REGIONAL HETEROGENEITY OF OVINE MYOFIBER INCLINATION ANGLE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 肌纤维倾斜角的量化是计算肌纤维缩短应变和模拟心脏功能所必需的。本研究揭示了跨壁肌纤维倾斜角的区域差异。用定量组织学技术研究了5只健康绵羊心脏的局部螺旋角，在8个环向排列的心肌块和4个横跨左心室(LV)的切片上，平均螺旋角度为9.4(SD 2.2)。中壁肌纤维的平均倾斜角为-7°(SD 9)，但具有较好的空间不均一性(乳头肌附近的后外侧壁和前外侧壁平均为0°，其他区域平均为-9°)。跨壁节距(每壁深度的角度变化)平均为93？(SD 21)，后壁最低(51？)，前外侧最高(130？)。跨壁肌纤维取向符合三次函数，均方根误差为18°(SD 6°)。均方根拟合误差最小的是赤道中外侧段(9°)，最大的均方根拟合误差是在基底后间隔段(33°)，提示后间隔壁肌纤维的排列可能比外侧壁的保守程度要低。我们的结果证实了先前发表的结果，但重要的是突出了肌纤维组织的区域差异，这可能会影响从计算模型获得的任何结果。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Quantification of myofiber inclination angle is necessary for calculating myofiber shortening strains and for modeling cardiac performance. This study offers insight into the regional differences in transmural myofiber inclination angle. Quantitative histologic techniques were used to characterize regional variations in myofiber orientation by examining the local helix angle in five healthy ovine hearts at an average of 9.4 (SD 2.2) transmural locations in eight circumferentially arranged blocks and within four slices across the left ventricle (LV). The mean midwall myofiber inclination angle was -7¿ (SD 9), but was better characterized by spatial heterogeneity (an average of 0¿ in the posterolateral and anterolateral wall near the papillary muscles, and -9¿ in all other regions). The transmural pitch (angular change per wall depth) averaged 93¿ (SD 21) and was lowest in the posterior wall (51¿ in the basal posterior sector) and highest in the anterolateral wall (130¿ in the mid-equatorial anterolateral sector). Transmural myofiber orientations were fit with cubic functions with a mean RMS error of 18¿ (SD 6¿). The lowest RMS fit error was in the lateral mid-equatorial sector (9¿) and highest RMS fit error was in the basal postero-septal sector (33¿) indicating that myofiber arrangement in the postero-septal wall may be less conserved than within the lateral wall. Our results corroborate previously published results, but importantly highlight regional differences in myofiber organization that may impact any results obtained from computational models.