Infective Endocarditis Flashcards
What is infective endocarditis?
An infection involving the endocardial surface of the heart, including the valvular structures, the chordae tendineae, sites of septal defects or the mural endocardium.
Sources of infective endocarditis
Vascular catheters
Recent dental work
IV drug use
Aetiology of infective endocarditis
Viridans group streptococci (most common cause- 40-50%)
S.aureus (especially acute presentation, IVDUs)
Enterococci
Coagulase-negative staphylococci
Staphylococcus epidermidis (mainly in prosthetic valves)
Haemophilus parainfluenzae
Actinobacillus
Streptococcus bovis is associated with colorectal cancer
Fungi
Pathophysiology of infective endocarditis
IE typically develops on the valvular surfaces of the heart, which have sustained endothelial damage secondary to turbulent blood flow.
Signs & symptoms of infective endocarditis
Fever/chills Night sweats Malaise Fatigue Anorexia Weight loss Myalgia Weakness Arthralgias Headache SOB Meningeal signs Cardiac murmur Janeway lesions Osler nodes Roth spots Splinter haemorrhages Cutaneous infarcts Chest pain Back pain Palatal petechiae
Risk factors of infective endocarditis
Prior hx of infectious endocarditis
Presence of artificial prosthetic heart valves
Certain types of congenital heart disease
Post-heart transplant
Presence of cardiac implanted electronic device or intravascular catheters
Acquired degenerative valve disease
Mitral valve prolapse (MVP) with valvular regurgitation
Hypertrophic cardiomyopathy
IV drug use
Diagnosis of infective endocarditis
FBC
CRP
LFTs
Electrolyte panel like Mg
Three sets of blood cultures 1 hour apart- at peak of fever
Urinalysis
Echocardiogram must be obtained- show vegetations
ECG- signs of heart block
CT- look for emboli in organs e.g. spleen, brain
MRI
ESR
Differentials of infective endocarditis
Rheumatic fever
Atrial myxoma
Libman-sacks endocarditis
Non-bacterial thrombotic endocarditis
What is the Duke criteria?
Major criteria:
Positive blood culture for IE (persistently positive blood culture)
Evidence of endocardial involvement- abscess, oscillating intracardiac mass.
Minor criteria:
Predisposing heart condition or IV drug use
Fever over 38
Valvular phenomenon- major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, conjunctival haemorrhage, Janeway lesions.
Immunological phenomenon- glomerulonephritis, Osler nodes (tender subcutaneous nodules on distal pads of digits), Roth spots (retinal haemorrhages with small, clear centres), Rheumatoid factor.
Microbiological evidence-Positive blood cultures not meeting major criteria
Echocardiogram- consistent with IE but not meeting major criteria
To be diagnosed with IE, must meet 2 major criteria or 1 major and 3 minor criteria or 5 minor criteria
Management of IE
This is guided by identification of the causative organism and whether the infective valve is native or prosthetic (treatment should be longer >6 weeks) Initial management is aimed at controlling: breathing, airway and circulation. Broad-spectrum antimicrobial therapy is required. Surgery is indicated in: Haemodynamic embarrassment Persistent bacteraemia HF Overwhelming sepsis Valvular obstruction Perivalvular abscess Fungal IE Intracardiac fistulae Valve perforation or dehiscence Recurrent embolic episodes Prosthetic valve endocarditis
Why is IE is a diagnostic challenge?
Clinical history is variable based on:
Causative microorganism
Presence/absence of pre-existing cardiac disease
Presence/absence of prosthetic valves or cardiac devices.
IE may present as an acute or subacute/chronic disease
IE doesn’t always present with high fever
BCNIE can occur in 31% of IE cases due to previous antibiotic administration.
Who is more likely to fungi IE?
IV drug users
Immunocompromised patients
Prosthetic valves
Fungi IE needs surgical management.
