Infective Endocarditis
Introduction
Infective endocarditis is a bacterial infection of the endocardial surface of the heart, most commonly the valves. A high index of suspicion is needed as it is a very serious but commonly missed diagnosis.
Staphylococci (vast majority) and streptococci spp are the most common pathogens.
Risk Factors
Structural Defects – Prosthetic Valves, Rheumatic heart disease, Septal defects, Mitral valve prolapse, Congenital heart disease
Especially if dental or high risk surgery
IVDU – most commonly have right heart valve lesions
Foreign Bodies – PPM, Central venous catheter.
Clinical Features
Endocarditis is a multi-system disease. Symptoms and signs are usually non specific.
Symptoms
Systemic symptoms
Fever, malaise, headache, myalgia, arthralgia, anorexia, weight loss
Symptoms of complications
e.g. chest pain, SOB, Abdo Pain
Complications
Valve destruction leading to heart failure
Septic emboli to the lungs, brain, liver or spleen leading to abscesses
Stroke
Renal Failure
Anaemia
Differential Diagnosis
Fever of Unknown Origin
Infective – Pneumonia, abdo/pelvic abscess, TB (pulm + extrapulm), HIV, CMV, EBV
Inflammatory – SLE, Rheumatoid
Malignancy - lymphoma
Clinical Investigations
Diagnostic Criteria
Modified Dukes Criteria is used to make diagnosis
2 major criteria, or
1 major and 3 minor criteria, or
Five minor criteria
Major Criteria
Positive blood cultures for Infective endocarditis pathogen
Evidence of endocardial involvement on echo i.e. vegetation or abscess
New valvular regurgitation on echo.
Minor Criteria
Risk Factor
Fever > 38
Vascular Phenomena
septic emboli, Janeway lesion, Conjunctival petechia
Immunological phenomena
Glomerulonephritis, Roth Spots, Osler Nodes
Microbiological Evidence
positive blood culture but don’t fulfil major criteria
Echo findings
consistent with IE but don’t fulfil major criteria
Management & Disposition
Initial Resuscitation
ABC Approach
IV Fluid resus as required
Specific Management
3 sets of blood cultures must be taken 30 minutes apart prior to commencing antibiotics.
Can be a shorter period if patient critically unwell
Broad spectrum antibiotics to cover likely pathogens, as per local guidelines pending culture results.
E.g. Ceftriaxone 2g IV + Vancomycin 25mg/kg IV + Gentamicin 3mg/kg IV
Cardio-thoracic surgical intervention may be necessary in some cases
Symptomatic Management
Anti pyretics are best avoided so not to mask fevers
Disposition
All patients with ? IE should be admitted to hospital to have the diagnosis confirmed and the appropriate treatment initiated
Infectious Diseases, Microbiology, Cardiology +/- Cardio-thoracics should all be involved in the patients care
References
1. Case courtesy of Dr Yair Glick, Radiopaedia.org, rID: 53674
2. Hung K, Cameron P et al. Chapter 5.7 Heart valve emergencies. Adult Textbook of Emergency Medicine 4th edition.
3. Mylonakis E, Calderwood S. Infective Endocarditis in Adults. N Engl J Med, Vol 345, No. 18. 2001
4. https://litfl.com/infective-endocarditis/
5. SJH Prescribers Capsule. Empiric Antimicrobial Guidelines. Bacterial Endocarditis
This blog was written by Dr Deirdre Glynn and was last updated in November 2020