AKA after BAV

Gabrielle Morris

68yo male with a smouldering periprosthetic knee infection considered unsalvageable, requiring AKA.

Background

  • AF
  • Large MCA stroke (likely embolic) while on rivaroxaban, since changed to warfarin. Residual hemiparesis.
  • T2DM HbA1c 6.1%

Issues

  • Severe AS
    • Previously known to be moderate.
    • Rpt TTE at anaesthetic registrar’s request while an inpatient several months ago awaiting AKA (delayed as patient was not mentally ready for the procedure).
    • TTE showed severe AS.
    • Patient had an aortic balloon valvuloplasty
    • Was due to have AKA soon after while off his anticoagulation however COVID resurgence delayed the procedure until now.

Discussion

Balloon aortic valvuloplasty

  •  
    • BMJ best practice
      • First line therapy for clinically unstable patients or those with severe AS who require urgent non-cardiac surgery (due to the absence of requirement for anticoagulation, in contrast to aortic valve replacement, and the short recovery time)
      • Re-stenosis rates are high at 6/12
      • No proven mortality advantage however patients may have significant symptomatology and haemodynamic improvements, which may offer a window for more definitive care (if appropriate)
      • Mortality ~ 3% from the procedure
      • This patient’s AS was reduced to ‘moderate’ severity through the procedure.
  • Grading AS
    • Classical descriptions using mmHg pressure gradient across valve and valve area
    • Dimensionless index useful. This is the ratio of the LV outflow tract (LVOT) time-velocity integral to that of the aortic valve jet. DI does not require the calculation of LVOT cross-sectional area, which is a cause of erroneous assessment and underestimation of AVA
    • This patient’s mean gradient did not meet the severe criteria but this may be due to LV failure (itself a sign of severe AS).

  • Haemodynamic mx considerations under anaesthesia
    • CO is preload dependent – adequate filling P needed for non-compliant LV
    • Sinus rhythm with low normal HR needed for adequate filling time and LV myocardial perfusion.
    • High/normal SVR and DBP to maintain coronary perfusion.
    • Beware neuraxial -> drop in SVR and preload
    • Adequate analgesia to prevent catecholamine surges.

Plan:

  • Proceed to OT