Wk 33: Infective endocarditis

Question 1

Which side of the heart does infective endocarditis usually affect?

Answer 1

Left side

• Right: IV drug abuse

Question 2

What are the risk factors of infective endocarditis?

Answer 2

• Rheumatic + congenital HD
• Prosthetic valves + cardiac devices
• Injection drug use
• Immunosuppression

Question 3

What is the pathophysiology of infective endocarditis?

Answer 3

• Endothelial damage on valve of heart
• Platelet + fibrin adhere to underlying collagen surface
• Bacteremia = colonisation of thrombus, further deposition of fibrin + platelet aggregation
• Develops into mature infected vegetation

Question 4

What is the most common cause of IE?

Answer 4

• Viridans group streptococci
• Staph a

Question 5

What is acute infective endocarditis?

Answer 5

Days + wks:

• Fever w/ headache
• Stroke symptoms
• Chest + back pain
• Dyspnoea on exertion

Question 6

What are the 2 classifications of IE based on the location?

Answer 6

• Native valve endocarditis
• Prosthetic valve endocarditis

Question 7

What is native valve endocarditis?

Answer 7

• Absence of IV drugs: viridian group strept
• IV drug use: staph a

Question 8

What is prosthetic valve endocarditis?

Answer 8

• W/in 1 yr if implantation: early PVE (staph a or coagulase -ve staph)
• After 1 yr: late PVE

Question 9

What are the symptoms of subacute IE?

Answer 9

Less specific:

• Fever, chill
• Night sweats
• Fatigue
• WL
• Splinter haemorrhage, osler nodes, roth spots, janeway lesions
• Clubbing

Question 10

How is IE diagnosed?

Answer 10

• Clinical, microbiology + echocardiography
• Modified duke criteria
• European society cardiology criteria

Question 11

What is the problem with the modified duke criterias?

Answer 11

Lower accuracy: prosthetic valve endocarditis, pacemaker or defib

Question 12

What investigations are needed to diagnose IE?

Answer 12

• Blood cultures
• Echocardiography
• FBC, CRP, U+E, LFTs
• Urinalysis
• ECG

Question 13

What investigation can be considered to diagnose IE?

Answer 13

• Rheumatoid factor
• ESR

Tomography

• MRI

Question 14

How are blood cultures taken?

Answer 14

3 sets, 30 min intervals before starting antimicrobial treatment

Question 15

What is the treatment for IE?

Answer 15

• Bactericidal combination
• Surgery - remove infection + drain abscess (start antimicrobial)

Question 16

What are the important points for taking gentamicin multiple daily dosing?

Answer 16

• 3 divided dose (every 8 hrs)
• Measure conc after 3/4 doses then every 3 days + after dose change
• Post dose: 1 hr after dose 3-5mg/l (if high dec dose)
• Pre-dose: <1mg/L (if high inc dose interval)

Question 17

What are the side effects of gentamicin?

Answer 17

• Nephrotoxicity
• Ototoxicity
• GI effects
• Infusion reactions

Question 18

When do you measure the conc of vancomycin?

Answer 18

2nd day of treatment

Question 19

What are the s/e of vancomycin?

Answer 19

• Nephrotoxicity
• Ototoxicity
• Hypersensitivity

Question 20

What are predictors of poor outcome?

Answer 20

• Old age
• Prosthetic valve IE
• Diabetes
• HF
• Renal failure
• Staph a + fungi

Question 21

What are the complications of IE?

Answer 21

• Acute HF
• Systemic embolism
• AKI
• Splenic abscess

Question 22

What are the counselling points to avoid IE?

Answer 22

• Strict dental hygiene: follow up twice a year
• Disinfect wounds
• Discourage piercings + tattooing
• Limit infusion catheters

Question 23

Which patients are classed high risk for prophylaxis treatment?

Answer 23

• Prosthetic valve
• Previous IE
• CHD

Question 24

What is the prophylaxis for dental procedures at risk?

Answer 24

• Amox/ampicillin
• Allergic: clindamycin