Thursday, 18 November 2010

MRCP revision battle 53.4: Infective endocarditis

Infective endocarditis is diagnosed by Dukes criteria, which requires:
  • 2 major criteria OR
  • 1 major and 2 minor criteria OR
  • all 5 minor criteria.
Major criteria are:
  • positive blood culture
    • typical organism in 2 separate cultures OR
    • persistently +blood cultures
  • endocardial involvement
    • positive echo
    • new valvular regurgitation
Minor criteria are:
  • fever >38C
  • vascular/immunological signs
  • predisposition (IVDU, valve replacemen)
  • positive blood culture that doesn't mean major criteria
  • positive echo that doesn't meet major criteria

Vascular/immunological signs include:
  • Janeway lesions
  • Oslers nodes
  • splinter haemorrhages
  • Roth spots

40% of cases of endocarditis occur in patients with no previous problems.
30% have had rheumatic heart disease.

Commonest causative organism is streptococcus viridans (alpha haemolytic)
Commonest organism in IVDUs is staphlycoccus aureus.
Commoenst organism within 6 weeks of valve surgery is staph epidermidis.

Usually bicuspid valve affected, except in IVDUs where the tricuspid valve is most commonly affected.

Mortality from strep in 5%, staph around 30%

Poor prognostic factors:
  • s. aureus
  • prosthetic valve
  • culture negative
  • low complement

  • initial blind therapy: fluclox and gent
  • prosthetic valve/penicillin allergy: vancomycin and rifampicin and gent
  • staph: fluclox/vanc and gen
  • strep: benzylpenicillin and gent

Surgery if:
  • abscess
  • recurrent emboli
  • severe valve incompetence
  • cardiac failure

Random MRCP facts:
  • prolongation of PR suggests aortic valve abscess
  • if causative organism is found to be strep bovis look for an associated bowel malignancy.

On to upper GI bleeds...