Kaul S, Kelly P, Oliner J D, Glasheen W P, Keller M W, Watson D D
Department of Medicine, University of Virginia School of Medicine, Charlottesville.
J Am Coll Cardiol. 1989 Feb;13(2):468-82. doi: 10.1016/0735-1097(89)90528-7.
It was hypothesized that regional myocardial blood flow could be measured using myocardial contrast echocardiography. Accordingly, arterial blood was perfused into the coronary circulation in 16 dogs. In Group 1 dogs (n = 8), blood flow to the cannulated left circumflex artery was controlled with use of a roller pump, whereas in Group 2 dogs (n = 8) blood flow to the left anterior descending coronary artery was controlled by a hydraulic occluder placed around it. Sonicated microbubbles (mean size 4 microns) were used as the contrast agent. In Group 1 dogs the microbubbles were injected subselectively into the left circumflex artery, whereas in Group 2 dogs they were injected selectively into the left main coronary artery and two-dimensional echocardiographic images were recorded. Computer-generated time-intensity curves were derived from these images and variables of these curves correlated with transmural blood flow measured with radiolabeled microspheres. A gamma-variate function (y = Ate-alpha t) best described the curves, and alpha (a variable of curve width) correlated well with transmural blood flow at different flow rates in all Group 1 and Group 2 dogs (mean r = 0.81 and 0.97, respectively). Other variables of the curve width also correlated well with myocardial blood flow, but peak intensity had a poor correlation with myocardial blood flow in both groups of dogs (r = 0.39 and r = 0.63, respectively). When data from all dogs were pooled, Group 1 dogs still showed good correlation between variables of curve width and myocardial blood flow (r = 0.81); Group 2 dogs did not (r = 0.45). The difference between the two sets of dogs was related to the site of contrast agent injection. It is concluded that measurement of the transit time of microbubbles through the myocardium with two-dimensional echocardiography accurately reflects regional myocardial blood flow. Although injection of contrast agent selectively into the left main coronary artery only allows measurement of relative flow, it may be feasible to measure absolute flow by injecting contrast agent subselectively into a coronary artery. Myocardial contrast echocardiography may, therefore, offer the unique opportunity of simultaneously assessing regional myocardial perfusion and function in vivo.
研究假设可以使用心肌对比超声心动图来测量局部心肌血流。因此，将动脉血灌注到16只狗的冠状动脉循环中。在第1组狗（n = 8）中，使用滚轴泵控制插管的左旋支动脉的血流，而在第2组狗（n = 8）中，通过放置在左前降支冠状动脉周围的液压闭塞器控制其血流。使用超声处理的微泡（平均大小4微米）作为造影剂。在第1组狗中，微泡被选择性地注入左旋支动脉，而在第2组狗中，它们被选择性地注入左主冠状动脉，并记录二维超声心动图图像。从这些图像中得出计算机生成的时间-强度曲线，并将这些曲线的变量与用放射性标记微球测量的透壁血流相关联。伽马变量函数（y = Ate-αt）最能描述这些曲线，并且α（曲线宽度的一个变量）在所有第1组和第2组狗中不同流速下与透壁血流都有很好的相关性（平均r分别为0.81和0.97）。曲线宽度的其他变量也与心肌血流有很好的相关性，但两组狗的峰值强度与心肌血流的相关性都很差（r分别为0.39和0.63）。当汇总所有狗的数据时，第1组狗曲线宽度变量与心肌血流之间仍显示出良好的相关性（r = 0.81）；第2组狗则没有（r = 0.45）。两组狗之间的差异与造影剂注射部位有关。结论是，用二维超声心动图测量微泡通过心肌的渡越时间能准确反映局部心肌血流。虽然仅将造影剂选择性地注入左主冠状动脉只能测量相对血流，但将造影剂选择性地注入冠状动脉分支来测量绝对血流可能是可行的。因此，心肌对比超声心动图可能提供在体内同时评估局部心肌灌注和功能的独特机会。
