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Assessment of left atrial appendage function by transesophageal echocardiography. Implications for the development of
Insights
Left atrial appendage (LAA) thrombus formation is linked to poor LAA contraction and dilation. Echocardiography reveals distinct LAA function patterns associated with thrombus in sinus rhythm and atrial fibrillation.
Area of Science:
- Cardiology
- Medical Imaging
Background:
- The left atrial appendage (LAA) is a common site for thrombus formation.
- Understanding LAA function is crucial for preventing thromboembolic events.
Purpose of the Study:
- To prospectively evaluate the echocardiographic and Doppler patterns of LAA function in patients with and without LAA thrombus.
- To correlate LAA function with LAA size and rhythm (sinus rhythm vs. atrial fibrillation).
Main Methods:
- Transesophageal echocardiography (TEE) was used to assess LAA function in 82 patients.
- Measurements included LAA dimensions, ejection fraction, and Doppler velocities.
- Patients were categorized by cardiac rhythm and presence of LAA thrombus or spontaneous contrast.
Main Results:
- In sinus rhythm, thrombus was associated with larger LAAmax and LAAmin, reduced LAA ejection fraction, and lower peak Doppler velocity compared to controls.
- In atrial fibrillation, patients with spontaneous contrast or thrombus had larger LAAmax and a more static LAA appearance.
- LAA dysfunction (poor contraction and dilation) was evident in patients with thrombus.
Conclusions:
- The LAA exhibits a characteristic emptying pattern in sinus rhythm.
- LAA thrombus formation in both sinus rhythm and atrial fibrillation is associated with impaired LAA contraction and LAA dilation.
Background:
The predilection of the left atrial appendage (LAA) for thrombus formation has long been known.
Methods And Results:
We prospectively studied the two-dimensional echocardiographic and Doppler patterns of LAA function in 82 patients by transesophageal echocardiography. In the 63 patients in sinus rhythm, LAA area was measured during LAA diastole at the onset of the electrocardiographic (ECG) P wave (LAAmax) and after LAA systole at the ECG R wave (LAAmin) and LAA ejection fraction was calculated as (LAAmax-LAAmin)/LAAmax; peak Doppler velocity was recorded from the LAA outlet. The 58 patients in sinus rhythm without LAA thrombus were grouped according to left atrial size on transthoracic echocardiography; 39 patients had a left atrial size of less than 40 mm (group 1) and 19 had a left atrial size of 40 mm or greater (group 2). Five patients in sinus rhythm had LAA thrombus. In the 19 patients with atrial fibrillation or flutter LAAmax was measured independent of the ECG; three of these patients had LAA spontaneous contrast, four had thrombus, and one had both. Patients in sinus rhythm without LAA thrombus demonstrated a characteristic pattern of a contractile LAA apex and a noncontractile base with color flow and pulsed Doppler evidence of LAA emptying that coincided with the P wave. Patients in sinus rhythm with LAA thrombus had a mean +/- SD LAAmax (8.0 +/- 1.5 cm2) larger than that in group 1 (5.0 +/- 1.9 cm2) (p less than 0.01) but not group 2 (6.7 +/- 3.1 cm2), LAAmin (6.5 +/- 1.0 cm2) larger than that in both group 1 (2.3 +/- 1.5 cm2) and group 2 (4.2 +/- 2.7 cm2) (p less than 0.01), and LAA ejection fraction (17 +/- 11%) and LAA velocity (0.24 +/- 0.10 m/sec) less than those in both group 1 (55 +/- 21% and 0.48 +/- 0.24 m/sec, respectively) and group 2 (45 +/- 27% and 0.46 +/- 0.24 m/sec, respectively) (p less than 0.01). Patients with atrial fibrillation or flutter with LAA spontaneous contrast and/or thrombus had LAAmax (10.4 +/- 6.6 cm2) greater than that in patients with atrial fibrillation or flutter without LAA contrast and/or thrombus (6.8 +/- 3.0 cm2) (p less than 0.05). The LAA appeared as a static pouch in seven of eight of the former compared with in two of 11 of the latter. When attempted, Doppler demonstrated a recognizable fibrillatory LAA outflow velocity pattern in none of three in the former versus four of seven in the latter group.
Conclusions:
We conclude that the LAA has a characteristic pattern of emptying in sinus rhythm. LAA thrombus formation in sinus rhythm and atrial fibrillation is associated with both poor LAA contraction and LAA dilation.