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Left atrial appendage

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Title: Left atrial appendage  
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Subject: Auricle, List of subjects in Gray's Anatomy: V. Angiology, Trabeculae carneae, Right atrial appendage
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Left atrial appendage

Left atrial appendage
Heart seen from above. (Left auricula labeled at bottom left.)
Section of the heart showing the ventricular septum. (Left auricula labeled at upper right.)
Latin auricula sinistra
Gray's subject #138 533

The left atrial appendage (LAA)[1] (left auricular appendix,[2] auricula,[2] left auricle[3]) is a muscular pouch connected to the left atrium of the heart.

It has a distinct embryologic origin.[4]


Although the LAA is sometimes called the left auricle,[5] in older texts the term "left auricle" was often used differently to describe the structure now known as the left atrium.


The LAA is a small pouch located high in the left atrium; it is within the pericardium and has a wall adjacent to the left ventricle. It appears to "function as a decompression chamber during left ventricular systole and during other periods when left atrial pressure is high".[6]

Clinical significance

In patients with atrial fibrillation, mitral valve disease, and other conditions, blood clots have a tendency to form in the LAA.[6] Blood clots caused by atrial fibrillation stem from the LAA in more than 90% of cases.[7] They may dislodge (forming emboli), which may lead to ischemic damage to the brain, kidneys, or other organs supplied by the systemic circulation.[8] Left atrial appendage occlusion is an experimental treatment to prevent stroke in atrial fibrillation.[9]

It can serve as an approach for mitral valve surgery.[10]


Functions as a reservoir for the left atrium.


The left atrial appendage can be seen on a standard posteroanterior x-ray, where the lower level of the left hilum becomes concave.[11]

Additional images


This article incorporates text from a public domain edition of Gray's Anatomy.

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