Week Four - Case Two

Question 1

what is infective endocarditis

Answer 1

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

Question 2

where will staph. aureus commonly infect in IV drug users

Answer 2

most commonly infect the tricuspid valve

Question 3

what is the epidemiology of infective endocarditis

Answer 3

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.

Question 4

what is the mortality rate without treatment

Answer 4

close to 100%

Question 5

what are the valvular damage risk factors for infective endocarditis

Answer 5

previous rheumatic heart disease

age related valvular degeneration

prosthetic valve

Question 6

what is the risk factor with IV drug use

Answer 6

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

Question 7

what does endocardial damage lead to

Answer 7

the formation of thrombi at the damaged site

Question 8

what is the thrombus mainly made up of

Answer 8

platelets and fibrin

Question 9

where does the endocardial damage tend to occur

Answer 9

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.

Question 10

where do these thrombi and IE tend to occur

Answer 10

at sites of high haemodynamic pressure, due to the increased shearing force in these areas.

Question 11

what are the two factors that are essentially required for infective endocarditis

Answer 11

1. 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
2. abnormal/unusual endocardial tissue

Question 12

what do we call it when a thrombi has been colonised by bacteria

Answer 12

vegetation

Question 13

why is infective endocarditis particularly hard to treat with antibiotics

Answer 13

because the platelets and fibrin in the vegetation prevent antibiotic agent, and white blood cells from being in direct contact with the bacteria

Question 14

what valves are most commonly affected and why

Answer 14

the aortic and mitral valves are most commonly affected because these exist in a higher pressure system than the tricuspid and pulmonary valves

Question 15

what infection is more common in drug users

Answer 15

right sided infection - although the mechanism for this is poorly understood

Question 16

what two symptoms mean it is endocarditis until proven otherwise

Answer 16

if the patient has a new murmur and a fever

Question 17

what is SBE

Answer 17

IE most commonly presents sub-acute with an insidious course. in this instance it is sometimes refer to as sub-acute bacterial endocarditis

Question 18

what is the acute presentation of IE

Answer 18

Fever + new heart murmur (90%)
Petechiae (50%)

Question 19

what are petechiae

Answer 19

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

Question 20

what are petechiae caused by

Answer 20

bleeding under the skin - they are non-blanching

Question 21

what type of failure can develop rapidly

Answer 21

Cardiac / renal failure can develop rapidly (50-70%)

Haematuria secondary to renal failure present in about 70% of patients

Question 22

what are splinter haemorrhages

Answer 22

red lines that run vertically along the nails.

a non-specific sign often associated with rheumatologic conditions as well as infective endocarditis

Question 23

what is the sub-acute presentation

Answer 23

the above +
rigours
fever
splenomegaly

Question 24

what infection causes an enlarged liver and spleen

Answer 24

coxiella infection

Question 25

what are Osler's nodes

Answer 25

these are painful swellings at the fingertips; commonly due to vasculitis

Question 26

what are Janeway lesions

Answer 26

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.

Question 27

what is the pathology behind Janeway lesions

Answer 27

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

Question 28

when do they most commonly occur

Answer 28

in endocarditis that is Staphylococcal in origin

Question 29

what are Osler's nodes

Answer 29

these are painful red lesions on the palms and soles.

Question 30

what are Osler's nodes caused by

Answer 30

immune complex deposition. this causes a localised immune response, resulting in a tender red swelling.

Question 31

what is the main difference between Osler's and Janeway nodes

Answer 31

The main difference between Osler’s nodes and Janeway lesions is that Osler’s nodes are tender and janeway lesions are not!

Question 32

what are Roth spots

Answer 32

these are retinal haemorrhages with a pale or yellow centre

Question 33

what is the most common causatory organism

Answer 33

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.

Question 34

what is Q fever

Answer 34

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.

Question 35

what is brucella and where will it affect

Answer 35

Brucella is associated with contact with goats, and will often affect the aortic valve.

Question 36

what criteria do we use for definitive information on making a diagnosis of infective endocarditis

Answer 36

the Duke criteria

Question 37

what is the Major Duke criteria

Answer 37

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

Question 38

what is the minor Duke criteria

Answer 38

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

Question 39

when is Infective endocarditis definitely present

Answer 39

2 major criteria present OR 1 major criteria, 3 minor criteria OR 5 minor criteria

Question 40

when is infective endocarditis possibly present

Answer 40

1-4 minor criteria AND No other more likely diagnosis

Question 41

what does TTE stand for

Answer 41

Transthoracic echocardiography

Question 42

what is TTE

Answer 42

this is rapid and non-invasive, and has a high specificity for visualising vegetations, however, the sensitivity is only 60-70%

Question 43

which test has a higher sensitivity than the TTE

Answer 43

the TOE test - as it may identify vegetations of 1mm or above

Question 44

what would an ECG in infective endocarditis show

Answer 44

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

Question 45

what may a CXR show

Answer 45

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

Question 46

what is the general treatment recommendation for acute presentation of IE

Answer 46

flucloxacillin, gentamycin

Question 47

what is the general treatment recommendations for a subacute presentation of IE

Answer 47

benzylpenicillin, gentamycinwhat

Question 48

is the general treatment recommendation for prosthetic valve / resistant organism in IE

Answer 48

triple therapy of vancomycin, gentamycin and rifampicin

Question 49

what is the usual substitute if person has a penicillin allergy

Answer 49

vancomycin is used

Question 50

what are the indications for surgery

Answer 50

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

Question 51

what are the classical peripheral signs you should look for with infective endocarditis

Answer 51

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.§

Question 52

what specific diagnostic criteria are used to make a diagnosis of infective endocarditis

Answer 52

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.

Question 53

what does blood culture-negative infective endocarditis

Answer 53

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.

Question 54

what is the main focus of endocarditis management

Answer 54

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)