Endocarditis Flashcards
What is infective endocarditis?
Involving the endocardial surface of the heart, including the valvular structures, the chordae tendineae, sites of septal defects, or the mural endocardium.
What are the most common pathogens causing infective endocarditis?
- Viridans group streptococci.
- Staphylococcus aureus.
- Enterococci.
- Coagulase-negative staphylococci.
- Haemophilus parainfluenzae.
What are the risk factors for infective endocarditis?
- 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
What are the signs of infective endocarditis?
- Tachycardia
- Meningeal signs
- Cardiac murmur
- Janeway lesions
- Osler nodes
- Roth spots
What are the symptoms of infective endocarditis?
- Fever and chills
- Night sweats
- Fatigue
- Anorexia
- Weight loss
- Weakness
- Arthalgia
- Headache
- Dyspnoea
Briefly describe Janeway lesions
Haemorrhagic, macular, painless plaques with a predilection for the palms and soles
Briefly describe Osler nodes
Small, painful, nodular lesions usually found on the pads of the fingers or toes
Briefly describe Roth spots
Oval, pale, retinal lesions surrounded by haemorrhage detected on fundoscopy
Briefly describe splinter haemorrhages
A longitudinal, red-brown haemorrhage under a nail
What investigations should be ordered for infective endocarditis?
- FBC
- Serum chemistry panel with glucose
- Urinalysis
- Blood cultures
- ECG
- Echocardiogram
- CXR
- CT
Why investigate FBC?
Most patients have a normocytic, normochromic anaemia.
Leukocytosis is seen in about one third of cases often with neutrophilia.
Why investigate serum panel with glucose?
Provides baseline assessment.
May shown normal or elevated urea.
Why investigate urinanlysis?
Septic emboli are common complications of IE, and urinalysis may demonstrate active sediment assisting in the clinical diagnosis.
RBC casts; WBC casts; proteinuria; pyuria.
Why investigate blood cultures?
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.
Why investigate ECG?
Progression of the infection may lead to conduction system disease.
May show prolonged PR interval; non-specific ST/T wave abnormalities or AV block.
Why investigate echocardiogram?
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).
Why investigate using CXR?
Rule out cardiomegaly or pulmonary oedema.
Why investigate using CT?
Compare favourably with transthoracic echocardiogram in detecting valvular abnormalities in patients with IE, but may miss small defects.
May show valvular abnormalities and vegetations.
Why is infective endocarditis difficult to diagnose?
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.
What criteria is used to describe infective endocarditis?
Duke criteria
Briefly describe Duke’s criteria for diagnosing infective endocarditis
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
Briefly describe the treatment for suspected infective endocarditis
Suportive care and empirical antibiotic therapy (once cultures have been collected).
How long is the duration of antibiotic treamtent required in infective endocarditis?
6 weeks
What is the antibiotic of choice if treating empirically in infective endocarditis?
If native valve or prosthetic valve fitted <1 y: ampicillin, flucloxacillin and gentamicin
If prosthetic valve: vancomycin, gentamicin and rifampicin
When is surgery appropriate as a treatment for infective endocarditis?
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.
When is antibiotic prophylaxis appropriate?
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
What is the antibiotic of choice in antibiotic prophylaxis?
Amoxicillin
What differentials should be considered in infective endocarditis?
- Non-bacterial thrombotic endocarditis
How does infective endocarditis and non-bacterial thrombotic endocarditis differ?
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
