Moulton M J, Downing S W, Creswell L L, Fishman D S, Amsterdam D M, Szabó B A, Cox J L, Pasque M K
Department of Surgery, Washington University, St. Louis, Missouri, USA.
Ann Thorac Surg. 1995 Oct;60(4):986-97; discussion 998. doi: 10.1016/0003-4975(95)00521-l.
The pathophysiology of regional mechanical dysfunction in the border zone (BZ) region of left ventricular aneurysm was studied in an ovine model using magnetic resonance imaging tissue-tagging and regional deformation analysis.
Transmural infarcts were created in adult Dorsett sheep (n = 8) by ligation of the distal homonymous coronary artery and were allowed to mature into left ventricular aneurysms for 8 to 12 weeks. Animals were imaged subsequently using double oblique magnetic resonance imaging with radiofrequency tissue tagging. Short axis slices were selected for analysis that included predominantly the septal component of the aneurysm as well as adjacent BZ regions in the anterior and posterior ventricular walls. Dark grid patterns of magnetic presaturations were placed on the myocardium and tracked as they deformed during the diastolic, isovolumic systolic, and systolic ejection phases of the cardiac cycle. Regional ventricular wall strains were calculated in BZ regions and regions remote from the aneurysm and compared with strains measured in corresponding regions from normal control sheep (n = 6).
Diastolic midwall circumferential strains (fiber extensions) were relatively preserved, but abnormal circumferential lengthening strains were observed in the BZ regions during isovolumic systole. Peak circumferential strains ranged from 0.04 to 0.07 in the BZ regions but averaged -0.05 in the normal hearts (p = 0.002 for the anterior BZ and p = 0.001 for the posterior BZ). Midwall end-systolic fiber strains were depressed in the anterior BZ (-0.03 to -0.09 for the BZ versus -0.11 for the normal heart, p < 0.0001) but not in the posterior BZ (p = 0.19).
Our data support the theory that the stretching of BZ fibers during isovolumic systole contributed to a reduction in fiber shortening during systolic ejection and thus reduced the overall contribution of these fibers to forward ventricular output.
使用磁共振成像组织标记和区域变形分析，在绵羊模型中研究了左心室动脉瘤边缘区（BZ）区域局部机械功能障碍的病理生理学。
通过结扎成年多塞特羊（n = 8）同名冠状动脉的远端制造透壁梗死，并使其发展为左心室动脉瘤8至12周。随后使用带有射频组织标记的双斜磁共振成像对动物进行成像。选择短轴切片进行分析，这些切片主要包括动脉瘤的间隔成分以及前、后心室壁中的相邻BZ区域。将磁性预饱和的暗网格图案放置在心肌上，并在心动周期的舒张期、等容收缩期和收缩射血期跟踪其变形情况。计算BZ区域和远离动脉瘤区域的局部心室壁应变，并与正常对照羊（n = 6）相应区域测量的应变进行比较。
舒张期室壁中层圆周应变（纤维伸展）相对保留，但在等容收缩期BZ区域观察到异常的圆周延长应变。BZ区域的峰值圆周应变范围为0.04至0.07，而正常心脏的平均峰值圆周应变 为 -0.05（前BZ区域p = 0.002，后BZ区域p = 0.001）。前BZ区域的室壁中层收缩末期纤维应变降低（BZ区域为-0.03至-0.09，正常心脏为-0.11，p < 0.0001），而后BZ区域则未降低（p = 0.19）。
我们的数据支持这样的理论，即等容收缩期BZ纤维的拉伸导致收缩射血期纤维缩短减少，从而降低了这些纤维对心室前向输出的总体贡献。
