• Is a microbial infection of the endocardial
(endothelial) surface of the heart.
• Native or prosthetic heart valves are the most
commonly involved sites.
• Septal defects, the mural endocardium, or
intravascular devices such as intracardiac
patches, surgically constructed shunts,
intravenous catheters can be involved.
• Infective endarteritis – involving arteries,
including PDA, the great vessels, aneurysms,
or arteriovenous shunts.
• Classification as acute or subacute not advised
• Better classification based on etiologic agent.
• Most cases are caused by relatively small
number of micro-organisms.
• Gram positive cocci account for 90% of cases
• Streptococcus viridans – are the most
common causes at all ages.
• Staphylococcus aureus & CONS – 2nd most
common culprit organisms.
• Gram negative organisms – account for less
than10% of cases.
• Anaerobic organisms rarely cause endocarditis
• Fungal endocarditis – one of the most feared
forms (complications, like embolization are
• Blood culture negative endocarditis – about 5
– 10% of cases.
N.B. A diagnosis of culture – negative
endocarditis is made when a patient has
clinical and/or echocardiographic evidence of
IE but blood culture is persistently negative.
Pre-existing congenital or acquired lesion of the
heart or great vessels (usual)
Damage to the endothelium & formation of
non-bacterial thrombotic endocarditis (NBTE)
on the surface of the damaged endothelium
8. Relative risk of IE for underlying
cardiac lesions & conditions
Previous episode of endocarditis
Complex cyanotic congenital heart diseases
(e.g. single ventricle states, TGA, TOF)
Surgically corrected systemic artery to
pulmonary artery shunts
Injection drug use
Indwelling central venous catheters
• Virtually all vegetations occur in areas where
there is a pressure gradient with resulting
turbulence of blood flow.
• Sites of high velocity jets where most
vegetations occur are on the atrial side of the
atrioventricular valves and ventricular side of
the semilunar valves.
• Bacteremia can cause fever and systemic
• Endocarditis involving the left side of the
heart frequently results in peripheral
embolization, leading to ischemia, infarction
or mycotic aneurysms.
• Positive blood culture (off antibiotics) – very
• Elevated acute phase reactants – very
• Anemia – in most cases
• Hematuria – in most cases
• Presence of rheumatoid factor – infrequent
• Leukocytosis - infrequent
15. Blood culture
• Three separate sets of blood cultures, each
from a separate venipuncture over a 24hr
• 1 to 3mL in infants and young children, 5 to
7mL in older children and 20 to 30mL in adults
• Two – dimensional echocardiography – principal
• Sensitivity of more than 80%.
• Neither sensitivity nor specificity is 100%.
• Transthoracic echo – more helpful in children with
normal cardiac anatomy or with isolated valvular
abnormalities and septal defects.
• Transesophageal echo – more sensitive in picking
smaller vegetations, paravalvular leaks and
complications such as dehiscence of prosthetic
22. Definition of terms used in the Modified Duke criteria for the
diagnosis of IE
1. Blood culture positive for infective endocarditis (IE)
A. Typical micro – organisms consistent with IE from 2 separate blood
i. Viridans streptococci, streptococcus bovis, HACEK group,
staphylococcus aureus; or
ii. Community acquired enterococci in the absence of a primary focus; or
B. Micro – organisms consistent with IE from persistently positive blood
cultures defined as follows:
i. At least 2 positive cultures of blood samples drawn ≥ 12hrs apart; or
ii. All of 3 or a majority of ≥ 4 separate cultures of blood (with 1st and last
sample drawn ≥ 1 hour apart)
C. Single positive blood culture for Coxiella burnetii or anti – phase 1 IgG
antibody titer > 1: 800.
23. Definition of terms …
2. Evidence of endocardial involvement
A. Echocardiogram positive for IE (TEE recommended for
patients with prosthetic valves, rated at least “possible IE”
by clinical criteria, or complicated IE [paravalvular abscess];
TTE as first test in other patients) defined as follows:
i. Oscillating intracardiac mass on valve or supporting
structures, in the path of regurgitant jets, on implanted
material in the absence of alternative anatomic
ii. Abscess; or
iii. New valvular regurgitation (worsening or changing or pre-
existing murmur not sufficient)
24. Definition of terms …
1. Predisposition, predisposing heart condition, or injection
2. Fever > 38°C
3. Vascular phenomena, major arterial emboli, septic
pulmonary infarcts, mycotic aneurysm, intracranial
hemorrhages, and Janeway lesions
4. Immunologic phenomena: glomerulonephritis, Osler nodes,
Roth spots, and rheumatoid factor
5. Microbiologic evidence: positive blood culture, but does not
meet a major criterion, or serologic evidence of active
infection with organism consistent with IE
25. Definition of IE according to the
modified Duke criteria
Definite infective endocarditis (IE):
1. Pathologic criteria:
A. micro – organisms demonstrated by culture
or histologic examination of a vegetation, a
vegetation that has embolized, or an
intracardiac abscess specimen; or
26. Definition of IE …
B. Pathologic lesions; vegetation or intracardiac
abscess confirmed by histologic examination
showing active endocarditis
2. Clinical criteria
A. 2 major criteria
B. 1 major and 3 minor criteria
C. 5 minor criteria
27. Definition of IE …
1. 1 major and 1 minor criteria
2. 3 minor criteria
1. Firm alternative diagnosis explaining evidence of
2. Resolution of IE syndrome with antibiotic
treatment for ≤ 4 days; or
3. No pathologic evidence of IE at surgery or autopsy,
with antibiotic treatment for ≤ 4 days; or
4. Does not meet the criteria for possible IE as above
28. Antimicrobial therapy
With in vegetations, organisms are embedded in very
Relatively low rates of bacterial metabolism and cell
division decreased susceptibility to beta – lactam
and other cell wall active antibiotics.
Bactericidal rather than bacteriostatic antibiotics
29. Antimicrobial …
Complete eradication of the organisms requires 4 to
6 weeks of antibiotic treatment.
Parenteral administration recommended.
Combination of antibiotics against the commonest
Indications for surgery include:
Significant embolic events,
Persistent infection, and
Progressive cardiac failure
Prophylactic regimens for dental, oral, or
respiratory tract procedures:
Amoxicillin 50mg/kg p.o. 30 to 60 min before
Ampicillin or cefazoline or ceftriaxone, IM or
IV, if unable to take oral medications.
Clindamycin or cephalexin or azithromycin or
clarithromycin for penicillin allergic patients.