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

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.

Protective effects of acute exercise prior to doxorubicin on cardiac function of breast cancer patients: A proof-of-concept RCT

“…Systolic SR is a better correlate of the peak positive first derivative of LV pressure (dP/dtmax), a surrogate of myocardial contractility, than strain [28]. Our systolic SR results were similar to the effect on dP/dtmax observed in the preclinical version of the current study, where the exercise session significantly attenuated the decrease in contractility that occurred in the CON [6].…”

Experimental validation of the prestretch-strain relationship as a non-invasive index of left ventricular myocardial contractility

“…Table 3) and will provide an inaccurate assessment of LV function, particularly in patients with valvular heart disease or heart failure [9]. Other proposed non-invasive measurements such as fractional shortening, end-systolic volume or global longitudinal strain have been demonstrated to be also sensitive to loading [9,23].…”

Imaging of Myocardial Fibrosis and Its Functional Correlates in Aortic Stenosis: A Review and Clinical Potential

“…Accordingly, to bypass this limitation in the chronic overloaded LV, the pressure-strain loop-based method is a promising tool for assessment and monitoring of myocardial function in patients with AS, but this method is still under investigation. Recently, novel techniques of derived tissue tracking by CMR cine acquisitions, such as CMR tagging and feature tracking, have provided a detailed characterization of LV global and regional contractility and reasonable agreement in the assessment of myocardial deformation in patients with AS [53-55]. However, several technical limitations may affect quantitative results and lead to variability among different readers [56-58].…”