STRUCTURAL BASIS FOR REGIONAL HETEROGENEITY OF LEFT VENTRICULAR FUNCTION

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。导言：这项工作验证了左心室所有区域的中壁肌纤维并非沿周向定向的假设，而且肌纤维定向的区域梯度是不均匀的。肌纤维排列的区域差异除了影响MRI组织标记菌株的解释外，还应影响区域功能。方法：对5只羊实施安乐死，冠状动脉注射5%缓冲戊二醛原位固定心脏。在1.5T GE Signa Excite扫描仪上使用自定义弥散张量加权成像序列对中心室切片进行成像。局部肌纤维方向定义为扩散张量的主特征向量与局部周向之间的夹角。左室中壁定义为心外膜和心内膜之间径向壁深度的50%。

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. INTRODUCTION: This work tests the hypothesis that midwall myofibers are not oriented in the circumferential direction in all regions of the left ventricle and furthermore that regional gradients in myofiber orientation are heterogeneous. Regional differences of myofiber arrangement should impact regional function in addition to having implications for the interpretation of MRI tissue tagging strains. METHODS: Five sheep were euthanized and the hearts were subsequently fixed in situ by coronary injection of 5% buffered glutaraldehyde. Mid-ventricular slices were imaged on a 1.5T GE Signa Excite scanner using a custom diffusion tensor weighted imaging sequence. Local myofiber direction was defined as the angle (?) between the primary eigenvector of the diffusion tensor and the local circumferential direction. The left ventricular midwall was defined as 50% radial wall depth between the epicardium and endocardium.