Infective endocarditis and prosthetic valves Flashcards Preview

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Define infective endocarditis

Infection of:

  • Heart valves: normal or prosthetic
  • Endothelial surface of the heart
  • Congenital defects eg. VSD, PDA, valve defects


List the valves affected in infective endocarditis

(Commonest to rarest)

  • Mitral valve
  • Aortic valve
  • Combined mitral and aortic
  • Tricuspid valve: IVDU
  • Pulmonary valve


Describe the pathophysiology of infective endocarditis

  1. Non-bacterial thrombotic endocarditis
    • Endothelial damage or valve damage
    • Promotes platelet and fibrin deposition
  2. Organisms adhere and grow, forming infected vegetation
  3. Biofilm protect the bacterial vegetation from host defence mechanisms


When does infective endocarditis' incidence peak?

  • Developing countries: Children and young adults
    • Due to rheumatic fever
  • Developed countries: 55-60yrs


Name four risk factors for infective endocarditis

  • >60yr Male
  • IVDU: includes tricuspid lesion
  • HIV
  • Poor dental hygiene
  • Prosthetic heart valve
  • Congenital heart defects
  • Rheumatic valve disease: developing countries
  • Mitral valve prolapse; bicuspid aortic valve
  • Chronic haemodialysis


Name two pathogens associated with infective endocarditis

  • Early (within 60d of valve surgery): poorer prognosis
    • Staph aureus: acute presentation; IVDU
    • Staph epidermidis: nosocomial infection
      • Peri-op + 2/12 post-op valve replacement
  • Late (after 60d post-valve surgery)
    • Strep viridans (5-60% of subacute cases)
    • Staph aureus
    • HACEK organisms (rare): more insidious

Fungal endocarditis may occur


List five presenting features of infective endocarditis

  • Systemic: Fever, chills, anorexia, weight loss
  • Murmur (85%), heart failure, conduction abnormalities
  • Vascular phenomena:
    • Stroke, MI, or embolisation to lung/spleen/kidney
    • Splinter haemorrhage
    • Janeway lesions: flat painless lesions on palms
  • Immunologic phenomena:
    • Osler's nodes: swollen painful lesions on fingers
    • Roth spots on fundoscopy
    • Glomerulonephritis; rheumatoid factor


Differentiate between Janeway lesions and Osler's nodes

  • Janeway lesions: flat painless lesions on palms
  • Osler's nodes: swollen painful lesions on fingers


Describe the presentation of subacute infective endocarditis

  • Fatigue, anorexia, weight loss
  • Low-grade fever
  • Flu-like illness
  • Polymyalgia-like symptoms
  • Back or pleuritic pain
  • Abdominal symptoms


Name three causes of right-sided infective endocarditis

  • IVDU
  • HIV
  • Cardiovascular devices
    • eg. pacemaker wires; prosthetic right heart valves


Outline the Duke diagnostic criteria for infective endocarditis

Definite IE = 1 pathological; 2 major; 1 major + 3 minor; or 5 minor

  • Pathological:
    • Microorganisms in vegetation
    • Pathologic lesions
  • Major:
    • Positive blood cultures
    • Endocardial involvement
  • Minor:
    • Predisposing heart condition or IVDU
    • Fever >38
    • Vascular phenomena
    • Immunological phenomena
    • Microbiological evidence: does not meet 'major'


Request four investigations for suspected infective endocarditis?

  • FBC, U+Es, LFTs, CRP
  • Blood cultures x3
  • ECG: MI, heart failure, conduction abnormalities
  • Echocardiogram: vegetations, abscess, valve damage
  • Urinalysis: haematuria due to renal embolism


What is the mortality rate in untreated infective endocarditis?

Almost 100% mortality if untreated


Outline the treatment of infective endocarditis

Always consult a microbiologist and cardiologist

  • Requires at least 4 weeks of IV antibiotics
    • Dependent on organism
    • Should respond within 48h
  • Empirical ABX:
    • Benzylpenicillin + Gentamicin
    • Ceftriaxone/meropenam + Vancomycin
  • Surgerical valve replacement


State three complications of infective endocarditis

  • MI, pericarditis, arrhythmias
  • Heart valve insufficiency
  • Congestive heart failure
  • Sinus of Valsalva aneurysm
  • Aortic root abscess
  • Arterial emboli or infarction
  • Arthritis, myositis
  • Glomerulonephritis, AKI
  • Stroke; Mesenteric or splenic infarct


What types of prosthetic valves are available?


Differentiate between mechanical and tissue prosthetic valves

Mechanical valves:

  • More durable
  • More thrombogenic; requires lifetime warfarin
  • Heart sounds are louder and unique 'clicking'

Tissue valves

  • Tend to degenerate after 10 years
  • Less thrombogenic; does not require lifetime warfarin
  • Heart sounds comparable to native valves