Flow volume is the product of flow velocity times the cross-sectional area of the slow steam. In a closed system, the volume of blood flow is the same inside and outside of a stenosed area (continuity equation). Thus the flow volume in the stenotic area should equal the flow volume in the area proximal to the stenosis.


stenotic area =

= ((proximal area) * (proximal flow velocity)) / (stenotic flow velocity)



• The area proximal to the stenosis can be calculated from the left ventricular outflow tract diameter measured in 3-dimensional images.



• A calculated aortic valve areas of less than 0.75 square centimeters in the adult is considered to indicate hemodynamically severe aortic stenosis.


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