STRUCTURAL BASIS FOR REGIONAL HETEROGENEITY OF LEFT VENTRICULAR FUNCTION

点击翻译按钮获取中文摘要

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.