Radermecker M A, Chaussende F, Struble C, Grandjean P A, Fourny J, Focant B, Gerard P, Serteyn D, Limet R
Department of Cardiovascular Surgery, University Hospital of Liège, Belgium.
Cardiovasc Surg. 1997 Oct;5(5):516-25. doi: 10.1016/s0967-2109(97)00040-9.
An understanding of the biomechanical characteristics of striated skeletal muscles involved in cardiocirculatory assistance is a prerequisite to assess their efficacy and to evaluate their haemodynamic benefits. Six goats had their latissimus dorsi muscles evaluated by isometric strain gauge testing. Total tension, and both active and passive force development at different preloads were measured. The relationship between muscle impedance and starting length was also studied. Four additional muscles were submitted to isometric and isotonic strain gauge testing after 3 months of chronic electrical stimulation (Broussais Hospital protocol) with the contralateral muscle serving as a control. In isometric testing, both conditioned and unconditioned goat latissimus dorsi displayed a Frank-Starling length-tension curve, and a linear relationship between muscle impedance and starting length was found. Chronic stimulation preserved muscle mass and isometric force. Transformed muscles showed a mean 59% reduction of maximal shortening velocity; means (s.d.) residual shortening velocity at maximal work and power output was 0.17(0.07) m/s. The work and power output were both reduced 65% after stimulation, and the residual maximal power at optimal preload varied from approximately 7.7 and 9.6 W/kg. It is concluded that, following the Broussais protocol, the goat latissimus dorsi muscle retained mass and most of its isometric force-generating capacity, but lost significant work and power potential. The residual power output did not, however, preclude the possibility of a significant cardiocirculatory contribution, providing that the conditions for optimal energy transduction are adequately delineated.
了解参与心脏循环辅助的横纹骨骼肌的生物力学特性，是评估其功效和血流动力学益处的先决条件。六只山羊的背阔肌通过等长应变仪测试进行评估。测量了不同预负荷下的总张力以及主动和被动力的发展。还研究了肌肉阻抗与起始长度之间的关系。另外四只肌肉在经过3个月的慢性电刺激（布鲁塞医院方案）后，接受等长和等张应变仪测试，对侧肌肉作为对照。在等长测试中，条件化和未条件化的山羊背阔肌均呈现出Frank-Starling长度-张力曲线，并且发现肌肉阻抗与起始长度之间存在线性关系。慢性刺激保留了肌肉质量和等长力。经转化的肌肉最大缩短速度平均降低了59%；在最大功和功率输出时的平均（标准差）残余缩短速度为0.17（0.07）m/s。刺激后功和功率输出均降低了65%，在最佳预负荷下的残余最大功率在约7.7至9.6W/kg之间变化。得出的结论是，按照布鲁塞方案，山羊背阔肌保留了质量及其大部分等长力产生能力，但失去了显著的功和功率潜力。然而，只要充分确定最佳能量转换的条件，残余功率输出并不排除对心脏循环有显著贡献的可能性。
