Low haemolysis pulsatile impeller pump: design concepts and experimental results

Area of Science:

• Biomedical Engineering
• Cardiovascular Devices
• Fluid Dynamics

Background:

• Development of implantable blood pumps is crucial for treating heart failure.
• Minimizing haemolysis (blood cell damage) is a key challenge in artificial circulatory support devices.
• Existing nonpulsatile pumps can cause significant haemolysis.

Purpose of the Study:

• To design and evaluate a pulsatile fully implantable impeller pump with reduced haemolysis.
• To optimize impeller geometry for physiological pulsatile blood flow.
• To investigate the relationship between pump design, operating parameters, and haemolysis.

Main Methods:

• Designed a pulsatile impeller based on 3D fluid dynamics theory, incorporating specific spiral geometries for vanes and shroud.
• Engineered the impeller to minimize blood velocity and shear stress during periodic speed changes.
• Controlled mean flow rate and pressure via voltage adjustment; pulse shape by voltage waveform and systole/diastole ratio.

Main Results:

• The pulsatile impeller pump achieved a mean flow rate of 4 L/min and mean pressure of 100 mmHg (40 mmHg pulse pressure).
• The index of haemolysis (IH) for porcine blood was 0.020, only slightly higher than the nonpulsatile pump (0.016).
• Optimal conditions for minimal regurgitation included a 40% systole period and 5 V pulse for 40 mmHg pulse pressure.

Conclusions:

• The developed pulsatile impeller pump effectively generates physiological pulsatile flow with low haemolysis.
• The impeller's specific geometric design is critical for minimizing shear stress and blood damage.
• This pulsatile pump offers a promising alternative to nonpulsatile devices, with comparable power consumption and improved haemolysis profile.