Infective endocarditis

Question 1

What is infective endocarditis?

Answer 1

Infection of intracardiac endocardial structures - mainly heart valves

Question 2

Name 3 organisms that can cause infective endocarditis

Answer 2

Streptococci
Staphylococci
Enterococci

Question 3

Explain the pathophysiology behind infective endocarditis?

Answer 3

During a period of bacteraemia - vegetations form.

These vegetations consist of platelets, fibrin and infective organisms - deposited on heart valves.

They may destroy valve leaflets/invade myocardium/

Question 4

What are the risk factors for infective endocarditis

Answer 4

Cardiac factors: previous endocarditis, prosthetic valve/ICD, valvular or congenital heart disease

Non cardiac factors: IV drug use, IV catheter, recent surgical/dental procedure (basically anything that creates an opening for microbes to enter)

Question 5

Infective endocarditis can be classified as native valve endocarditis/prosthetic valve endocarditis. What causes native valve endocarditis and what causes prosthetic valve endocarditis?

Answer 5

Native valve endocarditis: Staph aureus, viridans streptococci. Seen often in IV drug users

Prosthetic valve endocarditis: MRSA. Typically nosocomial (originates in hospital)

Question 6

What signs and symptoms does infective endocarditis present with?

Answer 6

Fever, fatigue, dyspnea, weight loss. Also causes splinter haemorrhages and Janeway lesions

Typically acute infection (within 2 weeks) but not always

Heart murmur upon auscultation

Question 7

Splinter haemorrhages and janeway lesions are clinical signs of infective endocarditis. How are they caused?

Answer 7

Vegetations may break off from valves and cause septic emboli.

These septic emboli lodge into fingernails –> splinter haemorrhages

Or the emboli lodge into palms of hands/feets –> janeway lesions

Question 8

Aside from fever, fatigue, weight loss and dyspnea, or splinter haemorrhages/janeway lesions, what other symptoms/signs can infective endocarditis cause

Answer 8

Brain embolisation causing an embolic stroke or intracerebral haemorrhage

Or arterial emboli, pulmonary infarcts or conjunctival haemorrhage

Question 9

Sometimes, infective endocarditis causes the body to produce bacterial antigen-antibody complexes which can be deposited. What clinical signs may this manifest as?

Answer 9

Oslers nodes (hands/feet) or Roth’s spots (in the eyes) - THESE are “autoimmune”

Can also manifest as glomerulonephritis in the kidneys

Question 10

What is the first step in diagnosing someone with infective endocarditis?

Answer 10

Investigation taking 3 blood culture samples - to test for aerobic bacteria, anaerobic bacteria and fungi

Question 11

What scan is also done to help diagnose infective endocarditis?

Answer 11

Echocardiography
Usually trans thoracic echo done before trans oesophageal

But sometimes (prosthetic valve/ICD/valve abnormalities prior/obesity/chest wall deformity) transoesophageal done first

Question 12

Diagnosis of infective endocarditis is based off Dukes criteria. What is the first major criterion?

What is the second main criteria

Answer 12

Microbiological evidence of organism

Seeing evidence of endocardial disease - e.g. new valvular regurgitation / echo showing vegetation abscess, or partial dehiscence of prosthetic valve

Question 13

If infective endocarditis is suspected, an ECG is done. What should you look for on the ECG

Answer 13

1. Any signs of heart block,
2. PR Delay with isolated prolonged PR interval
3. Signs of cardiac ischaemia may suggest septic emboli has leaked into coronary circulation

Question 14

How is infective endocarditis treated?

Answer 14

With high dose bactericidal antibiotics for 6 weeks

Typically ampicillin-sulbactam and gentamicin

If patient can’t tolerate beta-lactams, give vancomycin, gentamicin and ciprofloxacin