Infective endocarditis

Question 1

what is the definition of infective endocarditis?

Answer 1

infection of the endocardium or valvular endothelium if the heart

Question 2

what is the epidemiology of infective endocarditis?

Answer 2

more common in developing countries
elderly
prosthetic valves
young IV drug users
congenital heart defects
males

Question 3

what is the aetiology of infective endocarditis?

Answer 3

• Staphylococcus aureus (IVDU, diabetes and surgery) - most common cause
• Pseudomonas aeruginosa
• Streptococcus viridans (dental problems) - GRAM POSITIVE, alpha haemolytic and optochin resistant (Strep. mutans, strep, sanguis, strep. milleri & strep. oralis)
- right side endocarditis = IV drug users

Question 4

what is the pathophysiology of infective endocarditis?

Answer 4

consequence of organisms in blood stream and abnormal cardiac endothelium that facilitates their adherence and growth
-bacteria present due to:
• Poor dental hygiene
• IV drug use
• Soft tissue infections - Damaged endocardium promotes platelet and fibrin deposition, which allows organisms to adhere and grow, leading to an infected vegetation
- Aortic and mitral valves are most commonly involved - IV drug users are the exception since right-sided lesions are more common in them
- Virulent organisms destroy the valve they are on resulting in regurgitation and worsening heart failure

Question 5

what are the key presentations of infective endocarditis?

Answer 5

risk factor presence
cardiac murmur
night sweats, malaise, fatigue, anorexia, weight loss, myalgias
Fever plus:
- Prosthetic material inside the heart
- Risk factor for infective endocarditis e.g. IV drug user
- Newly developed ventricular arrhythmias or conduction disturbances

Question 6

what are the signs of infective endocarditis?

Answer 6

Newly developed ventricular arrhythmias or conduction disturbances
New valve lesion/regurgitant murmur
Embolic events of unknown origin
Sepsis of unknown origin
Haematuria, glomerulonephritis and suspected renal infarction
Embolisation of vegetations e.g. stroke, pulmonary embolus, bone infections, kidney dysfunction and myocardial infarction
Valve dysfunction result in in arrhythmia and heart failure
Splinter haemorrhages on nail beds of fingers
Embolic skin lesions - black spots on skin (infarcts causes by bits of infective vegetation blocking small capillaries)
Osler nodes - tender nodules in the digits
Janeway lesions - haemorrhages and nodules in the fingers
Roth spots - retinal haemorrhages with white or clear centres seen on fundoscopy
Petechiae - small red/purple spots caused by bleeds in the skin

Question 7

what are the symptoms of infective endocarditis?

Answer 7

Headache, fever, malaise, confusion, and night sweats, finger clubbing, chest pain, back pain, palatal petechiae

Question 8

what is the first line and gold standard investigations for infective endocarditis?

Answer 8

Dukes criteria
Blood cultures:
• 3 sets from different sites over 24 hours
• Take BEFORE ANTIBIOTICS STARTED
• Identifies in 75% of cases
Transthoracic echo (TTE) - safe, non invasive, no discomfort BUT often poor images so low sensitivity but can identify vegetations (if greater than 2mm) - however a negative TTE DOES NOT exclude the diagnosis of infective endocarditis
Transoesophageal echo (TOE) - much more sensitive but very uncomfortable, is useful for visualising mitral lesions and possible development of aortic root abscess - BETTER AT DIAGNOSING, ANSWER THIS IN EXAM!
FBC - normochromic and normocytic anaemia, leukocytes, neutrophils
CRP and ESR - raised
serum urea, electrolytes and glucose
LFTs
urinalysis - microscopic haematuira, RBC casts; WBC casts; proteinuria; pyuria
ECG - prolonged PR interval

Question 9

what are the differential diagnoses for infective endocarditis?

Answer 9

Other causes of fever of unknown origin (FUO) e.g. pulmonary embolism, DVT, lymphoma, drug fever, cotton fever

Question 10

how is infective endocarditis managed?

Answer 10

• Antibiotic treatment (which one is decided on organism ascertained from cultures) for 4-6 weeks
• If not staphylococcus then use penicillin ideally Benzylpenicillin &
  Gentamicin (doesn’t work on own since cannot get through bacterial cell wall)
• If staphylococcus then use Vancomycin & Rifampicin (if MRSA)
• Treat complications e.g. arrhythmia, heart failure, heart block, embolisation, stroke rehab and abscess drainage
• Surgery - removing valve and replacing with prosthetic one:
  • Operate if the infection cannot be cured with antibiotics i.e. returns after treatment
  • Operate to remove infected devices
  • Operate to remove large vegetations before they embolise
• In term of prevention recommend GOOD ORAL HEALTH and inform patients of symptoms that may indicate infective endocarditis

Question 11

how is infective endocarditis monitored?

Answer 11

Echocardiography to evaluate valvular and ventricular function.
Continued dental evaluation.
Patient education on recurrence.
Ongoing observation.

Question 12

what are the complications of infective endocarditis?

Answer 12

Heart problems, such as heart murmur, heart valve damage and heart failure
Stroke
Pockets of collected pus (abscesses) that develop in the heart, brain, lungs and other organs
Blood clot in a lung artery (pulmonary embolism)
Kidney damage

Question 13

what is the prognosis of infective endocarditis?

Answer 13

Mortality approx. 25%, poor prognosis