Wave propagation in coupled left ventricle-arterial system. Implications for aortic pressure

Area of Science:

• Cardiovascular Physiology
• Biomechanical Engineering
• Hemodynamics

Background:

• Understanding the mechanical performance of the coupled left ventricle-arterial system is crucial.
• Wave propagation properties are known to influence cardiovascular dynamics.

Purpose of the Study:

• To examine the effects of wave propagation properties (global reflection coefficient, pulse wave velocity, characteristic impedance) on the mechanical performance of the coupled left ventricle-arterial system.
• To quantify these effects on aortic pressure and flow, while controlling other determinants.

Main Methods:

• Isolated rabbit hearts subjected to real-time, computer-controlled physiological loading.
• Arterial circulation modeled with a lossless tube and a complex load.
• Precise and independent control of arterial properties.

Main Results:

• Wave propagation properties affected aortic pressure and flow morphologies.
• Diastolic and mean aortic pressure, and stroke volume decreased monotonically with increases in reflection coefficient, pulse wave velocity, or characteristic impedance.
• Effects on peak systolic pressure were variable, and overall effects on mean and peak systolic pressure were modest (<10% and <5%), while diastolic pressure effects were greater.

Conclusions:

• Data do not support the hypothesis that peak systolic pressure can be significantly altered by manipulating wave propagation properties alone.
• Diastolic pressure is more sensitive to changes in wave propagation properties than systolic pressure.