Numerical Estimation of Blood Damage in Artificial Organs

Abstract

The aim of this study was to determine a method for the numerical estimation of blood damage. Normally, human or animal blood is used for in vitro evaluation of lysis by artificial organs. However, blood has some disadvantages: large biological variability and different initial test conditions lead to nonreproducible test results. For that reason, it would be an advantage to have a numerical method for blood damage estimation. This proposed method is based on the calculation of an integrated hemolysis and platelet lysis index along the path line in the flow field of the artificial organ. The time-dependent shear stress related lysis is based on known experimental data. In order to calibrate these data, the method was first applied to blood circulation in the human body. The results showed that the known data overestimate hemolysis by a factor of approximately 25. Next, the method was applied to a standard Björk-Shiley valve. The flow through a valve was simulated with the computational fluid dynamics program FLUENT. The calculation of lysis was added into FLUENT and done automatically. The results showed that the Björk-Shiley valve increased the hemolysis index by 7% if implanted in the human body circulation.

Investigation on Mechanical and Bio-Mechanical Performance of a Centrifugal Blood Pump

“…Hemolysis is also important due to the fact that high level of free hemoglobin is a toxin for the kidneys and can lead to organ failure [1]. During a blood pump operation, the main reason for the hemolysis is the shear stress generated by rotation of the rotating parts [2,3]. Due to the limitation of experiment and complexities in flow characteristics, especially inside the pump, there are obstacles for investigating the details in a real case(in vivo condition).…”

High-Resolution Measurement of the Unsteady Velocity Field to Evaluate Blood Damage Induced by a Mechanical Heart Valve

“…The knowledge of the mechanical loading of cells as a function of time allows for the calculation of the cumulative blood damage. In this paper we chose to use the platelet damage models proposed by Goubergrits and Affeld 19 and Grigioni et al 20 . Both models respect the principle of causality 20,40 , reproduce the original empirical model introduced by Giersiepen et al 15 under constant shear stress and account for the loading history previously sustained by the blood cell 20,21 .…”

“…Geometry and dynamics of artificial occluders promote abnormal features such as jets, separation, and vortex shedding, which can subject cell trajectories to prolonged or intermittent exposure to large shearing forces 5,6 . It has been suggested that flow structures in these fields are effective at scales down to tens of µm 7,8 or mathematical models 15,[19][20][21][22] . Since cellular response to stress is dependent on history, such models must be integrated over the Lagrangian trajectory of a cell through the flow field of a given device in order to predict flow-induced blood damage.…”

“…The flow field should be characterised at sufficient spatial resolution to enable all relevant flow features to be measured, and at sufficient temporal resolution to allow stress to be recorded over the history of a cell as it is convected through the field. To date, blood damage index in MHVs has been calculated only from numerical data, either for hemolysis 19 or thrombosis 23,24 . Although…”

“…That enables the application of the Lagrangian tracking approach used to date almost exclusively in numerical investigations. We evaluate two blood damage models which have been proposed to predict platelet activation accounting for the non-linear dependence on exposure time in a physically sound fashion [19][20][21][22] . The integration of those models along almost 25,000 trajectories provides an estimate of platelet activation in the bulk forward flow during systole and moreover allows for evaluation of the relevance of the increased measurement resolution.…”