人体心脏心室肌纤维三维结构的研究

目的探索人体心脏心室肌纤维的三维结构。方法获取8例人体心脏,供者均为男性,年龄(81.9±7.2)岁,心脏质量(455.6±65.7)g。心脏放入装满水的塑料容器中,立即进行弥散张量磁共振扫描,从供者死亡到标本扫描的间隔时间为(18.6±5.2)h。扫描使用3.0T,GECV/I型磁共振机进行,采用8通道线圈扫描,sshEPI和SENSE扫描序列,层厚3mm,b值1000s/mm2,TR2000ms,TE86.4ms,FOV14cm×14cm,Voxels 128×128,Resolution 1.1mm×1.1mm×3mm。然后采用GE Advantage Windows workstation通过纤维追踪进行心肌纤维的可视化重建,显示并观察心肌纤维的三维结构。结果左心室前壁,室间隔,后壁及游离壁处的纤维均存在两个走行方向不同纤维层面,心内膜下层心肌纤维从基底部到心尖呈现纵斜形向下走行,中层的心肌纤维从心尖到基底部呈现横斜形向上走行,两者在心尖部呈螺旋形连接。结论人体心脏心室肌纤维的三维结构与Torrent心肌带假说所阐述的结构特征基本一致。

Study of the three-dimensional structure of the ventricular myocardial fiber in human heart

Objective To study the three-dimensional structure of ventricular myocardial fiber in human heart. Methods Eight human heart were obtained from male donors aged 81.9±7.2 years with a heart weight of 455.6±65.7 g. Each sample was immersed in water and scanned by diffusion tensor magnetic resonance imaging (DT-MRI) using a 3 Tesla Exicte HD by an eight-channal head coils. The duration was 18.6±5.2 h from heart arresting to the scanning. The data were obtained using the protocol of single shot echo planarimaging (sshEPI) and sensitivity encoding (SENSE). The SENSE-sshEPI-scans (TE/TRZ86.4/2000 ms) of the whole heart were carried out (b= 1000 s/mm~2, voxels 128×128, resolution 1.1 mm×1.1 mm×3 mm, and FOV 14 cm×14 cm). Fiber tracking and reconstruction were performed using GE Advantage Windows Workstation.The three-dimensional structure of the ventricular myocardial fiber was observed. Results The left ventricular myocardial fibers showed two layers with different directions of alignment in such regions as the anterior, septum, and posterior walls and the free left ventricular wall. The subendocardial layer ran obliquely from the base to the apex, and the middle layer ran obliquely upward from the base to the apex. The two layers were linked together and aligned in the pattem ofhelical coils near the apex. Conclusions The three-dimensional structure of the myocardial fibers in human heart conforms to Torrent's hypothesis of helical ventricular myocardial band (HVMB).