Ultrasound Strain Imaging of Altered Myocardial Stiffness

Abstract

Background-In this study we evaluate the diastolic deformation of ischemic/reperfused myocardium and relate this deformation to tissue elastic properties. Methods and Results-Farm pigs were subjected to left anterior descending coronary artery occlusion followed by reperfusion to create either stunning (nϭ12) or transmural myocardial infarction (nϭ12). Ultrasound-derived radial strain rates (SR) and strain were measured in the ischemic and remote walls. Myocardial stiffness was estimated from diastolic pressure-wall thickness relationship obtained from preload alterations. At reperfusion, end-systolic strain (⑀ sys ) was significantly reduced in both stunned and infarcted walls compared with their remote walls (3Ϯ3% versus 26Ϯ2% and 1Ϯ0% versus 33Ϯ5%, respectively; PϽ0.0001) or baseline values. Diastolic passive deformation (⑀ A ) and rates of deformation during early (E SR ) and late (A SR ) diastole were comparable between stunned and remote walls (⑀ A : 7.3Ϯ1.6% versus 7.9Ϯ1.9%; E SR : Ϫ2.7Ϯ0.4 s Ϫ1 versus Ϫ2.6Ϯ0.5 s

Left Ventricular Systolic and Diastolic Function in Patients With Apical Ballooning Syndrome Compared With Patients With Acute Anterior ST-Segment Elevation Myocardial Infarction: A Functional Paradox

“…18,19 Postsystolic shortening or thickening is also a sensitive marker of ischemia and myocardial viability. 20,21 In our study, the akinetic but viable myocardium of patients with ABS showed more prominent postsystolic shortening.…”

Echocardiographic evaluation of diastolic heart failure

“…Voigt, et al 137 demonstrated that the quantification of postsystolic myocardial S estimated post‐systolic shortening in ischemic myocardium. Pislaru, et al 138 and Park, et al 139 showed that regional diastolic SR can evaluate diastolic stiffness during myocardial stunning and infarction, aiding in viability assessment. There is evidence in an animal model that segmental early diastolic SR correlates with the degree of interstitial fibrosis 139 .…”

In Vivo Assessment of Myocardial Stiffness with Acoustic Radiation Force Impulse Imaging

“…Conversely, strain is easier to quantify as it can be calculated through imagebased algorithms that track tissue motion. One method to measure strain is through a temporal integration of strain rate, which can be measured from the difference in tissue velocities at two points within the myocardium (Heimdal et al, 1998;Pislaru et al, 2004). Another method to measure strain is from the spatial gradient of tissue displacements.…”

“…These methods have shown promise in the detection of ischemic or infarcted myocardium (Garot et al, 1999;Lyseggen et al, 2005;Pislaru et al, 2004). However, without measuring stress, these images are vulnerable to misinterpretation as observed variations could be due to the intrinsic non-uniform deformation of the heart.…”