Infective Endocarditis (2*)

Question 1

Which factors increase the risk?

Which co-morbid conditions increase the risk?

What are the most common causes?

Answer 1

➊ • Age, Male
• Poor dentition and dental infections
• IVDU

➋ • Valvular HD
• Prosthetic valves
• IV devices .e.g. central lines, shunts
• Haemodialysis
• HIV

➌ • Staph (most common)
• Strep
• Entero

Question 2

Outline its pathophysiology

Answer 2

(1) Transient Bacteraemia – Can occur from e.g. poor dentition, dental infections, prosthetic valve, IVDU
(2) Damage to valve
(3) Formation of vegetations – When this happens, the endothelium is exposed, leading to thrombus formation around the central cluster of the pathogen = Vegetation
• This makes it hard for the immune system to remove the pathogen (endocardium is also poorly vascularised) – So, a prolonged course of strong Abx is needed to treat
• These vegetations have potential to embolise and cause further complications

N.B. Immune complexes can be formed and deposited in organs like the kidneys, skin and eyes (T3 hypersensitivity)

Question 3

Presentation:
What are the 2 main symptoms at which you should suspect IE?

What may be found O/E?

Answer 3

N.B. Presentation is diverse and variable – Can present acutely and progress rapidly w/symptoms of HF (typically on normal valves), or it can present subacutely/chronically w/non-specific symptoms (typically on abnormal/prosthetic valves)

➊ • Fever
• New/changing heart murmur

➋ • Tachycardia
• Splinter haemorrhages
• Osler nodes/Janeway lesions

Question 4

Investigations:
Why should an ECG be done?
→ What does this indicate?
→ What needs to be done if this is found?

What other investigations need to be done?

What are other indicators for surgical intervention?

Answer 4

➊ To exclude 1st degree AV Block (Prolonged PR Interval)
→ Aortic root abscess, which is a rare complication of IE
→ Surgical repair

➋ ● Blood culture – 3 sets taken 30 mins apart from 3 separate peripheral sites
● Bloods – FBC, CRP, U&E, LFT
● Echo - 1st line imaging
● Urine dip – Check for renal involvement

➌ ● Extensive valve damage
● Prosthetic valve endocarditis
● Persistent infection despite medical therapy
● Large vegetations
● Serious embolisation
● Fungal endocarditis
● Progressive cardiac failure

Question 5

How is it managed?

What are the complications?

Answer 5

➊ Long-term IV Abx

➋ • Aortic root abscess (1st degree HB/Prolonged PR)
• Acute valvular insufficiency → HF
• Embolic complications e.g. stroke
• Infection e.g. osteomyelitis, septic arthritis