P1350 New 3D Doppler flow method for quantitation of aortic regurgitation

Abstract

Abstract Funding Acknowledgements Centre for Innovative Ultrasound Solutions, NTNU OnBehalf Centre for Innovative Ultrasound Solutions Introduction The echocardiographic assessment of valvular regurgitation severity may be challenging. This is reflected in the current EACVI and ASE recommendations, which are quite extensive and include numerous parameters. To date, there are no widely reliable quantitative methods. Moreover, the inter-observer variability in the overall severity assessment is substantial. Purpose Development of a new, automated 3D Doppler method for reliable and accurate quantitation of regurgitant volume. Methods A 3D high frame rate plane wave imaging sequence is employed to insonate the vena contracta region of the jet using a modified GEVU Vivid E95 system with a 4V probe. In this way we obtain spectral information from all voxels within the sample volume of approximately 2cm x 2cm x 2cm. Vena contracta is localised from the plane containing the maximum velocities and its cross sectional area determined by a power threshold. Velocity-time-integral is then estimated for all voxels within the designated cross sectional area. For clinical validation, we include patients with aortic regurgitation ranging from mild to severe with a stable sinus rhythm. 3D flow data is recorded immediately after a comprehensive standard echocardiographic exam. The standard exam undergoes expert evaluation in accordance with EACVI recommendations. 3D flow data are currently processed and analysed offline by an independent investigator, blinded to the results from the standard exam. Results The results from the first twelve patients are presented in Figure 1. Compared to expert echocardiographic evaluation, the 3D flow method seems to overestimate the regurgitant volume in some patients with mild aortic regurgitation. This may be caused by limitations in lateral resolution. Due to failure of aligning the vena contracta within the sample volume, there is a significant underestimation of regurgitant volume in one patient (Figure 1: red dot). As 3D flow analysis is currently performed offline, this was not obvious at the time of recording. The 3D flow method clearly discriminates the other two patients with severe aortic regurgitation from the patients with mild or moderate regurgitation. Conclusion We find these preliminary results encouraging, motivating further work on method refinement and validation. Abstract P1350 Figure 1