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7 M-Mode Echocardiography
7. 1 Principle of M-Mode Echocardiography
Fig. 7.1 M-mode echocardiography provides unidimensional imaging of moving objects over time. Only the top point of the soccer ball is detected and its location is shown over time.
7. 2 Aortic Valve
Fig. 7.2 Top: M-mode records the characteristic echo of the noncoronary and left coronary aortic leaflets, behind which is the left atrium (parasternal window). Bottom: Characteristic parallelogram of the aortic valve opening in systole. In diastole the valve edges appear as a highly reflective line.
7. 3 Mitral Valve
Fig. 7.3 Top: The ultrasound beam traces the typical biphasic pattern of mitral valve opening motion (first wave: ventricle relaxation, second wave: atrial contraction). Bottom: The monitor shows the M-shaped pattern of movement of the anterior mitral leaflet above and the small W-shaped pattern of the posterior leaflet below.
7. 4 Left Ventricle
Fig. 7.4 Top: Ventricular diameter and wall thickness can be recorded in the parasternal view. Bottom: Typical thickening and inward motion of the myocardium can be seen in systole.
8 Doppler Echocardiography
8. 1 The Doppler Effect
Fig. 8.1 The Doppler effect describes the change in frequency of a moving source of sound. The sound of an approaching ambulance is perceived to be higher pitched than the sound of one driving away. Velocity can be calculated based on the frequency shift.
8. 2 Imaging Blood Flow
Fig. 8.2 Using the Doppler principle, it is possible to image blood flow not only in terms of velocity but also in terms of flow direction.
8. 3 Imaging Doppler Spectra on the Monitor Screen
Fig. 8.3 Top: When the transducer is positioned at the angle shown in the diagram, the direction of blood flow is toward the transducer head. Bottom: Motion toward the transducer is displayed above the zero baseline on the monitor.
Fig. 8.4 Top: If the transducer is tilted in the opposite direction, the Doppler signal records blood flow moving away from it. Bottom: Motion away from the transducer is shown below the zero baseline on the monitor.
8. 4 Continuous-Wave (CW) Mode
Fig. 8.5 Top: CW mode records all Doppler pulses in a unidimensional ultrasound beam. Bottom: CW Doppler recording of transmitral flow: Flow into the left ventricle is toward the transducer and therefore displayed above the zero baseline.
Fig. 8.6 Aortic outflow in the apical three-chamber view: Flow is away from the transducer (top) and thus displayed below the zero baseline (bottom).
8. 5 Pulsed-Wave (PW) Mode
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