Infective Endocarditis

16/09/2013 by admin | Cardiology

 

Definition

  1. is a form of endocarditis caused by infectious agents – often bacterial
  2. can be short incubation (often staph), and long incubation (often strep)
  3. if endocariditis in absence of organism = marantic endocarditis (no infective organism seen).

 

  1. Some I.E. will not show organisms on testing = negative endocarditis pathogens include Aspergillus species, Brucella species, Coxiella burnetii, Chlamydia species, and HACEK bacteria. Another possible reason for culture negativity, even with the more typical pathogens, is prior antibiotic treatment

 

Endocarditis can also be classified by the side of the heart affected:

  1. Patients who inject narcotics or other drugs intravenously (IVDU) may introduce infection which will travel to the right side of the heart classically affecting the tricuspid valve, and most often caused by S. aureus.
  2. In other patients without a history of intravenous exposure, endocarditis is more frequently left-sided
    1. o IV exposure to staph = RH.
    2. o no exposure = LH

 

Incidence

Epidemiology

Presenting complaint

  1. Fever in 97%
  2. malaise and endurance fatigue in 90%
  3. A new or changing heart murmur (due to vegetations/lesions), weight loss, and coughing occurs in 35%
  4. Vascular phenomena:
    1. o Septic embolism
    2. o Janeway lesions (painless on hands/feet)
    3. o Intracranial hemorrhage
    4. o Conjunctival hemorrhage
    5. o Splinter hemorrhages (seen in sub-acute I.E.)
    6. o Renal Infarct
    7. o Infarct Spleen.
  5. Immunologic phenomena:
    1. o Glomerulonephritis
    2. o Osler’s nodes (painful, on hands/feet)
    3. o Roth’s spots (retinal haemorrhages) +CWS
    4. o Positive serum rheumatoid factor (if L-sided)
  6. Other signs may include; night sweats, rigors, anemia (haemolysis of RBC due to compromised valve), splenomegaly, clubbing.

 

Diagnostic tools/investigations

  1. Duke criteria
  2. As the Duke criteria is based heavily on the results of echocardiography

 

Aetiology

  1. Bacteraemia due to dental procedures – viridans streptococci
  1. Colorectal cancer (mostly Streptococcus bovis)
  2. Urinary tract infections (mostly enterococci)
  3. IV drug (S. aureus) use can all introduce large numbers of bacteria.
  4. With a large number of bacteria, even a normal heart valve may be infected.
  5. immunodeficiency or immunosuppression, malignancy, diabetes, and alcohol abuse = increase the risk of developing infective endocarditis
  6. Altered blood flow around the valves can cause disease

 

  1. Bugs include :
  2. Viridans Alpha-hemolytic streptococci
  3. Enterococcus.
  4. Pseudomonas species
  5. P. aeruginosa
  6. S. bovis
  7. Clostridium septicum
  8. HACEK organisms seen more in children (=Haemophilus parainfluenzae, Aggregatibacter aphrophilus, Cardiobacterium himinis,m Eikenella corrodens, Kingella kingae).
  9. Fungi: Candida albicans
  10. Viral infection: viral myocarditis or viral pericarditis.

 

Pathophysiology

  1. Valves are avascular therefore poor immune cell supply
  2. If an organism (such as bacteria) attaches to a valve surface and forms a vegetation, the host immune response is blunted. The lack of blood supply to the valves also has implications on treatment, since drugs also have difficulty reaching the infected valve
  3. Damaged vascular endothelium will also promote platelet and fibrin deposition, upon which bacteria can take hold
  4. Valvular lesions are a major cause of such damage, as are ’jet lesions’ resulting from ventricular septal defects or patent ductus arteriosus
  5. Increased risk of I.E – if turbulent flow = RF, jet lesions [VSD/PFO – NOT ASD], damaged/artificial valves.

 

Hereditary? Infective? How does it spread?

Treatment and management (conservative/medical/surgical)

  1. High dose IV Abs to get to lesions – due to valves being avascular
  2. Antibiotics are continued for a long time, typically two to six weeks.
  3. Specific drug regimens differ depending on the classification of the endocarditis as acute or subacute (acute necessitating treating for S. aureus with oxacillin or vancomycin in addition to gram-negative coverage). Fungal endocarditis requires specific anti-fungal treatment, such as amphotericin B.
  4. Viridans-group streptococci, which are highly sensitive to penicillin  
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