颈内动脉分叉处动脉瘤的血流动力学特点

Hemodynamic stress characteristics of aneurysms of the internal carotid artery bifurcation

目的动脉分叉处承受更大的血流动力学压迫,容易形成脑动脉瘤,但是我们发现颈内动脉分叉处(ICBi)的动脉瘤通常不生长在ICB的顶点,而是位于大脑前动脉弯曲的顶点。本文回顾研究了ICBi动脉瘤的血流动力学特点。方法回顾研究了18个ICBi动脉瘤患者,测量了动脉瘤的瘤体直径、瘤颈宽度,大脑前动脉水平段(A1段)和大脑中动脉水平段(M1段)的管径,瘤颈中点距离颈内动脉顶点的长度,对比了大脑前动脉和大脑中动脉分别由颈内动脉发出后形成的弯曲度,注意了动脉瘤的生长方向。结果16例动脉瘤生长在大脑前动脉弯曲的顶点。动脉瘤体的最大直径为2.45～15.05(平均5.74±2.91)mm,瘤颈宽度1.46～6.21(平均2.51±1.07)mm。动脉瘤颈中心距离颈内动脉分叉顶点0～2.91(平均1.72±0.79)mm。大脑前动脉水平段管径1.77～3.08(平均2.22±0.37)mm,大脑中动脉水平段管径2.32～3.64(平均2.93±0.51)mm。动脉瘤向前或向上生长的4例,向后上、后、或后下生长的14例。17例患者的大脑前动脉由颈内动脉发出后形成的弯曲明显大于大脑中动脉的弯曲度。结论ICBi动脉瘤规律性地从大脑前动脉起始段的弯曲顶点出生长。与血管弯曲的方向一致,动脉瘤通常突向后方。血流剪切力在弯曲顶点的局部血管壁的作用是动脉瘤形成的关键因素。

Objective Arterial bifurcations are sites of maximal hemodynamic stress,where cerebral aneurysms commonly develop.However,in our experience with endovascular treatment and surgery treatment for aneurysms of the internal carotid artery（ICA） bifurcation,we often experienced that the aneurysmal neck did not necessarily exist only at the ICA bifurcation（ICBi）,but often at the apex of the outer（lateral） wall of the curved anterior cerebral artery.In this study,we have retrospectively evaluated the hemodynamic stress characteristics of aneurysms at the ICBi.Methods Eighteen ICBi aneurysms in 18 consecutive patients were studied retrospectively.The size of the aneurysms,the vessel curvature of the anterior cerebral artery（ACA） and middle cerebral artery（MCA）,and the diameter of the ACA and MCA were measured.Furthermore,to study the relationship between the location of the aneurysmal neck and the bifurcation of the ICA,the distance between the midline of the aneurysmal neck and the apex of the internal carotid artery bifurcation was measured.Results The average aneurysm size was 5.74±2.91mm and the average neck was 2.51±1.07mm.The curvature of the ACA was significant bigger than of the MCA.The average diameters of the ACA and MCA were 2.22±0.37 mm and 2.93±0.51 mm,respectively.The average distance between the midline of the aneurysmal neck and the ICA was 1.72±0.79mm,and almost aneurysmal necks of the ICBi arose from the side of the ACA.Conclusion ICBi aneurysms are deviated to the side of the A1 segment of the ACA,where the artery might suffer higher hemodynamic stress.Our preliminary results indicate that the high wall shear stress is the key factor for the formation and development of intracranial aneurysms arose from curved anterior cerebral arteries.