Vortex formation time-to-left ventricular early rapid filling relation: model-based prediction with echocardiographic...

Area of Science:

• Cardiovascular Physiology
• Fluid Dynamics
• Biomedical Engineering

Background:

• Left ventricular (LV) early rapid filling generates a toroidal vortex, quantified by vortex formation time (VFT).
• VFT, a dimensionless index, relates to LV aspirational fluid column length-to-diameter ratio.
• LV wall motion drives transmitral flow (E-wave) and vortex formation, linking VFT to diastolic function (DF).

Purpose of the Study:

• To elucidate the causal relationship between VFT and diastolic function (DF) using kinematic modeling.
• To validate a novel kinematic model for calculating VFT (VFT(kinematic)) and its relation to DF parameters.
• To integrate fluid mechanics and chamber kinematics in DF assessment.

Main Methods:

• Utilized a validated kinematic model of LV filling for the E-wave, incorporating stiffness, viscoelasticity, and load.
• Calculated VFT(kinematic) using the model's curvilinear E-wave area and peak effective orifice diameter.
• Predicted VFT as a function of the peak E-wave to peak mitral annular tissue velocity (E/E') ratio: (E/E')(3/2).

Main Results:

• VFT(kinematic) demonstrated a strong correlation with the predicted (E/E')(3/2) relationship (R(2) = 0.63).
• Calculated VFT(Gharib) and VFT(kinematic) were well-correlated (R(2) = 0.66) across 262 cardiac cycles from 12 subjects.
• The study validated the fluid mechanics-to-chamber kinematics relation in diastolic function assessment.

Conclusions:

• VFT(kinematic) serves as a novel diastolic function index computable from global kinematic filling parameters.
• This validation unifies previously disparate DF assessment methods.
• The study elucidates the mechanistic basis for the strong correlation between VFT and the (E/E') ratio.