Simulation of left atrial function using a multi-scale model of the cardiovascular system

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Biomedical Engineering

Background:

• The left atrium's complex roles (reservoir, conduit, pump) challenge traditional modeling.
• The time-varying elastance theory has limitations and uncertainties regarding load independence.

Purpose of the Study:

• To develop and validate a multi-scale mathematical model for the left atrium and ventricle.
• To bypass limitations of elastance theory in characterizing atrial function.

Main Methods:

• A multi-scale model integrating sarcomere behavior with macroscopic cardiac chamber dynamics was developed.
• Model parameters were identified using reference dog hemodynamic data.
• Simulations were performed to assess physiological role reproduction and validate against experimental data.

Main Results:

• The model successfully reproduced the left atrium's physiological roles, including biphasic pressure waves and an eight-shaped pressure-volume loop.
• Model validation against a preload reduction experiment (inferior vena cava occlusion) showed agreement with seven out of eight measured indices.
• The model demonstrated realistic left atrial pressure-volume loop dynamics.

Conclusions:

• The presented multi-scale mathematical model accurately represents the left atrium's functions and pressure-volume dynamics.
• This model serves as a viable alternative to the time-varying elastance theory for detailed left atrial and ventricular analysis.