org/wiki/Infective_endocarditis

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Small, linear splinter hemorrhages under the nails that are usually asymptomatic - http://simple-cardio.blogspot.com/2012/06/peripheral-signs-of-infective....

 

Clinical Presentation:

  • Non-specific signs – fever, myalgia, arthralgia, headache, malaise, anorexia, weight loss – are common
  • Classic signs – Roth spots (retinal hemorrhages with a pale center), Janeway lesions (nontender macules on fingers and soles), Osler nodes (painful lesions on hands and feet), and splinter hemorrhage – are rare in children

 

Diagnosis

  • Pathologic evidence of intracardiac or embolized vegetation or intracardiac abscess OR
  • 2 major, 1 major and 3 minor, or 5 minor of the Duke Criteria:

Duke Criteria - Major Criteria

● Positive blood culture*

Positive echocardiogram (vegetation, paravalvular abscess, or valve dehiscence after surgery). While transesophageal echo recommended in adults, transthoracic echo is fine in children. 

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Vegetation on the tricuspid valve byechocardiography. Arrow denotes the vegetation. - http://en.wikipedia.org/wiki/Infective_endocarditis

New valvular regurgitation (by auscultation, not echocardiogram)


Duke Criteria - Minor Criteria

● Predisposing heart condition (including prior IE)

● Injection drug use

● Fever (temperature >100.4° F [38° C])

● Major arterial emboli

● Septic pulmonary infarcts

● Mycotic aneurysm

● Intracranial hemorrhage

● Conjunctival hemorrhage

● Janeway lesions (painless hemorrhagic lesions on palms and soles)

janeway.png
Nontender, erythematous and nodular Janeway lesions - http://simple-cardio.blogspot.com/2012/06/peripheral-signs-of-infective....

● Glomerulonephritis

● Osler nodes (painful lesions on hand or fingertips)

osler node.jpg
Osler's lesions found on the hand and fingers of a 43 year old male with subacute bacterial endocarditis. - http://en.wikipedia.org/wiki/Osler%27s_node

Roth spots (retinal hemorrhages)

roth spot.png
Oval shaped, Roth spots, white centered hemorrhages present on the retina of a patient with infective endocarditis - http://simple-cardio.blogspot.com/2012/06/peripheral-signs-of-infective....

Positive rheumatoid factor

● Single positive blood culture

● Serologic evidence of active infection with an organism consistent with IE


Note: Splinter hemorrhagees and erythrocyte sedimention rate are not criteria. Also, there are no minor echo criteria, ie, valvular regurgitation alone is not a criterion.

*A positive blood culture is a major criterion when 1) there is growth on two occasions of a microorganism typical for IE (eg, viridans group Streptococcus, Staphylococcus aureus, or enterococcus), OR 2) there are persistently postiive blood cultures (two positive cultures from samples 12 h apart or three positive cultures drawn 1 h apart) of a microorganism consistent with IE, such as S epidermidis, OR 3) Coxiella burnetii (Q fever) grows from a single blood culture, or there is serologic evidence of C burnetii (IgG titer _1:800).

From Li JS, Sexton DJ, Mick N, et al. Proposed modifications to the Duke Criteria for the diagnosis of infective endocarditis. Clin Infect Dis. 2000;30:633–638. Used with permission from the University of Chicago Press.

 

 Treatment

  • If blood cultures have not come back and need to begin treatment, generally begin empiric coverage against staph and strep with penicillin or ampicillin plus gent for 4-6 weeks; IV treatment most effective
  • Surgery indicated in those with persistent blood cultures after two weeks of appropriate treatment, fungal vegetations, abscess formation, worsening heart failure, or systemic emboli

 

Prophylaxis

In 2007, the American Heart Association (AHA) revised its criteria for bacterial prophylaxis against endocarditis. Current guidelines state that only those individuals with the following conditions require one dose antibiotic prophylaxis prior to undergoing dental procedures:

  1. A prosthetic heart valve or who have had a heart valve repaired with prosthetic material.
  2. A history of endocarditis.
  3. A heart transplant with abnormal heart valve function
  4. Certain congenital heart defects including:
    • Cyanotic congenital heart disease (birth defects with oxygen levels lower than normal), that has not been fully repaired, including children who have had a surgical shunts and conduits.
    • A congenital heart defect that's been completely repaired with prosthetic material or a device for the first six months after the repair procedure.
    • Repaired congenital heart disease with residual defects, such as persisting leaks or abnormal flow at or adjacent to a prosthetic patch or prosthetic device.

Check the American Heart Association (LINK BELOW) for the most up to date recommendations.

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Click on the wallet card below, print it out, and give it to families as a reminder of the need for prophylaxis. The card also contains information on what antibiotics to use, and specific dosing instructions.

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www.heart.org

Click HERE for a SPANISH VERSION

References

  1. Ferrieri, P., et. al. (2002) "Unique features of infective endocarditis in childhood." Pediatrics, 109(5). 
  2. Hoyer. A., and Silberbach, M. (2005). "Infective endocarditis." Pediatrics in Review, 26(11).
  3. Johnson, D. (2007). "New guidelines on preventing infective endocarditis end routine antibiotic prophylaxis before dental treatment for most patients." AAP News, 28(9). 

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