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. 2016 May 15;310(10):H1330-9.
doi: 10.1152/ajpheart.00947.2015. Epub 2016 Mar 11.

The influence of acute unloading on left ventricular strain and strain rate by speckle tracking echocardiography in a porcine model

Geir Olav Dahle  1 , Lodve Stangeland  2 , Christian Arvei Moen  2 , Pirjo-Riitta Salminen  3 , Rune Haaverstad  3 , Knut Matre  2 , Ketil Grong  2
Affiliations

The influence of acute unloading on left ventricular strain and strain rate by speckle tracking echocardiography in a porcine model

Geir Olav Dahle et al. Am J Physiol Heart Circ Physiol. .

Abstract

Noninvasive measurements of myocardial strain and strain rate by speckle tracking echocardiography correlate to cardiac contractile state but also to load, which may weaken their value as indices of inotropy. In a porcine model, we investigated the influence of acute dynamic preload reductions on left ventricular strain and strain rate and their relation to the pressure-conductance catheter-derived preload recruitable stroke work (PRSW) and peak positive first derivative of left ventricular pressure (LV-dP/dtmax). Speckle tracking strain and strain rate in the longitudinal, circumferential, and radial directions were measured during acute dynamic reductions of end-diastolic volume during three different myocardial inotropic states. Both strain and strain rate were sensitive to unloading of the left ventricle (P < 0.001), but the load dependency for strain rate was modest compared with strain. Changes in longitudinal and circumferential strain correlated more strongly to changes in end-diastolic volume (r = -0.86 and r = -0.72) than did radial strain (r = 0.35). Longitudinal, circumferential, and radial strain significantly correlated with LV-dP/dtmax (r = -0.53, r = -0.46, and r = 0.86), whereas only radial strain correlated with PRSW (r = 0.55). Strain rate in the longitudinal, circumferential and radial direction significantly correlated with both PRSW (r = -0.64, r = -0.58, and r = 0.74) and LV-dP/dtmax (r = -0.95, r = -0.70, and r = 0.85). In conclusion, the speckle tracking echocardiography-derived strain rate is more robust to dynamic ventricular unloading than strain. Longitudinal and circumferential strain could not predict load-independent contractility. Strain rates, and especially in the radial direction, are good predictors of preload-independent inotropic markers derived from conductance catheter.

Keywords: acute left ventricular unloading; contractility; speckle tracking echocardiography; strain; strain rate.

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Figures

Fig. 1.
Fig. 1.
Typical waveforms from conductance catheter and echocardiographic speckle tracking (left) during an acute dynamic preload reduction with end-diastole (solid lines) and end-systole (dashed lines), corresponding pressure volume loops (top right) with end-systolic pressure-volume relation (dashed green line) and logarithmic end-diastolic pressure-volume relation (solid red line), and short-axis B-mode images at end-diastolic frame (bottom right) with overlayed speckle tracking-derived circumferential strain estimate. A, B, and C: corresponding times. LV, left ventricle; V, volume; P, pressure; dP/dt, the 1st derivative of pressure; SR, radial strain; SC, circumferential strain; SrR, radial strain rate; SrC, circumferential strain rate.
Fig. 2.
Fig. 2.
Relative changes in speckle tracking strain (S; A, C, and E) and strain rate (Sr; B, D, and F) in the longitudinal (L), circumferential (C), and radial (R) direction of the left ventricle related to corresponding changes in end-diastolic volume (EDV) with linear regression and 95% confidence intervals. β, Slope of regression; r, regression coefficient; p, P value for regression.
Fig. 3.
Fig. 3.
Longitudinal strain (A and C) and strain rate (B and D) vs. preload recruitable stroke work (PRSW) and maximum of first derivative of left ventricular pressure (dP/dtmax) with corresponding regression lines and 95% confidence intervals. Regression functions with regression coefficients and P values.
Fig. 4.
Fig. 4.
Circumferential strain (A and C) and strain rate (B and D) vs. PRSW and maximum of first derivative of left ventricular pressure (dP/dtmax) with corresponding regression lines and 95% confidence intervals. Regression functions with regression coefficients and P values.
Fig. 5.
Fig. 5.
Radial strain (A and C) and strain rate (B and D) vs. PRSW and maximum of first derivative of left ventricular pressure (dP/dtmax) with corresponding regression lines and 95% confidence intervals. Regression functions with regression coefficients and P values.
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