[show abstract][hide abstract] ABSTRACT: Stent deployment across the aneurysmal neck has been established as one of the endovascular methods to treat intracranial aneurysms with or without coils.
The purpose is to study the possible adverse effects of deployment of the new flow-diverter stent-like devices (FD) on the flow characteristics of saccular aneurysm models.
Numerical simulations of the blood flow patterns in the artificial models of three aneurysms were studied. One model was designed without an FD stent, the second model with one FD stent, and the third model with two stents. Numerical simulation for incompressible laminar blood flow was conducted in the three artificial cerebral aneurysm models by means of computational fluid dynamics.
There was a noticeable increase in the values of the circumferential pressure distributed on the walls of the aneurysm after stent deployment; this led to an increase the tension of the aneurysm surface and was considered to be an adverse effect. This pressure increase was further aggravated by the deployment of another stent. However, there is a beneficial effect of using FD stents, translating into the reduction of the flow velocity inside the aneurysm and wall shear stress at the inflow zone. This reduction decreases further with the deployment of another stent.
Aneurysms become tenser after the deployment of one flow-diverter stent and (more tense still) after after the deployment of another stent. This principle should be kept in mind when choosing which group of aneurysms is the best candidate for such a treatment strategy. This study recommends deploying several FD stents during endovascular procedures until complete arrest of the blood flow occurs during the procedure; otherwise, the aneurysm may become tenser and dangerous if a slow blood flow jet still exists inside it at the end of the procedure.
[show abstract][hide abstract] ABSTRACT: Parent vessel plays an important role in aneurysm formation and rupture. The diameter of either the A1 arteries is the peculiar key controlling the flow of the anterior communicating artery (ACOMA) aneurysms (ANs).
The purpose is to study the effect of parent vessel dominancy, that is, the diameter of the A1 artery, on the flow characteristics of the ACOMA ANs.
Numerical simulations for the flow patterns in six artificial models have been studied. Three models are designed with aneurysms and three models without. The two A1s were equal in two models. In the other two models, the nondominant A1 diameters were decreased by 50%. Again, the nondominant A1s were decreased by another 50% in the last two models. Each pair was designed with and without aneurysms in the ACOMA.
The ACOMA shows lower velocity magnitudes and wall shear stresses when the two A1s are equal. However, if one A1 is dominant with a 50% difference from the other A1, there is higher shear stress on the ACOMA itself and in the inflow zone of the aneurysm that increases more with further reduction of the nondominant A1 by another 50%. An area of high corner pressure at the bifurcation of the dominant A1 into the ACOMA and A2 exists and increases in value with the decrease of diameter of the other nondominant A1.
Aneurysms located in the ACOMA with differences of 50% or more between the two A1s are subjected to more flow stresses.