Slice-by-Slice Pressure-Volume Loop Analysis Demonstrates Native Differences in Regional Cardiac Contractility and...

Area of Science:

• Cardiovascular Imaging
• Cardiac Mechanics
• Biomedical Engineering

Background:

• Myocardial infarction (MI) leads to adverse left ventricular (LV) remodeling, affecting diastolic and systolic properties.
• Current assessment of regional LV function relies on load-dependent measures like slice ejection fraction (sEF).
• Load-independent measures are needed to better study infarction-induced LV remodeling.

Purpose of the Study:

• To evaluate regional variations in load-independent systolic and diastolic function using 2D real-time MRI.
• To compare these load-independent measures with a load-dependent measure (sEF).
• To assess functional changes during inotropic agent infusion.

Main Methods:

• A validated 2D real-time MRI technique was employed.
• Slice-by-slice load-independent measures of systolic and diastolic function were assessed.
• Measurements were taken in 11 sheep at rest and during dobutamine infusion.

Main Results:

• Slice-derived ejection fraction (sEF) showed regional differences, with higher values in the apex.
• Slice-derived end-systolic pressure-volume relationship (sESPVR) was lower in the apex.
• Load-independent measures revealed regional variations that contradicted sEF findings, with altered responses to inotropic stimulation.

Conclusions:

• Slice-derived load-independent measures demonstrate regional variations in LV function distinct from load-dependent measures.
• This imaging approach offers advanced, slice-based functional assessment for studying LV remodeling.
• The findings may aid in developing targeted therapies for post-MI remodeling.