Infective Endocarditis

Question 1

What is Infective Endocarditis?

Answer 1

Infective endocarditis (IE) is an infection of the endocardium (inner lining of the heart and valves). It causes local damage within the heart as well as systemic effects (Caused by infected emboli). Infective endocarditis can present either acutely but more commonly presents sub acutely (over weeks/months).

Question 2

What are the causes of infective endocarditis?

Answer 2

Common - Streptococcus Viridians, Staphylococcus aureus, Streptococcus bovis, Escherichia coli, Coxiella Burnetii
Prosthetic valves - Staphylococcus Epidermidis
Others (HACEK Gram negative organisms) – Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella
Endocarditis can also be caused by non-infective causes – Malignancy, SLE

Question 3

What will you find on a History taking of Infective endocarditis

Answer 3

Symptoms:
Acute – New/Changing Murmur, Acute Heart Failure, Fever, Systemic Emboli (Stroke, AKI, Glomerulonephritis, PE)
Subacute - Fever, Chills, Night sweats, Malaise, Fatigue, Anorexia, Weight loss, Myalgia, Palpitations, Arthritis

Risk Factors:
Skin Breaches - E.g. Medical Lines, IV drug use, Unlicensed Tattoo Parlours 
Renal Failure
Immunosuppression
Diabetes 
Prosthetic Heart valves – Mechanical increased risk
Congenital Heart Disease 
Underlying Valve disease/abnormality  
Poor dental hygiene 

Differentials:
SLE
Cardiac Neoplasm
Pericarditis – Lack of ECG changes of pleural rub
MI – Uncharacteristic MI pain, ECG changes
Pneumonia/PE/Pneumothorax

Question 4

What will you find on examination of Infective Endocarditis?

Answer 4

End of the bed:
Fever - Indicates Infection
Petechial rash
Hands:
Splinter Haemorrhages (top)
Osler’s Nodes - small, painful, nodules usually found on the pads of the fingers or toes (middle)
Janeway Lesions – Irregular painless macules on the palm of the hand (normally the thenar or hypothenar eminence) (bottom)
Clubbing - Chronic IE only
Face:
Poor dental hygiene - risk factor
Roth Spots (retinal haemorrhages with pale centres) in eyes
Chest:
New or changing cardiac murmur - Most commonly aortic regurgitation
Abdomen:
Splenomegaly

Question 5

What investigations will you order in suspected infective endocarditis?

Answer 5

Bedside:
Urinalysis - Microscopic Haematuria
ECG - To look for conduction defects e.g. heart block and to rule out pericarditis/MI
Blood Cultures (3 sets from various locations and times before commencing treatment)

Bloods:
FBC - Normocytic anaemia, Neutrophilia (Raised Neutrophils)
ESR/CRP - Raised
Rheumatoid factor - Positive (No idea why)
U&E - To look for sepsis and rule out metastatic cancer
LFT’s – To rule out sepsis and rule out metastatic cancer
Troponin – May be slightly raised but to rule out an MI
Clotting – If sepsis suspected

Imaging:
CXR – May show complications e.g. Heart Failure, Pericardial effusion or Pulmonary effusion. Rules out lung pathology
Transthoracic Echo – Diagnostic (Done within 24 hours to look for vegetation)

Question 6

What is the treatment of infective endocarditis?

Answer 6

Requires a Multi-Disciplinary approach with cardiology and Micro
Lifestyle:
Risk Factor reduction in high risk patient groups e.g. IV drug users or prosthetic heart valves
Maintain oral healthy
Educate about symptoms and when to come to doctor
Explain the risk of invasive procedures, like dentistry, body piercing and tattoos.

Medical:
Antibiotics - Benzylpenicillin and Gentamicin empirically
Flucloxacillin and gentamicin can be used in staph suspected (e.g. IV drug user)
Consult microbiologists once sample cultured and sensitivity recorded to ask advice
Requires weekly echo and biweekly ECG/Bloods to monitor treatment

Surgery:
Can be used in the treatment of complications e.g. Heart failure, emboli, abscess formation

Question 7

What is the scoring system used for infective endocarditis?

Answer 7

Modified Dukes Criteria
Major Factors:
• Positive Blood Cultures, either:
o for a typical infective endocarditis organism in 2+ cultures
o consistently positive e.g. 3 cultures >12 hour apart
o Coxiella Burnetti Positive
• Involvement of the endocardium:
o Positive Echo
o Abnormal prosthetic valve on CT
o Paravalvular lesion on CT
Minor Factors:
• Predisposing Risk Factor e.g. IV drug use, Valve abnormality
• Temp > 38
• Vascular Phenomenon – Emboli/Janeway lesion
• Immunological Phenomenon – Glomerulonephritis/Osler’s Nodes/Roth Spots
• Positive Blood culture not meeting criteria of major
Diagnostic: 2 major 1 minor, 1 major 3 minor, 5 minor