A dynamic double helical band as a model for cardiac pumping

Area of Science:

• Computational modeling
• Cardiovascular mechanics
• Biophysics

Background:

• The heart's pumping function relies on complex mechanics.
• Understanding the interplay between ejection volume and twist is crucial.

Purpose of the Study:

• To investigate the mechanical and timing relationship between ejected volume and left ventricular twist.
• To model the heart's pumping function using a double helical muscle fiber band.
• To determine the role of excitation patterns in physiological heart mechanics.

Main Methods:

• Finite-element computational modeling.
• Utilizing a double helical muscle fiber band model.
• Simulating various excitation patterns.

Main Results:

• The double helical model accurately reproduces physiological ejection fraction (up to 60%) without overstraining muscle fibers.
• Ejection fraction is largely independent of excitation patterns.
• Left ventricular twist is also independent of excitation type.
• The physiological relationship between ejection fraction and twist is achieved with Purkinje-type excitation.
• Optimal timing coordination requires excitation originating near the apex septum.

Conclusions:

• The timing of cardiac excitation is critical for efficient heart pumping.
• The origin of the excitation front influences the coordination of ejection and twist dynamics.
• Findings offer insights for bioinspired pump design.