General:
Mild to moderate AR common and usually well tolerated.
Acute may be secondary to:
- Infective endocarditis
- Aortic dissection
Echo findings in acute AR:
- Colour – AR visualised in multiple views
- Hyperdynamic non-dilated LV
- Premature MV closure/MV flattening on M-mode/PLAX.
Assessment:
Measurement of aorta in all routine points.
Careful interrogation for possible aetiology/dissection flap.
Colour flow mapping:
Measure vena contracta.
Measure jet width on colour/colour m-mode and express as percentage of diameter of LVOT.
Either measure heigh 5-10mm below AV cusps or vena contracta (narrowest position of jet)
Remember to measure perpendicular to jet.
CW measurement:
Measured from apex in A5C/A3C.
Always check measurement in multiple views.
Visual inspection of signal density – low density vs high vensity.
Trace AR VTI and pressure 1/2 time.
Assess for reverse flow within aortic arch:
Visual assessment via colour for whether flow is holodiastolic, fills around half of diastole or only seen at the start of diastole.
Worth also seeing how far down aorta flow reversal is seen.
PW in arch and measure end diastolic velocity – won’t be possible unless holodiastolic.
Optional measures:
Can be helpful to consider when conflicting values.
Stroke volume calculations:
- MV stroke volume:
0.785 x (MV annulus diameter)^2 x MV VTI
- LVOT stroke volume:
0.785 x (LVOT diameter)^2 x LVOT VTI
- AR regurgitation volume:
LVOT SV – MV SV
- AR regurgitation fraction:
Regurgitation volume / LVOT SV x 100 (%)
- Regurgitation orifice area:
Regurgitation volume / AR VTI
Assess Severity:
Indications for Surgery:
Various indications exist in patients with asymptomatic severe AR:
- LV systolic diameter >50mm (or >25mm/m^2)LV diastolic diameter >70mm
- LV ejection fraction <50%
- Aortic dilation
- Combination of severity features in select cases.
Implication for Critical Care:
Use sedative with limited effect on myocardium – avoid propofol.
Use low dose vasopressors to maintain CVS integrity – high doses will case CVS collapse.
Treat bradycardia <80bpm – slow rate increases regurgitation time.
Early surgical consultation.
Echo features of severe chronic AR with subsequent LV dilation should be included in decisions for escalation.
Maintain stable SVR and avoid bradycardia.