Table 1.

Definitions

Strain (ε; %)	The proportional change in myocardial length between end-diastole and end-systole $\mathrm{\epsilon }=(\mathrm{L}-{\mathrm{L}}_0)/{\mathrm{L}}_0=\mathrm{\Delta }\mathrm{L}/{\mathrm{L}}_0$
End-systolic strain (%)	Strain measured at end-systole (defined as the time of aortic valve closure)
Peak systolic strain (%)	Strain measured at time of greatest systolic deformation
Global strain (%)	Average strain for all myocardial segments
Pre-stretch	Brief lengthening of myocardial segment in early systole prior to systolic shortening
Post-systolic shortening (or post-systolic strain)	Peak strain occurring in early diastole
Strain Rate (SR; sec−1)	Change in strain per unit time $\text{SR}=\mathrm{\Delta }\mathrm{\epsilon }/\mathrm{\Delta }\mathrm{t},$
Rotation (degrees)	Degrees of LV rotation viewed from the apex
LV twist (degrees)	Rotation of the apex relative to the base, or, the absolute apex-to-base difference in rotation
Torsion (degrees per centimeter)	Apex-to-base gradient in the rotation angle of the LV long axis where the twist angle is divided by the distance between base and apex

LV = Left ventricle; ε = strain; L= length at end-systole; L₀ = initial length measured at end-diastole; t = time (seconds); SR = strain rate