Department of Surgery, University of California at San Francisco and San Francisco Veterans Affairs Medical Center, San Francisco, California, USA.
Ann Thorac Surg. 2013 Jan;95(1):148-54. doi: 10.1016/j.athoracsur.2012.07.036. Epub 2012 Sep 13.
Myocardial function deteriorates during ventricular remodeling in patients with congestive heart failure (HF). Ventricular restraint therapy using a cardiac support device (CSD) is designed to reduce the amount of stress inside the dilated ventricles, which in turn halts remodeling. However, as an open mesh surrounding the heart, it is unknown what the mechanical properties of the CSD are in different fiber orientations.
Composite specimens of CorCap (Acorn Cardiovascular, Inc, St. Paul, MN) CSD fabric and silicone were constructed in different fiber orientations and tested on a custom-built biaxial stretcher. Silicone controls were made and stretched to detect the parameters of the matrix. CSD coefficients were calculated using the composite and silicone matrix stress-strain data. Stiffness in different fiber orientations was determined.
Silicone specimens exerted a linear behavior, with stiffness of 2.57 MPa. For the composites with 1 fiber set aligned with respect to the stretch axes, stiffness in the direction of the aligned fiber set was higher than that in the cross-fiber direction (14.39 MPa versus 5.66 MPa), indicating greater compliance in the cross-fiber direction. When the orientation of the fiber sets in the composite were matched to the expected clinical orientation of the implanted CorCap, the stiffness in the circumferential axis (with respect to the heart) was greater than in the longitudinal axis (10.55 MPa versus 9.70 MPa).
The mechanical properties of the CorCap demonstrate directionality with greater stiffness circumferentially than longitudinally. Implantation of the CorCap clinically should take into account the directionality of the biomechanics to optimize ventricular restraint.
充血性心力衰竭（HF）患者心室重构过程中心肌功能恶化。使用心脏支持装置（CSD）进行心室约束治疗旨在减少扩张心室内部的应力，从而阻止重构。然而，由于它是围绕心脏的开放式网，因此尚不清楚 CSD 在不同纤维方向上的机械性能如何。
以不同纤维方向构建了 CorCap（Acorn Cardiovascular，Inc，明尼苏达州圣保罗）CSD 织物和硅酮的复合标本，并在定制的双向拉伸机上进行测试。制作了硅酮对照品并进行拉伸以检测基质的参数。使用复合和硅酮基质的应力-应变数据计算 CSD 系数。确定了不同纤维方向的刚度。
硅酮标本表现出线性行为，其刚度为 2.57 MPa。对于与拉伸轴对齐的 1 纤维组的复合材料，沿纤维组对齐方向的刚度高于交叉纤维方向（14.39 MPa 比 5.66 MPa），表明交叉纤维方向的顺应性更高。当复合材料中纤维组的方向与植入的 CorCap 的预期临床方向匹配时，在与心脏相对的圆周轴方向上的刚度大于在纵轴方向上的刚度（10.55 MPa 比 9.70 MPa）。
CorCap 的机械性能表现出各向异性，其圆周方向的刚度大于纵向方向。临床上植入 CorCap 时应考虑生物力学的方向性，以优化心室约束。
