Hademenos G J, Massoud T F, Viñuela F
Department of Radiological Sciences, University of California Los Angeles School of Medicine, USA.
Neurosurgery. 1996 May;38(5):1005-14; discussion 1014-5. doi: 10.1097/00006123-199605000-00030.
Hemodynamics play a significant role in the propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage and in influencing both therapeutic strategies and their complications. AVM hemodynamics are difficult to quantitate, particularly within or in close proximity to the nidus. Biomathematical models represent a theoretical method of investigating AVM hemodynamics but currently provide limited information because of the simplicity of simulated anatomic and physiological characteristics in available models. Our purpose was to develop a new detailed biomathematical model in which the morphological, biophysical, and hemodynamic characteristics of an intracranial AVM are replicated more faithfully. The technique of electrical network analysis was used to construct the biomathematical AVM model to provide an accurate rendering of transnidal and intranidal hemodynamics. The model represented a complex, noncompartmentalized AVM with 4 arterial feeders (with simulated pial and transdural supply), 2 draining veins, and a nidus consisting of 28 interconnecting plexiform and fistulous components. Simulated vessel radii were defined as observed in human AVMs. Common values were assigned for normal systemic arterial pressure, arterial feeder pressures, draining vein pressures, and central venous pressure. Using an electrical analogy of Ohm's law, flow was determined based on Poiseuille's law given the aforementioned pressures and resistances of each nidus vessel. Circuit analysis of the AVM vasculature based on the conservation of flow and voltage revealed the flow rate through each vessel in the AVM network. Once the flow rate was established, the velocity, the intravascular pressure gradient, and the wall shear stress were determined. Total volumetric flow through the AVM was 814 ml/min. Hemodynamic analysis of the AVM showed increased flow rate, flow velocity, and wall shear stress through the fistulous component. The intranidal flow rate varied from 5.5 to 57.0 ml/min with and average of 31.3 ml/min for the plexiform vessels and from 595.1 to 640.1 ml/min with an average of 617.6 ml/min for the fistulous component. The blood flow velocity through the AVM nidus ranged from 11.7 to 121.1 cm/s with an average of 66.4 cm/s for the plexiform vessels and from 446.9 to 480 dyne/cm2 with an average of 463.5 dyne/cm2 for the fistulous component. The wall shear stress ranged in magnitude from 33.2 to 342.1 dyne/cm2 with an average of 187.7 dyne/cm2 for the plexiform vessels and from 315.9 to 339.7 cm/s with an average of 327.8 cm/s for the fistulous component. The described novel biomathematical model characterizes the transnidal and intranidal hemodynamics of an intracranial AVM more accurately than was possible previously. This model should serve as a useful research tool for further theoretical investigations of intracranial AVMs and their hemodynamic sequelae.
血流动力学在颅内动静脉畸形（AVM）出血倾向、影响治疗策略及其并发症方面发挥着重要作用。AVM血流动力学难以量化，尤其是在畸形血管团内部或其附近。生物数学模型是研究AVM血流动力学的一种理论方法，但由于现有模型中模拟的解剖和生理特征过于简单，目前提供的信息有限。我们的目的是开发一种新的详细生物数学模型，更忠实地复制颅内AVM的形态、生物物理和血流动力学特征。采用电网络分析技术构建生物数学AVM模型，以准确呈现经畸形血管团和畸形血管团内的血流动力学。该模型代表一个复杂的、非分隔的AVM，有4条动脉供血支（模拟软脑膜和经硬膜供血）、2条引流静脉以及一个由28个相互连接的丛状和瘘状成分组成的畸形血管团。模拟血管半径根据在人类AVM中观察到的情况确定。为正常体动脉压、动脉供血支压力、引流静脉压力和中心静脉压指定了常见值。利用欧姆定律的电学类比，根据泊肃叶定律在给定上述各畸形血管团血管的压力和阻力的情况下确定流量。基于流量和电压守恒对AVM血管系统进行电路分析，揭示了AVM网络中每条血管的流速。一旦确定了流速，就可以确定速度、血管内压力梯度和壁面剪应力。通过AVM的总容积流量为814 ml/min。对AVM的血流动力学分析显示，通过瘘状成分的流速、血流速度和壁面剪应力增加。畸形血管团内丛状血管的流速在5.5至57.0 ml/min之间变化，平均为31.3 ml/min；瘘状成分的流速在595.1至640.1 ml/min之间变化，平均为617.6 ml/min。通过AVM畸形血管团的血流速度在11.7至121.1 cm/s之间变化，丛状血管平均为66.4 cm/s；瘘状成分的壁面剪应力在315.9至339.7 dyne/cm²之间变化，平均为463.5 dyne/cm²。壁面剪应力的大小在33.2至342.1 dyne/cm²之间变化，丛状血管平均为187.7 dyne/cm²；瘘状成分的血流速度在315.9至339.7 cm/s之间变化，平均为327.8 cm/s。所描述的新型生物数学模型比以前更准确地表征了颅内AVM的经畸形血管团和畸形血管团内的血流动力学。该模型应作为一种有用的研究工具，用于对颅内AVM及其血流动力学后遗症进行进一步的理论研究。
