Hydrodynamical comparison of aortic arch cannulae

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Fluid Dynamics

Background:

• Aortic arch cannulae are used in cardiac surgery.
• High-velocity blood flow from cannulae can cause aortic wall damage and non-cardiac complications.
• Cannula design influences blood flow dynamics and potential complications.

Purpose of the Study:

• To compare the hydrodynamic performance of different aortic arch cannulae.
• To assess the spatial velocity distribution and exit forces of various cannula designs.
• To identify cannula designs that minimize the risk of aortic wall erosion.

Main Methods:

• An in vitro steady flow setup was used to compare six different 24 Fr cannulae.
• Ultrasound Doppler velocimetry measured spatial velocity distribution.
• Exit forces were calculated by integrating velocity profiles.
• Pressure drop across cannula tips was measured.

Main Results:

• The four rectangular sidehole design exhibited the lowest exit velocity (0.85 m/s) and force per jet (0.03 N).
• Round sideholes on cannulae were found to be ineffective, directing less than 1% of the flow.
• Angled tip cannulae reduce aortic wall force as the angle of incidence deviates from 90 degrees.
• The four sidehole design had the lowest pressure drop, while open tip cannulae had the highest.

Conclusions:

• Cannula design significantly impacts blood flow velocity and force.
• A four-sidehole cannula design is recommended to minimize aortic wall trauma and associated complications.
• Angled tip cannulae may offer further advantages in reducing force on the aortic wall.