ABSTRACT
Anatomy and pathology The left atrial appendage (LAA) is a small, muscular sacculation of the left atrium (LA) located between the left upper pulmonary vein and the left ventricle, overlapping the proximal left circumflex artery. It is a derivative of the primitive atrium and has a wide anatomic variability. Its size ranges from 20 to 45 mm in length and 15 to 35 mm in orifice diameter.1 In more than two-thirds of the population the LAA consists of two or more lobes originating from one common orifice. Among other cardiac structures the left atrial appendage releases atrionatriuretic peptide (ANP), a polypeptide promoting diuresis.
