Flow features and device‐induced blood trauma in CF‐VADs under a pulsatile blood flow condition: A CFD comparative study. (6th October 2017)

• Record Type: Journal Article
• Authors: Chen, Zengsheng; Jena, Sofen K.; Giridharan, Guruprasad A.; Koenig, Steven C.; Slaughter, Mark S.; Griffith, Bartley P.; Wu, Zhongjun J.
• Is Part Of: International journal for numerical methods in biomedical engineering. Volume 34:Number 2(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-10-06
• Subjects: blood fluid dynamics -- blood trauma -- exposure time -- scalar shear stress -- VAD; Biomedical engineering -- Periodicals; Imaging systems in medicine -- Periodicals; Numerical analysis -- Periodicals; Engineering mathematics -- Periodicals; 610.28
• DOI: 10.1002/cnm.2924
• Languages: English
• ISSNs: 2040-7939

Abstract

Abstract: In this study, the flow features and device‐associated blood trauma in 4 clinical ventricular assist devices (VADs; 2 implantable axial VADs, 1 implantable centrifugal VAD, and 1 extracorporeal VAD) were computationally analyzed under clinically relevant pulsatile flow conditions. The 4 VADs were operated at fixed pump speed at a mean rate of 4.5 L/min. Mean pressure difference, wall shear stress, volume distribution of scalar shear stress (SSS), and shear‐induced hemolysis index (HI) were derived from the flow field of each VAD and were compared. The computationally predicted mean pressure difference across the 3 implantable VADs was ~70 mmHg, and the extracorporeal VAD was ~345 mmHg, which matched well with their reported pressure‐flow curves. The axial VADs had higher mean wall shear stress and SSS compared with the centrifugal VADs. However, the residence time of the centrifugal VADs was much longer compared with the axial VADs because of the large volume of the centrifugal VADs. The highest SSS was observed in one axial VAD, and the longest exposure time was observed in 1 centrifugal VAD. These 2 VADs generated the highest HI. The shear‐induced HI varied as a function of flow rate within each cardiac cycle. At fixed pump speed, the HI was greatest at low flow rate due to longer exposure time to shear stress compared with at high flow rate. Subsequently, we hypothesize that to reduce the risk of blood trauma during VAD support, shear stress magnitude and exposure time need to be minimized. Abstract : In this study, we found that axial ventricular assist devices had higher mean shear stress and shorter blood residence time compared with centrifugal ventricular assist devices. The shear‐induced hemolysis index varied as a function of flow rate within each cardiac cycle. Under the pulsatile flow condition, the scalar shear stress field in the two axial ventricular assist devices was more sensitive to the flow rate change compared with that of the two centrifugal ventricular assist devices.