Infective endocarditis Flashcards
What symptoms when seen together should be treated as infective endocarditis until proven otherwise
Fever + new murmur
Which individuals are considered at risk of IE?
- Past IE
- Past rheumatic fever
- IV drug abuser
- Damaged or replaced valve
- Structural congenital heart disease
- Hypertrophic cardiomyopathy
In individuals at known risk of IE, what symptom(s) should prompt immediate blood cultures?
Fever lasting >1 week
What is infective endocarditis?
An inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves.
What is the chief cause of acute IE?
Staph. aureus
What are risk factors for acute IE?
Dermatitis IV injections Renal failure Organ transplantation DM Post-op wounds
What is the usual entry site for the infective agent in acute IE
Skin
How does acute IE present?
Acute heart failure with or without emboli
How is IE classified?
Acute IE: Occurs on normal valves. Occurs suddenly over days to weeks
Subacute IE: Occurs on abnormal valves. Often due to streptococci of low virulence and causes mild to moderate illness which progresses slowly over weeks and months
What are the risk factors for subacute IE?
Aortic or mitral valve disease Tricuspid valves in IV drug users Coarctation Patent ductus ateriosus VSD Prosthetic valves
How is IE on prosthetic valves classified?
Early: within 60 days of valve surgery; poor prognosis
Late: haematogenous
What are the causes of IE?
Bacteraemia Strep. viridans is a common cause (>35%) Other causes: - Enterococci -Staph aureus/epidermidis -Diptheroids -Rarely HACEK gram negative bacteria (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella)
What are the main types of signs seen in IE?
Septic signs
Cardiac signs due to cardiac lesions
Immune complex deposition
Embolic phenomena
What septic signs are seen in IE?
Fever Rigours Night sweats Malaise Weight loss Anaemia Splenomegaly Clubbing
What signs of cardiac lesions are seen in IE?
Any new murmur or a changing pre existing murmur should raise the suspicion of endocarditis
Vegetations may cause valve destruction and severe regurgitation or valve obstruction
An aortic abscess causes prolongation of the PR interval and may lead to complete AV block
LVF is a common cause of death
What signs of immune complex deposition are seen in IE?
Vasculitis Microscopic haematuria Glomerulonephritis Acute renal failure Roth spots Splinter haemorrhages Osler nodes
What are Roth spots?
Boat-shaped retinal haemorrhage with pale centre
What signs of emboli are seen in IE?
Abscesses in the relevant organ e.g. brain, heart, kidney, spleen or skin- termed Janeway lesions
What features are pathognomonic (specific)
for IE
Janeway lesions
Osler’s nodes
How can you differentiate between Osler’s nodes and Janeway lesions?
Osler nodes: painful, usually seen on pads of fingers and toes
Janeway lesions: non-tender, usually seen on the palms or soles of feet
What are the diagnostic criteria for IE?
Duke Criteria: 2 major or 1 major and 3 minor or all 5 minor criteria are diagnostic
What are the major Duke criteria for IE?
Positive blood culture:
- Typical organism in 2 separate cultures
- Persistently positive blood cultures e.g. 3>12h apart (or majority if ≥4)
Endocardium involved:
-Positive echocardiogram for vegetation, abscess, dehiscence of prosthetic valve
OR
-New valvular regurgitation (change in murmur is not sufficient)
What are the major Duke criteria for IE?
Predisposition (cardiac lesion; IV drug abuse)
Fever >38 degrees C
Vascular/immunological signs
Positive blood culture that does not meet major criteria
Positive echocardiogram that does not meet major criteria
What is more common, acute or subacute infective endocarditis?
SBE
