LV dimensions have historically been measured on a M-mode scan

The M-mode recording is made in a similar way as described under ejection fraction

The blue line refers to M-mode at the level of the left ventricle

M-mode recording in the PLAX view along the three different transection lines give different information about the LV function:

1) Through the left ventricle (LV)
– LV dimensions and fractional shortening (FS) are obtained along cursor line 1

2) Through the anterior mitral leaflet
– mitral septal separation (MSS) is obtained along cursor line 2

3) Through the aorta and left atrium
– left atrium dimension is obtained along cursor line 3

The FS and EF calculations are only applicable if there is no regional variability in myocardial function

M-mode sonoanatomy:

– At the top recording through the left ventricle

– In the middle through the anterior mitral leaflet

– At the bottom through the aorta and left atrium

On the screen:
1) Display the parasternal long axis view (PLAX)
2) Make sure you transect the LV so it appear largest
3) Freeze a full cine loop covering a whole heart cycle
4) Use the trackball to scroll to diastole (just before the aortic valve opens)
5) Activate the measurement button (machine dependent)
6) Measure as perpendicular to the septum and posterior wall as possible
7) Measure only the free of the tip of the mitral leaflets
8) Repeat for systole when convenient

The image below is a typical greyscale M-mode recording of the left ventricle in the parasternal long axis view with:

– The 2D reference image on top (red box)

– The M-mode recording at the bottom (yellow box)

Because M-mode is a one dimensional display it has a very high time (temporal) resolution

To collect the echocardiographic M-mode data in the parasternal long axis view (FATE position 3) the cursor line alternately transects:

– The left ventricle (1 red line)
– The anterior mitral leaflet (2 green line)
– The aorta and left atrium (3 blue line)