Experimental Fluid Mechanics of Pulsatile Artificial Blood Pumps

Abstract

The fluid mechanics of artificial blood pumps has been studied since the early 1970s in an attempt to understand and mitigate hemolysis and thrombus formation by the device. Pulsatile pumps are characterized by inlet jets that set up a rotational "washing" pattern during filling. Strong regurgitant jets through the closed artificial heart valves have Reynolds stresses on the order of 10,000 dynes/cm 2 and are the most likely cause of red blood cell damage and platelet activation. Although the flow in the pump chamber appears benign, low wall shear stresses throughout the pump cycle can lead to thrombus formation at the wall of the smaller pumps (10-50 cc). The local fluid mechanics is critical. There is a need to rapidly measure or calculate the wall shear stress throughout the device so that the results may be easily incorporated into the design process. 65 Annu. Rev. Fluid Mech. 2006.38:65-86. Downloaded from www.annualreviews.org Access provided by University of California -San Diego on 02/04/15. For personal use only.

A Fluid Dynamics Study in a 50 cc Pulsatile Ventricular Assist Device: Influence of Heart Rate Variability

“…PIV has been used extensively in previous Penn State fluid mechanic investigations of the 50 cc device [6,9,12,13,15,16]. For this study, an Nd:YAG laser, part of a Gemini PIV 15 system (New Wave Research, Inc., Fremont, CA) directed two 532 nm polarized lasers, capable of delivering 120 mJ laser pulsations with a 5-10 ns pulse width, to an attenuator to regulate energy exiting the laser shutter.…”

“…It has been estimated that nearly 81 Â 10 6 Americans are affected by some form of cardiovascular disease, with greater than 5 Â 10 6 diagnosed with heart failure (HF) [1]. The American Heart Association/American College of Cardiology has classified the progression of HF into four stages (A-D) of increasing severity which has led to guidelines for diagnosis and treatment.…”

“…It has been shown that the potential for thrombus formation in LVADs is associated with the blood material interface, the surface topography, and the fluid mechanics within the device [6]. Over the past four decades, Penn State has sought to understand these phenomena through the development of pneumatic and pusher plate driven pulsatile LVADs.…”

Left Ventricular Heart Assist Device using MC and ECG Feedback

“…As known the ventricles contract after 300 ms from the beginning of the cardiac cycle (Ventricles Contraction Time -t VC ), so a constant coefficient (CC) can be determined as T ECG /t VC to have CC=2.667 [10]. It is clear that the ventricles contraction time changes according to the change in HR.…”

Modelagem matemática da fluidodinâmica não-newtoniana e bifásica simplificada da hemólise induzida mecanicamente em sistemas de bombeamento centrífugo de sangue

“…Em bombas rotativas de sangue, as tensões de cisalhamento elevadas que geralmente ocorrem em torno das bordas dos impulsores podem chegar a valores três ordens de grandeza superiores em relação aos máximos típicos na circulação sanguínea humana (Sallam e Hwang, 1984), (Grigioni et al, 1999), (Lu et al, 2001), (Chua et al, 2007), , . Enquanto o limite superior de tensão de cisalhamento que ocorre no sistema circulatório humano chega próximo ao valor de 15 Pa (Koutsiaris et al, 2013), os valores aos quais as hemácias podem ser submetidas quando atravessam dispositivos de assistências circulatória, tais como bombas centrífugas, podem atingir até 1000 Pa (Deutsch et al, 2006).…”