Porenta G, Schima H, Pentaris A, Tsangaris S, Moertl D, Probst P, Maurer G, Baumgartner H
Ludwig Boltzmann Research Institute for Cardiac Surgery, University of Vienna, Austria.
Ultrasound Med Biol. 1999 Jun;25(5):793-801. doi: 10.1016/s0301-5629(99)00033-2.
The present study evaluates the use of intracoronary velocity measurements by Doppler guidewires for assessing coronary obstructions. In vitro experiments were performed in a flow model using acrylic phantoms of coronary stenoses with different configurations (stenosis area: 56%, 75% and 89%; stenosis length: 1 and 5 mm; stenosis border: tapering or abrupt). Nonpulsatile laminar flow conditions of a test fluid were established at flow rates ranging from 0.5 to 2.0 mL/s to simulate baseline flow and flow after vasodilation. Peak Doppler velocity was measured proximal to, within and distal to the model stenoses. Computer simulations were employed to calculate radial flow profiles with and without a Doppler wire aligned with the vessel center. In 84 in vitro flow experiments, peak Doppler velocity correlated well with the average flow velocity as calculated from the actual flow rate and the vessel's cross-sectional area proximal to (r = 0.98, SEE = 1.4, p < 0.001) and within (r = 0.97, SEE = 16.4, p < 0.001) the stenosis. However, the ratio of calculated average velocity to Doppler-measured peak velocity was significantly different from 0.5, the expected value for a parabolic flow profile (0.76+/-0.08, 0.81+/-0.14; p < 0.001). Acceptable accuracy was found for the Doppler estimation of stenosis severity using the continuity equation (error: 0.9+/-1.2% and -4.6+/-3.5% for stenosis with a length of 5 mm and 1 mm, respectively). Doppler velocity reserve significantly underestimated the true flow reserve for the 56% and 75% stenoses (p < 0.01). Computer simulations demonstrated significant alterations of flow profiles by the wire, which explained the observed underestimation of the true flow reserve by the Doppler velocity reserve. Thus, Doppler guidewire measurements of intracoronary flow velocities are useful to assess the severity of coronary stenoses. However, the in vitro results and computer simulations indicate that guidewires alter the flow profile, so that Doppler velocity reserve may underestimate the true flow reserve.
本研究评估了使用多普勒导丝进行冠状动脉内速度测量以评估冠状动脉阻塞的情况。在体外实验中，使用具有不同构型（狭窄面积：56%、75%和89%；狭窄长度：1和5毫米；狭窄边界：逐渐变细或突然变窄）的冠状动脉狭窄丙烯酸模型在流动模型中进行实验。在流速范围为0.5至2.0 mL/s的条件下建立测试流体的非搏动性层流状态，以模拟基线血流和血管扩张后的血流。在模型狭窄近端、内部和远端测量峰值多普勒速度。采用计算机模拟来计算有无与血管中心对齐的多普勒导丝时的径向血流分布。在84次体外血流实验中，峰值多普勒速度与根据实际流速和狭窄近端（r = 0.98，标准误 = 1.4，p < 0.001）及内部（r = 0.97，标准误 = 16.4，p < 0.001）血管横截面积计算得出的平均流速密切相关。然而，计算得出的平均速度与多普勒测量的峰值速度之比显著不同于抛物线血流分布的预期值0.5（0.76±0.08，0.81±0.14；p < 0.001）。使用连续性方程进行多普勒狭窄严重程度估计时发现了可接受的准确性（对于长度为5毫米和1毫米的狭窄，误差分别为0.9±1.2%和 -4.6±3.5%）。对于56%和75%的狭窄，多普勒速度储备显著低估了真实血流储备（p < 0.01）。计算机模拟表明导丝导致血流分布发生显著改变，这解释了观察到的多普勒速度储备对真实血流储备的低估。因此，冠状动脉内血流速度的多普勒导丝测量对于评估冠状动脉狭窄的严重程度是有用的。然而，体外结果和计算机模拟表明导丝会改变血流分布，从而使多普勒速度储备可能低估真实血流储备。
