Infective endocarditis

Question 1

What is infective endocarditis?

Answer 1

Infection of heart valves or other endocardial lined structures within the heart such as septal defects, pacemaker leads, surgical patches etc

Question 2

Who are the people who are most commonly affected by infective endocarditis?

Answer 2

elderly
IVDUs
those with congenital heart disease
those with prosthetic heart valves

Question 3

What is the clinical presentation of infective endocarditis?

Answer 3

depends on site and organism

1. systemic infection signs eg fever, sweating
2. signs of embolisation of infected material eg stroke, PE, cutaneous and ocular manifestations, bone infection, kidney dysfunction, MI
3. valve dysfunction - may hear a heart murmur, if there is tricuspid regurgitation, there may be changes in the JVP
4. heart failure
5. arrhythmia

Question 4

List some complications of IE

Answer 4

infective emboli
holes in heart valves 
arrhythmia 
heart failure 
heart block

Question 5

What is a native valve?

Answer 5

valve you were born with

Question 6

What are the cause of infective endocarditis?

Answer 6

abnormal, regurgitant or prosthetic heart valves - eg bicuspid aortic valve or leaking mitral valve
plus introduction of infectious material into the blood or directly onto the heart during surgery- iatrogenic
previous IE - as previous IE damages the heart valves

Question 7

Which organisms cause IE?

Answer 7

alpha haemolytic strep (eg S. pneumonia, viridans strep)
S. aureus 
Coliforms
Candida
Apsergillus 
Pseudomonas
Enterococci eg E. faecalis 
Culture negative endocarditis - Coxiella burnetii, Chlamydia psittaci

Question 8

Explain the pathogenesis of IE

Answer 8

sterile platelet-fibrin nidus is present (so may have been some previous endocardial injury)
then bacterial adhere to this platelet-fibrin nidus
vegetations then form
NB - some organisms with high virulence can infect normal human heart valves eg S. aureus

Question 9

What are is the criteria called used to diagnose IE?

Answer 9

Duke criteria

Question 10

What are the major criteria for diagnosis according to the duke’s criteria?

Answer 10

1. positive blood cultures

2. evidence of endocarditis on echo or new valve regurgitation

Question 11

what are the 5 minor criteria for diagnosis of IE according to Duke’s criteria?

Answer 11

a) predisposing factors - eg heart condition or IVDU
b) fever - >38˚
c) vascular phenomena - major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhages, conjunctival haemorrhages
d) immune phenomena - glomerulonephritis, Osler’s nodes, Roth’s spots
e) equivocal (ambiguous) blood cultures

Question 12

How many of the Duke criteria are needed for definite diagnosis of IE?

Answer 12

2 major criteria
OR
1 major + 3 minor
OR
5 minor

Question 13

When is diagnosis of IE possible with the Duke criteria?

Answer 13

1 major + 1 minor
OR
3 minor

Question 14

What type of investigations can be done for endocarditis?

Answer 14

a) ECG - ischaemia or infarction, new heart block
b) Transthoracic echo is really important to detect a vegetation
c) may need additional TOE for diagnosis if TTE is not clear
d) blood cultures - NB may not always be positive
e) other lab diagnostics - Raised ESR/CRP, monitor response to treatment with CRP
normochromic- normocytic anaemia present

Question 15

What are the advantages and disadvantages of transthoracic echo?

Answer 15

safe
non-invasive
no discomfort

poor images so lower sensitivity

Question 16

What are the advantages and disadvantages of transoesophageal echo?

Answer 16

excellent pictures
generally safe

risk of perforation or aspiration
large tube being pushed down oesophagus is unpleasant

Question 17

What are the peripheral stigmata of IE?

Answer 17

Petechiae
splinter haemorrhages 
Osler's nodes 
Janeway lesions 
Roth's spots on fundoscopy

Question 18

What are Osler’s nodes?

Answer 18

small, tender, purple, erythematous subcutaneous nodules, usually found on the pulp of the digits formed by immune complex deposition

Question 19

What are Janeway lesions?

Answer 19

erythematous, macular, nontender lesions on the fingers, palm, or sole not immune complex deposition, but due to microabscesses in the dermis caused by septic emboli and markednecrosiswith inflammatory infiltrate

Question 20

What are Roth’s spots?

Answer 20

retinalhemorrhageswith white or pale centers, caused by immune complex mediated vasculitis often resulting from bacterialendocarditis.
retinal infarcts may be seen

Question 21

How is IE treated?

Answer 21

IV antibiotics for 6 weeks - choice of agent depends on culture sensitivity
treat complications eg arrhythmia, heart failure, heart block, embolisation, stroke, abscess drainage etc
surgery - eg cardiac to replace heart valve or vascular surgery to remove emboli

Question 22

Which antibiotics may you give for Strep infection?

Answer 22

amoxicillin, penicillin or cefuroxime

Question 23

Which antibiotics would you give for S. aureus infection?

Answer 23

flucloxacillin WITH gentamycin

Question 24

What are the indications for surgery?

Answer 24

a) the infection cannot be cured with antibiotics
b) complications - aortic root abscess, severe valve damage
c) remove infected devices
d) to replace valve
e) to remove large vegetations before they embolise

Question 25

what is the prevention of IE?

Answer 25

NICE: do not give antibiotic prophylaxis to anyone
ESC: consider prophylaxis in high risk pts eg those with prosthetic heart valves, previous IE and cyanotic heart disease before interventions esp dental

Question 26

As an F1, what should you do when there is a pt who could have IE?

Answer 26

a) do lots of blood cultures - usually 3 blood cultures with at least 6 hours in between
b) always write ?IE on differential of pts with sepsis and request an echo esp in high risk pts

Question 27

How can you tell if antibitoic treatment has not worked on sb with IE?

Answer 27

the infection reoccurs after treatment

CRP doesn’t fall