Marks M P, Tsai C, Chee H
Department of Radiology, Stanford (Calif) University Medical Center, USA.
AJNR Am J Neuroradiol. 1996 Jan;17(1):29-34.
To evaluate the physical characteristics and behavior of coils for endovascular therapy.
Mechanically detachable coils were constructed with simple helical (4 mm X 10 cm and 8 mm X 30 cm) and pretzel shapes (4 mm X 5 cm) made from three metals using 0.003- and 0.004-in wire. Stiffness or pliability, frictional resistance, shape memory, and coil stability were evaluated in vitro.
The 0.004-in wire stock coils proved significantly stiffer when compared with the 0.003-in coils. Tungsten coils proved least pliable; platinum coils were intermediate in stiffness; and nitinol coils were softest. Frictional resistance in the catheter was greatest for stiffer coils. The 5-cm pretzel coil consistently created more frictional force than the 10- or 30-cm simple helical coils. Despite a shorter length, the 4-mm simple helical coil exerted more frictional force than the 8-mm coil. Stiffer metal coils constructed of larger-diameter wire (0.004 in) were more stable than softer coils.
Stiffer coils exert greater frictional forces within the catheter and a greater resistive force during bending but are more stable after placement. Frictional forces also depend on the complex three-dimensional shape of the coil and the diameter of the turns in that shape rather than coil length. These data suggest that a family of coils of different metals is optimal for varied intravascular needs.
评估用于血管内治疗的线圈的物理特性和行为。
使用0.003英寸和0.004英寸的导线，用三种金属制成简单螺旋形（4毫米×10厘米和8毫米×30厘米）和麻花形（4毫米×5厘米）的机械可分离线圈。在体外评估其刚度或柔韧性、摩擦阻力、形状记忆和线圈稳定性。
与0.003英寸的线圈相比，0.004英寸的线坯线圈明显更硬。钨线圈柔韧性最差；铂线圈刚度居中；镍钛诺线圈最软。较硬的线圈在导管中的摩擦阻力最大。5厘米的麻花形线圈始终比10厘米或30厘米的简单螺旋形线圈产生更大的摩擦力。尽管长度较短，但4毫米的简单螺旋形线圈比8毫米的线圈施加的摩擦力更大。由较大直径导线（0.004英寸）制成的较硬金属线圈比较软的线圈更稳定。
较硬的线圈在导管内施加更大的摩擦力，弯曲时产生更大的阻力，但放置后更稳定。摩擦力还取决于线圈复杂的三维形状以及该形状中线圈匝数的直径，而非线圈长度。这些数据表明，不同金属的一系列线圈对于满足不同的血管内需求最为理想。
