Regional deformation and contractile function in canine right ventricular free wall

Area of Science:

• Cardiovascular Physiology
• Cardiac Mechanics
• Biomedical Engineering

Background:

• Understanding regional differences in right ventricular free wall (RVFW) function is crucial for diagnosing cardiac conditions.
• Previous studies have not fully elucidated the localized contractile function across different RVFW regions.

Purpose of the Study:

• To investigate regional deformation and contractile function of the canine RVFW using biplane cinefluorography.
• To assess how increased RV afterload affects these regional mechanical parameters.

Main Methods:

• Biplane cinefluorography was employed to track marker displacement and calculate regional deformation (fractional area reduction) and its rate.
• Pulmonary artery (PA) occlusion was used to induce acute RV afterload increase.
• Deformation analysis was performed on inflow, midventricular, and outflow regions of the RVFW.

Main Results:

• The outflow region exhibited maximal fractional area reduction and rate of reduction during systole under both control and increased afterload conditions.
• Increased RV afterload (PA occlusion) significantly impacted only the outflow region's deformation.
• Regional shortening directions closely correlated with local myocardial fiber orientations, suggesting deformation reflects myofiber behavior.

Conclusions:

• The outflow region of the canine RVFW demonstrates distinct mechanical properties and is most sensitive to afterload changes.
• RVFW deformation is a summation of local myofiber mechanics, highlighting the importance of regional analysis in cardiac function assessment.