Reliability of left atrial strain reference values: A 3D echocardiographic study

Figures

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  Fig 1. How to measure left atrial volume, length, and strain using 2D echocardiography. A and B: left atrial endocardial border tracking on the apical four-chamber (A) and two-chamber (B) views from which disk-area and length were determined. C and D: Corresponding left atrial strain curves.

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  Fig 2. How to measure left atrial strain and length using 3D echocardiography. A: The center of the mitral valve was registered and the angle was changed so that dotted lines dissected the maximal LA length in three apical views extracted from 3DE datasets. B: Software determined the LA endocardial border in 3D space. C: LA longitudinal strain curve and a 3D cast of the left atrium. D: Cropped view of 3DE datasets. E and F: Under the guidance of the short axis view of the left atrium, anterior-posterior and commissure-commissure views showing full visualization of LA longitudinal distance were obtained, from which we measured the LA longitudinal distance between the center of the mitral annular plane and the LA roof at end-diastole and end-systole. 3DE, three-dimensional echocardiography; Ao, aorta; AP, anterior-posterior view; CC, commissure-commissure view; ED, end-diastole; ES, end-systole; MV, mitral valve; LA, left atrium; LV, left ventricle; RV, right ventricle; PreA, pre-atrial contraction.

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  Fig 3. CMR feature tracking analysis of LA. A: A cut-plane optimized for the left ventricle (yellow arrows) and that optimized for the left atrium (orange arrows) were determined using apical long-axis SSFP images. These planes rotated to the same degree to generate apical four-chamber and two-chamber views aimed for the left ventricle (B and C) and those aimed for the left atrium (E and F). D: Feature tracking of the LA wall using LV-focused, two-chamber view and the corresponding LA strain curve. G: Feature tracking of the LA wall using LA-focused, two-chamber view and the corresponding LA strain curve. LAVmax, maximal LA volume; LAVmin, minimal LA volume; LALS, LA longitudinal strain.

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  Fig 4. Comparisons of left atrial strain and length using 2DE analysis. A: LA longitudinal strain in apical four-chamber view (4C LALS), apical two-chamber view (2C LALS), and their average (biplane LALS). B: LA length comparing apical four-chamber and apical two-chamber at end-diastole (left panel) and at end-systole (right panel). C: A linear correlation between average left atrial length at end-diastole and biplane left atrial longitudinal strain. D: A linear correlation between average left atrial length at end-systole and biplane left atrial longitudinal strain.

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  Fig 5. A paired comparison and correlation of left atrial volumes, emptying fraction, and strain between 2DE and 3DE. A and B: Indexed maximal and minimal left atrial volumes (LAVIx, LAVIn) between 2DE and 3DE (upper panel) and their correlation (lower panel). C: Left atrial emptying fraction (LAEF) between the two methods (upper panel) and their correlation (lower panel). D: Left atrial strain between the two methods (upper panel) and their correlation (lower panel).

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  Fig 6. A paired comparison of left atrial length between 2DE and 3DE. A: End-diastole. B: End-systole.

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  Fig 7. Correlations between biplane LA strain and LA length in patients with cardiovascular disease (n = 53). A: A linear correlation between average left atrial length at end-diastole and biplane left atrial longitudinal strain. B: A linear correlation between average left atrial length at end-systole and biplane left atrial longitudinal strain. Red rectangles represent patients. Data from normal subjects are superimposed (blue triangles).

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  Fig 8. Comparison of LA length and strain among standard 2D images, LA focused 2D images, and 3D echocardiography. Values are expressed as medians and (interquartile ranges).

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  Fig 9. Difficulty in obtaining an optimized LA view. Panel A shows a cardiac magnetic resonance image of the heart and surrounding structures. Panel B shows a subject in whom there is some distance between the chest wall and the heart apex. This is typical of large-bodied westerners. In such cases, there is space on the chest wall to record both the left ventricle and the left atrium (blue arrows). However, the LA long axis runs more caudally (red arrow); thus, it is quite difficult to obtain an optimal LA view. Panel C depicts a subject whose apex is located behind the chest wall. This is typical of slender Japanese subjects. Since the scanning area is limited, only angulation of the transducer enables a different cut-plane of the left atrium. However, it is difficult to make significant changes in long axis delineation of the LA wall. Delineation changes cause subtle changes in both the LA long axis diameter and LA strain.