In vitro correlation between the effective and geometric orifice area in aortic stenosis

Background: Planimetry of aortic stenosis can be performed when Doppler measurements are unavailable. We sought to evaluate if, as advised in guidelines, the geometric orifice area (GOA) threshold value of 1 cm(2) was concordant with the threshold of 1 cm(2) of the effective orifice area (EOA), and the factors influencing the contraction coefficient (EOA/GOA ratio). Methods: In an in vitro mock circulatory system, we tested 6 degrees of AS severity (3 severe and 3 nonsevere), and 3 levels of flow (<150 ml/s, 150-200 ml/s, >250 ml/s). The EOA was calculated by Doppler-echocardiography, and the GOA was measured with dedicated software after camera acquisition. Results: In all but the very low flow condition, an EOA of 1 cm(2) corresponded to a GOA of 1.2 cm(2). The contraction coefficient increased with both the flow and the stenosis severity. For very severe stenoses, the EOA and the GOA were interchangeable. Conclusion: As observed in clinical studies, the GOA was larger than the EOA, and a GOA between 1 and 1.2 cm(2) should not discard the possibility of severe aortic stenosis. (C) 2020 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.