Dynamic hemodynamic energy loss in normal and stenosed aortic valves

Area of Science:

• Cardiovascular Mechanics
• Biomedical Engineering
• Fluid Dynamics

Background:

• Aortic valve (AV) stenosis can lead to heart failure, characterized by the heart's inability to generate sufficient power.
• Evaluating AV performance and disease severity using energy efficiency offers a direct measure of hydrodynamic contributions to heart failure.

Purpose of the Study:

• To develop and validate a novel method for computing the rate of energy dissipation over systolic time.
• To investigate the impact of varying hemodynamic conditions and stenosis levels on energy dissipation patterns in the aortic valve.

Main Methods:

• Modified the Navier-Stokes momentum equation to compute energy dissipation rate as a function of systolic time.
• Conducted in vitro experiments using a porcine aortic valve under varied stroke volumes, heart rates, and stenosis levels.

Main Results:

• The energy dissipation waveform exhibits a distinct pattern skewed toward late systole, attributed to flow instabilities.
• Increased heart rate and stroke volume elevate energy dissipation, while preserving the waveform's normalized shape.
• Progressive stenosis increases energy dissipation and alters the normalized waveform shape.

Conclusions:

• The distinct energy dissipation waveform signature associated with stenosis suggests potential for dynamic analysis as a clinical tool for aortic valve evaluation.
• This method provides a novel approach to assess aortic valve function and disease severity.