Infective Endocarditis Flashcards
Define
DEFINITION: infection of intracardiac endocardial structures (mainly heart valves)
Causes
Most common organisms causing 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)
Epidemiology
UK Incidence: 16-22/1 million per year
Symptoms
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
Signs
gnise 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
Investigations
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
Management
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
Complications
Valve incompetence
Intracardiac fistulae or abscesses
Aneurysm
Heart failure
Renal failure
Glomerulonephritis
Arterial emboli from the vegetations shooting to the brain, kidneys, lungs and spleen
Prognosis
FATAL if untreated
15-30% mortality even WITH treatment
