Related Experiment Video
Updated: Aug 14, 2026
Acute Myocardial Infarction in Rats
Published on: February 16, 2011
Quantitative assessment of regional myocardial function in a rat model of myocardial infarction using tagged MRI
D Thomas1, V A Ferrari, M Janik
1University of Pennsylvania, Department of Radiology, B6 Blockley Hall, 423 Guardian Drive, Philadelphia, PA, 19104-6069, USA.
Abstract:
We characterized global and regional left ventricular (LV) function during post myocardium infarction (MI) remodeling in rats, which has been incompletely described by previous MRI studies. To assess regional wall motion, four groups of infarcted animals corresponding to 1-2, 3-4, 6-8 and 9-12 weeks post-MI respectively were imaged using a fast gradient echo sequence with a 2D spatial modulation of magnetization (SPAMM) tagging preparation. An additional group was serially imaged (1-2 and 6-7 weeks post-MI) to assess the global function. Regional and global functional parameters of infarcted rats were compared to non-infarcted normal rats. Compared to normal rats, a decrease in ejection fraction (70 +/-7 vs. 40 +/- 8%, p<0.05) was observed in rats with MI. Maximal and minimal principal stretches (lambda1, lambda2) and strains (E1, E2), principal angle (beta) and displacement varied regionally in normal rats but deviated significantly from the normal values in rats with MI particularly in the infarcted and adjacent zones. Not only was strain magnitude reduced segmentally post-MI, but strain direction became more circumferentially oriented, particularly in rats with larger infarctions. We report the first regional myocardial strain values in normal and infarcted rats. These results parallel findings in humans, and provide a unique tool to examine regional mechanical influences on the remodeling process.
Insights
Myocardium infarction (MI) in rats significantly impairs global and regional left ventricular (LV) function, altering strain magnitude and direction. These findings offer a new method for studying post-MI remodeling mechanics.
Area of Science:
- Cardiovascular Imaging
- Cardiac Mechanics
- Animal Models
Background:
- Previous magnetic resonance imaging (MRI) studies have incompletely described left ventricular (LV) remodeling post-myocardium infarction (MI).
- Understanding regional LV function is crucial for characterizing the mechanical consequences of MI.
Purpose of the Study:
- To characterize global and regional LV function during post-MI remodeling in rats.
- To establish regional myocardial strain values in normal and infarcted rat models.
Main Methods:
- Four groups of infarcted rats were imaged at various weeks post-MI using a fast gradient echo sequence with 2D spatial modulation of magnetization (SPAMM) tagging.
- Global function was assessed via serial imaging in an additional group.
- Regional and global functional parameters were compared between infarcted and normal rats.
Main Results:
- Infarcted rats showed a significant decrease in ejection fraction compared to normal rats (40 +/- 8% vs. 70 +/-7%).
- Regional strain parameters (magnitude, direction, angle, displacement) deviated significantly from normal values in infarcted and adjacent zones.
- Strain magnitude was reduced segmentally post-MI, with a more circumferential orientation, especially in larger infarctions.
Conclusions:
- This study provides the first regional myocardial strain values in normal and infarcted rats.
- The observed changes in regional function parallel findings in humans.
- These results offer a valuable tool for investigating regional mechanical influences on post-MI remodeling.
