Infective endocarditis (CV) Flashcards
Define infective endocarditis.
Infection of the endocardium (including valvular structures, chordae tendineae, sites of septal defects or the mural endocardium) that typically affects one or more heart valves
Which groups is infective endocarditis most common in? (2)
- M>F
- > 60 years old
List the valves in the order of likeliness of being affected in infective endocarditis from most to least.
MATP
- mitral
- aortic
- tricuspid (but most likely affected in IVDU)
- pulmonary
Which valve is most likely affected in IVDU-infective endocarditis?
Tricuspid valve
What is the pathophysiology of infective endocarditis?
- vegetations (platelets, fibrin, infective organisms) form when organisms deposit on the valves during a period of bacteraemia
- they destroy valve leaflets, invade myocardium or aortic wall –> abscess cavities
- activation of the immune system can lead to formation of immune complexes –> vasculitis, glomerulonephritis, arthritis
Describe the course of infective endocarditis.
Follows an acute course, presenting with acute heart failure +/- emboli
(Can also be subacute)
What is the most common causative agent of acute infective endocarditis?
Staphylococcus aureus
List risk factors for infective endocarditis caused by S. aureus. (2)
- patients with prosthetic valves
- IV drug use
What is commonly the causative agent of infective endocarditis if <2 months post-valve surgery?
Staphylococcus epidermidis
What is the most common causative agent of subacute infective endocarditis?
Streptococcus viridans (a-haemolytic) - mainly affects pre-damaged native valves, commonly caused by dental procedures
What is commonly the causative agent of infective endocarditis associated with GI malignancy?
Streptococcus bovis
What is atrial myxoma (differential to infective endocarditis)?
Benign tumour most common in LA - presence of mass on echocardiogram distinguishes it from IE
- mitral valve obstruction (mid-diastolic murmur)
- systemic embolisation
- constitutional symptoms
What are the clinical features of infective endocarditis? (8)
- fever/chills
- new cardiac murmur
- dyspnoea on exertion
- night sweats, malaise, fatigue, anorexia, weight loss, myalgias
- weakness
- arthralgias
- headache
- skin lesions
What may you find on examination in infective endocarditis? (10)
- embolic phenomena:
- splinter haemorrhages (under fingernails)
- Janeway lesions (painless macule on palms and soles, blanch)
- vasculitic lesions due to immune complex depositions:
- Osler nodes (painful nodules on finger/toe pads)
- Roth spots (white centred retinal haemorrhage on fundoscopy caused by septic emboli)
- petechiae on pharyngeal and conjunctival mucosa
- glomerulonephritis
- new cardiac murmur (MATP)
- pyrexia + tachycardia
- clubbing
- signs of anaemia
What acronym can we use to remember the signs of infective endocarditis?
FROM JANE C:
- Fever
- Roth spots
- Osler nodes
- Murmur
- Janeway lesions
- Anaemia
- Nail - splinter haemorrhages
- Emboli
- Clubbing
What are some risk factors for infective endocarditis? (6)
- prosthetic heart valves
- abnormal heart valves (e.g. congenital, calcification, rheumatic heart disease)
- dental procedures (/hygiene)
- IV drug use (more likely to present with right-sided valve problems)
- structural congenital heart disease
- turbulent blood flow
What are the first-line investigations for infective endocarditis? (4)
- blood cultures
- echocardiography (transthoracic first-line, transoesophageal better image)
- FBC
- CRP
What do we do before commencing Abx therapy for infective endocarditis?
- obtain 3 sets of blood cultures from different sites at 30-minute intervals prior to Abx initiation
- if patients is very unwell do not delay empirical Abx therapy while waiting to take 3 sets
- repeat 4-72h after treatment to assess effectiveness
What is the most sensitive diagnostic test for infective endocarditis?
- transthoracic echo - valvular, mobile vegetations
- do transoesophageal echo (better image) if:
- prosthetic valve/intracardiac device
- transthoracic echo comes back negative
What would FBC show in infective endocarditis?
High neutrophils, normocytic anaemia
What might ECG show in infective endocarditis? (3)
- prolonged PR interval
- non-specific ST/T wave abnormalities
- AV block
What diagnostic criteria is used for infective endocarditis?
