Week Four - Case Two Flashcards
what is infective endocarditis
condition caused by infection of the endocardium by bacteria, or rarely fungus. it most commonly affects the heart valves but can occur anywhere along the lining of the heart or blood vessels
where will staph. aureus commonly infect in IV drug users
most commonly infect the tricuspid valve
what is the epidemiology of infective endocarditis
50% of all cases of infective endocarditis will occur on normal valves. This type of infection tends to follow and acute course.
50% of infections occur on abnormal tissue, and these infections will tend to follow a sub-acute course.
what is the mortality rate without treatment
close to 100%
what are the valvular damage risk factors for infective endocarditis
previous rheumatic heart disease
age related valvular degeneration
prosthetic valve
what is the risk factor with IV drug use
more chance of multiple organisms with IV drug users. IV drug users are usually affected at the tricuspid valve, and the right side of the heart
often the endocarditis is less clinically severe in IV drug users
what does endocardial damage lead to
the formation of thrombi at the damaged site
what is the thrombus mainly made up of
platelets and fibrin
where does the endocardial damage tend to occur
The endocardial damage tends to occur around damaged valves, as aberrant jets of blood around these valves cause increased shearing forces in the endocardium, leading to endocardial damage. Also, the valve cusps themselves are avascular, and thus normal immune responses in this region are impaired.
where do these thrombi and IE tend to occur
at sites of high haemodynamic pressure, due to the increased shearing force in these areas.
what are the two factors that are essentially required for infective endocarditis
- the presence of organisms in the blood - many things cause this. common mechanisms include poor dental hygiene, IV drug use, soft tissue infection and iatrogenic causes
- abnormal/unusual endocardial tissue
what do we call it when a thrombi has been colonised by bacteria
vegetation
why is infective endocarditis particularly hard to treat with antibiotics
because the platelets and fibrin in the vegetation prevent antibiotic agent, and white blood cells from being in direct contact with the bacteria
what valves are most commonly affected and why
the aortic and mitral valves are most commonly affected because these exist in a higher pressure system than the tricuspid and pulmonary valves
what infection is more common in drug users
right sided infection - although the mechanism for this is poorly understood
what two symptoms mean it is endocarditis until proven otherwise
if the patient has a new murmur and a fever
what is SBE
IE most commonly presents sub-acute with an insidious course. in this instance it is sometimes refer to as sub-acute bacterial endocarditis
what is the acute presentation of IE
Fever + new heart murmur (90%)
Petechiae (50%)
what are petechiae
these are red/purple spots of 1-2mm in diameter.
they often form at sites of trauma, and in this instance they will usually disappear within a couple days.
extreme bouts of vomiting, coughing or crying can also produce them around the eyes.
they mat also be a sign of low platelet count
what are petechiae caused by
bleeding under the skin - they are non-blanching
what type of failure can develop rapidly
Cardiac / renal failure can develop rapidly (50-70%)
Haematuria secondary to renal failure present in about 70% of patients
what are splinter haemorrhages
red lines that run vertically along the nails.
a non-specific sign often associated with rheumatologic conditions as well as infective endocarditis
what is the sub-acute presentation
the above +
rigours
fever
splenomegaly
what infection causes an enlarged liver and spleen
coxiella infection
what are Osler’s nodes
these are painful swellings at the fingertips; commonly due to vasculitis
what are Janeway lesions
These are non-tender, small erythematous or haemorrhagic or nodular lesions on the palm or the sole, and generally about 2-4mm in diameter. They are specific for endocarditis.
what is the pathology behind Janeway lesions
the lesion is in the dermis, and made up of necrotic tissue with inflammatory infiltrate.
the epidermis is not affected and they are caused by septic emboli
when do they most commonly occur
in endocarditis that is Staphylococcal in origin
what are Osler’s nodes
these are painful red lesions on the palms and soles.
what are Osler’s nodes caused by
immune complex deposition.
this causes a localised immune response, resulting in a tender red swelling.
what is the main difference between Osler’s and Janeway nodes
The main difference between Osler’s nodes and Janeway lesions is that Osler’s nodes are tender and janeway lesions are not!
what are Roth spots
these are retinal haemorrhages with a pale or yellow centre
what is the most common causatory organism
Staphylococcus Auerus is the most common causatory organism. Gram-positive tend to be more common than Gram-negative, because Gram- positive have better adherence to endocardium.
