Coronary artery disease remains the leading cause
of death in the United States with over 1 million acute coronary events
predicted to take place in 2019 alone. Heart failure, a common and deadly
sequela of myocardial infarction (MI), is attributed to adverse ventricular
remodeling driven by cardiomyocyte death, inflammation, and mechanical factors.
Despite strong evidence suggesting the importance of myocardial mechanics in
driving cardiac remodeling, many in vivo MI studies still rely on 2D
analyses to estimate global left ventricular (LV) function and approximate
strain using a linear definition. These metrics, while valuable in evaluating
the overall impact of ischemic injury on cardiac health, do not capture regional
differences in myocardial contractility. The objective of this work is
therefore to expand upon existing ultrasound studies by enabling regional
analysis of 3D myocardial strain. By integrating our recently developed
four-dimensional ultrasound (4DUS) imaging technique with a direct deformation
estimation algorithm for 3D strain, we identified unique remodeling patterns
and regional strain differences between two murine models of MI with different
infarct severities. By constructing 3D strain maps of the remodeling LVs, we
were able to capture strain heterogeneity and characterize a sigmoidal strain
profile at infarct border zones. Finally, we demonstrated that the maximum
principal component of the 3D Green-Lagrange strain tensor correlates with LV remodeling
severity and is predictive of final infarct size. Taken together, the presented
work provides a novel and thorough approach to quantify regional 3D strain, an
important component when assessing post-MI remodeling.
Funding
American Heart Association Scientist Development Grant (14SDG18220010)
Indiana Clinical and Translational Sciences Institute
National Center for Advancing Translational Sciences