Infective Endocarditis

Question 1

What is the definition of infective endocarditis?

Answer 1

Infection of intracardiac endocardial structures (mainly heart valves)

Question 2

What is the aetiology 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)

Question 3

What is the pathophysiology of infective endocarditis?

Answer 3

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

Question 4

What are the risk factors associated with infective endocarditis?

Answer 4

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 5

What is the epidemiology of infective endocarditis?

Answer 5

UK Incidence: 16-22/1 million per year

Question 6

What are the presenting symptoms of infective endocarditis?

Answer 6

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 7

What are the signs of infective endocarditis upon physical examination?

Answer 7

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

Question 8

What are the appropriate investigations for infective endocarditis?

Answer 8

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

Question 9

What is the management plan for infective endocarditis?

Answer 9

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 10

What are the possible complications of infective endocarditis?

Answer 10

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 11

What is the prognosis for patients with infective endocarditis?

Answer 11

FATAL if untreated

15-30% mortality even WITH treatment