engleski

A fluid-solid growth study of thrombus-laden aneurysm progression

Hemodynamic changes are undoubtedly an important factor in the arterial lesion progression, and very likely in intraluminal thrombus (ILT) formation and deposition, [1]. Thus, the logical new step in numerical modelling of abdominal aortic aneurysm (AAA) growth is loose coupling of computational fluid dynamics (CFD) models over a cardiac cycle (time scale in milliseconds) with long-term G&R models of the evolving wall and ILT (time scale in days), referred as fluid-solid-growth (FSG) model. The concept of the FSG framework was first proposed by Humphrey & Taylor in 2008 [2]. There were very few attempts applying the FSG model to AAAs (e.g., [3]), but all neglecting thrombus. In this work we present an FSG model of thrombus-laden aneurysm. In our framework, the long-term G&R model, presented in [4], runs until maximal luminal diameter is increased sufficiently (e.g., 1 mm). At that time G&R analysis is interrupted, luminal surface for CFD simulation is generated, and hemodynamic analysis over several cardiac cycles is performed. If predefined conditions for thrombus deposition are not met (e.g. time averaged wall shear stress (TAWSS) did not decrease below the threshold value), G&R continues without adjustments. However, when requirements are fulfilled, new thrombus finite elements are added to the aneurysm finite element model at the location defined by hemodynamic analysis. Interestingly, with lower predefined threshold values of TAWSS that determines the thrombus deposition, the deposition becomes more asymmetrical. This asymmetrical deposition consequently leads to a reduced AAA expansion of the shielded distal part of the aneurysmal sac and aneurysmal apex shifts upward. Furthermore, with delayed ILT deposition at the proximal part of the aneurysm, the area covered by thin, proteolytically active ILT is increased. This leads to additional expansion of the proximal side and further deformation of the aneurysm sac due to increased degradation of the underlying wall.

Fluid-structure-growth, intraluminal thrombus, finite elements

nije evidentirano