Robertson Scott W, Cheng Christopher P, Razavi Mahmood K
Nitinol Devices & Components, Fremont, CA, USA.
J Endovasc Ther. 2008 Dec;15(6):663-71. doi: 10.1583/08-2528.1.
To examine the effects of swallowing and side-to-side head turning on stents in the internal carotid artery.
Seven patients (4 men; mean age 76.9 years) who underwent carotid artery stenting for the treatment of atherosclerotic cervical carotid artery disease were examined with cine fluoroscopy. Geometric processing techniques were used to quantify carotid stent deformations due to head turning and swallowing forces. The variables measured included radial, axial, and crush deformations, as well as radii of stent curvatures during tested maneuvers.
Radial deformations of the stented vessels were significantly less than axial and crush deformations, ranging from -10.2% to 15.5%. Axial deformations in response to both swallowing and head turning were positive (average 4.5%, range -14.5% to 14.1%), indicating a general lengthening of the stented vessel due to biomechanical motions. Crush strains exhibited the largest range of all of the deformation modes during both swallowing and head turning. Strain values ranged from -18.7% to 25.9% in the anteroposterior direction and from -25.6% to 21.9% in the lateral direction. Head turning produced fairly symmetrical crushing of the stent. Conversely, swallowing resulted in a preferential medial crush of the stented artery due to contraction of the pharyngeal constrictor muscles. Curvature measurements revealed a tightest radius of curvature of approximately 1.5 cm during ipsilateral head turning, with average values during both swallowing and head turning of approximately 10 cm.
In general, head turning toward the stented artery produced greater deformation in the vessels than swallowing. Since patients are expected to undergo far more swallowing cycles than head turns, however, the accumulated deformations from swallowing may be more significant and should be considered in the design of fatigue resistant stents for carotid arteries.
研究吞咽及头部左右转动对颈内动脉支架的影响。
对7例（4例男性；平均年龄76.9岁）因动脉粥样硬化性颈段颈动脉疾病接受颈动脉支架置入术的患者进行荧光电影透视检查。采用几何处理技术量化因头部转动和吞咽力导致的颈动脉支架变形。测量的变量包括径向、轴向和挤压变形，以及测试动作期间支架曲率半径。
支架血管的径向变形明显小于轴向和挤压变形，范围为-10.2%至15.5%。吞咽和头部转动引起的轴向变形均为正值（平均4.5%，范围为-14.5%至14.1%），表明由于生物力学运动，支架血管普遍延长。在吞咽和头部转动过程中，挤压应变在所有变形模式中范围最大。应变值在前后方向上为-18.7%至25.9%，在横向方向上为-25.6%至21.9%。头部转动导致支架出现相当对称的挤压。相反，由于咽缩肌收缩，吞咽导致支架动脉出现偏向内侧的挤压。曲率测量显示，同侧头部转动时曲率半径最紧约为1.5 cm，吞咽和头部转动期间的平均值约为10 cm。
一般来说，向支架动脉一侧转动头部比吞咽在血管中产生的变形更大。然而，由于预计患者吞咽周期远多于头部转动次数，因此吞咽累积的变形可能更显著，在设计抗疲劳颈动脉支架时应予以考虑。
