Cape E G, Skoufis E G, Weyman A E, Yoganathan A P, Levine R A
Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Boston 02114.
Circulation. 1989 Jun;79(6):1343-53. doi: 10.1161/01.cir.79.6.1343.
The noninvasive Doppler assessment of regurgitant volume from jet size is limited by the fundamental inequality of jet volume and regurgitant volume and by the dependence of jet dimensions on driving pressure and instrument settings for a given flow volume. Therefore, this study addresses the hypothesis that an equation could be derived from basic physical principles to quantify regurgitant volume with velocities that can be directly measured by Doppler echocardiography. The principle of conservation of momentum for free turbulent jets resembling many cardiac lesions yields an equation for regurgitant volume as a function of maximum jet velocity, a distal centerline velocity, and the intervening distance. This theory was tested throughout a range of physiologic flow rates and pressures (orifice velocities) in steady flow for 0.08-0.40 cm2 circular orifices and a noncircular orifice and in physiologic pulsatile flow for 0.08 and 0.20 cm2 circular orifices. Plots of centerline velocities versus axial distance coincided with those expected for such jets. Calculated and actual volumetric flows agreed well by linear regression in the turbulent jet: for steady flow rates, y = 0.98x + 0.09 (r = 0.99, SEE = 0.14 l/min), with similar correlations for circular and noncircular orifices; for pulsatile flow, y = 1.02x + 0.03 for peak flow rate (r = 0.98, SEE = 0.18 l/min) and y = 1.02x + 0.58 for total regurgitant volume (r = 0.95, SEE = 0.81 ml). There was no significant effect of orifice size or location of velocity measurement within the turbulent jet. Therefore, for free jets resembling many clinical lesions, regurgitant flow rate and volume can be calculated noninvasively from Doppler velocities without planimetry of jet area. Because the required information is intrinsic to the jet, this method should apply regardless of associated valvular lesions. It should also apply to orifices of variable shape because turbulent eddies obliterate the details of flow at the orifice. The special case of jets impinging on walls must be considered separately for both this technique and flow mapping.
通过射流大小对反流容积进行无创多普勒评估，受到射流容积与反流容积基本不等式的限制，以及射流尺寸对驱动压力和给定流量下仪器设置的依赖性的限制。因此，本研究探讨了这样一个假设，即可以从基本物理原理推导出一个方程，用多普勒超声心动图可直接测量的速度来量化反流容积。类似于许多心脏病变的自由湍流射流的动量守恒原理，得出了一个反流容积方程，该方程是最大射流速度、远端中心线速度和其间距离的函数。在0.08 - 0.40平方厘米圆形孔口和一个非圆形孔口的稳定流中，以及在0.08和0.20平方厘米圆形孔口的生理搏动流中，在一系列生理流速和压力（孔口速度）范围内对该理论进行了测试。中心线速度与轴向距离的关系图与此类射流预期的图相吻合。在湍流射流中，通过线性回归计算得到的容积流量与实际容积流量吻合良好：对于稳定流速，y = 0.98x + 0.09（r = 0.99，标准误差估计值SEE = 0.14升/分钟），圆形和非圆形孔口的相关性相似；对于搏动流，峰值流速时y = 1.02x + 0.03（r = 0.98，SEE = 0.18升/分钟），总反流容积时y = 1.02x + 0.58（r = 0.95，SEE = 0.81毫升）。孔口尺寸或湍流射流内速度测量位置没有显著影响。因此，对于类似于许多临床病变的自由射流，可以从多普勒速度无创计算反流流速和容积，而无需测量射流面积。由于所需信息是射流固有的，无论相关瓣膜病变如何，该方法都应适用。它也应适用于形状可变的孔口，因为湍流涡旋消除了孔口处流动的细节。对于这种技术和血流图绘制，撞击壁面的射流这种特殊情况必须单独考虑。
