To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Video 1 Video looking into the left atrial appendage (LAA); ‘smoke’ can be seen coming out of the LAA indicating its patency and communication with the left atrium. View Video 1 at http://movie-usa.glencoesoftware.com/video/10.1530/ERP-17-0076/video-1. The clot thickens: an incompletely ligated left atrial appendage Merrill Thomas, Anna Grodzinsky, and Martin Zink 2018. 5:K41-K45 DOI: 10.1530/ERP-17-0076 Download Original Video