Left ventricular strain and strain rate: Characterization of the effect of load
in human subjects
European Journal of Echocardiography (2010) 11, 283–289
Left ventricular (LV) strain and strain rate have been proposed as novel indices of systolic function; however, there are limited data about the effect of acute changes on these parameters.
Simultaneous Millar micromanometer LV pressure and echocardiographic assessment were performed on 18
patients. Loading was altered sequentially by the administration of glyceryl trinitrate (GTN) and saline fluid
loading. Echocardiographic speckle tracking imaging was used to quantify the peak systolic strain (S) and peak systolic
strain rate (SR S) and dp/dt max was recorded from the micromanometer data. GTN administration decreased preload (LV end diastolic pressure [LVEDP]: 15.7 vs. 8.4 mmHg, P , 0.001) and afterload (end systolic wall stress:74 vs. 43 103dyn/cm2, P , 0.001). Administration of fluid increased preload (LVEDP: 11.3 vs. 18.1 mmHg, P , 0.001) and increased wall stress (53 vs. 62 103dyn/cm2, P , 0.003). Administration of GTN resulted in increased circumferential SR S (21.2 vs. 21.7s21, P , 0.01) and longitudinal SR S (20.9 vs. 21.0s21, P , 0.001). The administration of fluid resulted in decreased circumferential SR S (21.5 vs. 21.3s21, P , 0.01) and ongitudinal
SR S (21.0 vs. 20.9s21, P , 0.01). As preload and afterload increased, decrease in circumferential SR S (r ¼ 0.63, P , 0.001; r ¼ 0.56, P,0.001) and longitudinal SR S were observed (r ¼ 0.42, P , 0.003; r ¼ 0.49 P , 0.001).
Circumferential and longitudinal peak strain and systolic strain rate are sensitive to acute changes in load, an important factor that needs to be considered in their application as indices of systolic function.
Vários pesquisadores têm apontado o Strain como método equivalente ou superior ao Simpson.
Mas as influências da pré e pós carga no método são significativas.
Isso também ocorre no Simpson, mas já foi melhor avaliado ao longo do tempo.
Enquanto a Fração de ejeção 3D em tempo real não se populariza, vamos de Simpson mesmo!