Aortic valve area can be calculated by using the principle of conservation of mass — “What comes in must go out”.
Aortic valve area indexed to body surface area should be considered for the large and small extremes of body surface area.
AVA cm2
Normal – 3.0-4.0
Mild – >1.5
Moderate – 1.0-1.5
Severe – <1.0
AVAI cm2/m2
Mild – >0.85
Moderate – >0.60-0.85
Severe – >0.6
For patients with prosthetic aortic valves, patient-prosthesis mismatch is suspected when effective orifice area (EOA) indexed to body surface area <0.85 to 0.9 cm2/m2. Patient-prosthesis mismatch is considered severe when EOA index <0.65.