Duke criteria for infective endocarditis:
- definitive diagnosis: 2 majors OR 1 major+3 minor OR 5 minor
- possible diagnosis: 1 major+1 minor OR 3 minor
What acronym helps us remember the major and minor Duke criteria for infective endocarditis?
BE TIMER
What are the major Duke criteria for infective endocarditis? (2)
BE (TIMER)
- Blood culture positive >/=2 times 12hrs apart for typical microorganism consistent with IE, or single positive culture for Coxiella burnetti or positive antibody titre
- Echocardiogram +ve for IE - vegetation, abscess, partial dehiscence of prosthetic valve, new valvular regurgitation
- (PET-CT shows abnormal activity around site of prosthetic valve)
- (cardiac CT shows paravalvular lesions)
What are the minor Duke criteria for infective endocarditis? (5)
(BE) TIMER
- Temperature >38C (fever)
- Immunological phenomena - Osler’s nodes, Roth spots, RF, glomerulonephritis
- Microbiological evidence - blood culture not meeting major criteria, serological evidence of active infection with organism consistent with IE
- Embolic (vascular) phenomena - arterial/septic emboli, infarcts, intracranial/conjunctival/splinter haemorrhages, Janeway lesions
- Risk factors - predisposing heart condition or IVDU
What signs on echocardiogram indicate infective endocarditis (major Duke criteria)? (4)
- vegetation
- abscess
- partial dehiscence of prosthetic valve
- new valvular regurgitation
What are some immunological phenomena seen in infective endocarditis (minor Duke criteria)? (4)
- Osler’s nodes
- Roth spots
- rheumatoid factor
- glomerulonephritis
What are some embolic phenomena seen in infective endocarditis (minor Duke criteria)? (4)
- arterial/septic emboli
- infarcts
- intracranial/conjunctival/splinter haemorrhages
- Janeway lesions
What are some differential diagnoses for infective endocarditis? (4)
- rheumatic fever
- atrial myxoma - waxing and waning symptoms, echo shows mass, mid-diastolic murmur
- Libman-Sacks endocarditis - asymptomatic, autoantibody profile
- non-bacterial thrombotic endocarditis - produced by tumours, underlying hypercoagulable state
How do you manage suspected infective endocarditis?
- supportive care (fluids + O2) AND
- blood cultures first AND
- broad-spectrum (empirical) Abx: benzylpenicillin, gentamicin
- native valve: amoxicillin +/- gentamicin
- if penicillin allergic/MRSA/severe sepsis: vancomycin + gentamicin
- prosthetic valve: vancomycin + gentamycin + rifampicin
- consider valve replacement surgery if IE causing congestive HF
What Abx is used for S. aureus infective endocarditis, if patient has a native valve?
Flucloxacillin
If penicillin allergic/MRSA - vancomycin + rifampicin
What Abx is used for S. aureus infective endocarditis, if patient has a prosthetic valve?
Flucloxacillin + low-dose gentamicin + rifampicin
If penicillin allergic/MRSA - replace flucloxacillin with vancomycin
What Abx is used for Staphylococcus epidermidis infective endocarditis?
Vancomycin - since coagulase -ve Staphylococci are resistant to flucloxacillin
What Abx is used for Streptococcus viridans (or other fully-sensitive Streptococci) infective endocarditis?
Benzylpenicillin
(Add low-dose gentamicin if less sensitive Streptococci)
If penicillin-allergic: vancomycin + low-dose gentamicin
What are some indications for urgent valvular replacement (surgery) in infective endocarditis? (6)
- PR interval prolongation - indicates aortic abscess
- severe valvular incompetence
- infections resistant to Abx/fungal infections
- cardiac failure refractory to standard medical treatment (severe congestive HF)
- recurrent emboli after Abx therapy
- pregnancy
What are some complications of infective endocarditis? (8)
- valve incompetence
- intracardiac fistulae/abscesses
- aneurysm
- heart failure
- renal failure
- glomerulonephritis
- splenic abscess
- arterial emboli from vegetations breaking off –> brain (ischaemic stroke), kidneys, lung, spleen
What is the best indicator of prognosis in infective endocarditis?
Heart failure
