title: 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.
authors.affiliation: Department of Cardiology, Ziekenhuis Oost-Limburg, Genk, Belgium; Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Philippe B
authors.initials: PB
authors.lastname: Bertrand
authors.affiliation: Department of Cardiology, Ziekenhuis Oost-Limburg, Genk, Belgium; Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Lars
authors.initials: L
authors.lastname: Grieten
authors.affiliation: Department of Cardiology, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: De Meester
authors.affiliation: Department of Cardiology, Ziekenhuis Oost-Limburg, Genk, Belgium; Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Frederik H
authors.initials: FH
authors.lastname: Verbrugge
authors.affiliation: Department of Cardiology, Ziekenhuis Oost-Limburg, Genk, Belgium; Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Wilfried
authors.initials: W
authors.lastname: Mullens
authors.affiliation: Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Verhaert
authors.affiliation: Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Maximo
authors.initials: M
authors.lastname: Rivero-Ayerza
authors.affiliation: Department of Cardiology, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Werner
authors.initials: W
authors.lastname: Budts
authors.affiliation: Department of Cardiology, Ziekenhuis Oost-Limburg, Genk, Belgium; Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium. Electronic address: pieter.vandervoort@zol.be.
authors.forename: Pieter M
authors.initials: PM
authors.lastname: Vandervoort
mesh_terms: D016477:Artifacts; D020517:Atrial Appendage / Q000000981:diagnostic imaging* / Q000601:surgery*; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000601:surgery*; D017548:Echocardiography, Transesophageal / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055989:Septal Occluder Device
keywords: Echocardiography; Left atrial appendage closure; Ultrasound physics