Validation of numerically simulated ventricular flow patterns during left ventricular assist device support

Abstract

Intraventricular flow patterns during left ventricular assist device support have been investigated via computational fluid dynamics by several groups. Based on such simulations, specific parameters for thrombus formation risk analysis have been developed. However, computational fluid dynamic simulations of complex flow configurations require proper validation by experiments. To meet this need, a ventricular model with a well-defined inflow section was analyzed by particle image velocimetry and replicated by transient computational fluid dynamic simulations. To cover the laminar, transitional, and turbulent flow regime, four numerical methods including the laminar, standard k-omega, shear-stress transport, and renormalized group k-epsilon were applied and compared to the particle image velocimetry results in 46 different planes in the whole left ventricle. The simulated flow patterns for all methods, except renormalized group k-epsilon, were comparable to the flow patterns measured using particle image velocimetry (absolute error over whole left ventricle: laminar: 10.5, standard k-omega: 11.3, shear–stress transport: 11.3, and renormalized group k-epsilon: 17.8 mm/s). Intraventricular flow fields were simulated using four numerical methods and validated with experimental particle image velocimetry results. In the given setting and for the chosen boundary conditions, the laminar, standard K-omega, and shear–stress transport methods showed acceptable similarity to experimental particle image velocimetry data, with the laminar model showing the best transient behavior.

Multi‐constituent simulation of thrombus formation at LVAD inlet cannula connection: Importance of Virchow’s triad

“…The insertion depth of the IC in the LV was approximately 20 mm. At the atrium, a conduit of 30 mm diameter and 30 mm height was added to promote a developed velocity profile and represent the outflow jet typical to this configuration 20 . A uniform velocity boundary condition was prescribed at the inlet of the entrance region (corresponding to constant flow rate of 5 L min –1 ).…”

“…At the atrium, a conduit of 30 mm diameter and 30 mm height was added to promote a developed velocity profile and represent the outflow jet typical to this configuration. 20 A uniform velocity boundary condition was prescribed at the inlet of the entrance region (corresponding to constant flow rate of 5 L min -1 ). No-slip boundary conditions were set at the walls of the LV and the inflow cannula.…”

“…However, those published have focused exclusively on simulation of fluid dynamics. Using Computational Fluid Dynamics (CFD) simulations of the cannulated left ventricle, investigators have been able to determine the importance of physical factors affecting the flow, such as cannula positioning, ventricle size, and cannula geometry 7,17‐22 . In general, these numerical studies assessed thrombogenic potential via interpretation of velocity fields and shear stress.…”

“…Using Computational Fluid Dynamics (CFD) simulations of the cannulated left ventricle, investigators have been able to determine the importance of physical factors affecting the flow, such as cannula positioning, ventricle size, and cannula geometry. 7,[17][18][19][20][21][22] In general, these numerical studies assessed thrombogenic potential via interpretation of velocity fields and shear stress. Supraphysiological shear stress is associated with platelet activation while inadequate shear stress in stagnation regions is presumed to promote platelet aggregation and deposition.…”

Effects of the atrium on intraventricular flow patterns during mechanical circulatory support

“…In a previous study, the laminar method showed better agreement with the experimental results of ventricular flow fields compared to the turbulence models. 22 As a consequence, blood was here assumed a Newtonian fluid—with a density of 1060 kg/m 3 and a dynamic viscosity of 0.0035 Pa s—and in laminar conditions.…”