Kimball B P, Dafopoulos N, LiPreti V
Cardiovascular Investigation Unit, Toronto Hospital, University of Toronto, Ontario, Canada.
Am J Cardiol. 1989 Jul 1;64(1):6-10. doi: 10.1016/0002-9149(89)90644-9.
Traditional quantitative coronary arteriographic measurements have largely ignored geometric variables, which may be important in determining the obstructive nature of coronary stenoses. To illustrate the relation between standard quantitative coronary arteriography and calculated transstenotic fluid dynamics, 25 patients with 1-vessel disease referred for coronary angioplasty were analyzed. Minimal lumen diameter and percent stenosis were measured and the values compared with calculations of pressure loss that used standard hydraulic formulas encompassing both frictional and separation components within the stenotic segments. Baseline flow velocity was assumed to equal 4 cm/s and normal hyperemic flow response was presumed to equal 5 times that of baseline. Fluid dynamic estimates suggested that initial translesional pressure gradients would develop at a minimal diameter of 0.6 mm (80% diameter), with an exponentially severe pressure differential beyond a minimal coronary diameter of 0.3 mm (92% diameter). Maximal velocities were calculated based upon an assumed normal hyperemic flow response of 5 times that of baseline, with the demonstration of early impairment of hyperemic flow reserve at minimal diameters of 1.2 mm (46% diameter). Furthermore, hyperemic flow reserve was completely abolished at a minimal diameter of 0.3 to 0.5 mm (89 to 92% diameter). Beyond a minimal diameter of 0.2 mm (93% diameter), resting hypoperfusion was anticipated with flow velocities below the initially assumed value (4 cm/s). Thus, it is feasible to estimate transstenotic pressure losses and maximal coronary flow velocity by applying Newtonian fluid dynamic equations to actual angiographic stenoses in man. These calculations generally correlate with traditional quantitative arteriographic estimates of stenosis severity, although other geometric parameters such as lesion length, "exit angle" and blood viscosity may alter transstenotic hemodynamics.
传统的冠状动脉造影定量测量方法在很大程度上忽略了几何变量，而这些变量在确定冠状动脉狭窄的阻塞性质方面可能很重要。为了阐明标准冠状动脉造影定量测量与计算得出的跨狭窄段流体动力学之间的关系，我们对25例因冠状动脉成形术而转诊的单支血管病变患者进行了分析。测量了最小管腔直径和狭窄百分比，并将这些值与使用标准水力公式计算的压力损失进行比较，该公式涵盖了狭窄段内的摩擦和分离成分。假定基线流速等于4厘米/秒，并假定正常充血血流反应等于基线的5倍。流体动力学估计表明，初始跨病变压力梯度将在最小直径为0.6毫米（直径的80%）时出现，在冠状动脉最小直径超过0.3毫米（直径的92%）时，压力差呈指数级增大。基于假定正常充血血流反应为基线的5倍来计算最大流速，结果表明在最小直径为1.2毫米（直径的46%）时充血血流储备早期受损。此外，在最小直径为0.3至0.5毫米（直径的89%至92%）时，充血血流储备完全消失。在最小直径超过0.2毫米（直径的93%）时，预计会出现静息性灌注不足，血流速度低于最初假定的值（4厘米/秒）。因此，将牛顿流体动力学方程应用于人体实际血管造影狭窄来估计跨狭窄段压力损失和最大冠状动脉流速是可行的。这些计算结果通常与传统的冠状动脉造影定量测量得出的狭窄严重程度估计值相关，尽管其他几何参数，如病变长度、“出口角度”和血液粘度可能会改变跨狭窄段血流动力学。
