Assessment of the morphology and mechanical function of the left atrial appendage by real-time three-dimensional transesophageal echocardiography.

Background: The left atrial appendage (LAA) is an important source of thrombus formation. We investigated the feasibility of the recently developed real-time three-dimensional transesophageal echocardiography (RT3D-TEE) method in assessment of the morphology and function of the LAA.

Methods: Ninety-six consecutive patients (58 males with a mean age of (43.4 ± 12.5) years) who were referred for 2-dimensional (2D) transesophageal echocardiography (TEE) underwent additional RT3D-TEE. LAA morphology was visualized in multiple views. Orifice size, depth, volumes and ejection fraction (EF) of the LAA, were measured.

Results: All the patients underwent RT3D-TEE examination without complications. Ninety-two patients (95.8%) had adequate images for visualization and quantitative analysis of the LAA. The LAA exhibited great variability with respect to relative dimensions and morphology. LAA orifice area was (3.8 ± 1.2) cm(2) with a diameter of (2.4 ± 0.9) cm × (1.4 ± 0.6) cm. The mean depth of the LAA was (2.9 ± 0.7) cm. End-diastolic volume (EDV-LAA), end-systolic volume (ESV-LAA) and EF of the LAA were (6.2 ± 3.7) ml, (4.1 ± 2.8) ml, and 0.35 ± 0.16, respectively. EDV-LAA, ESV-LAA and the orifice area of the LAA in patients with atrial fibrillation (AF) were larger than those without AF, whereas the EF was smaller in the AF patients.

Conclusions: Defining LAA morphology and quantitative analysis of the size and function of the LAA with superior quality and resolution of images using RT3D-TEE is feasible. This technique may be an ideal tool for guidance of the LAA occlusion procedure. Determination of LAA volumes and volume-derived EF by RT3D-TEE provides new insights into the analysis of LAA function.