Apparent arterial compliance

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Hemodynamics

Background:

• Estimating total arterial compliance is essential for understanding cardiovascular health.
• Direct measurement of arterial compliance is not feasible.
• Traditional lumped models (e.g., Windkessel) rely on assumptions of linearity and infinite pulse wave velocity.

Purpose of the Study:

• To generalize the Windkessel model by incorporating finite pulse wave velocity.
• To introduce a new concept of "apparent compliance" that describes the pressure-volume relationship as a function of frequency.
• To analyze the influence of heart rate, peripheral resistance, and pulse wave reflection on this relationship.

Main Methods:

• Applied transmission theory to a linear arterial system model with finite pulse wave velocity.
• Described arterial compliance as a complex, frequency-dependent function relating input pressure to stored volume.
• Derived the concept of "apparent compliance" from this pressure-volume relationship.

Main Results:

• The generalized Windkessel model incorporates finite pulse wave velocity.
• Arterial compliance is described as a complex function of frequency.
• This frequency-dependent relationship is influenced by heart rate, peripheral resistance, and pulse wave reflection.

Conclusions:

• Introduced the concept of "apparent compliance" as a frequency-dependent measure.
• "Apparent compliance" differs from total arterial compliance due to finite pulse wave velocity.
• This new concept provides a more comprehensive understanding of arterial hemodynamics and complements "apparent pulse wave velocity."