Infective Endocarditis Flashcards
Define infective endocarditis
DEFINITION: infection of intracardiac endocardial structures (mainly heart valves)
Explain the aetiology/risk factors of infective endocarditis
Streptococci (40%) - mainly a-haemolytic S. viridans and S. bovis
Staphylococci (35%) - S. aureus and S. epidermidis
Enterococci (20%) - usually E. faecalis
Other organisms:
- Haemophilus
- Actinobacillus
- Cardiobacterium
- Coxiella burnetii
- Histoplasma (fungal)
Pathophysiology
Vegetations form when organisms deposit on the heart valves during a period of bacteraemia
The vegetations are made up of platelets, fibrin and infective organisms
They destroy valve leaflets, invade the myocardium or aortic wall leading to abscess cavities
Activation of the immune system can lead to the formation of immune complexes –> vasculitis, glomerulonephritis, arthritis
Risk Factors
Abnormal valves (e.g. congenital, calcification, rheumatic heart disease)
Prosthetic heart valves
Turbulent blood flow (e.g. patent ductus arteriosus)
Recent dental work/poor dental hygiene (source of S. viridans)
Summarise the epidemiology of infective endocarditis
UK Incidence: 16-22/1 million per year
Recognise the presenting symptoms of infective endocarditis
Fever with sweats/chills/rigors
NOTE: this might be relapsing and remitting
Malaise
Arthralgia
Myalgia
Confusion
Skin lesions
Ask about recent dental surgery or IV drug use
Recognise the signs of infective endocarditis on physical examination
Pyrexia
Tachycardia
Signs of anaemia
Clubbing
New regurgitant murmur or muffled heart sounds
Frequency of heart murmurs:
Mitral > Aortic > Tricuspid > Pulmonary
Splenomegaly
Vasculitic Lesions
Roth spots on retina
Petechiae on pharyngeal and conjunctival mucosa
Janeway lesions (painless macules on the palms which blanch on pressure)
Osler’s nodes (tender nodules on finger/toe pads)
Splinter haemorrhages
Identify appropriate investigations for infective endocarditis
Bloods Urinalysis Blood Culture Echocardiography Duke's Classification
Generate a management plan for infective endocarditis
Antibiotics for 4-6 weeks
On clinical suspicion = EMPIRICAL TREATMENT
- Benzylpenicillin
- Gentamicin
Streptococci - continue the same as above
Staphylococci
- Flucloxacillin/vancomycin
- Gentamicin
Enterococci
- Ampicillin
- Gentamicin
Culture Negative
- Vancomycin
- Gentamicin
SURGERY - urgent valve replacement may be needed if there is a poor response to antibiotics
Bloods
FBC - high neutrophils, normocytic anaemia
High ESR/CRP
U&Es
NOTE: a lot of patients with infective endocarditis tend to be rheumatoid factor positive
Urinalysis
Microscopic haematuria
Proteinuria
Blood Culture
Do microscopy and sensitivities as well
Echocardiography
Transthoracic or transoesophageal (produces better image)
Duke’s Classification
A method of diagnosing infective endocarditis based on the findings of the investigations and the symptoms/signs
