John smith a 58 year old patient with a history of rheumatic fever, severe aortic stenosis and hypertension was admitted and found to have infective endocarditis. He was initially treated with antibiotics and later underwent an aortic valve replacement.
Common symptoms of aortic stenosis may include:
- Chest pain or discomfort: this can range from mild pain to severe chest pain or tightness. It is often experienced during exertion.
- Shortness of breath/exertional dyspnoea
- Exertional syncope
- Heart failure
Rheumatic fever occurs following an immunological reaction to a recent (2-6 week old) streptococcus pyogenes infection. It is a type 2 hypersensitivity reaction that occurs due to antibody cross-reactivity of anti-M protein antibodies with heart muscle. Aschoff bodies are seen in the heart.
Infective endocarditis (IE) is a infection of the endocardium, which is the inner lining of the heart chambers and heart valves.
- Strep viridians (most common cause 40-50%). The two most common are streptococcus mitis and strep sanguinis. Both commonly found in the mouth and in particular dental plaque so endocarditis caused by these organisms is linked with poor dental hygiene or following a dental procedure. It affects the mitral valve (damaged valves)
- Staphylococcus epidermidis occurs on prosthetic valves within the first 2 months and occurs due to perioperative contamination.
- Staph aureus has an acute presentation tends to occur in IVDU and affects the tricuspid valve.
- Streptococcus Bovis: associated with colorectal cancer.
· S. Viridans
· S. Bovis
· S. aureus
· S. Epidermidis
Systemic features of infective endocarditis include:
- Roth spots
- Splinter haemorrhages
- Osler’s nodes
- Micro haematuria due to glomerulonephritis
- Janeway lesions
- Embolic abscesses
Infective endocarditis is diagnosed using the dukes criteria. For diagnosis a patient needs to fulfil:
- 2 major and 1 minor criterion
- 1 major and 3 minor criterion
- 5 minor criteria
The major criteria include:
- Positive blood cultures for infective endocarditis
- Typical microorganism for infective endocarditis from 2 separate blood cultures
- Evidence of endocardial involvement
- positive echocardiogram for infective endocarditis
- new valvular regurgitation
The minor criteria include:
- Predisposing heart condition or intravenous drug use
- Fever: 38C
- Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, conjunctival haemorrhages, and Janeway lesions
- Immunologic phenomena: Glomerulonephritis, Osler nodes, Roth spots, or Rheumatoid factor
- Microbiologic evidence: positive blood culture but not meeting major criterion as noted previously or serologic evidence of active infection with organism consistent with infective endocarditis
- echocardiography findings consistent with infective endocarditis but not meeting major criteria as noted previously
- High concentration of organisms present within the vegetation
- Vegetation has a fibrin meshwork that shields bacteria
- Bacteria form biofilm