Hemolysis and thrombus formation which are critical concerns in designing a long-term implantable ventricular assist device (VAD) have impeded the widespread use of VADs. In this study, thus, the three-dimensional fluid domain of blood flow in a small bichamber positive displacement VAD (25 ml) with a magnetically levitated moving pusher plate was simulated by the means of a finite element package called ADINA. To optimize the function of the pump for minimizing shear stress induced blood damage, three different driver patterns (linear, sinusoidal, and Guyton’s pulse) were investigated. The first pattern produced a constant flow, whereas the two others created pulsatile flows. The flow pattern and the distribution of shear stress of each pattern were observed for comparison. It was revealed that the three types of motions may induce less than 0.06% red blood cell damage. Moreover, in comparison to the other patterns not only did the sinusoidal motion of the pusher plate cause less risk of hemolysis, but in comparison to the linear pattern, it produced a pulsatile flow which reduced the stagnation areas in chambers, lowering the probability of thrombosis. In addition, this motion eliminates the probability of cavitations as compared with the Guyton’s pulse pattern.
From the *Department of Mechanical Engineering (Biomechanics Group), Islamic Azad University of Najafabad, Najafabad, Iran; and †Department of Mechanical Engineering (Biomechanics Group), Sahand University of Technology, Tabriz, Iran.
Submitted for consideration October 2012; accepted for publication in revised form January 2014.
Disclosure: The authors have no conflicts of interest to report.
Reprint Requests: Hanieh Niroomand Oscuii, Department of Mechanical Engineering (Biomechanics Group), Sahand University of Technology, Sahand New Town, PO Box 51335/1996, Tabriz, Iran. Email: firstname.lastname@example.org.