Measuring real-time blood viscosity with a ventricular assist device

Area of Science:

• Biomedical Engineering
• Cardiovascular Technology
• Fluid Dynamics

Background:

• Ventricular assist devices (VADs) are crucial for blood circulation in artificial hearts.
• Measuring blood parameters like viscosity is essential but requires additional devices.
• Integrating measurement capabilities into existing VADs is desirable to minimize invasiveness.

Purpose of the Study:

• To adapt a VAD for intrinsic blood viscosity measurement.
• To eliminate the need for separate viscometers in artificial heart systems.
• To validate the accuracy of VAD-based viscosity measurements.

Main Methods:

• Radial vibration excitation of the VAD impeller using its magnetic levitation system.
• Simultaneous exposure of blood to low (≈100/s) and high (>10,000/s) shear rates.
• Determination of the dominant shear rate influencing apparent viscosity measurements.

Main Results:

• The VAD-based viscosity measurements showed good agreement with a reference concentric cylindrical viscometer.
• The mean absolute deviation was 0.12 mPa·s for porcine blood samples.
• The method accurately measured blood viscosity across a range of 2.32 to 2.75 mPa·s.

Conclusions:

• A VAD can be effectively adapted to measure blood viscosity.
• This integrated approach reduces complexity and invasiveness in artificial heart systems.
• The proposed method offers a reliable alternative for in-situ blood viscosity monitoring.