Infective Endocarditis Flashcards
What is infective endocarditis?
Infective endocarditis is an endovascular infection of cardiovascular structures including cardiac valves, atrial and ventricular endocardium, large intrathoracic vessels and intracardiac foreign bodies i.e. prosthetic valves and pacemaker.
Broadly speaking, endocarditis is a result of two main factors. What are these?
- Bacteraemia due to poor dental hygiene, intravenous drug use, soft tissue infections
or
- Assoc. with diagnostic/therapeutic procedures i.e. central procedures, intravascular cannula, cardiac surgery or permanent pacemakers.
How does a damaged endocardium increase the risk endocarditis?
Damaged endocardium promotes platelet and fibrin deposition, allowing organisms to adhere and grow => infected vegetations = endocarditis.
There are two types of infected lesions:
- Valvular lesions
- Jet lesions
What is the difference between the two?
Valvular lesions create non-laminar flow.
Jet lesions form septal defects or a patent ductus arteriosus leading to abnormal vascular endothelium.
Which 2 valves are most commonly affected in infective endocarditis?
Aortic and mitral valves
What are the common organisms from dental disease/procedure which may lead to endocarditis?
Alpha-haemolytic viridian streptococci
1/3 - 1/2 no. of cases of total endocarditis cases
Which organisms may lead to endocarditis as a result of
i. prolonged indwelling vascular catheters (esp for TPN) and antibiotic use,
ii. and intravenous drug users (who dissolve heroin in infected lemon juice)?
Staph. aureus
Candida (rare)
Native or prosthetic valve endocarditis
Which organisms may lead to endocarditis as a result of
i. early infection (poor prognosis) within 60 days of valve surgery
ii. late infection occurring more than 60 days after valve surgery and presumed to have been acquired in community?
i. Staph. aureus and staph. epidermidis ;
Poor outcome with MRSA
ii. Strep. viridans (50-70%) ;
Staph. aureus (25%)
Which organism may lead to endocarditis following a soft tissue infection i.e. diabetes, intravenous drug users and patients with longstanding + poorly cared for I.V. catheters?
Staph. aureus
Which organism may lead to endocarditis following genitourinary disease or procedure, or prolonged hospitalisation?
Enterococci
Fever + new murmurs = endocarditis until proven otherwise.
Any fever lasting >1wk in at risk patients => blood cultures.
INFO CARD
Acute infective endocarditis tend to occur on normal valves.
What can an acute infective endocarditis present with?
What is the most common organism causing this?
- Acute endocarditis can presents with acute heart failure ± emboli.
- Staph. aureus
What are the risk factors for acute infective endocarditis?
- Skin breaches (Dermatitis ; IV lines ; wounds)
- Renal failure
- Immunosuppression
- Diabetes
What is the mortality rate with acute infective endocarditis?
5-50%
Endocarditis on abnormal valves tends to be subacute in nature.
What are the risk factors for this?
- Aortic or mitral valve disease
- Tricuspid valves in IV drug user
- Coarctation
- Patent duct arteriosus
- Ventral septal defects
- Prosthetic valves
Rarely, a group of organisms may cause endocarditis which can lead to a more insidious course. Name these organisms.
HACEK - gram -ve bacteria
H = Haemophillus A = Actinobacillus C = Cardiobacterium E = Eikenella K = Kingella
What is the clinical presentation for a high clinical suspicion for endocarditis?
Mention:
i. septic signs
ii. cardiac lesions
iii. Cutaneous lesions
iv. Embolic phenomena
v. Immune complex deposition
i. Septic signs : Fever, rigors, night sweats, malaise, weight loss, anaemia, splenomegaly and clubbing
ii. Cardiac lesions : New/change in existing murmur => vegetations may cause valve obstruction and severe regurgitation or valve obstruction.
iii. Cutaneous lesions : Roth spots (boat shaped retinal haemorrhage with pale centre) ; Splinter haemorrhages ; Osler’s nodes (painful pulp infarcts)
iv. Embolic phenomena : emboli may cause abscess in brain, heart, kidney, spleen, gut, lung (if right sided endocarditis) or skin (Janeway lesions - painless, erthamatous haemorrhagic macules on palms or soles)
v. Immune complex deposition : Vasculitis ; glomerulonephritis ; acute kidney injury
* Janeway lesions and osler nodes together are suggestive of endocarditis.
What is the clinical presentation for a low clinical suspicion for endocarditis?
Fever + none of the signs mentioned before
What criteria is used to diagnose endocarditis?
Modified Duke’s Criteria for endocarditis
Duke’s criteria is made up of 2 parts: major criteria and minor criteria.
Describe the major criteria.
- Positive blood culture:
=> Typical organism in 2 separate cultures
OR
=> Persistently +ve blood cultures i.e. 3 >12h apart
OR
=> Single +ve blood culture for Coxiella burnetii
.
- Endocardium involved:
=> +ve echocardiogram (vegetation, abscess, pseudo aneurysm)
OR
=> Abnormal activity around prosthetic valve on PET/CT or SPECT/CT
OR
=> Paravalvular lesions on cardiac CT
Duke’s criteria is made up of 2 parts: major criteria and minor criteria.
Describe the minor criteria.
- Predisposition (cardiac lesion; IV drug abuse)
- Fever >38 degrees celcius
- Vascular phenomena (emboli, Janeway lesions etc)
- Immunological phenomena (Glomerulonephritis, osler’s nodes)
- +ve blood culture that doesn’t meet the Major Criteria
How do you diagnose a definitive endocarditis using the Duke’s criteria?
Definitive endocarditis:
=> 2 major criteria OR
=> 1 major and 3 minor criteria OR
=> All 5 minor criteria
What are the 8 possible investigations carried out to confirm endocarditis and their findings?
- List all areas tested for in a blood test
- Name the 1st & 2nd line of imagining and what they may reveal
- Blood cultures: 3 sets from different venepuncture site
- Serological tests: Consider Coxiella Legionella, Chlamydia in culture -ve cases
- Blood tests:
i. FBC: normochromic, normocytic anaemia, reduced Hb,
neutrophilic (increased WBC),
ii. Serum creatinine & electrolyte: Increased urea & creatinine
iii. Inflammatory markers: high ESR/CRP,
iv. Rheumatoid factor +ve
3. Urinalysis: proteinuria and microscopic haematuria
4. ECG: prolonged PR, heart block assoc. with aortic root abscess
5. Chest X-ray: Pulmonary oedema in left-sided disease, pulmonary emboli/abscess in right-sided disease
6. Transthoracic Echocardiography: vegetations, valvular dysfunction, abscesses => 1st line imaging, non-invasive
7. Transoesophageal Echocardiography: prosthetic valve endocarditis, aortic root abscess => 2nd line imagine; invasive
8. CT-PET: emboli in speen, brain etc
Approx. 10% of endocarditis is culture negative.
What are the possible explanations for a negative cultures?
- Most likely prior anti-biotic use, therefore Hx very important to establish
- Some organisms fail to grow in normal blood cultures i.e. Coxiella Burnetii
