Transmural Wave Speed Gradient May Distinguish Intrinsic Myocardial Stiffening from Preload-Induced Changes in Operational Stiffness in Shear Wave Elastography

• Published in: IEEE transactions on biomedical engineering Vol. 70; no. 1; pp. 1 - 12
• Main Authors: Caenen, Annette, Bezy, Stephanie, Petrescu, Aniela, Werner, Annegret, Voigt, Jens-Uwe, Dhooge, Jan, Segers, Patrick
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.01.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Cardiac shear wave elastography; Computational modeling; Data analysis; Elasticity Imaging Techniques - methods; Finite element analysis; Finite element method; finite element model; Heart - diagnostic imaging; hemodynamic loading; Hemodynamics; Humans; intrinsic stiffness; Load modeling; Microsurgery; Myocardium; operational stiffness; Pressure; Propagation; Shear; Solid modeling; Stiffening; Stiffness; Strain; Ventricle; Wave physics; Wave propagation
• ISSN: 0018-9294; 1558-2531; 1558-2531
• DOI: 10.1109/TBME.2022.3188441

Background : Shear wave elastography (SWE) is a promising technique to non-invasively assess myocardial stiffness based on the propagation speed of mechanical waves. However, a high wave propagation speed can either be attributed to an elevated intrinsic myocardial stiffness or to a preload-induced increase in operational stiffness . Objective : Our objective was to find a way to discriminate intrinsic myocardial stiffening from stiffening caused by an increased pressure in SWE. Methods : We used the finite element method to study the shear wave propagation patterns when stiffness and/or pressure is elevated, compared to normal stiffness and pressure. Numerical findings were verified in a few human subjects. Results : The transmural wave speed gradient was able to distinguish changes in intrinsic stiffness from those induced by differing hemodynamic load (a speed of ±3.2 m/s in parasternal short-axis (PSAX) view was associated with a wave speed gradient of -0.17±0.15 m/s/mm when pressure was elevated compared to 0.04±0.05 m/s/mm when stiffness was elevated). The gradient however decreased when stiffness increased (decrease with a factor 3 in PSAX when stiffness doubled at 20 mmHg). The human data analysis confirmed the presence of a wave speed gradient in a patient with elevated ventricular pressure. Conclusion : Cardiac SWE modeling is a useful tool to gain additional insights into the complex wave physics and to guide post-processing. The transmural differences in wave speed may help to distinguish loading-induced stiffening from intrinsic stiffness changes. Significance : The transmural wave speed gradient has potential as a new diagnostic parameter for future clinical studies.