Characterization of the Relationship between Systolic Shear Strain and Early Diastolic Shear Strain Rates: Insights into Torsional Recoil

Early diastolic left ventricular (LV) untwisting has been evaluated as a manifestation of LV recoil, reflecting the release of elastic energy stored during systole. The primary goal of this study was to characterize the relationship between systolic strain (e.g., circumferential strain and the shear strains that comprise twist) with the resulting early diastolic shear strain rates, including the rate of untwisting. A further goal was to characterize these relationships regionally from apical to basal locations. Cardiac magnetic resonance imaging tissue tagging was used to measure circumferential strain, global and regional (apex, mid, basal) twist (θ), and circumferential-longitudinal (ϵCL) and circumferential-radial (ϵCR) shear strains along with the corresponding untwisting rates (dθ/dt) and diastolic shear strain rates (dϵ/dt) in 32 healthy males (33 ± 7 yr). LV untwisting rates and shear strain rates measured during early diastole varied significantly with the measurement location from apex to base (P...