State-of-the-Art Review
Left Atrial Appendage: Embryology, Anatomy, Physiology, Arrhythmia and Therapeutic Intervention

https://doi.org/10.1016/j.jacep.2016.06.006Get rights and content
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Abstract

Known for the pathological connection to atrial fibrillation (AF), the left atrial appendage (LAA) is the most common source of thromboembolism in patients with AF and may be an arrhythmogenic source for the maintenance of AF. Potential interventions of the LAA for stroke prevention have recently been developed through better understanding its anatomy and physiology. Occlusion of the LAA is an alternative to the use of life-long anticoagulation in selected nonvalvular AF cases. The PROTECT-AF (The WATCHMAN LAA Closure Device for Embolic PROTECTion in Patients with Atrial Fibrillation) and PREVAIL (Randomized Trial of LAA Closure vs. Warfarin for Stroke/Thromboembolic Prevention in Patients with Non-valvular Atrial Fibrillation) randomized controlled trials demonstrated that LAA exclusion using the Watchman percutaneous device is not inferior to warfarin. However, the appendage is structurally complex and has considerable morphological variations among individuals, and it can be challenging to generalize the device for all patients. Continued technological developments including occlusion/ligation through epicardial, endocardial, or surgical approaches, as well as operator expertise regarding LAA anatomy, physiology, and pathophysiology, should improve interventional outcomes. Furthermore, the optimal strategy for re-entrant tachyarrhythmias arising from LAA remains unknown. Whereas an observational study suggested that LAA isolation was more effective than focal ablation, LAA isolation may be associated with significant impairments in LAA contractility, predisposing individuals to a risk of thrombosis.

Key Words

anatomy
closure
left atrial appendage
ligation
pathophysiology
physiology

Abbreviations and Acronyms

AF
atrial fibrillation
CT
computed tomography
LAA
left atrial appendage
LA
left atrium
LOM
ligament of Marshall
LSPV
left superior pulmonary vein
LV
left ventricle
PA
pulmonary artery
PV
pulmonary vein
TEE
transesophageal echocardiography

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Dr. Asirvatham is an uncompensated consultant for Abiomed, Atriccure, Biotronik, Biosense Webster, Boston Scientific, Medtonic, Medtelligence, St Jude Medical, Sanofi Aventis, Wolters Kluwer, Elsevier, and Zoll; and is a patent holder with Aegis, Access Point Technologies, Nevro, Sanovas, and Sorin Medical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.