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Objectives |
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At the completion of this chapter, the user will be able to: |
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- Understand normal left atrial, left atrial appendage, and pulmonary vein anatomy
- Describe normal physiology of the left atrium, left atrial appendage and pulmonary veins
- Obtain TEE acoustic window views of left atrium, left atrial appendage, and pulmonary veins
- Describe normal and abnormal structures of the left atrium, left atrial appendage, and pulmonary veins
- Differentiate normal and abnormal pulmonary vein flow patterns
- Discuss abnormal connections, drainage and obstructions of the pulmonary veins
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Introduction |
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The left atrium and pulmonary veins serve multiple functions during the cardiac cycle. The left atrium serves as a reservoir of pulmonary venous return during left ventricular contraction and as an active pump at the end of left ventricular diastole. The left atrium and pulmonary veins function as a conduit during left ventricular diastole. The anatomy and flow during the cardiac cycle can be shown echocardiographically. The echocardiographic anatomic signs and patterns of flow can indicate various disease processes and the effects on the left atrial function and filling of the left ventricle. |
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Anatomy |
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| The left atrium is a thin walled, oval chamber that is a posterior cardiac structure. The left atrium consists of the main left atrial cavity and the left atrial appendage. The borders of the left atrium are the mitral valve (MV) which is placed inferiorly, interatrial septum (IAS) is medially, and the posterior, lateral and superior walls of the atrium are free walls not adjacent to other cardiac structures. The left atrial appendage is lateral. There are four pulmonary veins that empty into the left atrium from the lungs. They are the left upper (LUPV) and lower (LLPV) (superior and inferior) and right upper (RUPV) and lower RLPV) (superior and inferior). |
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LA Anatomy Image
3 Chamber View |
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| The endocardial surface of the left atrium is normally smooth and contiguous except for the insertions of the four pulmonary veins posterior. The left atrial appendage opening is anterolateral and the mitral valve orifice is inferior. Unlike the right atrium, only the left atrial appendage contains pectinate muscles. The atrial tissue that surrounds the main cavity of the left atrium is smooth. The atrial septum is smooth except for an indentation in the middle caused by the foramen ovale. The interatrial septum (IAS) separates the left and right atrium. Septal abnormalities may include patent foramen ovale (PFO) or atrial septal defects. Patent foramen ovale is present in 25-30% of patients. |
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LA and LAA Anatomy Image
2 Chamber View |
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