Physiological pulsatile flow experiments in a model of the human aortic arch

Area of Science:

• Cardiovascular fluid dynamics
• Biomechanical engineering
• Medical device design

Background:

• Understanding blood flow in the aorta is crucial for diagnosing and treating cardiovascular diseases.
• The complex geometry of the aortic arch significantly influences blood flow patterns.
• Previous studies often simplified aortic arch geometry, limiting insights into physiologically relevant flow dynamics.

Purpose of the Study:

• To experimentally investigate physiologically relevant pulsatile flow in a human aortic arch model.
• To analyze the effects of aortic arch curvatures and tapering on fluid motion.
• To characterize secondary flow motions and flow reversals during the cardiac cycle.

Main Methods:

• Fabrication of a clear acrylic model aortic arch from a human aorta cast.
• Integration of the model into a mock-circulatory system with a prosthetic aortic valve.
• Utilizing flow visualization techniques for qualitative analysis of fluid motion.
• Employing a three-sensor hot-film velocity probe for quantitative velocity measurements (axial, radial, tangential).

Main Results:

• Identification of strong secondary fluid motions, specifically helical flows, near the inner aortic wall.
• Observation that these helical flows dissipated during diastole.
• Detection of dramatic flow reversals along the inner wall at the onset of diastole.
• Quantitative data confirmed rapid reversal of axial velocity near the inner wall during early diastole.

Conclusions:

• The human aortic arch geometry induces complex secondary flow patterns.
• Flow reversals during diastole significantly influence and dissipate these secondary motions.
• These findings provide critical data for understanding hemodynamics in the aortic arch and informing cardiovascular research.