Infective endocarditis

Question 1

what is infective endocarditis?

Answer 1

Microbial infection of normal heart valve, prosthetic heart vale or endothelial surface of the heart or CHD (VSD/ASD)

Question 2

what increases the risk of developing infective endocarditis?

Answer 2

Heart tissue predisposed:

• valvular disease (aortic/mitral)
• prosthetic valve
• CHD
• previous IE

Increased exposure:

• Poor dental hygiene
• Central/IV lines
• post-op wound infection
• IV drug use

Immunocompromised

• diabetes
• organ transplant

Question 3

Describe the pathophysiology behind I.E

Answer 3

High pressure of blood flow sometimes can damage endothelial surfaces

Fibrin and platelets aggregate

Transient bacteraemia delivers pathogens and sometimes they can adhere to these damaged surfaces

Platelets and fibrin protect the bacteria from the immune system = vegetation

Question 4

what organisms commonly cause I.E

Answer 4

S. Aureus
Strep Viridans

HACEK = haemophilus, actinobacillus, cardiobacterium, Eikenella, Kingella. (these all culture -ve)

Question 5

how can I.E present?

Answer 5

New onset murmur + fever first off

systemic infection/sepis

valvular/cardiac damage

embolism of vegetation

immune complex formation:

• glomerulonephritis
• roth spots
• oslers nodes
• janeway lesions

Question 6

what investigations would you do in someone presenting with I.E?

Answer 6

Blood cultures x3 at different times and sites
FBC - WCC
U&E - kidney function
ESR/CRP - infection
ECG 
ECHO

Question 7

Outline the dukes criteria

Answer 7

Major criteria =

• typical organisms found in 2 consecutive blood culture samples or Atypical persistently found in separate blood culture samples
• murmur: positive echo findings, or no valvular regurgitation

Minor criteria =
- predisposition
- valvular/immunological signs
- Fever >38
positive blood cultures but does not meet major criteria
- positive echo but does not meet major 

For diagnosis = 2 major, 1 major and 3minor or 5minor

Question 8

how is I.E treated?

Answer 8

Benzylpenicillin and Gentamicin (give vancomycin if pen allergic)

4 week IV course

Question 9

when is surgery considered in i.E?

Answer 9

valve obstruction
HF
myocardial abscess

Question 10

How are immunocompromised patients managed in terms of reducing their risk of I.E?

Answer 10

Prophylactic Abx are no longer recommended

Educate about good oral hygiene and avoiding piercing etc

Educate about symptoms and seeking advice

Question 11

what is the difference between acute and subacute IE?

Answer 11

Acute often occurs by S. Aureus infection

• rapidly destructive
• worse prognosis
• acute fever and haemodynamically unstable

Sub acute:

• more slow onset
• more likely strep viridans
• slow progressive with fever and malaise