超声血流向量成像评价犬急性心肌缺血时舒张期左心室流体能量损耗

目的 应用超声血流向量成像(VFM)技术可视量化评价急性心肌缺血比格犬舒张期左心室血流的能量损耗变化。方法 分别对10只比格犬开胸模型基础和急性缺血状态行VFM检查,存图后导入血流向量标测软件分析获得等容舒张期(T1)、舒张早期(T2)、舒张早期快速充盈(T3)、舒张中期(T4)、舒张晚期心房收缩期(T5)、舒张晚期快速充盈期(T6)左心室整体和基底、中间、心尖水平能量损耗,以及涡旋面积、涡旋循环强度。定性观察并比较两种状态下结果。将缺血状态左心室整体能量损耗与涡旋面积、循环强度进行相关分析。结果 缺血状态下舒张期各时相血流的运动方向相对不规则,出现典型的湍流及涡旋的波动,能量损耗的分布区域大且相对离散。与基础状态相比,缺血状态下左心室整体能量损耗均增高,其中在T1、T4、T5、T6,差异有统计学意义(P均<0.05)。同样,缺血状态左心室基底、中间水平能量损耗在T1、T4、T5、T6较基础状态增高(P均<0.05),缺血状态左心室心尖水平能量损耗在T1、T6上较基础状态增高(P均<0.05)。在T4、T5、T6,缺血状态下涡旋面积及循环强度均较基础状态增高(P均<0.05),且其分别与左心室整体能量损耗显著相关(r分别为0.61、0.71、0.55和0.79、0.83、0.65, P<0.05)。结论 急性心肌缺血诱导产生左心室血流湍流和异常的涡旋状态,导致舒张期流体能量损耗的增高,超声血流能量损耗参数能够敏感地反映缺血状态左心室血流动力学的改变。

Vector flow mapping in quantitative evaluation on left ventricular blood flow energy loss during diastole in beagles models with acute myocardial ischemia

Objective To assess the left ventricular (LV) flow energy loss (EL) during diastole in beagles models with acute myocardial ischemia with vector flow mapping. Methods Totally 10 anesthetized open-chest beagle models underwent VFM inspection at baseline and after coronary artery ligation. The LV global EL, the EL at the basal, middle, apical levels of LV, and vortex area, vortex circulation at isovolumic relaxation period (T1), early diastole period (T2), rapid filling of early diastole period (T3), middle diastole period (T4), atrial contraction of late diastole period (T5), rapid filling of late diastole period (T6) were compared. Results Typical turbulant flow and vorticity fluctuation caused by irregular blood motion during diastole were observed in ischemia, and the distribution of EL were large and dispersal.The global EL in acute ischemia significantly increased than those of baseline at the T1, T4, T5, T6. And the EL at the basal, middle levels in acute ischemic also increased than those of baseline at the T1, T4, T5, T6 (P<0.05). The EL at apical levels in acute ischemic also increased than those of baseline at the T1, T6 (P<0.05). The vortex area and circulation in acute ischemia increased than those of baseline at the T4, T5, T6 (P<0.05), and significant linear correlations were found between EL and vortex area, vortex circulation at T4, T5, T6 (r=0.61, 0.71, 0.55 and 0.79, 0.83, 0.65, P<0.05). Conclusion The typical turbulence and abnormal vorticity were induced by ischemia, which caused the process of high fluid EL. The EL derived from VFM is a sensitive parameter for assesment LV hydrodynamics in ischemia.