AS: Aortic Valve Area (Cont)

Derivation of valve area is based the continuity equation which states that the flow passing through the LVOT has to equal the flow through the AV. Echocardiographic derived measurements are based on maximal instantaneous gradient which provide a more accurate assessment then non-physiologic peak-to-peak gradients observed on invasive studies. In general, the VTI (cm) is felt provide a more accurate assessment of valve area however peak velocity (m/sec) can also be used.

The normal aortic valve area is 3-4 cm². Symptoms tend to not be apparent until the AS is severe (<1cm²). If a patient presents with symptoms and the AVA is measured in the mild-moderate range alternative causes should be explored before attributing them to AS alone.