Regional myocardial three-dimensional principal strains during postinfarction remodeling

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Cardiac Mechanics

Background:

• Left ventricular (LV) remodeling after myocardial infarction (MI) significantly alters cardiac mechanics.
• Understanding the mechanical response of the LV to MI requires serial strain quantification.
• Principal strains simplify the analysis of complex 3D myocardial strain data.

Purpose of the Study:

• To quantify three-dimensional (3D) principal strains in the LV during post-myocardial infarction (MI) remodeling.
• To assess the mechanical behavior of myocardial regions (remote, border zone, infarct) over time after MI.
• To establish the relationship between principal strain evolution and adverse LV remodeling.

Main Methods:

• Utilized a porcine model to study LV remodeling post-MI.
• Employed magnetic resonance imaging (MRI) for serial function and strain measurements at baseline, 1 week, and 4 weeks post-infarct.
• Measured 3D principal strains using 3D acquisition and optical flow for displacement tracking.

Main Results:

• Observed significant alterations in principal strains across all myocardial regions as the LV remodeled.
• Found decreased maximum principal strain magnitude in remote, border zone, and infarct regions.
• Noted rotation of maximum principal strain angles away from the radial direction in border zone and infarct regions, correlating with adverse LV remodeling.

Conclusions:

• Demonstrated the feasibility of serial 3D principal strain measurement after MI in pigs using advanced imaging and optical flow techniques.
• Results indicate progressive infarct stretching and reduced contractile function in remote and border zone myocardial regions.
• 3D principal strain analysis provides valuable insights into the mechanical consequences of myocardial infarction.