Global Longitudinal Strain (GLS)

Lagrangian strain is defined as the change in length of an object within a certain direction relative to its baseline length:

$$\text{Strain(\%)}=\frac{L_t-L_0}{L_0}$$

where $L_t$ is the length at time $t$, and $L_0$ is the initial length at time 0.

The most commonly used strain-based measure of LV global systolic function is GLS, which is usually assessed by speckle-tracking echocardiography (STE). On 2DE, peak GLS describes the relative length change of the LV myocardium between end-diastole and end-systole:

$$\text{GLS(\%)}=\frac{M{L}_s-M{L}_d}{M{L}_d}$$

where $ML$ is myocardial length at end-systole ($M{L}_s$) and end-diastole ($M{L}_d$). Because $M{L}_s$ is smaller than $M{L}_d$, peak GLS is a negative number.

• GLS measurements should be made in the three standard apical views, i.e. A4C, A2C, A3C, and averaged.
• ⚠️ When regional tracking is suboptimal in more than two myocardial segments in a single view, the calculation of GLS should be avoided.
  • In such cases, alternative indices may be used to gain insight into longitudinal LV function, such as mitral annular plane systolic excursion or pulsed Doppler tissue imaging (DTI)-derived mitral annular peak systolic velocity (s’).