Experimental Study Of Architecture Of Ventricular Myocardial Fibers Of Isolated Heart

Objective:To study and explore the entire spatial information of the ventricular myocardial fibers with application of the diffusion tensor magnetic resonance imaging (DT-MRI) technology, we can acquire entire spatial information of the ventricular myocardial fibers after the diastolic pig hearts and human hearts accepted DT-MRI scans and the myocardial fibers were reconstructed, Myocardial fiber helix angle and transverse angle were measured at this time so that spatial orientation and information of the ventricular myocardial fibers can be analyzed quantitatively and qualitatively.Methods:1. Ten isolated pig hearts. Cardioplegia was immediately infused into the coronary sinus after thoraeotomy so that cardiac arrest can be acquired in in the end diastole. The isolated pig hearts was fixed by solution with agarose gel and Copper Sulphate. Heart samples accepted DT-MRI scans within 20 minutes and visualized and reconstructed the myocardial fibers. We observed spatial orientation of ventricular myocardial fibers, and selected the related parts of the fiber track points. Myocardial fiber helix angle and transverse angle were measured in the point and the analyzed statistically.2. Eight postmortem patient's hearts.The isolated human hearts accepted DT-MRI scans and the myocardial fibers were reconstructed. Myocardial fiber helix angle and transverse angle were measured in the related sand selected point and the analyzed statistically. To explore the laws of spatial orientation of ventricular myocardial fibers. Results:1. Spatial structure orientation of ventricular myocardial fibers showed consistency and similarity at different place and deck after the diastolic pig hearts and human hearts accepted DT-MRI scans and the myocardial fibers were reconstructed.Left ventricular wall's myofiber formed two nearly perpendicular and dominant populations, ventricular myocardial fibers keep entire continuity, and have its specific spatial distribution and orientation.2. The myocardial fibers of left ventricular of pig heart have obvious different helix angle from inner to outer, helix angle of the inner is largest, the middle is minimum, the outer is between them. Helix angle of the inner fibers in basal part, middle part and apex of heart decrease gradually. Helix angle of the inner fibers in basal part are consistent with that of the inner in the middle part of left ventricular (P>0.05), but they were significantly larger than the helix angle of myocardial fibers in apex of heart (P<0.05). The middle fibers also have this rule, but helix angle of the outer myocardial fibers increased from basal part to the apex of heart. Helix angle of the outer fibers in apex of heart are consistent with that of the outer in the middle part of left ventricular (P>0.05), but they were significantly larger than the helix angle of myocardial fibers in basal part (P<0.05).The transverse angle of inner, middle and outer fibers were greatly similarly in basal part and middle part, but the mean transverse angle of the apex of hear were significantly larger than that of basal part and middle part.3. The structure and spatial orientation of the myocardial fibers of isolated human were similar with pig hearts.the helix angle and transverse angle of human heart showed similarities with pig hearts.Conclusion:1. Myocardial fibers can be successfully reconstructed by diffusion tensor magnetic resonance imaging (DT-MRI) technology.2. Myocardial fibers of isolated pig heart and human heart had layered and orderly structure, each layer has specific spatial orientation, ventricular myocardial fibers keep entire continuity, the characteristics mentioned above are consistent with description the ventricular myocardial band theory. 3. Myocardial fiber helix and angle transverse angle of pig heart and human heart may have important significance, spatial orientation and information of the ventricular myocardial fibers can be analyzed quantitatively by means of them, The two angles and the change of the angles show the two-helical structure of the heart.