FLOW PATTERNS OF A NON-NEWTONIAN BLOOD ANALOG IN THE 50CC PSU VENTRICULAR ASSIST DEVICE

Mechanical blood pumps are becoming increasingly important as the need for heart transplants far outweighs the available hearts each year. The 70cc Penn State blood pump has had clinical success. However, there is a need for a smaller blood pump for smaller adults, which would provide the same long-term circulatory support. The current 50 cc Penn State blood pump has had problems with in vivo thrombus formation, indicating poor hemodynamic flow through the device. Previous research was conducted mainly using a Newtonian blood analog (mineral oil) to study the flow fields in the device. Since blood is not a Newtonian fluid, there is a desire to study the flow field of the device using a Non-Newtonian blood analog fluid, a Xanthan gum and glycerin solution with viscoelastic properties similar to blood. Particle Image Velocimetry (PIV) is used to capture images of the flow field. To obtain clear images the blood analog must have the same index of refraction as the acrylic assist device chamber. Alterations to the Xanthan gum and glycerin formula included using sodium iodide to gain the desired index of refraction and sodium thiosulfate to make the solution colorless. The use of PIV in conjunction with a Non-Newtonian blood analog identifies problem areas in the device. Also, the PIV system provides images at any time in the heart beat cycle, so the time within the cardiac cycle when poor wall washing occurs is also identified.