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Figure 4 Comparison of the effective orifice area (EOA) measured by Doppler (or by catheter for the data of Voelker et al. [21]) (circles) and the EOA predicted from equation 4 (squares) for the 1.5-cm² rigid circular orifice and the bioprosthetic valve tested in the present study (A), and for rigid circular orifices of 1.5 cm² and 2.0 cm² tested in vitro by Voelker et al. (21) (only transvalvular flow rate was provided in their study) (B). The horizontal doted line indicates the value of the EOA at the normal flow rate. The area in sparse hatchings represents the part of the change in EOA that is likely attributable to the unsteady effects, and the area in right hatchings likely represents the part that is attributable to the change in the geometric orifice area.