Computational evaluation of the thrombogenic potential of a hollow-fiber oxygenator with integrated heat exchanger during extracorporeal circulation

Abstract

The onset of thromboembolic phenomena in blood oxygenators, even in the presence of adequate anticoagulant strategies, is a relevant concern during extracorporeal circulation (ECC). For this reason, the evaluation of the thrombogenic potential associated with extracorporeal membrane oxygenators should play a critical role into the preclinical design process of these devices. This study extends the use of computational fluid dynamics simulations to guide the hemodynamic design optimization of oxygenators and evaluate their thrombogenic potential during ECC. The computational analysis accounted for both macro- (i.e., vortex formation) and micro-scale (i.e., flow-induced platelet activation) phenomena affecting the performances of a hollow-fiber membrane oxygenator with integrated heat exchanger. A multiscale Lagrangian approach was adopted to infer the trajectory and loading history experienced by platelet-like particles in the entire device and in a repetitive subunit of the fiber bundles. The loading history was incorporated into a damage accumulation model in order to estimate the platelet activation state (PAS) associated with repeated passes of the blood within the device. Our results highlighted the presence of blood stagnation areas in the inlet section that significantly increased the platelet activation levels in particles remaining trapped in this region. The order of magnitude of PAS in the device was the same as the one calculated for the components of the ECC tubing system, chosen as a term of comparison for their extensive diffusion. Interpolating the mean PAS values with respect to the number of passes, we obtained a straightforward prediction of the thrombogenic potential as a function of the duration of ECC.

Hemodynamic and thrombogenic analysis of a trileaflet polymeric valve using a fluid–structure interaction approach

“…An in-house Matlab (MathWorks, Natick, MA, USA) code was implemented to calculate the stress tensor and to render its laminar components into a scalar stress value (σ) to represent the dynamic mechanical stimulation acting on the particles (Apel et al, 2001; Pelosi et al, 2014). The linear integrative Stress Accumulation (SA) model was adopted to weight the scalar stress over the exposure time (T): $\mathrm{SA}={\int }_0^{\mathrm{normalT}}\sigma \mathrm{dt}$ (Alemu et al, 2010).…”

Shear-mediated platelet activation in the free flow: Perspectives on the emerging spectrum of cell mechanobiological mechanisms mediating cardiovascular implant thrombosis

“…Starting in the early 2000s, researchers began examining platelet activation in response to complex non-physiological fluid shear stress waveforms utilizing markers including thrombin and P-selectin (Zhang et al, 2003; Zhang et al, 2002). Our group expanded on these studies by subjecting gel-filtered platelets repeatedly to dynamic shear stress waveforms, both in a controlled fashion (Nobili et al, 2008; Sheriff et al, 2013) and to conditions extracted from computational fluid dynamics (CFD) simulations of CVIDs (Claiborne et al, 2013; Girdhar et al, 2012; Pelosi et al, 2014; Piatti et al, 2015), to mimic activation of platelets recirculating through devices. Both types of waveforms were selected based on their stress accumulation (SA), or product of the shear stress and exposure time dose, where simulation-extracted waveforms were representative of specific physical or high stress accumulation “hotspot” regions.…”

Computational investigation of hemodynamics in hardshell venous reservoirs: A comparative study

“…The modelling applied in the present work differs from the previous studies in several points. The membrane is not included in the present solution domain.…”

“…The flow in the hardshell reservoir can exhibit, in general, laminar and turbulent behavior at the same time in different regions, depending on the geometry and operating conditions. Both Gage and Jones and colleagues assumed a laminar flow throughout, whereas turbulent flow was assumed in the study of Pelosi based on RANS. In all cases, a Newtonian behavior was assumed for the blood .…”