left atrial appendage
A small, ear-shaped pouch extending from the left atrium that is a common site of thrombus formation in atrial fibrillation.
Full Definition
The left atrial appendage (LAA) is a tubular, muscular extension of the left atrium with a complex, multilobed anatomy that varies significantly between individuals. In patients with atrial fibrillation, the LAA is the most common site of thrombus formation due to blood stasis resulting from reduced contractile function and altered flow patterns. LAA thrombus is a major source of cardioembolic stroke in AF patients. Assessment requires high-quality transesophageal echocardiography or cardiac CT to visualize the appendage and detect thrombus, spontaneous echo contrast, or reduced flow velocities. In patients with contraindications to anticoagulation, LAA occlusion devices can be implanted to prevent thromboembolic events. Normal LAA emptying velocities are typically >40 cm/s, with lower velocities indicating increased stroke risk.
Usage
Usage note: Always assess for thrombus in AF patients; specify emptying velocities when measured.
In Context
- "TEE revealed no thrombus in the left atrial appendage with normal emptying velocities." — Transesophageal echocardiography report
- "The patient underwent successful left atrial appendage occlusion with a closure device." — Interventional procedure note