The Use of M Mode in Heart Conditions

This chapter deals with M Mode or Motion Mode, which usually is the second step in the Protocol after the creation of the 2D picture. While 2D image is in the form of a movie, the M Mode is in the form of a graph. The reason the M Mode is included in the protocol is because it has a much higher frame rate (1000–2000 frames/s also called Hertz) as compared to the 2D picture (30–100 frames/s). Hence, its accuracy in recording the movement of the walls and valves of the Heart (y Axis) over time (x Axis), is much higher. The recording of the M Mode is unidimensional. Usually, a Duplex image (2D and M Mode on the same screen) is obtained, so that it facilitates the accurate positioning of the Cursor on the 2D image to obtain an optimal M Mode image. In this chapter, the acquisition of M Mode image is described step by step in every view. It is important to know that the primary requirement of the M Mode image is, the cursor should cut across the structure perpendicularly whether it is Walls of the Heart or the Valves of the Heart. This is in contrast to the Doppler, especially Spectral Doppler, in which the cursor should be parallel to the blood flow in order to obtain an optimal image. It is important to know that while the Doppler gives information about the blood flow, the M Mode gives information about the accurate location of the Walls and Valves over time and not blood flow. The M Mode is significant in that many pathological conditions have unique characteristics in the graph, and the sonographer can infer from the graph, the pathology he is dealing with. After reading this chapter, the Sonographer should become familiar with a number of pathological conditions and how to diagnose them using the M Mode to create a Preliminary Report.