Mathematical evidence for flow-induced changes in myocardial oxygen consumption

Area of Science:

• Physiology
• Biophysics
• Mathematical Modeling

Background:

• Oxygen consumption in the heart is influenced by coronary perfusion pressure and blood flow.
• Understanding this relationship is crucial for diagnosing and treating cardiac conditions.

Purpose of the Study:

• To determine the mechanism linking oxygen consumption to coronary perfusion pressure and blood flow.
• To develop and validate a mathematical model for oxygen transport in the heart.

Main Methods:

• Developed a mathematical model of oxygen transport and consumption in an isolated-perfused feline heart.
• Incorporated Michaelis-Menten kinetics and one-dimensional diffusion.
• Used adaptive finite-difference integration and simplex minimization to fit experimental data.

Main Results:

• The flow-dependent oxygen consumption model showed a 30% lower error than the pressure-induced model.
• The model indicated a flow-related mechanism is responsible for observed oxygen consumption changes.
• Found that the Michaelis-Menten constant varies with oxygen tension.

Conclusions:

• A flow-related mechanism, not pressure, primarily drives oxygen consumption changes in the heart.
• The mathematical model provides a robust framework for studying cardiac oxygen dynamics.
• The Michaelis-Menten kinetics constant is not fixed and depends on oxygen tension.