Computational Flow Study of the Continuous Flow Ventricular Assist Device, Prototype Number 3 Blood Pump

Abstract

A computational fluid dynamics study of blood flow in the continuous flow ventricular assist device, Prototype No. 3 (CFVAD3), which consists of a 4 blade shrouded impeller fully supported in magnetic bearings, was performed. This study focused on the regions within the pump where return flow occurs to the pump inlet, and where potentially damaging shear stresses and flow stagnation might occur: the impeller blade passages and the narrow gap clearance regions between the impeller-rotor and pump housing. Two separate geometry models define the spacing between the pump housing and the impeller's hub and shroud, and a third geometry model defines the pump's impeller and curved blades. The flow fields in these regions were calculated for various operating conditions of the pump. Pump performance curves were calculated, which compare well with experimentally obtained data. For all pump operating conditions, the flow rates within the gap regions were predicted to be toward the inlet of the pump, thus recirculating a portion of the impeller flow. Two smaller gap clearance regions were numerically examined to reduce the recirculation and to improve pump efficiency. The computational and geometry models will be used in future studies of a smaller pump to determine increased pump efficiency and the risk of hemolysis due to shear stress, and to insure the washing of blood through the clearance regions to prevent thrombosis.

The use of computational fluid dynamics in the development of ventricular assist devices

“…The implementations of these CFD packages are either based on the finite volume23 method or finite element method. Fluent 36, 37, 38, 39, 40, 41 and CFX 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 11, 57, 58, 59, both available from ANSYS, Inc. (Canonsburg, PA) and STAR-CD from CD-Adapco 60, 61 (Melville, New York) are the CFD software packages used most often for analysis and modelling of blood flow in VADs. In addition, AcuSolve from ACUSIM Software 62 (Mountain View, CA) and Adina from Adina R&D (Watertown, MA) are also used.…”

“…Several more implantable devices are currently under development (HeartQuest 74, HeartMate III 75, Tokyo Medical and Dental University and Tokyo Institute for Technology’s Heart 76, Ibaraki University’s Heart 77, Levitronix ® UltraMag ™ 78 and MiTiHeart ™ 79). The HeartQuest has been developed with extensive use of CFD 44, 45, 46, 48. It is 35 mm high, 75 mm diameter, weighs 440 g and is fitted into the upper left quadrant of the abdomen.…”

Models and finite element techniques for blood flow simulation

“…In particular, ventricular assists devices (VADs) have seen application of numerical techniques (Bludszuweit 1995, Miyazoe et al 1999, Anderson et al 2000, Apel et al 2001, Behr et al 2004b, leading to increased understanding of time-dependent flow fields inside the device, and enabling comparative studies between alternative virtual prototypes. We present our experience in CFD modeling of Baylor GYRO pump in Section 2.…”

Performance analysis of ventricular assist devices using finite element flow simulation

“…Even with rapid prototyping capabilities, the experimental studies are constrained by cost and time limitations, and do not generally allow for looking at a large number of alternative designs. Some pumps that were modelled numerically are Utah-Virginia CFVAD3 [4], Impella Intracardiac Pump [5], Nikkiso HPM [6], Aries Iso ow [7] and others. In the case of Pittsburgh Streamliner [8,9], the modelling was used to optimize the shape of certain axial pump components, based on numerically computed ow ÿeld.…”