Crowley J J, Shapiro L M
Regional Cardiac Unit, Papworth Hospital, Cambridge, UK.
Circulation. 1995 Nov 1;92(9 Suppl):II25-30. doi: 10.1161/01.cir.92.9.25.
Cardiac catheterization is the only practical method of assessing internal mammary artery graft patency. A noninvasive method would be useful in patients with recurrence of anginal symptoms after coronary artery bypass graft surgery. We hypothesized that transthoracic echocardiography could provide information on blood velocity and anatomy and therefore has the potential to allow measurement of blood flow.
High-frequency (5 MHz) transthoracic echocardiography was performed on 41 consecutive patients (mean age, 67 +/- 6 years) who had had left internal mammary artery grafts to the left anterior descending coronary artery (LAD) and were undergoing coronary angiography because of recurrence of anginal symptoms. The results were compared with those from 19 patients (mean age, 58 +/- 11 years) in whom an ungrafted left internal mammary artery was assessed and with those from 15 patients (mean age, 61 +/- 12 years) who had angiographically normal coronary arteries in whom the LAD was studied. Doppler velocity profiles of the left internal mammary graft were obtained in 35 of the 41 study patients (81%). In all cases, a biphasic pattern of blood flow was recorded that corresponded to systole and diastole. Two different flow patterns were observed. In 25 patients with a normal graft or moderate (< 70%) stenosis (group A), blood flow velocity was maximal during diastole. This pattern was also seen in the LAD control group. In 10 patients with severe (> 70%) graft stenosis (group B), blood velocity was maximal during systole, and low velocities were recorded during diastole. This pattern was also seen in the ungrafted internal mammary artery control group. The diastolic fraction of the velocity time integrals for group A was 0.77 +/- 0.07 and for group B was 0.27 +/- 0.01 (P < .05). A diastolic velocity time integral fraction < 0.5 predicted severe stenosis with a sensitivity and specificity of 100%. The ratio of systolic-to-diastolic peak velocities for group A was 0.54 +/- 0.26 and for group B was 3.45 +/- 0.74 (P < .05). A systolic-to-diastolic peak velocity ratio > 1 predicted severe stenosis with a sensitivity of 100% and specificity of 85%. Mean graft blood flow was 63 +/- 21 mL/min. There was no significant difference in mean blood flow between any of the patient groups studied.
High-frequency transthoracic echocardiography allows identification of the left internal mammary grafts and measurement of blood flow. Compared with patent grafts or those with moderate lesions, severe stenoses demonstrated different Doppler velocity patterns. Use of this technique may allow noninvasive detection of significant stenoses of the left internal mammary artery graft.
心脏导管插入术是评估乳内动脉移植血管通畅性的唯一实用方法。对于冠状动脉旁路移植术后出现心绞痛症状复发的患者，一种非侵入性方法将很有用。我们推测经胸超声心动图可以提供有关血流速度和解剖结构的信息，因此有潜力用于测量血流量。
对41例连续患者（平均年龄67±6岁）进行了高频（5MHz）经胸超声心动图检查，这些患者接受了左乳内动脉至左前降支冠状动脉（LAD）的移植，因心绞痛症状复发而正在接受冠状动脉造影。将结果与19例评估未移植左乳内动脉的患者（平均年龄58±11岁）以及15例冠状动脉造影正常且研究LAD的患者（平均年龄61±12岁）的结果进行比较。41例研究患者中有36例（81%）获得了左乳内移植血管的多普勒速度曲线。在所有病例中，均记录到与收缩期和舒张期相对应的双相血流模式。观察到两种不同的血流模式。在25例移植血管正常或中度（<70%）狭窄的患者（A组）中，舒张期血流速度最大。这种模式在LAD对照组中也可见。在10例严重（>70%）移植血管狭窄的患者（B组）中，收缩期血流速度最大，舒张期记录到低血流速度。这种模式在未移植乳内动脉对照组中也可见。A组速度时间积分的舒张期分数为0.77±0.07，B组为0.27±0.01（P<0.05）。舒张期速度时间积分分数<0.5预测严重狭窄的敏感性和特异性均为100%。A组收缩期与舒张期峰值速度之比为0.54±0.26，B组为3.45±0.74（P<0.05）。收缩期与舒张期峰值速度比>1预测严重狭窄的敏感性为100%，特异性为85%。平均移植血管血流量为63±21mL/min。所研究的任何患者组之间的平均血流量均无显著差异。
高频经胸超声心动图可识别左乳内移植血管并测量血流量。与通畅的移植血管或有中度病变的移植血管相比，严重狭窄表现出不同的多普勒速度模式。使用该技术可能允许非侵入性检测左乳内动脉移植血管的显著狭窄。
