Etiology and relevance of the figure-of-eight artifact on echocardiography after percutaneous left atrial appendage closure with the Amplatzer Cardiac Plug

Abstract

Background: The Amplatzer Cardiac Plug (ACP) device, used for percutaneous left atrial appendage closure, frequently presents as an unexplained figure-of-eight on echocardiography. The aim of this study was to clarify the figure-of-eight display of the ACP device during echocardiography and to relate this finding to device position and function.

Methods: A mathematical model was developed to resemble device geometry and predict the echocardiographic appearance of the ACP device. In addition, an in vitro setup was used to validate the model. Finally, echocardiographic images of consecutive patients referred for percutaneous left atrial appendage closure (n = 24) were analyzed for the presence of a figure-of-eight display.

Results: Because the ACP device resembles an epitrochoid curve, those points with tangent vector perpendicular to the ultrasound waves are emphasized, resulting in a figure-of-eight display, which can be replicated in vitro in the coronal imaging position. We found the figure-of-eight display in 100% (11 of 11) of three-dimensional periprocedural transesophageal images and in 87% (34 of 39) of postprocedural transthoracic echocardiographic images.

Conclusions: The figure-of-eight display of the ACP device during echocardiography is the result of the specific epitrochoid geometry of the device mesh and its interaction with ultrasound waves. It is important to recognize the figure-of-eight as being a normal imaging artifact of a correctly deployed device in the coronal imaging position on both transesophageal and transthoracic echocardiography. In the future, this could be used during follow-up to aid clinical practitioners in assessing device position and function.

Keywords: Echocardiography; Left atrial appendage closure; Ultrasound physics.