What global diastolic function is, what it is not, and how to measure it

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Cardiac Mechanics

Background:

• Diastolic function (DF) is crucial for four-chamber heart dynamics but often underappreciated.
• Traditional DF indexes lack causal mechanisms, limiting accuracy in quantifying stiffness and relaxation.
• Leonardo da Vinci noted early observations on heart chamber dynamics.

Purpose of the Study:

• To provide a global perspective on diastolic function (DF) causality and clinical relevance.
• To develop and validate novel kinematic models for heart diastolic function.
• To offer load-independent indexes for accurate DF quantification.

Main Methods:

• Developed kinematic models of isovolumic relaxation and suction-initiated filling.
• Validated models against physiological principles and experimental data.
• Characterized DF based on elastic recoil, cross-bridge relaxation, and load interactions.

Main Results:

• Novel models quantify the balance between cardiac stiffness and relaxation.
• Causality-based modeling provides load-independent DF indexes.
• Revealed new insights into ventricular-atrial function and filling dynamics.

Conclusions:

• Global DF is determined by elastic recoil and relaxation, modulated by load.
• The new models offer mechanistic physiological insight beyond traditional indexes.
• Accurate measurement of diastolic function is achievable through causal modeling.