Infective Endocarditis Echocardiography

OVERVIEW

• TOE superior to TTE (90% vs 50% sensitive)
• echocardiographic findings are part of the major and minor criteria for diagnosis of infectious endocarditis
• prosthetic valve endocarditis requires ECHO technicians that understand the type of valve (bioprosthestic, homograft, mechanical) and the normal findings

USE

Helpful in:

(1) finding vegetation and determining size
(2) diagnosing complications -> paravalvular abscess and fistula
(3) examining underlying morphology
(4) assess severity of valve function (regurgitation)
(5) cardiac function
(6) imaging of other heart valves

DIAGNOSTIC CRITERIA

Use the Modified Duke Criteria (see Duke Criteria for Infective Endocarditis)

• Two major criteria, or
• One major and three minor criteria, or
• Five minor criteria

Major criteria

• Positive blood culture for Infective Endocarditis 
  Typical microorganism consistent with IE from 2 separate blood cultures, as noted below:
  — viridans streptococci, Streptococcus bovis, or HACEK group, or
  —community-acquired Staphylococcus aureus or enterococci, in the absence of a primary focus
  or Microorganisms consistent with IE from persistently positive blood cultures defined as:
  — 2 positive cultures of blood samples drawn >12 hours apart, or
  — all of 3 or a majority of 4 separate cultures of blood (with first and last sample drawn 1 hour apart)
• Evidence of endocardial involvement
  Positive echocardiogram for IE defined as :
  — oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation, or
  — abscess, or
  —new partial dehiscence of prosthetic valve
• New valvular regurgitation (worsening or changing of preexisting murmur not sufficient)

Minor criteria

• Predisposition: predisposing heart condition or intravenous drug use
• Fever: T> 38.0° C (100.4° F)
• Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions
• Immunologic phenomena: glomerulonephritis, Osler’s nodes, Roth Spots, and rheumatoid factor
• Microbiological evidence: positive blood culture but does not meet a major criterion as noted below¹ or serological evidence of active infection with organism consistent with IE
• Echocardiographic findings: consistent with IE but do not meet a major criterion as noted above

¹ Excludes single positive cultures for coagulase-negative staphylococci, diphtheroids, and organisms that do not commonly cause endocarditis.