Infective Endocarditis (NC) Flashcards
What is infective endocarditis?
Infection of endocardium - Usually bacterial or fungal infection of the inner lining of the heart valves
How does the endocardium get infected in the first place?
When microbes enter the blood stream: via broken skin/abscess, during a dental or medical procedure, injection with and infected needle (common in drug users)
Microbes latch onto heart valves - more likely if the valves are damaged as it helps with adherence and forming vegetations
What are the risk factors if infective endocarditis?
Cardiac factors
- previous endocarditis
- prosthetic valve or pacemaker
- valvular or congenital heart disease
Non-cardiac factors
- intravenous drug users
- intravenous catheter
- immunosuppression
- recent dental or surgical procedure
What are the categorisation of infective endocarditis?
Native valve endocarditis - effects previously normal heart valve
Prosthetic valve endocarditis - effects prosthetic valves duh
Which bacteria is native valve endocarditis usually caused by?
Staphylococcus aureus
Streptococci Viridians
OFTEN seen in intravenous drug users as these Bactria are found in the skin
Which bacteria is prosthetic valve endocarditis usually caused by?
Staphylococcus aureus - usually MRSA (methycillinresistant)
What are the symptoms of infective endocarditis
Fever, fatigue, dyspnea and weight loss
Typically acute - occurs within 2 weeks but can be subacute or chronic which develops over a few months
Usually heart murmur caused by turbulent blood flowing past vegetation
Symptoms from septic embolus (if there is any):
Splinter haemorrhages
Janeway lesions
Embolic stroke
Intracerebral haemorrhage
Oslers nodes (fingers and toes)
Roth spots (eye)
Glomerulonephritis (kidney)
Other: arterial emboli, pulmonary infarcts and conjunctival haemorrhage
How are septic embolis formed and what can they cause?
If vegetations detatch from valve and enter blood stream them become a septic embolus
These septic emboli can lodge under finger nails causing splinter haemorrhages or in palms or shoes of feet causing Janeway lesions, brain embolization (emboli stroke or intercerebral haemorrhage)
Other things it can cause: arterial emboli, pulmonary infarcts and conjunctival haemorrhage
From other complications of septic emoli:
Osler nodes
Roth spots
Glomerulonephritis (kidney)
What are Janeway lesions?
Irregular, nontender hemorrhagic macules located on the palms, soles of the feet, and plantar surfaces of the toes. They typically last for days to weeks. They are usually seen with the acute form of bacterial endocarditis.
How to diagnose infective endocarditis?
Collect 3 sets of blood cultures:
- aerobic bacteria
- anaerobic bacteria
- fungi
Must be at 10 ml and each taken from different venous puncture sites
Carry out echocardiography - looking for vegitations of the way the valve is moving (2 types of echocardiograms)
What are the 2 types of echocardiogram from diagnosis infective endocarditis? What are the pros/cons?
1.) transthoracic echocardiography: non-invasive, cheap but lower sensitivity
2.) transesophageal echocardiography: higher sensitivity but it is i ase and requires sedation
*some cases transesophageal echo is done first - this is for individuals who have prosthetic valves, implantable cardiac devices, prior valve abnormalities (e.g previous endocarditis) or obese patients or patients with a chest wall deformity
How to confirm diagnosis of infectious endocarditis?
Dukes criteria
What is dukes criteria? How to use it to tell if the diagnosis for endocarditis is definite or possible?
Has major and minor criteria
For definite endocarditis:
2 major
1 major and 3 minor
5 minor
For possible endocarditis:
1 major plus 1 minor
3 minor criteria
What is the major criteria for endocarditis?
POSITIVE BLOOD CULTURE FOR INFECTIVE ENDOCARDITIS:
- typical microorganism for infective endocarditis from two separate blood cultures: Viridians streptococci, S. aureus, S. bovis, HACEK group (haemophilus, aggregatibacter, cardiobacterium, eikenella, kingella or enterococci in the absence of primary focus, OR
-Persistently positive blood culture, defined as recovery of microorganism consistent with infective endocarditis from:
• Blood cultures drawn more than 12 hours apart, OR
• All of three or a majority of four or more separate blood cultures, with first and last drawn at least 1 hour apart
- Positive blood culture for Coxiella burnetii or anti-phase 1 IgG antibody titer > 1:800
EVIDENCE FOR ENDOCARDIAL INVOLVEMENT:
- Positive echocardiogram for infective endocarditis
• Oscillating intracardiac mass, on valve or supporting structures, or in the path of regurgitant jets, or on implanted material, in the absence of an alternative anatomic explanation, OR
• Abscess, OR
• New partial dehiscence of prosthetic valve, OR
- New valvular regurgitation (increase or change in preexisting murmur not sufficient)
What is the minor dukes criteria for endocarditis?
Minor Criteria
- Predisposition: predisposing heart condition or intravenous drug use
- Fever >38.0° C (100.4° F)
- Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial
hemorrhage, conjunctival hemorrhages, Janeway lesions - Immunologic phenomena: glomerulonephritis, Osler nodes, Roth spots, rheumatoid factor
- Microbiologic evidence: positive blood culture but not meeting major criterion or serologic evidence of active infection with organism consistent with infective endocarditis