what is Q fever
this is disease caused by coxiella burnetti and is most commonly found in people who have been working with farm animals; it is also found in cats and dogs. It is highly infectious. It most commonly affects the aortic valve, and there may be liver complications and purpura. Life-long antibiotic therapy may be required.
what is brucella and where will it affect
Brucella is associated with contact with goats, and will often affect the aortic valve.
what criteria do we use for definitive information on making a diagnosis of infective endocarditis
the Duke criteria
what is the Major Duke criteria
Positive blood culture for infective organisms (on 2 separate tests if >12 hours apart, or on 3/3 or 3/4 tests >1 hour apart)
Evidence of IR from other tests:
Echocardiogram shows:
- strictures, unusual blood flow, implanted /unusual material
- Abscesses
New valve regurgitation
what is the minor Duke criteria
Fever >38’C
Predisposition to IE; e.g. IV drug user, congenital heart condition, prosthetic valve
Unusual echo, but not with findings stated above
Immunological factors present; Roth spots, Osler’s nodes, glomerulonephritis, rheumatoid factor
Blood cultures positive, but major criteria not satisfied
Vascular abnormalities; embolism, aneurysm, infarcts, conjunctival haemorrhage, intracranial haemorrhage etc
when is Infective endocarditis definitely present
2 major criteria present OR
1 major criteria, 3 minor criteria OR
5 minor criteria
when is infective endocarditis possibly present
1-4 minor criteria AND
No other more likely diagnosis
what does TTE stand for
Transthoracic echocardiography
what is TTE
this is rapid and non-invasive, and has a high specificity for visualising vegetations, however, the sensitivity is only 60-70%
which test has a higher sensitivity than the TTE
the TOE test - as it may identify vegetations of 1mm or above
what would an ECG in infective endocarditis show
may show signs of MI and conduction defects
a new AV block is suggestive of abscess formation
this test should be performed on admission and throughout hospital stay
what may a CXR show
evidence of heart failure and cardiomegaly.
in RSHF there may be pulmonary emboli and/or abcesses.
a combination of sepsis and pulmonary infiltrates on the CXR is highly suggestive of right sided endocarditis
what is the general treatment recommendation for acute presentation of IE
flucloxacillin, gentamycin
what is the general treatment recommendations for a subacute presentation of IE
benzylpenicillin, gentamycinwhat
is the general treatment recommendation for prosthetic valve / resistant organism in IE
triple therapy of vancomycin, gentamycin and rifampicin
what is the usual substitute if person has a penicillin allergy
vancomycin is used
what are the indications for surgery
IE resistant to antibiotic treatment
Often Gram-negative disease
Fungal disease resistant to treatment
IE causing embolic events
IE with CHF
Severe structural damage on echo
what are the classical peripheral signs you should look for with infective endocarditis
Petechiae - Common but nonspecific finding (remember to look at the mucosa)
Subungual (splinter) haemorrhages - Dark red linear lesions in the nail beds
Osler nodes - Tender subcutaneous nodules usually found on the distal pads of the digits
Janeway lesions – Non-tender maculae on the palms and soles
Roth spots - Retinal haemorrhages with small, clear centres; rare and observed in only 5% of patients.§
what specific diagnostic criteria are used to make a diagnosis of infective endocarditis
Modified Duke criteria for diagnosis of infective endocarditis are the clinical criteria and requires either of the following:
2 major criteria
1 major and 3 minor criteria
5 minor criteria.
what does blood culture-negative infective endocarditis
Blood culture-negative Infective Endocarditis (BCNIE) refers to Infective Endocarditis (IE) in which no causative micro-organism can be grown. BCNIE can occur in up to 31% of all cases of IE and most commonly arises as a consequence of previous antibiotic administration.
what is the main focus of endocarditis management
Early identification
Blood cultures from 3 separate sites before antibiotic administration (unless the patient is septic)
Transthoracic echo (TTE) is first line imaging modality
Transoesophageal echo (TOE) is used where there is high suspicion of IE but TTE is not confirmatory
Referral to endocarditis MDT
Assessment of embolic complications
Timing of surgery (in case of need for valve repair or replacement)
