Imaging of the left atrial appendage.

The LAA is the most common site of thrombus formation in nonvalvular atrial fibrillation. In nonvalvular atrial fibrillation, percutaneous LAA occlusion/exclusion is an alternative method of thromboembolism prevention for patients who are either ineligible for or too high risk to receive systemic anticoagulation therapy.  2D/3D transesophageal echocardiography has a critical role in all percutaneous LAA occlusion/exclusion procedures, including screening for eligibility, device sizing, intraprocedural guidance, and postprocedural follow up. This lecture will review planning and guidance for the most commonly used percutaneous LAA occlusion/exclusion devices worldwide include the Watchman and Amulet.