Introduction to M-Mode Echocardiography

A set of vocabulary terms and definitions covering the principles, technology, and clinical application of M-Mode echocardiography based on lecture materials.

M-Mode (motion mode)

An ultrasound technique that depicts reflector position and motion over time.

Purpose of M-Mode

Provides precise recording of the position (depth) and motion of the cardiac muscle, valves, and surrounding tissues, providing a means by which measurements can be made against normal values.

M-Mode Technology

A single crystal rapidly alternates between transmission and receiver modes to monitor rapidly moving structures with very high temporal resolution.

M-Mode Y-axis

The vertical axis of the display representing the distance (depth) of various interfaces from the transducer.

M-Mode X-axis

The horizontal axis of the display representing time (sweep) as anatomy is swept along the field of view.

M-Mode Sampling Rate

Information updated rapidly at a rate of $1800\,\text{frames/sec}$, providing excellent resolution compared to $30-60\,\text{frames/sec}$ in 2D imaging.

Cursor Positioning

The M-Mode line should be carefully positioned to transect the area of interest at $90\,\text{degrees}$ (perpendicular).

Intensity (Brightness)

Correspondence on the display to the strength of the reflection at each interface.

Nonmoving Structures

Anatomy that does not move appears as straight lines on the M-Mode sweep.

End-diastole (ECG Correlation)

Marked by the peak R wave (or when the LV cavity is largest), occurring in the frame after Mitral Valve closure.

End-systole (ECG Correlation)

Generally marked by the end of the T wave (or when the LA cavity is largest), occurring in the frame after Aortic Valve closure.

Icepick View

A term describing the M-Mode imaging plane that can be used along any plane throughout the heart, with the Parasternal window being standard.

Sweep Speed

A control adjusted for specific clinical situations to change the frequency of the time axis display.

LVEDD

Left Ventricular End-Diastolic Dimension, a measurement typically captured in M-Mode.

LVESD

Left Ventricular End-Systolic Dimension, a measurement typically captured in M-Mode.