Infective Endocarditis

Question 1

Define infective endocarditis.

Answer 1

Infection involving the endocardial structures of the heart (mainly the valves)

Question 2

Outline the pathophysiology of infective endocarditis.

Answer 2

Bacterial infection of valves leads to deposition of platelets and fibrin on the collagen of the valves, as well as infective bacteria.
These vegetations can lead to destruction of valve leaflets, abscesses, invasion of myocardium and aortic wall.

Question 3

What are some possible cardiac complications of infective endocarditis?

Answer 3

• Valve incompetence
• Abscess
• Intracardiac fistulae
• Aneurysm
• Heart failure

Question 4

What are some possible systemic complications of infective endocarditis?

Answer 4

• Renal failure
• Glomerulonephritis
• Arterial emboli: brain, lungs, spleen, kidneys

Question 5

What are the causative organisms for infective endocarditis?

Answer 5

• Strep viridans/Strep bovis (40%)
• Staph aureus/Staph epidermis in IVDA (35%)
• Enterococci faecalis (20%)
• HACEK organisms: Haemophilus, Actinobacillus, Cardiobaterium, Eikenella, Kingella

Question 6

What are some risk factors for infective endocarditis?

Answer 6

• Abnormal heart valve: congenital defects, calcification
• Turbulent flow: Patent ductus arteriosus, ventricular septal defect
• Recent dental procedures/IVDA

Question 7

How does infective endocarditis present (symptoms)?

Answer 7

• Fever, malaise, chills, sweats, rigors
• Dyspnoea
• Myalgia, arthralgia, headaches

Question 8

List some signs of infective endocarditis.

Answer 8

• Pyrexia, tachycardia, anaemia

- Vascular signs: Janeway lesions, Osler’s nodes, splinter haemorrhages, Roth spots

Question 9

How would you investigate infective endocarditis:

Answer 9

BLOODS

• FBC: leukocytosis, normocytic anaemia
• U&Es: Raised urea
• Raised CRP and ESR
• Rheumatoid factor test may be positive

BLOOD CULTURES
- Need 3 separate cultures, each 1h apart

URINE
- Haematuria, proteinuria

ECG

• Long PR interval
• ST abnormalities

ECHO
- valvular degeneration (better transoesophageal)

Question 10

How would you manage infective endocarditis empirically?

Answer 10

Benzylpenicillin and gentamicin

Question 11

How would you manage IE due to a Strep infection?

Answer 11

Benzylpenicillin and gentamicin

Question 12

How would you manage IE due to a Staph infection?

Answer 12

Flucloxacillin/vancomycin and gentamicin

Question 13

How would you manage IE due to an Enterococcal infection?

Answer 13

Ampicillin and gentamicin

Question 14

How would you manage IE due to a HACEK infection?

Answer 14

Ampicillin and gentamicin

Question 15

How would you manage IE with a negative blood culture?

Answer 15

Vancomycin and gentamicin

Question 16

What is the diagnostic criteria for IE?

Answer 16

Duke’s score:
Need 3 major signs OR 1 major and 2 minor OR 5 minor

Major Signs

• 2 separate positive blood cultures
• Echo showing valvular vegetation/abscess

Minor Signs

• Pyrexia >38
• Presence of risk factors
• Positive blood culture
• Positive echo
• Vascular signs

Question 17

When would you carry out a valve replacement in IE?

Answer 17

If the patient continues to deteriorate, despite antibiotic treatment

Question 18

What is the prognosis of IE?

Answer 18

If treated: 15-20% mortality

If untreated: can be fatal