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Normal and shear strains of the left ventricle in healthy human subjects measured by two-dimensional speckle tracking echocardiography.

Yuan LJ, Takenaka K, Uno K, Ebihara A, Sasaki K, Komuro T, Sonoda M, Nagai R - Cardiovasc Ultrasound (2014)

Bottom Line: The ECG was recorded simultaneously.Bland-Altman analysis shows very good agreement between measurements taken by the same observer and by two independent observers. "Myocardial sheets" theory also holds true for intact human LV.Moreover, dyssynchrony exists even in healthy human subjects, which should be considered when evaluating the diseased hearts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China. yuanlj@fmmu.edu.cn.

ABSTRACT

Background: Animal studies have shown that shear deformation of myocardial sheets in transmural planes of left ventricular (LV) wall is an important mechanism for systolic wall thickening, and normal and shear strains of the LV free wall differ from those of the interventricular septum (IVS). We sought to test whether these also hold for human hearts.

Methods: Thirty healthy volunteers (male 23 and female 7, aged 34 ± 6 years) from Outpatient Department of the University of Tokyo Hospital were included. Echocardiographic images were obtained in the left decubitus position using a commercially available system (Aloka SSD-6500, Japan) equipped with a 3.5-MHz transducer. The ECG was recorded simultaneously. The peak systolic radial normal strain (length change), shear strain (angle change) and time to peak systolic radial normal strain were obtained non-invasively by two-dimensional speckle tracking echocardiography.

Results: The peak systolic radial normal strain in both IVS and LV posterior wall (LVPW) showed a trend to increase progressively from the apical level to the basal level, especially at short axis views, and the peak systolic radial normal strain of LVPW was significantly greater than that of IVS at all three levels. The time to peak systolic radial normal strain was the shortest at the basal IVS, and increased progressively from the base to the apical IVS. It gradually increased from the apical to the basal LVPW in sequence, especially at short axis views. The peak of radial normal strain of LVPW occurred much later than the peak of IVS at all three levels. For IVS, the shear deformation was clockwise at basal level, and counterclockwise at mid and apical levels in LV long-axis view. For LVPW, the shear deformations were all counterclockwise in LV long-axis view and increased slightly from base to the apex. LVPW showed larger shear strains than IVS at all three levels. Bland-Altman analysis shows very good agreement between measurements taken by the same observer and by two independent observers.

Conclusion: "Myocardial sheets" theory also holds true for intact human LV. Moreover, dyssynchrony exists even in healthy human subjects, which should be considered when evaluating the diseased hearts.

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Related in: MedlinePlus

Measurement of radial normal strain of IVS and LVPW at mid level in parasternal LV long axis view (taken from Additional file2). Right panel shows radial normal strain curves for left ventricular posterior wall (LVPW) and interventricular septum (IVS). IVS strain peaks earlier than LVPW strain, and peak strain value is about 2 times larger in LVPW than in IVS. Ao = aorta, ECG = electrocardiogram, LA = left atrium, LV = left ventricle, and RV = right ventricle.
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Figure 2: Measurement of radial normal strain of IVS and LVPW at mid level in parasternal LV long axis view (taken from Additional file2). Right panel shows radial normal strain curves for left ventricular posterior wall (LVPW) and interventricular septum (IVS). IVS strain peaks earlier than LVPW strain, and peak strain value is about 2 times larger in LVPW than in IVS. Ao = aorta, ECG = electrocardiogram, LA = left atrium, LV = left ventricle, and RV = right ventricle.

Mentions: From an end-systolic single frame of the long-axis view, 2 points were designated at the basal , mid, and apical levels in the IVS (the LV-side endocardium and the RV-side endocardium) and corresponding 2 points was designated at the same levels in the LVPW (the endocardium and the epicardium) by a point-and-draw approach (Figure 2 and Additional file 2). The basal level was defined as the position just below the mitral leaflet, the mid level was defined as the level of the papillary muscle, and the apical level was defined as the position below the papillary muscle. Acoustic markers, the so-called speckles, equally distributed in the region of interest, could be followed throughout the entire cardiac cycle and parameters of myocardial deformation could be calculated by clicking processing button. In order to corresponding with the laminar structure orientation of the heart displayed in the study by LeGrice IJ and to verify the “myocardial sheets” theory also holds for intact human LV, endocardial to epicardial boarders were traced.


