Abstract
BackgroundProspective observation of hemodynamic changes before and after formation of brain aneurysms is often difficult. We used a vessel surface repair method to carry out a retrospective hemodynamic study before and after aneurysm formation in a ruptured aneurysm of the posterior communicating artery (RPcomAA) and an unruptured aneurysm of the posterior communicating artery (URPcomAA).MethodsArterial geometries obtained from three-dimensional digital subtraction angiography of cerebral angiograms were used for flow simulation by employing finite-volume modeling. Hemodynamic parameters such as wall shear stress (WSS), blood-flow velocity, streamlines, pressure, and wall shear stress gradient (WSSG) in the aneurysm sac and at the site of aneurysm formation were analyzed in each model.ResultsAt “aneurysm” status, hemodynamic analyses at the neck, body, and dome of the aneurysm revealed the distal aneurysm neck to be subjected to the highest WSS and blood-flow velocity, whereas the aneurysm dome presented the lowest WSS and blood-flow velocity in both model types. More apparent changes in WSSG at the aneurysm dome with an inflow jet and narrowed impaction zone were revealed only in the RPcomAA. At “pre-aneurysm” status, hemodynamic analyses in both models showed that the region of aneurysm formation was subjected to extremely elevated WSS, WSSG, and blood-flow velocity.ConclusionsThese data suggest that hemodynamic analyses in patients with ruptured or unruptured aneurysms using the vessel surface repair method are feasible, economical, and simple. Our preliminary results indicated that the arterial wall was subjected to elevated WSS, WSSG and blood-flow velocity before aneurysm generation. However, more complicated flow patterns (often with an inflow jet or narrowed impaction zone) were more likely to be observed in ruptured aneurysm.
Highlights
Prospective observation of hemodynamic changes before and after formation of brain aneurysms is often difficult
Hemodynamic analyses at the aneurysm status Based on Doppler ultrasound measurements, the blood flow velocity of internal carotid artery in the ruptured aneurysm of the posterior communicating artery (RPcomAA) and URPcomAA patients was 67.6 cm/s and 58.3 cm/s at the systolic phase, and 26.2 cm/s and 20.2 cm/s at the diastolic phase, with a mean heart rate of 79 bpm and 75 bpm, respectively
Hemodynamic analyses at pre-aneurysm status showed that the area of aneurysm formation of the parent artery was subject to extremely high wall shear stress (WSS), elevated blood velocity, and wall shear stress gradient (WSSG) changes compared with the adjacent arterial wall, in both models
Summary
Prospective observation of hemodynamic changes before and after formation of brain aneurysms is often difficult. Hemodynamic status is recognized as one of the most important factors responsible for the growth, development, and rupture of aneurysms [3]. Hemodynamic variables such as flow pattern, wall shear stress (WSS) and wall shear stress gradient (WSSG) have been hypothesized to be the causes of aneurysms [4]. The formation or growth of an aneurysm is caused by remodeling of the arterial wall under long-term, complicated hemodynamic actions [5,6]. Prospective observation of hemodynamic changes during the development of brain aneurysms is extremely difficult and often restricted because it is time-consuming, expensive, and ethical issues are involved [7]. Development of a more economic and efficient method to study hemodynamic changes before and after aneurysm growth, in ruptured or unruptured aneurysms, is crucial
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