Assessing myocardial stiffness with transient elastography using catheter-compatible miniature actuator

This study presents a proof-of-concept miniaturized transient elastography (TE) framework for measuring myocardial elasticity during catheter-based cardiac procedures. Recognizing that mechanical properties of myocardial tissue, particularly the shear modulus, offer valuable insight into the development and progression of cardiovascular conditions such as heart failure, we propose a TE system that can be integrated into existing intracardiac catheters. A miniature (2 mm × 2 mm) piezoelectric actuator was used to generate longitudinal shear waves (LSWs) in tissue-mimicking phantoms with varying shear moduli levels and in ex vivo porcine heart tissue. For validation, an ultrasound array transducer was used in this study to visualize the propagation of the LSWs generated by the actuator. Spatiotemporal displacement maps were analyzed to estimate shear wave speeds and corresponding shear moduli, with TE results showing strong agreement with values obtained using conventional acoustic radiation force-based shear wave elasticity imaging (SWEI). The TE and SWEI measurements showed no statistically significant differences. Ex vivo tissue measurements performed in different orientations relative to myocardial fiber direction confirmed the system's sensitivity to tissue anisotropy. Additionally, the technique successfully distinguished between fresh and fixed heart tissue, detecting a noticeable increase in stiffness due to preservation. These findings support the feasibility of a catheter-integrated TE device as a functional extension of existing clinical workflows, offering quantitative assessment of myocardial elasticity during routine catheterization procedures.