Wu Juefei, Barton David, Xie Feng, O'Leary Edward, Steuter John, Pavlides Gregory, Porter Thomas R
From the Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China (J.W.); Department of Cardiology, Internal Medicine, University of Nebraska Medical Center, Omaha (D.B., F.X., E.O'L., G.P., T.R.P.); and Nebraska Heart, Lincoln (J.S.).
Circ Cardiovasc Imaging. 2016 Aug;9(8). doi: 10.1161/CIRCIMAGING.116.004129.
Real-time myocardial contrast echocardiography (RTMCE) directly measures capillary flow (CBF), which in turn is a major regulator of coronary flow and resistance during demand or hyperemic stress. Although fractional flow reserve (FFR) was developed to assess the physiological relevance of an epicardial stenosis, it assumes maximal microvascular vasodilation and minimal resistance during vasodilator stress. Therefore, we sought to determine the relationship between CBF assessed with RTMCE during stress echocardiography and FFR in intermediate coronary lesions.
Sixty-seven vessels with 50% to 80% diameter stenoses by quantitative coronary angiography in 58 consecutive patients were examined with FFR and RTMCE (mean age, 60±13 years). RTMCE was performed using an incremental dobutamine (n=32) or exercise (n=26) stress protocol, and myocardial perfusion was assessed using a continuous infusion of ultrasound contrast. The presence or absence of inducible perfusion defects and wall motion abnormalities were correlated with FFR. Mean percent diameter stenosis was 60±9%. Eighteen stenoses (27%) had an FFR ≤ 0.8. Although 17 of the 18 stenoses that were FFR+ had abnormal CBF during RTMCE, 28 of the 49 stenoses (57%) that were FFR had abnormal CBF, and 24 (49%) had abnormal wall motion in the corresponding coronary artery territory during stress echocardiography.
In a significant percentage of intermediate stenoses with normal FFR values, CBF during demand stress is reduced, resulting in myocardial ischemia.
实时心肌对比超声心动图（RTMCE）可直接测量毛细血管血流（CBF），而CBF又是需求或充血应激期间冠状动脉血流和阻力的主要调节因素。尽管分数血流储备（FFR）已被用于评估心外膜狭窄的生理相关性，但它假定在血管扩张剂应激期间微血管最大程度地扩张且阻力最小。因此，我们试图确定在负荷超声心动图期间用RTMCE评估的CBF与中度冠状动脉病变中的FFR之间的关系。
对58例连续患者中通过定量冠状动脉造影显示直径狭窄50%至80%的67支血管进行了FFR和RTMCE检查（平均年龄60±13岁）。使用递增多巴酚丁胺（n = 32）或运动（n = 26）负荷方案进行RTMCE，并通过持续输注超声造影剂评估心肌灌注。诱导性灌注缺损和室壁运动异常的有无与FFR相关。平均直径狭窄百分比为60±9%。18支狭窄血管（27%）的FFR≤0.8。尽管在RTMCE期间，18支FFR+的狭窄血管中有17支CBF异常，但在49支FFR-的狭窄血管中有28支（57%）CBF异常，并且在负荷超声心动图期间，24支（49%）在相应冠状动脉区域有室壁运动异常。
在相当比例的FFR值正常的中度狭窄中，需求应激期间的CBF降低，导致心肌缺血。
