Shear Wave Imaging of Passive Diastolic Myocardial Stiffness

Abstract

ObjectivesThe aim of this study was to investigate the potential of shear wave imaging (SWI), a novel ultrasound-based technique, to noninvasively quantify passive diastolic myocardial stiffness in an ovine model of ischemic cardiomyopathy.BackgroundEvaluation of diastolic left ventricular function is critical for evaluation of heart failure and ischemic cardiomyopathy. Myocardial stiffness is known to be an important property for the evaluation of the diastolic myocardial function, but this parameter cannot be measured noninvasively by existing techniques.MethodsSWI was performed in vivo in open-chest procedures in 10 sheep. Ligation of a diagonal of the left anterior descending coronary artery was performed for 15 min (stunned group, n = 5) and 2 h (infarcted group, n = 5). Each procedure was followed by a 40-min reperfusion period. Diastolic myocardial stiffness was measured at rest, during ischemia, and after reperfusion by using noninvasive shear wave imaging. Simultaneously, end-diastolic left ventricular pressure and segmental strain were measured with a pressure catheter and sonomicrometers during transient vena caval occlusions to obtain gold standard evaluation of myocardial stiffness using end-diastolic strain-stress relationship (EDSSR).ResultsIn both groups, the end-systolic circumferential strain was drastically reduced during ischemia (from 14.2 ± 1.2% to 1.3 ± 1.6% in the infarcted group and from 13.5 ± 3.0% to 1.9 ± 1.8% in the stunned group; p <0.01). SWI diastolic stiffness increased after 2 h of ischemia from 1.7 ± 0.4 to 6.2 ± 2.2 kPa (p < 0.05) and even more after reperfusion (12.1 ± 4.2 kPa; p < 0.01). Diastolic myocardial stiffening was confirmed by the exponential constant coefficient of the EDSSR, which increased from 8.8 ± 2.3 to 25.7 ± 9.5 (p < 0.01). In contrast, SWI diastolic stiffness was unchanged in the stunned group (2.3 ± 0.4 kPa vs 1.8 ± 0.3 kPa, p = NS) which was confirmed also by the exponential constant of EDSSR (9.7 ± 3.1 vs 10.2 ± 2.3, p = NS).ConclusionsNoninvasive SWI evaluation of diastolic myocardial stiffness can differentiate between stiff, noncompliant infarcted wall and softer wall containing stunned myocardium.

Measuring Intraventricular Pressure Using Ultrasound Elastography

“…As was indicated previously, a number of studies have been performed to measure the potential of using SWEI measurements for systolic and diastolic functional assessment . Pernot et al reported a linear relationship between the maximum shear stiffness measurement and the intra‐ventricular pressure in systole after using an inotropic agent; the results reported here are consistent with those results .…”

“…We have previously investigated the potential of SWEI to provide contractility, compliance, and relaxation time constant measurements for cardiac function assessment . There are a number of publications regarding cardiac functional assessment using this method, and further details are included in the discussion section . However, the relationship between the intraventricular pressure and SWEI or ARFI measurements during the cardiac cycle has not been studied.…”

“…10,11 There are a number of publications regarding cardiac functional assessment using this method, and further details are included in the discussion section. [12][13][14] However, the relationship between the intraventricular pressure and SWEI or ARFI measurements during the cardiac cycle has not been studied.…”

How to diagnose heart failure with preserved ejection fraction: the HFA–PEFF diagnostic algorithm: a consensus recommendation from the Heart Failure Association (HFA) of the European Society of Cardiology (ESC)

“…Myocardial post-infarction/scar 49 Myocardial stunning 50 Epicardial coronary artery disease 51 Microvascular and endothelial dysfunction 52,53-55 Toxic…”

The power of ultrasound: treating secondary MR with sound waves

“…Collaboration between physicists who developed a high-frame-rate ultrasound system and cardiovascular investigators has allowed non-invasive measurement of vascular and myocardial stiffness. 1,2 In this current issue of the European Heart JournalCardiovascular Imaging, members of these groups, using a related technology, have employed ultrasound to treat as well as to image the heart 3 in mitral regurgitation (MR) secondary to myocardial infarction (MI) that causes mitral valve (MV) leaflet tethering mediated by chordae to the displaced papillary muscles (PMs). 4 This is a condition for which a strong need is perceived for improved approaches.…”