1. Definition
• 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.

2. Definition
• Infective endarteritis – involving arteries,
including PDA, the great vessels, aneurysms,
or arteriovenous shunts.
• Classification as acute or subacute not advised
(obsolete).
• Better classification based on etiologic agent.

3. Etiologies
• Most cases are caused by relatively small
number of micro-organisms.
• Gram positive cocci account for 90% of cases
(adult studies).
• Streptococcus viridans – are the most
common causes at all ages.
• Staphylococcus aureus & CONS – 2nd most
common culprit organisms.

4. Etiologies…
• Gram negative organisms – account for less
than10% of cases.
• Anaerobic organisms rarely cause endocarditis
in children.
• Fungal endocarditis – one of the most feared
forms (complications, like embolization are
common).

5. Etiologies…
• 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.

6. pathogenesis
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

7. Pathogenesis…
Occurrence of transient bacteremia
Adherence of bacteria to the NBTE
Proliferation of bacteria with in the vegetation

8. Relative risk of IE for underlying
cardiac lesions & conditions
High risk:
prosthetic valves
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

9. Relative risk…
Moderate risk
uncorrected PDA
Uncorrected VSD
Bicuspid Aortic valve
Mitral valve prolapse with regurgitation
Rheumatic mitral or aortic valve diseases
Other acquired valvular diseases
Hypertrophic cardiomyopathy

10. Pathogenesis…
• 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.

11. Clinical features
Result from:
Hemodynamic and structural changes caused
by the local infection
Embolization from vegetations, or
Immunologic reactions by the host

12. Clinical…
• Bacteremia can cause fever and systemic
toxicity.
• Endocarditis involving the left side of the
heart frequently results in peripheral
embolization, leading to ischemia, infarction
or mycotic aneurysms.

13. Clinical…
• Fever (most common)
• Nonspecific symptoms (myalgia, arthralgia, headache,
malaise) – in most cases
• Heart murmur – new or changing (infrequent)
• Heart failure (infrequent)
• Petechiae (infrequent)
• Embolic phenomena (infrequent)
• Splenomegaly (infrequent)
• Neurologic findings (infrequent)
• Osler nodes, Janeway lesions, Roth spots, splinter
hemorrhages (rare)

14. Laboratory
• Positive blood culture (off antibiotics) – very
common
• Elevated acute phase reactants – very
common
• 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
period.
• 1 to 3mL in infants and young children, 5 to
7mL in older children and 20 to 30mL in adults

16. Echocardiography
• Two – dimensional echocardiography – principal
diagnostic method.
• 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
valves

17. Mitral valve vegetations
Systole Diastole
LV
LA
RV
RA
LV
MV
TV
RA
LA
RV

18. Mitral and tricuspid valve vegetations
RV
LV
LA
RA

19. Aortic valve vegetations
Diastole Systole
LV
LA
AO.V
MV

20. Perforation in the anterior mitral valve
leaflet
2D Color frame

21. Parasternal short axis view (tricuspid and aortic
valve vegetations)
LA
RVOT
TV PV
PA
RA
AO.V

22. Definition of terms used in the Modified Duke criteria for the
diagnosis of IE
Major criteria
1. Blood culture positive for infective endocarditis (IE)
A. Typical micro – organisms consistent with IE from 2 separate blood
cultures:
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
explanation; or
ii. Abscess; or
iii. New valvular regurgitation (worsening or changing or pre-
existing murmur not sufficient)

24. Definition of terms …
Minor criteria
1. Predisposition, predisposing heart condition, or injection
drug use
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 …
Possible IE:
1. 1 major and 1 minor criteria
2. 3 minor criteria
Rejected IE:
1. Firm alternative diagnosis explaining evidence of
IE; or
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
General principles
 With in vegetations, organisms are embedded in very
high concentrations.
 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
preferred.

29. Antimicrobial …
 Complete eradication of the organisms requires 4 to
6 weeks of antibiotic treatment.
 Parenteral administration recommended.
 Combination of antibiotics against the commonest
offending agents.
 Indications for surgery include:
 Significant embolic events,
 Persistent infection, and
 Progressive cardiac failure

30. Prophylaxis
Prophylactic regimens for dental, oral, or
respiratory tract procedures:
Amoxicillin 50mg/kg p.o. 30 to 60 min before
procedure (standard).
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.