On the screen:

1) Display the correct apical 4 chamber view

2) Activate the cursor

3) Place the cursor line through the AV plane on the lateral wall

4) Activate M-mode recording

5) Freeze the image when correct M-mode recording is obtained

On the M-mode image:

– Activate LV measurement (machine dependent)

– Mark endocardium in diastole from the R-wave in ECG (septum and posterior wall – red)

– Repeat for systole where the posterior wall is maximally contracted – yellow

After marking has been finished:

– The fractional shortening is most often calculated automatically

– The EF is normally calculated automatically by the ultrasound machine using the Teicholtz formula

– Repeat measurements to enhance accuracy – e.g. three successive sinus beats

On the screen:

1) Display the correct PLAX view

2) Activate the cursor

3) Place the cursor line as perpendicular as possible to the septum and posterior wall

4) Place the cursor line just distal to the tip of the anterior mitral leaflet

5) Activate M-mode recording

6) Freeze the image when correct M-mode recording is obtained

From M-mode recording through the anterior mitral leaflet the distance between the anterior mitral leaflet and the interventricular septum can be measured

The shortest distance between anterior mitral leaflet and inter-ventricular septum is called mitral septal separation (MSS)

In the past there has been a trend to measure LV dimensions on the 2D image

The reasons are:
– Appreciating the difficulties in obtaining the correct M-mode scan (remember 2D imaging was not available when clinical echocardiography was developed and normal values established)
– The 2D image quality has improved dramatically over the last two decades
– The frame rate has increased significantly over the last two decades
– Very accurate 2D measurement tools have been developed

Measurements can be done in both diastole and systole

The dimensions of the LV myocardium and LV cavity should be measured from the parasternal long axis view alternatively in the short axis view

The left ventricle diastolic dimension (LVDd) and the left ventricle systolic dimension (LVSd) are both obtained from the M-mode recording through the left ventricle (red arrow)

Fractional shortening (FS) is calculated using the formula in the box below

2 * FS is a rough measure of EF

Ultrasound systems use the Teichholz formula for a more precise calculation of EF

Since volume estimates are derived from a one dimensional measure, the accuracy of the estimate depends on the ventricular geometry and regional myocardial variability

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

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 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