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Valve replacements

Clinical examination

  • Metallic valves
    • Metallic mitral valve: S1 sounds metallic
    • Metallic aortic valve: S2 sounds metallic 
    • There is often a click audible without a stethoscope
  • Tissue valves
    • Relevant heart sounds may be normal, loud or quiet
  • Systolic flow murmurs are normal for aortic valve replacements
  • Assess for valve function (signs of regurgitation of replaced valve), cardiac decompensation (signs of heart failure), and signs of infective endocarditis
  • Also look for signs of over-anticoagulation (bruising) and anaemia (haemolysis)

Indications for surgery

  • Left-sided valve dysfunction 
    • Any valve: associated LVF, symptomatic
    • If regurgitation, also: acute onset, associated LV dilation
    • If mitral, also: presence of pulmonary hypertension

NB: for MR, valve repair is preferred when possible; for MS, balloon valvuloplasty is preferred unless contraindicated (i.e. coexistent MR, thrombus or calcified valve).

  • Infective endocarditis
    • Associated heart failure 
    • Uncontrolled infection (fistula, enlarging vegetation, false aneurysm, aortic root abscess, persistently positive blood cultures, fungal/multidrug-resistant organism)
    • High embolic risk (persistent large vegetation)

NB: If prosthetic valve, surgery also indicated if: <2 months post-op, valve dysfunction or Staphylococcus aureus infection.

Types

  • Tissue valve
    • Usually porcine xenograft
    • Needs replacing after 10-15 years; sooner if patient is active
    • No need for warfarin
    • Recommended for older people, people with low life expectancy and females of child-bearing age
  • Mechanical valve
    • Longer lasting (older valves 20-30 years, newer valves >30 years)
    • Lifelong warfarin 
    • Makes a quiet clicking noise
    • Recommended for younger people (<60 years) so they don’t need repeat surgeries (unless female and of child-bearing age because warfarin is teratogenic) 

Procedure

  • Pre-operative: transthoracic ± transoesophageal echo, coronary angiography 
  • May be performed by:
    • Open surgery: via midline sternotomy
    • Minimally invasive surgery
      • Aortic valve: via right anterior mini-thoracotomy (2nd intercostal space) or mini-sternotomy
      • Mitral valve: via right lateral mini-thoracotomy (below nipple or in breast crease)
  • Patient is put on cardiopulmonary bypass while valve is replaced

NB: if there is also coronary artery disease, CABG is usually performed concurrently – check the legs for a vein grafting scar.

Questions

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