F Jamal

Can natural strain and strain rate quantify regional myocardial deformation? A study in healthy subjects

Strain rate (SR) and strain (epsilon) have been proposed as new ultrasound (US) indices for quantifying regional wall deformation, and can be measured from color Doppler myocardial data by determining the local spatial velocity gradient. The aim of this study was to define normal regional SR/epsilon values for both radial and longitudinal myocardial deformation. SR/epsilon profiles were obtained from 40 healthy volunteers. For radial deformation, posterior left ventricular (LV) wall SR/epsilon were calculated. For longitudinal, they were determined for basal, mid- and apical segments of the 1. septum; 2. lateral, 3. posterior and 4. anterior LV walls and for the 5. right ventricular (RV) lateral wall. SR/epsilon values describing radial deformation were higher than the corresponding SR/epsilon values obtained for longitudinal deformation. Longitudinal SR/epsilon were homogeneous throughout the septum and all LV walls. This was in contrast to the normal base-apex velocity gradient. The RV segmental SR/epsilon values were higher than those obtained from the corresponding LV wall and inhomogeneous (higher in the apical segments). SR/epsilon imaging appears to be a robust technique for quantifying regional myocardial deformation.

Abnormal Postsystolic Thickening in Acutely Ischemic Myocardium During Coronary Angioplasty: A Velocity, Strain, and Strain Rate Doppler Myocardial Imaging Study

We report a case in which the combination of gray scale imaging of wall thickness changes allied to color DMI regional velocity, strain, and strain rate data identified the development and regression of diastolic thickening in the acute ischemic segment during a right coronary artery percutaneous transluminal coronary angioplasty (PTCA). We also discuss the possible mechanisms and potential clinical implications of this finding.

Calculation of strain values from strain rate curves: how should this be done?

The noninvasive quantification of regional myocardial function is an important goal in clinical cardiology. Myocardial strain and strain rate indices are two methods of attempting to define regional myocardial function. Several approaches to extract these indices have been proposed in the literature, one of which is to extract the strain rate information as the spatial gradient in myocardial velocities that had been estimated using Doppler myocardial imaging techniques. In order to obtain information on the strain profile, the strain rate curve is time integrated. In practice however, the strain rate curves can be post-processed in several ways and different strain indices can be extracted. As no information exists on which scheme is advantageous, this paper attempts to define the optimal post-processing scheme for the clinical setting.

The relationship between regional integrated backscatter levels and regional strain

Integrated backscatter (IB) and its cyclic variation (CV) are echographic parameters often used for tissue characterization. To study the origin of CV, we correlated changes in IB with regional strain in healthy volunteers. Both radiofrequency (RF) and color Doppler myocardial imaging (CDMI) data were acquired from 10 volunteers (parasternal long axis view, posterior wall), using a clinical scanner at high frame rate. IB was extracted from the RF data. Regional radial strain was calculated by integrating the strain rate (SR) curve, extracted from the velocity data. For each volunteer, 3 consecutive heart cycles were averaged. The individual phases of the cardiac cycle (ejection, fast filling, diastasis and atrial contraction) of all datasets, were averaged. The negative radial strain (NRS) curve was plotted on top of the IB curve. During all phases of the cardiac cycle, NRS paralleled IB apart from early systole, where IB increased while NRS decreased. These results can be explained by correlating IB to regional three-dimensional strain (rather than just the radial component, e.g. wall thickening). NRS results in an increase in mean scatterer spacing and hence a decrease in IB level. Moreover, it has been shown that longitudinal contraction precedes the radial one. This could explain the increase in IB level during early systole since this early longitudinal strain could initially decrease scatterer spacing. Changes in myocardial reflectivity as measured by regional IB levels seem to be directly related to regional three-dimensional strain.

Quantitative regional myocardial strain and strain rate imaging provides additional information on myocardial function

We sought to investigate whether high frame rate ultrasound-derived regional strain rate and strain could yield new information on regional function in normal and stunned myocardium. Radial strain rate and strain were monitored during dobutamine infusion in 9 pigs with regional myocardial stunning and 7 controls. Inotropic stimulation resulted in a transitory reversal of deformation abnormalities of stunned myocardium as assessed with strain profiles. The contractile reserve of both stunned and normal myocardium was better quantified by the maximal systolic strain rate rather than by systolic strain.