Lunkenheimer P P, Redmann K, Florek J, Fassnacht U, Cryer C W, Wübbeling F, Niederer P, Anderson R H
Klinik und Poliklinik für Thorax-, Herz- und Gefässchirurgie, University Münster, Munster, Germany.
Heart. 2004 Feb;90(2):200-7. doi: 10.1136/hrt.2003.011650.
To test the hypothesis that two populations of myocardial fibres-fibres aligned parallel to the surfaces of the wall and an additional population of fibres that extend obliquely through the wall-when working in concert produce a dualistic, self stabilising arrangement.
Assessment of tensile forces in the walls of seven porcine hearts by using needle probes. Ventricular diameter was measured with microsonometry and the intracavitary pressure through a fluid filled catheter. Positive inotropism was induced by dopamine, and negative inotropism by thiopental. The preload was raised by volume load and lowered by withdrawal of blood. Afterload was increased by inflation of a balloon in the aortic root. The anatomical orientation of the fibres was established subsequently in histological sections.
The forces in the fibres parallel to the surface decreased 20-35% during systolic shrinkage of the ventricle, during negative inotropism, and during ventricular unloading. They increased 10-30% on positive inotropic stimulation and with augmentation in preload and afterload. The forces in the oblique transmural fibres increased 8-65% during systole, on positive inotropic medication, with an increase in afterload and during ventricular shrinkage, and decreased 36% on negative inotropic medication. There was a delay of up to 147 ms in the drop in activity during relaxation in the oblique transmural fibres.
Although the two populations of myocardial fibres are densely interwoven, it is possible to distinguish their functions with force probes. The delayed drop in force during relaxation in obliquely oriented fibres indicates that they are hindered in their shortening to an extent that parallels any increase in mural thickness. The transmural fibres, therefore, contribute to stiffening of the ventricular wall and hence to confining ventricular compliance.
验证如下假设：心肌纤维的两个群体——与心室壁表面平行排列的纤维以及斜穿心室壁的另一群体纤维——协同作用时会产生二元自稳定排列。
使用针式探头评估7个猪心脏心室壁的张力。通过微超声测量心室直径，并通过充满液体的导管测量心腔内压力。用多巴胺诱导正性肌力作用，用硫喷妥钠诱导负性肌力作用。通过容量负荷增加前负荷，通过抽血降低前负荷。通过在主动脉根部充气球囊增加后负荷。随后在组织学切片中确定纤维的解剖方向。
在心室收缩期、负性肌力作用期间和心室卸载期间，与表面平行的纤维中的力降低20% - 35%。在正性肌力刺激以及前负荷和后负荷增加时，它们增加10% - 30%。斜穿心室壁的纤维中的力在收缩期、正性肌力药物作用时、后负荷增加时和心室收缩期间增加8% - 65%，在负性肌力药物作用时降低36%。斜穿心室壁的纤维在舒张期活动下降延迟长达147毫秒。
尽管这两个心肌纤维群体紧密交织，但使用力探头可以区分它们的功能。斜向排列的纤维在舒张期力下降延迟表明它们的缩短受到阻碍，其程度与心室壁厚度的任何增加平行。因此，穿壁纤维有助于心室壁变硬，从而限制心室顺应性。
