Infective Endocarditis Flashcards

1
Q

What is infective endocarditis?

A

Involving the endocardial surface of the heart, including the valvular structures, the chordae tendineae, sites of septal defects, or the mural endocardium.

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2
Q

What are the most common pathogens causing infective endocarditis?

A
  • Viridans group streptococci.
  • Staphylococcus aureus.
  • Enterococci.
  • Coagulase-negative staphylococci.
  • Haemophilus parainfluenzae.
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3
Q

What are the risk factors for infective endocarditis?

A
  • Prior history of infectious endocarditis
  • Presence of artificial prosthetic heart valves
  • Certain types of congenital heart disease
  • Post-heart transplant
  • IV catheter
  • IV drug use
  • Recent dental or surgical procedure
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4
Q

What are the signs of infective endocarditis?

A
  • Tachycardia
  • Meningeal signs
  • Cardiac murmur
  • Janeway lesions
  • Osler nodes
  • Roth spots
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5
Q

What are the symptoms of infective endocarditis?

A
  • Fever and chills
  • Night sweats
  • Fatigue
  • Anorexia
  • Weight loss
  • Weakness
  • Arthalgia
  • Headache
  • Dyspnoea
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6
Q

Briefly describe Janeway lesions

A

Haemorrhagic, macular, painless plaques with a predilection for the palms and soles

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7
Q

Briefly describe Osler nodes

A

Small, painful, nodular lesions usually found on the pads of the fingers or toes

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8
Q

Briefly describe Roth spots

A

Oval, pale, retinal lesions surrounded by haemorrhage detected on fundoscopy

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9
Q

Briefly describe splinter haemorrhages

A

A longitudinal, red-brown haemorrhage under a nail

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10
Q

What investigations should be ordered for infective endocarditis?

A
  • FBC
  • Serum chemistry panel with glucose
  • Urinalysis
  • Blood cultures
  • ECG
  • Echocardiogram
  • CXR
  • CT
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11
Q

Why investigate FBC?

A

Most patients have a normocytic, normochromic anaemia.

Leukocytosis is seen in about one third of cases often with neutrophilia.

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12
Q

Why investigate serum panel with glucose?

A

Provides baseline assessment.

May shown normal or elevated urea.

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13
Q

Why investigate urinanlysis?

A

Septic emboli are common complications of IE, and urinalysis may demonstrate active sediment assisting in the clinical diagnosis.

RBC casts; WBC casts; proteinuria; pyuria.

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14
Q

Why investigate blood cultures?

A

It is generally recommended that 3 sets of blood cultures be obtained 1 hour apart prior to initiating antibiotic therapy to ensure greatest yield. The most common cause of culture-negative endocarditis is antibiotic therapy preceding blood cultures.

Bacteraemia; fungaemia.

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15
Q

Why investigate ECG?

A

Progression of the infection may lead to conduction system disease.

May show prolonged PR interval; non-specific ST/T wave abnormalities or AV block.

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16
Q

Why investigate echocardiogram?

A

Should be performed in all cases of suspected IE, as early as possible to confirm or rule out the diagnosis. Also has a role in assessment of prognosis, the prediction of embolic risk, and management during follow-up.

Valvular, mobile vegetations seen on echocardiogram.

Options include TEE or TOE (more sensitive).

17
Q

Why investigate using CXR?

A

Rule out cardiomegaly or pulmonary oedema.

18
Q

Why investigate using CT?

A

Compare favourably with transthoracic echocardiogram in detecting valvular abnormalities in patients with IE, but may miss small defects.

May show valvular abnormalities and vegetations.

19
Q

Why is infective endocarditis difficult to diagnose?

A

IE is often a difficult diagnosis to make because bacteraemia may not always lead to endocardial involvement, while endocardial involvement may occur in the absence of peripheral bacteraemia following previous antibiotic use.

20
Q

What criteria is used to describe infective endocarditis?

A

Duke criteria

21
Q

Briefly describe Duke’s criteria for diagnosing infective endocarditis

A

Must meet 2 major criteria or 1 major and 3 minor criteria or 5 minor criteria.

Major criteria:

  • Positive blood culture for infective endocarditis (IE)
  • Evidence of endocardial involvement (e.g. valve vegetation, abscess or new dehiscence of artificial valves)

Minor criteria:

  • Predisposing heart condition or intravenous drug use
  • Fever over 38°C
  • Vascular phenomenon such as major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, conjunctival haemorrhage, Janeway lesions
  • Immunological phenomenon such as glomerulonephritis, Osler nodes or Roth spots
  • Microbial evidence
  • Echocardiogram
22
Q

Briefly describe the treatment for suspected infective endocarditis

A

Suportive care and empirical antibiotic therapy (once cultures have been collected).

23
Q

How long is the duration of antibiotic treamtent required in infective endocarditis?

A

6 weeks

24
Q

What is the antibiotic of choice if treating empirically in infective endocarditis?

A

If native valve or prosthetic valve fitted <1 y: ampicillin, flucloxacillin and gentamicin

If prosthetic valve: vancomycin, gentamicin and rifampicin

25
Q

When is surgery appropriate as a treatment for infective endocarditis?

A

Indications for surgery include the following:

  • Haemodynamic instability/ severe heart failure
  • Overwhelming sepsis despite conventional antibiotic therapy
  • Perivalvular abscess, intracardiac fistulae, valve perforation, or dehiscence
  • Recurrent embolic episodes despite antibiotic therapy
  • Fungal endocarditis
  • Pregnancy

Surgical intervention is frequently required to cure the disease in patients with prosthetic valves.

26
Q

When is antibiotic prophylaxis appropriate?

A

Antibiotic prophylaxis is recommended only for patients with:

  • Underlying cardiac conditions associated with the highest risk of developing IE
  • All dental procedures that involve manipulation of gingival tissue or the periapical region of teeth, or perforation of the oral mucosa
  • Patients with prosthetic valves, including transcatheter-implanted prostheses and homografts, or valve repairs using prosthetic material
  • Patients who have suffered from a previous episode of IE
27
Q

What is the antibiotic of choice in antibiotic prophylaxis?

A

Amoxicillin

28
Q

What differentials should be considered in infective endocarditis?

A
  1. Non-bacterial thrombotic endocarditis
29
Q

How does infective endocarditis and non-bacterial thrombotic endocarditis differ?

A

Differentiating signs and symptoms:

  • Endocarditis in which sterile vegetations are deposited on cardiac valves
  • Most commonly associated with underlying trauma, malignancy, hypercoagulable states, previous rheumatic fever, chronic infections (e.g. TB, pneumonia, osteomyelitis), or autoimmune conditions (e.g. systemic lupus erythematosus or rheumatoid arthritis)
  • Patients may report signs and symptoms consistent with those underlying conditions

Differentiating investigations:

  • There is no destruction of the affected valve and no associated bacteraemia
  • Definitive diagnosis can only be made pathologically: findings show sterile vegetations on the surface of the valve