• Aortic stenosis
    • Aetiology
      • Degenerative calcific aortic stenosis
        • Associated with many of the risk factors for CVD
      • Congenital bicuspid valve
        • 2% of the population, accounts for 50% of <70s requiring aortic valve surgery
    • Aortic valve
      • Area is usually 2.5-3.5 cm²
      • Hypertrophy occurs to maintain pressure gradient without dilating or reducing c.o.
      • Eventually the ventricle becomes stiff causing diastolic dysfunction with reduced compliance
      • Consequently the LV becomes dependent on atrial contraction, which adds 40% instead of the usual 20% to LVEDV
      • LV oxygen requirement increases due to hypertrophy. Myocardial O₂ supply is reduced due to relatively low aortic pressure and increased LVEDP.
      • Eventually c.o, SV, and pressure gradient across the valve falls and dilatation occurs
    • Anaesthetic management
      • Invasive monitoring
      • Avoid hypotension
      • Beware regional techniques
      • Drugs to maintain vascular tone must be ready
      • Infusions better than boluses
      • Aim to maintain pre-anaesthetic BP values
      • Maintain sinus rhythm
      • In obstetrics - GA, slow increments of regional technique have both been used
      • Good pain control on a HDU is mandatory. They remain high risk post-op
    • Severity
      • Mild
        • 1.2-1.8 cm² or mean gradient 12-20mmHg
      • Moderate
        • 0.8-1.2 cm² or mean gradient 20-40mmHg
      • Severe
        • 0.6-0.8 cm² or mean gradient 40-50mmHg
      • Critical
        • <0.6 cm² or mean gradient >50mmHg
    • Ix
      • ECG shows LVH in 85%. TWI and ST depression can occur. AV block can be seen
      • CXR may be normal, signs of LVF may be seen.
      • Echo may assess valve area and gradient
        Max gradient (mmHg) = 4 x velocity (m/s)
        Mean gradient is also calculated
    • Examination
      • Slow rising pulse
      • Low volume
      • Carotid thrill/precordial thrill
      • ESM
    • Triad of symptoms
      • Syncope
      • Angina
      • Dyspnoea
    • Risk factor for cardiac complications in non-cardiac surgery
      • Risk increased with coexistent cardiac failure and arrhythmias
    • CEACCP
      Link:ceaccp.oxfordjournals.org/content/5/1/1.full.pdf?sid=8e2e6042-1392-4da7-8486-a833c41cb461