Regional dysfunction correlates with myofiber disarray in transgenic mice with ventricular expression of ras

Area of Science:

• Cardiology
• Biomedical Engineering
• Pathology

Background:

• Familial hypertrophic cardiomyopathy is characterized by focal myofiber disarray.
• Regional ventricular dysfunction is observed in hypertrophic cardiomyopathy patients.
• A direct correlation between regional dysfunction and myofiber disarray remains unestablished.

Purpose of the Study:

• To investigate the relationship between myofiber disarray and septal surface strain.
• To determine if myofiber disarray impacts regional cardiac function.

Main Methods:

• Utilized a transgenic mouse model with ventricular expression of the human oncogene ras, inducing regional myofiber disarray.
• Employed an isolated ejecting mouse heart preparation to record septal surface deformation.
• Generated nonhomogeneous septal surface strain maps and correlated them with histological myofiber disarray.

Main Results:

• Myofiber disarray near the right ventricle (RV) septal surface was associated with significantly smaller maximum principal shortening.
• Disarray near the RV surface or at the midwall correlated with significantly smaller surface shear strain.
• Surface shear strain serves as a local indicator of cardiac torsion.

Conclusions:

• Myofiber disarray is associated with reduced septal torsion.
• Focal myofiber disarray leads to diminished regional surface shortening.
• These findings provide direct evidence linking myofiber disarray to regional cardiac dysfunction.