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Fig. 4 | Cardiovascular Ultrasound

Fig. 4

From: Local myocardial stiffness variations identified by high frame rate shear wave echocardiography

Fig. 4

Explanation of the multi-layer TDI method used in this study, in one HCM patient having an inner layer scar. a: parasternal long axis and the focused TDI window over the interventricular septum; two M-Mode lines are traced, one in the outer layer and one in the inner layer, pointing towards the shear wave source. c: The mid panel is extracted from the Qlab postprocessing output and depicts synchronous ECG signal (green) and phonocardiogram (white). The average velocity line (pink line) is automatically generated by the software and should not be mistaken with the shear wave propagation velocity. Heart sounds are marked with S1 and S2. The onset of the second heart sound (S2) is marked with a white line and acts as reference for the onset of the aortic closure shear wave. b, d: local tissue velocity along the virtual M-mode lines traced in the outer layer (b) and inner layer (d). The entry and exit points of the shear wave along the two M-mode lines are marked with empty circles, connected by a white dashed straight line as reference. The aortic shear wave front slope is traced with yellow dashed lines. In panel B the wave front line is superposed on the reference line, but in panel D (inner layer) there is a visible shift in the slope, demonstrated by a deviation from the reference line

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