Human left atrial appendage anatomy and overview of its clinical significance

The left atrial appendage (LAA) is an important anatomic region since it is a source of thromboembolism in patients with atrial fibrillation. Although this anatomic and clinical relation it has received little attention until recent years.

This descriptive laboratory study was performed in 56 hearts of adult formalin fixed cadavers. The morphological characteristics of LAA were recorded. The distances between the orifices of left superior pulmonary veins (LSPV), circumflex artery, left anterior descending (LAD) artery, mitral valve and LAA were also measured in this study.

The morphological appearance of the LAA was classified into two different ways. There were two types according to the first classification: slender like a crooked finger (in 73.2%) and stump-like (in 26.8%). The lobe number of LAA was two in 64.3% specimens and three in 35.7%. The types of LAA were Cactus (24%), Chicken Wing (12%), Windsock (38%) and Cauliflower (26%) according to the second classification. The LAA orifice was oval-shaped in 37.5% and round-shaped in 62.5%. The bridge on the orifice was determined in one specimen. The longest diameter of LAA orifice was 16.5±4 mm. The presence of accessory left atrial appendage was observed in one specimen. The distance between LAA orifice and oval fossa was 27.5±5.5 mm.

We highlighted the anatomic features of LAA and LAA orifice. LAA diameters, shape and the relation between neighboring structures in relation to atrial fibrillation and surgical approaches were discussed.