Numerical studies of hemodynamic alterations in pre‐ and post‐stenting cerebral aneurysms using a multiscale modeling

Abstract

The aim of this work was to use a multiscale modeling to study the influence of stent deployment, with generic stents, on flow distributions within the vascular network and the hemodynamic alterations within the cerebral aneurysms pre‐ and post‐stenting. To achieve this goal, two image‐based anatomical cerebral aneurysm models were reconstructed along with the respective aneurysms post‐stenting models after deploying a 16‐ or 24‐wire stent. The investigation results revealed that the stent may increase the local pressure resistance resulting in flow alterations. The hemodynamic parameters demonstrated stent placement can reduce the intra‐aneurysmal pressure, decrease wall shear stress (WSS) at the neck region, and increase blood turnover time for aneurysm case I (sidewall aneurysm). These findings are consistent with the trends of hemodynamic changes reported previously. However, aneurysm case II (bifurcation aneurysm) showed gradually increased intra‐aneurysmal pressure and the pressure at the neck region, decreased WSS over the sac surface, and enhanced flow vortices within the aneurysm. When simulating the hemodynamics of pre‐ and post‐stenting aneurysms for a patient using measured flow waveforms, the flow alteration induced by the stent deployment may affect the hemodynamic predictions for the post‐stenting aneurysm. Thus, the remeasurement of boundary conditions once the morphology of the aneurysm is deformed is needed in follow‐up studies with a focus on aneurysm growth and stent deployment.

Effects of Pulsatile Flow Rate and Shunt Ratio in Bifurcated Distal Arteries on Hemodynamic Characteristics Involved in Two Patient-Specific Internal Carotid Artery Sidewall Aneurysms: A Numerical Study

“…To study the influences of the flow rate and shunt ratio on hemodynamic characteristics in ICASA models, two patient-specific cerebral aneurysm models (see Figure 1 ), i.e., (a) ICASA−1 (73-year-old, female), and (b) ICASA−2 (35-year-old, female), were built using an open source code, i.e., 3D Slicer, based on medical data provided by Miami Valley Hospital (Dayton, OH, USA) [ 47 , 48 ]. In the ICASA−1 model, the blood flows in through the ICA and flows out from the bifurcated distal arteries, i.e., posterior communicating artery (PComA) and ICA distal.…”

“…To systematically investigate the PFR effects on the intra-hemodynamic characteristics in the ICASA models, three transient pulsatile flow rate waveforms (i.e., PFR−I, PFR−II, and PFR−III) with a period of = 1.0 s were applied as the boundary conditions at the ICA inlet (see Figure 3 ), representing cardiac PFR conditions. Specifically, the waveform of PFR−II is based on pulsatile flow rates obtained from a validated 1D model, which has been studied in our previous investigations [ 47 , 60 ]. According to a statistical study determining blood flow rates in cerebral arteries [ 26 ], another two waveforms, i.e., PFR−I and PFR−III, were generated by multiplying 0.57 and 1.43 times of PFR−II, respectively, which fall into the 95% confidence interval of blood flow rate in ICA based on statistics [ 26 ].…”

“…Specifically, the volumetric shunt ratios (i.e., the minimum and the maximum), q A1 vs. q A2 , e.g., 64:36 [ 26 ] and 75:25 [ 62 ], were used to investigate the effects of flow-splitting variances in bifurcated distal arteries on hemodynamic behaviors. Additionally, the arterial walls are assumed to be stationary and non-slip, and the blood circulation system is operated under the pressure waveform (see Figure 3 ) obtained by previous studies [ 47 , 60 ].…”

Different Hemodynamic Characteristics and Resulting in Different Risks of Rupture Between Wide-Neck and Narrow-Neck Aneurysms

“…Strategies, including aneurysm clipping or embolization, stent implantation were used to reduce IAP, which avoided aneurysm rupture intraoperatively and reduced aneurysm recurrence and rupture postoperatively. Yu and colleagues ( 52 ) investigated the hemodynamic changes in pre-and-post stenting of aneurysms and found that stent placement can reduce IAP and WSS at the neck region in side-wall aneurysms. In another investigation ( 53 ), the 4 different stents (LVIS, LVIS Jr, Leo, Barrel VRD) showed IAP decreased significantly after stent implantation.…”

Virtual Reality Visualization of CFD Simulated Blood Flow in Cerebral Aneurysms Treated with Flow Diverter Stents

“…Some studies have focused on the simulation of the mechanical deployment of flow-diverter stents using finite element analysis to capture the clinically realistic FD deployment processes [3,13]. Some researchers have conducted stent deployment and CFD simulations simultaneously to investigate the influence of different stent deployment approaches and the location of stents on the hemodynamics of aneurysms by comparing untreated and stented vessels [9,14,15]. It is noted that the specifications of FD stents such as stent type, mesh porosity, and mesh pore density are other determining factors in the greater device efficacy, which have been considered by researchers using CFD simulations [6,8,16].…”