Abstract
Intracranial side aneurysms (IA) are pathological blood-filled bulges in cerebral blood vessels. Unlike healthy blood vessels where mass transport is dominated by convection, both diffusion and convection can play an active role in aneurysm sites. Here, we study via dye washout experiments and numerical simulations, the transport characteristics of particles (1 micron) and small molecules (300 Da) into simplified side aneurysms models following bolus injection. Time-lapse fluorescent microscopy imaging performed in our idealized aneurysm models showed that the parent artery geometry (located on the inner vs. outer curvature) as well as the aneurysm aspect ratio (AR) affect the washout kinetics while the pulsatile nature of the flow, maintained within the physiological range, carries only a minor effect. Importantly, in the absence of effective diffusion, particles that are located on slow streamlines linger within the aneurysm cavity, a phenomenon that could be of importance in deposition of cells and nano/micro-particles within aneurysms. Altogether, mass transport studies may provide valuable insights for better understanding of aneurysm pathophysiology as well as for the design of new diagnostic and theranostic nano-medicines.
Highlights
In addition to affecting the shear stress exerted on endothelial cells, abnormal blood flow affects mass transport at disease sites
As hemodynamics and transport properties are governed by aneurysm geometry, we explore aneurysms of different aspect ratios and at different parent artery geometries
To quantify the filling and washout kinetics within the different aneurysms, we define a region of interest which covers the aneurysm cavity and measure the average fluorescence intensity within the ROI as a function of time
Summary
In addition to affecting the shear stress exerted on endothelial cells, abnormal blood flow affects mass transport at disease sites. There has been an increased interest in studying the abnormal mass transport in aneurysms with particular focus on bio-molecules that can play a role in disease progression such as ATP, LDL and oxygen transport[7,12,13]. Besides the transport of blood borne molecules, another important convection-diffusion problem that has been studied widely is the transport of contrast agents into aneurysms. As hemodynamics and transport properties are governed by aneurysm geometry, we explore aneurysms of different aspect ratios (aneurysm/vessel diameter AR = 1.6 and 3.2) and at different parent artery geometries (inner/outer curvatures) The latter is known to affect the local Dean number defined as the ratio between the square root of the product of centripetal and inertial forces to the viscous forces, see Eq 2 where d is the parent artery diameter,r is its radius of curvature and Re is the Reynolds number[23]
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