Ng Martin K C, Yeung Alan C, Fearon William F
Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, CA 94305, USA.
Circulation. 2006 May 2;113(17):2054-61. doi: 10.1161/CIRCULATIONAHA.105.603522. Epub 2006 Apr 24.
A simple, reproducible invasive method for assessing the coronary microcirculation is lacking. A novel index of microcirculatory resistance (IMR) has been shown in animals to correlate with true microvascular resistance and, unlike coronary flow reserve (CFR), to be independent of the epicardial artery. We sought to compare the reproducibility and hemodynamic dependence of IMR with CFR in humans.
Using a pressure-temperature sensor-tipped coronary wire, thermodilution-derived CFR and IMR were measured, along with fractional flow reserve (FFR), in 15 coronary arteries (15 patients) under the following hemodynamic conditions: (1) twice at baseline; (2) during right ventricular pacing at 110 bpm; (3) during intravenous infusion of nitroprusside; and (4) during intravenous dobutamine infusion. Mean CFR did not change during baseline measurements or during nitroprusside infusion but decreased during pacing (from 3.1+/-1.1 at baseline to 2.3+/-1.2 during pacing, P<0.05) and during dobutamine infusion (from 3.0+/-1.0 to 1.7+/-0.6 with dobutamine, P<0.0001). By comparison, mean values for IMR and FFR remained similar throughout all hemodynamic conditions. The mean coefficient of variation between 2 baseline measurements was significantly lower for IMR (6.9+/-6.5%) and FFR (1.6+/-1.6%) than for CFR (18.6+/-9.6%; P<0.01). Mean correlation between baseline measurements and each hemodynamic intervention was superior for IMR (r=0.90+/-0.05) and FFR (r=0.86+/-0.12) compared with CFR (r=0.70+/-0.05; P<0.05).
Compared with CFR, IMR provides a more reproducible assessment of the microcirculation, which is independent of hemodynamic perturbations. Simultaneous measurement of FFR and IMR may provide a comprehensive and specific assessment of coronary physiology at both epicardial and microvascular levels, respectively.
目前缺乏一种简单、可重复的有创方法来评估冠状动脉微循环。一种新的微循环阻力指数（IMR）在动物实验中已显示与真正的微血管阻力相关，并且与冠状动脉血流储备（CFR）不同，它不依赖于心外膜动脉。我们试图比较IMR与CFR在人体中的可重复性和血流动力学依赖性。
使用带压力 - 温度传感器的冠状动脉导丝，在以下血流动力学条件下，对15条冠状动脉（15例患者）测量热稀释法得出的CFR和IMR以及血流储备分数（FFR）：（1）在基线时测量两次；（2）在右心室以110次/分钟起搏期间；（3）在静脉输注硝普钠期间；（4）在静脉输注多巴酚丁胺期间。平均CFR在基线测量期间或硝普钠输注期间没有变化，但在起搏期间（从基线时的3.1±1.1降至起搏期间的2.3±1.2，P<0.05）和多巴酚丁胺输注期间（从3.0±1.0降至多巴酚丁胺时的1.7±0.6，P<0.0001）降低。相比之下，在所有血流动力学条件下，IMR和FFR的平均值保持相似。IMR（6.9±6.5%）和FFR（1.6±1.6%）在两次基线测量之间的平均变异系数显著低于CFR（18.6±9.6%；P<0.01）。与CFR（r = 0.70±0.05；P<0.05）相比，IMR（r = 0.90±0.05）和FFR（r = 0.86±0.12）在基线测量与每种血流动力学干预之间的平均相关性更好。
与CFR相比，IMR对微循环的评估更具可重复性，且不受血流动力学干扰的影响。同时测量FFR和IMR可能分别在冠状动脉心外膜和微血管水平提供对冠状动脉生理学的全面且特异的评估。
