Sectional and segmental variability of left ventricular function: experimental and clinical studies using ultrafast...

Area of Science:

• Cardiovascular Imaging
• Cardiac Physiology
• Diagnostic Imaging Technology

Background:

• Assessing left ventricular function is crucial for diagnosing cardiac conditions.
• Previous methods lacked the spatial and temporal resolution to fully characterize regional myocardial function.
• Ultrafast computed tomography (UFCT) offers high-resolution imaging capabilities.

Purpose of the Study:

• To define the range of sectional and segmental left ventricular function in normal subjects using UFCT.
• To establish baseline patterns of normal left ventricular contraction.
• To determine if UFCT can identify predictable heterogeneity in myocardial function.

Main Methods:

• Employed ultrafast computed tomography (UFCT) for high spatial and temporal resolution imaging.
• Acquired multilevel tomographic images of the left ventricle (apex to base) at 17 frames/s after contrast agent infusion.
• Analyzed sectional and segmental left ventricular function in 11 normal dogs and 11 normal human volunteers.

Main Results:

• Demonstrated substantial, predictable heterogeneity in left ventricular contraction from apex to base in both dogs and humans.
• Observed a 40% lower average tomographic ejection fraction at the base compared to the apex (p < 0.05).
• Found relatively homogeneous circumferential segmental cavity contraction at the mid-papillary muscle level in humans when using an endocardial centroid reference.

Conclusions:

• Normal left ventricular contraction exhibits heterogeneity both between apex-to-base levels and circumferentially within a single level.
• The predictable patterns of contraction defined by UFCT in normal individuals are valuable for detecting regional abnormalities in disease.
• UFCT provides a robust tool for characterizing normal and potentially abnormal left ventricular mechanics.