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Echocardiography in M-mode
Last reviewed: 23.04.2024
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Echocardiography in M-mode
Despite the advantages of a two-dimensional image, echocardiography in M-mode (M - from motion, motion) remains a quick and simple technique. Unlike the two-dimensional technology, ultrasonic signals are transmitted and received along one beam with the recording of movements of the heart structures. The correct position of the beam is verified by simultaneous obtaining a two-dimensional image. Changes in the wall thickness and the size of the heart chambers and the pattern of motion of the valve structures are visualized and measured with a very high temporal resolution. Two examples of M-mode research are given below.
Doppler and color duplex echocardiography
Using Doppler and color duplex modes, one can visualize and quantify the cardiac blood flow. This is necessary to evaluate the heart valves when suspected of insufficiency or stenosis. In addition, it is possible to evaluate cardiac output when measuring blood flow in the aorta and pulmonary trunk and to detect blood flow abnormalities associated with congenital heart defects. In order for the Doppler study and color duplex sonography to be effective, it is necessary to take into account the results of traditional two-dimensional scanning.
Atrial-ventricular valves
The apical acoustic window, especially when using a four-chamber plane, is optimal for visualizing blood flow through the atrioventricular valves. Normal blood flow has the following color pattern: after the closure of the semilunar valves, atrial-ventricular valves are opened in the early phase of diastole; the blood flows through the pressure gradient between the atria and the relaxed ventricles along the entire width of the open valve lumen. The rapid flow of blood through the mitral valve looks like a cloud of red pixels with a central blur (red-blue). This causes a redistribution of blood flow in the left ventricle, the blood along the outflowing tract of the left ventricle slowly moves to the aortic valve (blue pixels). Atrial contraction causes the second phase of filling the ventricles. After this, the atrioventricular valves close and the systole begins. If the valves are intact, there is no regurgitant blood flow in the area of their valves. In this case, only the blue color can be detected in the outflow tract of the left ventricle towards the aortic valve. The red area reflects the ingress of blood into the left atrium from the pulmonary veins.
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