Christiaan Barnard Department of Cardiothoracic Surgery, University of Cape Town, Cape Town, South Africa.
J Vasc Surg. 2011 Nov;54(5):1439-50. doi: 10.1016/j.jvs.2011.05.023. Epub 2011 Jul 29.
Constriction of vein grafts with braided external nitinol meshes had previously led to the successful elimination of neointimal tissue formation. We investigated whether pulse compliance, smaller kink-free bending radius, and milder medial atrophy can be achieved by knitting the meshes rather than braiding, without losing the suppressive effect on intimal hyperplasia.
Pulse compliance, bending stiffness, and bending radius, as well as longitudinal-radial deformation-coupling and radial compression, were compared in braided and knitted nitinol meshes. Identical to previous studies with braided mesh grafts, a senescent nonhuman primate model (Chacma baboons; bilateral femoral interposition grafts/6 months) mimicking the clinical size mismatch between vein grafts and runoff arteries was used to examine the effect of knitted external meshes on vein grafts: nitinol mesh-constricted (group 1); nitinol mesh-constricted and fibrin sealant (FS) spray-coated for mesh attachment (group 2); untreated control veins (group 3), and FS spray-coated control veins (group 4).
Compared with braided meshes, knitted meshes had 3.8-times higher pulse compliance (3.43 ± 0.53 vs 0.94 ± 0.12%/100 mm Hg; P = .00002); 30-times lower bending stiffness (0.015 ± 0.002 vs 0.462 ± 0.077 Nmm(2); P = .0006); 9.2-times narrower kink-free bending radius (15.3 ± 0.4 vs 140.8 ± 22.4 mm; P = .0006), and 4.3-times lower radial narrowing caused by axial distension (18.0% ± 1.0% vs 77.0% ± 3.7%; P = .00001). Compared with mesh-supported grafts, neointimal tissue was 8.5-times thicker in group I (195 ± 45 μm) vs group III (23.0 ± 21.0 μm; P < .001) corresponding with a 14.3-times larger neointimal area in group I (4330 ± 957 × 103 μm(2)) vs group III (303 ± 221× 103 μm(2); P < .00004). FS had no significant influence. Medial muscle mass remained at 43.4% in knitted meshes vs the 28.1% previously observed in braided meshes.
Combining the suppression of intimal hyperplasia with a more physiologic remodeling process of the media, manifold higher kink-resistance, and lower fraying than in braided meshes makes knitted nitinol an attractive concept in external vein graft protection.
先前使用编织的外部镍钛诺网片对静脉移植物进行缩窄，成功消除了新生内膜组织的形成。我们研究了通过编织而不是编织来实现脉冲顺应性、更小的无扭结弯曲半径和更温和的中膜萎缩的可能性，而不会失去对内膜增生的抑制作用。
比较了编织和编织镍钛诺网片中的脉冲顺应性、弯曲刚度和弯曲半径，以及纵向-径向变形耦合和径向压缩。使用与以前的编织网片静脉移植物研究相同的衰老非人灵长类动物模型（Chacma baboons；双侧股间置移植物/6 个月）模拟静脉移植物和流出动脉之间的临床大小不匹配，以研究编织外部网片对静脉移植物的影响：镍钛诺网片缩窄（第 1 组）；镍钛诺网片缩窄并用纤维蛋白密封剂（FS）喷雾涂覆用于网片附着（第 2 组）；未处理的对照静脉（第 3 组）和 FS 喷雾涂覆的对照静脉（第 4 组）。
与编织网相比，编织网的脉冲顺应性高 3.8 倍（3.43±0.53%/100mmHg；P=0.00002）；弯曲刚度低 30 倍（0.015±0.002Nmm2；P=0.06）；无扭结弯曲半径小 9.2 倍（15.3±0.4mm；P=0.0006）；轴向扩张引起的径向缩小低 4.3 倍（18.0%±1.0%；P=0.00001）。与网片支持的移植物相比，第 I 组的新生内膜组织厚度增加了 8.5 倍（195±45μm），而第 III 组为 23.0±21.0μm（P<0.001），第 I 组的新生内膜面积增加了 14.3 倍（4330±957×103μm2），而第 III 组为 303±221×103μm2（P<0.00004）。FS 没有显著影响。编织网中的中膜肌肉质量保持在 43.4%，而以前观察到的编织网中的中膜肌肉质量为 28.1%。
将抑制内膜增生与中膜更生理性的重塑过程相结合，编织镍钛诺网片具有更高的抗扭结性和更低的磨损性，优于编织网片，这使其成为外部静脉移植物保护的一个有吸引力的概念。
