Numerical Analyses of Idealized Total Cavopulmonary Connection Physiologies with Single and Bilateral Superior Vena Cava Assisted by an Axial Blood Pump

Our study evaluated the hemodynamic performance of an axial flow blood pump surgically implanted in idealized total cavopulmonary connection(TCPC)models.This blood pump was designed to augment pressure from the inferior vena cava(IVC)to the pulmonary circulation.Two Fontan procedures with single and bilateral superior vena cava(SVC)were compared to fit the mechanical supported TCPC physiologies.Computational fluid dynamics(CFD)analyses of two Pump-TCPC models were performed in the analyses.Pressure-flow characteristics,energy efficiency,fluid streamlines,hemolysis and thrombosis analyses were implemented.Numerical simulations indicate that the pump produces pressure generations of 1 mm to 24 mm Hg for rotational speeds ranging from 2000 RPM to 5000 RPM and flow rates of 2 LPM to 4 LPM.Two surgical models incorporated with the pump were found to be insignificant in pressure augmentation and energy boost.The risk assessment of blood trauma and thrombosis generation was evaluated representatively through blood damage index(BDI),particle resident time(PRT)and relative resistant time(RRT).The hemolysis and thrombosis analyses declare the advantage of the pump supported bilateral SVC surgical scheme in balancing flow distribution and reducing the risk of endothelial cell destruction and trauma generation.

Efficient simulation of a low-profile visualized intraluminal support device: a novel fast virtual stenting technique

Background: The low-profile visualized intraluminal support (LVIS) stent has become a promising endovascular option for treating intracranial aneurysms. To achieve better treatment of aneurysms using LVIS, we developed a fast virtual stenting technique for use with LVIS (F-LVIS) to evaluate hemodynamic changes in the aneurysm and validate its reliability. Methods: A patient-specific aneurysm was selected for making comparisons between the real LVIS (R-LVIS) and the F-LVIS. To perform R-LVIS stenting, a hollow phantom based on a patient-specific aneurysm was fabricated using a three-dimensional printer. An R-LVIS was released in the phantom according to standard procedure. F-LVIS was then applied successfully in this aneurysm model. The computational fluid dynamics (CFD) values were calculated for both the F-LVIS and R-LVIS models. Qualitative and quantitative comparisons of the two models focused on hemodynamic parameters. Results: The hemodynamic characteristics for R-LVIS and F-LVIS were well matched. Representative contours of velocities and wall shear stress (WSS) were consistently similar in both distribution and magnitude. The velocity vectors also showed high similarity, although the R-LVIS model showed faster and more fluid streams entering the aneurysm. Variation tendencies of the velocity in the aneurysm and the WSS on the aneurysm wall were also similar in the two models, with no statistically significant differences in either velocity or WSS. Conclusions: The results of the computational hemodynamics indicate that F-LVIS is suitable for evaluating hemodynamic factors. This novel F-LVIS is considered efficient, practical, and effective.

Finite element modeling and simulation of the implantation of braided stent to treat cerebral aneurysm

Braided stents were widely used to treat cerebral aneurysms and computational fluid dynamics(CFD)was used to evaluate the therapeutic effects.But the aneurysm-artery geometry used in CFD were usually undeformed which is inconsistent with clinical findings.Our team developed a finite element modeling workflow to simulate implantation of braided stents in patient-specific aneurysm-artery model.An LVIS-based braided stent was deployed into an aneurysm-artery model.The stent fully expanded,causing obvious deformation on the aneurysm-artery model.The workflow which we developed could provide reasonable deformed geometries of aneurysm-artery and braided stent for CFD computation and possibly assist surgical planning.