Myosplint decreases wall stress without depressing function in the failing heart: A finite element model study
Myosplint decreases wall stress without depressing function in the failing heart: A finite element model study
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DOI：
10.1016/s0003-4975(03)00731-8
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发表时间：
2003-10-01
影响因子：
4.6
通讯作者：
Ratcliffe, MB
中科院分区：
文献类型：
--
作者：
Guccione, JM;Salahieh, A;Ratcliffe, MB
背景。 Myocor Myosplint 是一种经腔张力装置，旨在改变左心室 (LV) 形状并减少室壁应力。无法在完整的心脏中测量局部壁应力，并且手术重塑后的左心室功能常常与正性肌力药物和二尖瓣修复混淆。我们使用扩张的人类左心室的现实数学（有限元）模型来检验 Myosplint 降低局部心室纤维应力并改善左心室功能的假设。方法。使用有限元模型来模拟 Myosplint 对左心室每搏输出量/舒张末期压力 (Starling) 关系以及局部肌纤维方向应力区域分布（纤维应力）的影响，适用于各种舒张期和收缩末期材料特性。舒张心肌的非线性应力-应变关系相对于局部肌纤维方向是各向异性的。将主动纤维应力的弹性模型纳入全局扩张左心室壁的轴对称几何模型中。结果。舒张期顺应性和收缩末期弹性均在压力-容积图上向左移动。左心室舒张末期容积和收缩末期容积分别减少 7.6% 和 8.6%。平均舒张末期和收缩末期纤维应力分别降低了 24% 和 16%。尽管 Myosplint 对 Starling 关系的影响并不显着，但在低舒张期硬度 C、高峰值细胞内钙浓度 Ca-0 和高动脉弹性 E-A 时，这种关系有改善的趋势。值得注意的是，C 的效果是 Ca-0 和 E-A 的两倍。因此，舒张功能预计将成为 Myosplint 成功的主要决定因素。结论。 Myosplint 可减少纤维应力，且不会降低 Starling 关系。作为扩张型心肌病和终末期充血性心力衰竭患者的手术疗法，肌夹板应该比部分脑室切除术更有效。
Background. The Myocor Myosplint is a transcavitary tensioning device designed to change left ventricular (LV) shape and reduce wall stress. Regional wall stress cannot be measured in the intact heart and LV function after surgical remodeling is often confounded by inotropic agents and mitral repair. We used a realistic mathematical (finite element) model of the dilated human LV to test the hypothesis that Myosplint decreased regional ventricular fiber stress and improved LV function.Methods. A finite element model was used to simulate the effects of Myosplint on the LV stroke volume/enddiastolic pressure (Starling) relationship and regional distributions of stress in the local muscle fiber direction (fiber stress) for a wide range of diastolic and endsystolic material properties. The nonlinear stress-strain relationship for the diastolic myocardium was anisotropic with respect to the local muscle fiber direction. An elastance model for active fiber stress was incorporated in an axisymmetric geometric model of the globally dilated LV wall.Results. Both diastolic compliance and end-systolic elastance shifted to the left on the pressure-volume diagram. LV end-diastolic volume and end-systolic volumes were reduced by 7.6% and 8.6%, respectively. Mean end-diastolic and end-systolic fiber stress was decreased by 24% and 16%, respectively. Although the effect of Myosplint on the Starling relationship was not significant, there were trends toward an improvement in this relationship at low diastolic stiffness, C, high peak intracellular calcium concentration, Ca-0, and high arterial elastance, E-A. Of note, the effect of C was twice that of Ca-0 and E-A. Diastolic function would, therefore, be expected to be the prime determinant of success with Myosplint.Conclusions. Myosplint reduces fiber stress without a decrement in the Starling relationship. Myosplint should be much more effective than partial ventriculectomy as a surgical therapy for patients with dilated cardiomyopathy and end-stage congestive heart failure.