Sonomicrometry-Based Analysis of Post-Myocardial Infarction Regional Mechanics

Abstract

Following myocardial infarction (MI), detrimental changes to the geometry, composition, and mechanical properties of the left ventricle (LV) are initiated in a process generally termed adverse post-MI remodeling. Cumulatively, these changes lead to a loss of LV function and are deterministic factors in the progression to heart failure. Proposed therapeutic strategies to target aberrant LV mechanics post-MI have shown potential to stabilize LV functional indices throughout the remodeling process. The in vivo quantification of LV mechanics, particularly within the MI region, is therefore essential to the continued development and evaluation of strategies to interrupt the post-MI remodeling process. The present study utilizes a porcine MI model and in vivo sonomicrometry to characterize MI region stiffness at 14 days post-MI. Obtained results demonstrate a significant dependence of mechanical properties on location and direction within the MI region, as well as cardiac phase. While approaches for comprehensive characterization of LV mechanics post-MI still need to be improved and standardized, our findings provide insight into the issues and complexities that must be considered within the MI region itself.

Regional and temporal changes in left ventricular strain and stiffness in a porcine model of myocardial infarction

“…As such, improved regional assessment of temporal changes throughout the myocardium may enhance clinical evaluation of the rate and extent of the post-MI remodeling process. In vivo regional mechanical behavior has been assessed post-MI in both basic scientific and clinical studies using techniques such as sonomicrometry, cardiac magnetic resonance imaging, and tissue Doppler-derived imaging (16,33,34,37,40,41,45). Although these and other approaches have yielded critical information on the post-MI remodeling process, they have not been uniformly applied to assess LV regional function across the entire chamber and in a serial fashion because of several factors.…”

“…Although these and other approaches have yielded critical information on the post-MI remodeling process, they have not been uniformly applied to assess LV regional function across the entire chamber and in a serial fashion because of several factors. In large animal studies using sonomicrometry, high spatial and temporal resolution is offset by a limited field of view (16,33). In clinical studies, noninvasive approaches such as cardiac magnetic resonance imaging can provide high-fidelity regional assessment of LV function, but lengthy acquisition and postprocessing times make it impractical to collect repeated measurements (45).…”

Influence of Supraphysiologic Biomaterial Stiffness on Ventricular Mechanics and Myocardial Infarct Reinforcement

“…[6,20] The sonomicrometry crystal pairs were utilized to determine regional strain and LV volume. [21,22] Figure 2 illustrates the crystal locations and pairing utilized to determine regional ventricular function. The base-apex pair constituted the long-axis measurement and the anterior-posterior for short-axis measurement.…”

Influence of Supraphysiologic Biomaterial Stiffness on Ventricular Mechanics and Myocardial Infarct Reinforcement

“…Sonomicrometry and hemodynamic data were analyzed using custom designed algorithms with MATLAB (The Mathworks, Natick MA) and SonoLab software (Sonometrics). [6,20] The sonomicrometry crystal pairs were utilized to determine regional strain and LV volume [21,22]. Figure 2 illustrates the crystal locations and pairing utilized to determine regional ventricular function.…”