Chen Junjie, Packard René R Sevag
Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles.
Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles; Ronald Reagan UCLA Medical Center; Veterans Affairs West Los Angeles Medical Center;
J Vis Exp. 2020 Feb 6(156). doi: 10.3791/60547.
Zebrafish are increasingly utilized as a model organism for cardiomyopathies and regeneration. Current methods evaluating cardiac function fail to reliably detect segmental mechanics and are not readily feasible in zebrafish. Here we present a semiautomated, open-source method for the quantitative assessment of four-dimensional (4D) segmental cardiac function: displacement analysis of myocardial mechanical deformation (DIAMOND). Transgenic embryonic zebrafish were imaged in vivo using a light-sheet fluorescence microscopy system with 4D cardiac motion synchronization. Acquired 3D digital hearts were reconstructed at end-systole and end-diastole, and the ventricle was manually segmented into binary datasets. Then, the heart was reoriented and isotropically resampled along the true short axis, and the ventricle was evenly divided into eight portions (I-VIII) along the short axis. Due to the different resampling planes and matrices at end-systole and end-diastole, a transformation matrix was applied for image registration to restore the original spatial relationship between the resampled systolic and diastolic image matrices. After image registration, the displacement vector of each segment from end-systole to end-diastole was calculated based on the displacement of mass centroids in three dimensions (3D). DIAMOND shows that basal myocardial segments adjacent to the atrioventricular canal undergo the highest mechanical deformation and are the most susceptible to doxorubicin-induced cardiac injury. Overall, DIAMOND provides novel insights into segmental cardiac mechanics in zebrafish embryos beyond traditional ejection fraction (EF) under both physiological and pathological conditions.
斑马鱼越来越多地被用作心肌病和心脏再生的模式生物。目前评估心脏功能的方法无法可靠地检测节段力学，且在斑马鱼中不易实施。在此，我们提出一种用于定量评估四维（4D）节段心脏功能的半自动开源方法：心肌机械变形位移分析（DIAMOND）。使用具有4D心脏运动同步功能的光片荧光显微镜系统对转基因斑马鱼胚胎进行体内成像。在收缩末期和舒张末期重建获取的3D数字心脏，并将心室手动分割为二进制数据集。然后，将心脏重新定向并沿真正的短轴进行各向同性重采样，沿短轴将心室均匀分为八个部分（I - VIII）。由于收缩末期和舒张末期的重采样平面和矩阵不同，应用变换矩阵进行图像配准，以恢复重采样的收缩期和舒张期图像矩阵之间的原始空间关系。图像配准后，基于三维（3D）质心的位移计算每个节段从收缩末期到舒张末期的位移向量。DIAMOND表明，与房室管相邻的基底部心肌节段经历的机械变形最大，且最易受到阿霉素诱导的心脏损伤。总体而言，DIAMOND为斑马鱼胚胎在生理和病理条件下的节段心脏力学提供了超越传统射血分数（EF）的新见解。
