Infective endocarditis

Question 1

Define infective endocarditis

Answer 1

Infection of intracardiac endocardial structures (mainly

heart valves)

Question 2

Explain the aetiology/risk factors of infective endocarditis

Answer 2

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)

Vegetations form when organisms deposit on the heart valves during a period of bacteraemia, made 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)

Question 3

Summarise the epidemiology of infective endocarditis

Answer 3

UK Incidence: 16-22/1 million per year

Question 4

Recognise the presenting symptoms of infective endocarditis

Answer 4

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

Question 5

Recognise the signs of infective endocarditis on physical examination

Answer 5

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 haemorrhage

Question 6

Identify appropriate investigations for infective endocarditis

Answer 6

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

Question 7

Generate a management plan for infective endocarditis

Answer 7

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

Question 8

Identify the possible complications of infective endocarditis

Answer 8

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

Question 9

Summarise the prognosis for patients with infective endocarditis

Answer 9

FATAL if untreated

15-30% mortality even WITH treatment