Schneider R M, Morris K G, Chu A, Roberts K B, Coleman R E, Cobb F R
Circ Res. 1987 Jan;60(1):60-71. doi: 10.1161/01.res.60.1.60.
This study examined the relation between left ventricular (LV) function and the severity of acute myocardial ischemia in a conscious dog model. The LV ejection fraction (EF) was measured by multigated equilibrium radionuclide angiography, and regional myocardial blood flow was measured with radioactive microspheres before and 10 minutes after distal and then proximal occlusion of the left anterior descending (LAD, 13 dogs) or left circumflex (LC, 13 dogs) coronary artery. Two methods were used to evaluate the extent of ischemia. The first method determined the mass of myocardium that was ischemic based on different degrees of reduced blood flow. The second method estimated the severity of ischemia expressed as blood flow deficit resulting from each coronary occlusion. Global LV function was very sensitive to ischemia, and the relation between change in function and the degree of ischemia were described best by linear functions. The best linear correlation between mass of ischemic myocardium and percent reduction in EF resulted from the ischemic region defined as all tissue with 25% or greater reduction in blood flow, r = 0.84 for LAD (Y = 0.96X + 1.8) and r = 0.75 for LC (Y = 0.53X + 2.0) occlusions. Defining ischemic mass by more severe reduction in blood flow resulted in exclusion of ischemic myocardium that affected function. The myocardial blood flow deficit also correlated linearly with percent reduction in EF, r = 0.89 for LAD (Y = 1.31X + 2.7) and r = 0.81 for LC (Y = 0.83X - 0.1) occlusions. The slope of the regression lines using both analyses of ischemia were significantly greater (p less than 0.01) for LAD than LC occlusions, indicating that for comparable degrees of ischemia LAD as compared to LC occlusion decreased EF to a greater extent. Calculation of EF from attenuated corrected volumes resulted in small changes in LAD, but not LC, EF and did not account for the disproportionate effects of LAD and LC ischemia. In a separate group of studies (n = 18) EF measured by radionuclide angiography after LAD or LC occlusions correlated well with biplane contrast angiography r = 0.93, SEE 5.1. These data suggest that disproportionately greater effects of LAD compared to LC ischemia on global EF in the dog are due primarily to different pathophysiologic responses to ischemia.
本研究在清醒犬模型中检测了左心室（LV）功能与急性心肌缺血严重程度之间的关系。通过多门控平衡放射性核素血管造影测量左室射血分数（EF），并在左前降支（LAD，13只犬）或左旋支（LC，13只犬）冠状动脉远端及近端闭塞前和闭塞后10分钟，用放射性微球测量局部心肌血流量。采用两种方法评估缺血范围。第一种方法根据不同程度的血流减少确定缺血心肌的质量。第二种方法估计缺血严重程度，以每次冠状动脉闭塞导致的血流不足表示。整体左室功能对缺血非常敏感，功能变化与缺血程度之间的关系用线性函数描述最佳。缺血心肌质量与EF降低百分比之间的最佳线性相关性，来自定义为血流减少25%或更多的所有组织的缺血区域，LAD闭塞时r = 0.84（Y = 0.96X + 1.8），LC闭塞时r = 0.75（Y = 0.53X + 2.0）。通过更严重的血流减少来定义缺血质量，会导致影响功能的缺血心肌被排除。心肌血流不足也与EF降低百分比呈线性相关，LAD闭塞时r = 0.89（Y = 1.31X + 2.7），LC闭塞时r = 0.81（Y = 0.83X - 0.1）。使用两种缺血分析方法的回归线斜率，LAD闭塞时显著大于LC闭塞（p小于0.01），表明与LC闭塞相比，在同等缺血程度下，LAD闭塞使EF降低的程度更大。根据衰减校正体积计算EF，导致LAD的EF有小的变化，但LC的EF没有变化，且不能解释LAD和LC缺血的不成比例影响。在另一组研究（n = 18）中，LAD或LC闭塞后通过放射性核素血管造影测量的EF与双平面造影血管造影相关性良好，r = 0.93，标准误5.1。这些数据表明，与LC缺血相比，LAD缺血对犬整体EF的不成比例更大影响，主要是由于对缺血的不同病理生理反应。
