Poster session Wednesday 11 December all day display: 11/12/2013, 09:30-16:00 * Location: Poster area

Purpose: With the advent of percutaneous transcatheter device closures in congenital heart defects and the emergence of percutaneous left atrial appendage closure, there is an increasingly important role for echocardiographic guidance and control of device position and function. Disc occluder devices frequently present as an unexplained ‘figure-of-8’ on echocardiography. The aim of this study was to clarify this ‘figure-of-8’ display and to relate its morphology to transducer position and device type. Methods: A mathematical model was developed to resemble disc occluder geometry and to allow a numerical simulation of the echocardiographic appearance. In addition, we developed an in vitro set-up for echocardiographic analysis of various disc occluders and various transducer positions. Results: In the mathematical model of an epitrochoid curve (closely resembling disc occluder geometry) a ‘figure-of-8’ display is obtained when emphasizing points with tangent vector perpendicular to the direction of ultrasound waves. Decreasing imaging depth results in a more asymmetric ‘figure-of-8’, with small upper part and wide lower part. Clinical and in vitro data are in close agreement with these results (Figure 1). Furthermore a ‘figure-of-8’ display is only obtained in a coronal imaging position, and is similar for different commercially available disc occluder types. Conclusions: The ‘figure-of-8’ display in the ultrasound image of a disc occluder is an imaging artifact due to the specific ‘epitrochoidal’ geometry of a deployed device and its interaction with ultrasound waves. The morphology of the ‘figure-of-8’ depends on transducer position, i.e. imaging depth, and is similar for different device types.<cross-ref type="fig" refid="CHAPTERsub50452F1"></cross-ref> <fig loc="float" id="CHAPTERsub50452F1"><no>Figure 1</no><caption> Impact of imaging depth </caption> <link locator="13328720130530111142"></fig>