Normal and shear strains of the left ventricle in healthy human subjects measured by two-dimensional speckle tracking echocardiography.

Yuan LJ, Takenaka K, Uno K, Ebihara A, Sasaki K, Komuro T, Sonoda M, Nagai R - Cardiovasc Ultrasound (2014)

Measurement of radial normal strain of IVS and LVPW at mid level in parasternal LV long axis view (taken from Additional file2). Right panel shows radial normal strain curves for left ventricular posterior wall (LVPW) and interventricular septum (IVS). IVS strain peaks earlier than LVPW strain, and peak strain value is about 2 times larger in LVPW than in IVS. Ao = aorta, ECG = electrocardiogram, LA = left atrium, LV = left ventricle, and RV = right ventricle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016487&req=5

Figure 2: Measurement of radial normal strain of IVS and LVPW at mid level in parasternal LV long axis view (taken from Additional file2). Right panel shows radial normal strain curves for left ventricular posterior wall (LVPW) and interventricular septum (IVS). IVS strain peaks earlier than LVPW strain, and peak strain value is about 2 times larger in LVPW than in IVS. Ao = aorta, ECG = electrocardiogram, LA = left atrium, LV = left ventricle, and RV = right ventricle.
Mentions: From an end-systolic single frame of the long-axis view, 2 points were designated at the basal , mid, and apical levels in the IVS (the LV-side endocardium and the RV-side endocardium) and corresponding 2 points was designated at the same levels in the LVPW (the endocardium and the epicardium) by a point-and-draw approach (Figure 2 and Additional file 2). The basal level was defined as the position just below the mitral leaflet, the mid level was defined as the level of the papillary muscle, and the apical level was defined as the position below the papillary muscle. Acoustic markers, the so-called speckles, equally distributed in the region of interest, could be followed throughout the entire cardiac cycle and parameters of myocardial deformation could be calculated by clicking processing button. In order to corresponding with the laminar structure orientation of the heart displayed in the study by LeGrice IJ and to verify the “myocardial sheets” theory also holds for intact human LV, endocardial to epicardial boarders were traced.

Bottom Line: The ECG was recorded simultaneously.Bland-Altman analysis shows very good agreement between measurements taken by the same observer and by two independent observers. "Myocardial sheets" theory also holds true for intact human LV.Moreover, dyssynchrony exists even in healthy human subjects, which should be considered when evaluating the diseased hearts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China. yuanlj@fmmu.edu.cn.

ABSTRACT

Background: Animal studies have shown that shear deformation of myocardial sheets in transmural planes of left ventricular (LV) wall is an important mechanism for systolic wall thickening, and normal and shear strains of the LV free wall differ from those of the interventricular septum (IVS). We sought to test whether these also hold for human hearts.

Methods: Thirty healthy volunteers (male 23 and female 7, aged 34 ± 6 years) from Outpatient Department of the University of Tokyo Hospital were included. Echocardiographic images were obtained in the left decubitus position using a commercially available system (Aloka SSD-6500, Japan) equipped with a 3.5-MHz transducer. The ECG was recorded simultaneously. The peak systolic radial normal strain (length change), shear strain (angle change) and time to peak systolic radial normal strain were obtained non-invasively by two-dimensional speckle tracking echocardiography.

Results: The peak systolic radial normal strain in both IVS and LV posterior wall (LVPW) showed a trend to increase progressively from the apical level to the basal level, especially at short axis views, and the peak systolic radial normal strain of LVPW was significantly greater than that of IVS at all three levels. The time to peak systolic radial normal strain was the shortest at the basal IVS, and increased progressively from the base to the apical IVS. It gradually increased from the apical to the basal LVPW in sequence, especially at short axis views. The peak of radial normal strain of LVPW occurred much later than the peak of IVS at all three levels. For IVS, the shear deformation was clockwise at basal level, and counterclockwise at mid and apical levels in LV long-axis view. For LVPW, the shear deformations were all counterclockwise in LV long-axis view and increased slightly from base to the apex. LVPW showed larger shear strains than IVS at all three levels. Bland-Altman analysis shows very good agreement between measurements taken by the same observer and by two independent observers.

Conclusion: "Myocardial sheets" theory also holds true for intact human LV. Moreover, dyssynchrony exists even in healthy human subjects, which should be considered when evaluating the diseased hearts.

Show MeSH
Related in: MedlinePlus