Infective Endocarditis

Question 1

What is infective endocarditis?

Answer 1

When the inner lining of the heart (the endocardium) becomes inflamed secondary to an infection.

Question 2

What are risk factors for IE?

Answer 2

Age > 60 years
Male sex
Intravenous drug use - predisposition to Staph. aureus infection and right-sided valve disease e.g. tricuspid endocarditis
Poor dentition and dental infections

Question 3

What comorbidities increase the risk of IE?

Answer 3

Valvular disease (Rheumatic heart disease, mitral valve prolapse, aortic valve disease and other abnormalities)

Congenital heart disease

Prosthetic valves

Previous history of infective endocarditis

Intravascular devices e.g. central catheters, shunts

Haemodialysis

HIV infection

Question 4

What three key factors occurring simultaneously for IE to develop?

Answer 4

Transient bacteraemia
Damage to valvular tissue
Formation of vegetations

Question 5

What is the most common bacterial organism that is linked to IE?

Answer 5

Staphylococcus aureus is particularly linked to endocarditis in patients with prosthetic valves, acute endocarditis and intravenous drug use

Question 6

What gram +ve bacteria can cause IE?

Answer 6

Staphylococci (e.g. Staph aureus)
Streptococci (e.g. Strep viridans, Strep intermedius, Groups A, B, C, D, G)
Enterococci

Question 7

What gram -ve bacteria can cause IE?

Answer 7

HACEK organisms*
Non-HACEK organisms (e.g. Pseudomonas aeruginosa, Neisseria elongata)

*Haemophilus spp., Aggregatibacter actinomycetemcomitans, Cardiobacterium spp., Eikenella corrodens, Kingella kingae

Question 8

What fungi can cause IE?

Answer 8

Candida
Aspergillus

Question 9

Symptoms of IE

Answer 9

Fever is the most common symptom
Anorexia
Weight loss
Headache
Myalgia
Arthalgia
Night sweats
Abdominal pain
Cough
Pleuritic pain

Question 10

Signs of IE

Answer 10

Murmurs are also common. A patient with a fever and new murmur should always raise the suspicion of infective endocarditis.

Clinical signs of infective endocarditis include:

Janeway lesions - nontender macules on palms and soles
Osler nodes - tender subcutaneous nodules on the finger pads and toes
Roth spots - exudative haemorrhagic retinal lesions with pale centres
Microscopic haematuria and glomerulonephritis
Splinter haemorrhages
PR prolongation or complete AV block - sign of aortic root abscess

Question 11

Localised complications of IE

Answer 11

Valve destruction
Heart failure (secondary to valve regurgitation)
Arrhythmias and conduction disorders (e.g. AV block)
Myocardial infarction
Pericarditis
Aortic root abscess

Question 12

Systemic complications of IE

Answer 12

Emboli (e.g. stroke, splenic infarction)
Immune complex deposition (e.g. glomerulonephritis)
Septicaemia
Death

Question 13

IE prognosis

Answer 13

Patients who are elderly, who have multiple comorbidities and those who have prosthetic valves generally have worse outcomes, as do those with severe complications from endocarditis such as heart failure or stroke.

Question 14

First line investigation in IE

Answer 14

Blood culture - to be taken before antibiotics have been prescribed

The European Society of Cardiology (ESC) recommends that three sets of blood cultures (i.e. six bottles in total) should be taken, at least 30 mins apart, from three separate peripheral sites.

Question 15

What is used for IE diagnosis?

Answer 15

Duke criteria

Suspected cases can be definite IE, possible IE and rejected IE

Question 16

Major criteria - blood culture

Answer 16

Positive for typical microorganisms on two or more separate occasions including Strep viridans, Strep bovis, HACEK group, Staph aureus, Community-acquired enterococci (in the absence of a primary focus)

Persistently positive cultures for microorganisms consistent with IE: ≥2 positive blood cultures of blood samples drawn >12 h apart or all of 3 or a majority of ≥4 separate cultures of blood (with and last samples drawn ≥1 h apart)

A single positive culture for Coxiella burnetti or high antibody titre (>1:800)

Question 17

Major criteria - Evidence of endocardial involvement

Answer 17

Intra-cardiac vegetation (oscillating intracardiac mass)
Abscess
New valvular regurgitation (change in pre-existing murmurs is not included)
New partial dehiscence of prosthetic valve

Question 18

Minor criteria

Answer 18

Risk factors for infective endocarditis (see risk factors section)
Fever > 38oC
Vascular phenomena: septic emboli, Janeway lesions, conjunctival haemorrhage, intracranial haemorrhage
Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots, positive rheumatoid factor
Microbiological evidence: positive blood cultures which do not meet the major criteria

Question 19

How can you make a diagnosis of definite endocarditis?

Answer 19

To make a definite (i.e. confirmed) diagnosis of endocarditis, ONE of the following is required:

Direct evidence of infective endocarditis by histology or culture of organisms (e.g. from a vegetation)
TWO major criteria
ONE major + THREE minor criteria
FIVE minor criteria

Question 20

How can you make a diagnosis of possible endocarditis?

Answer 20

Endocarditis is possible when there are:

ONE major and ONE minor criterion
THREE minor criteria
In other words, there is some evidence of endocarditis, but not enough to make a definite diagnosis.

Question 21

When is a diagnosis of endocarditis rejected?

Answer 21

A diagnosis of endocarditis is rejected when there is:

A firm alternative diagnosis or
Sustained symptom resolution after <4 days of antibiotics

Question 22

What is the main stay of management?

Answer 22

The main stay of management is long term IV antibiotics (approximately 6 weeks minimum).

Question 23

What are indications for surgical repair?

Answer 23

Haemodynamic instability
Severe heart failure
Severe sepsis despite antibiotics
Valvular obstruction
Infected prosthetic valve
Persistent bacteraemia
Repeated emboli
Aortic root abscess

Question 24

What ECG change in a IE patient is an indication for surgery and why?

Answer 24

PR interval prolongation in a patient with Infective Endocarditis is an indication for surgery as it can be secondary to aortic root abscess