Thomas J D, Liu C M, Flachskampf F A, O'Shea J P, Davidoff R, Weyman A E
Noninvasive Cardiac Laboratory, Massachusetts General Hospital, Boston 02114.
Circulation. 1990 Jan;81(1):247-59. doi: 10.1161/01.cir.81.1.247.
Previous investigations have shown that the size of a regurgitant jet as assessed by color Doppler flow mapping is independently affected by the flow rate and velocity (or driving pressure) of the jet. Fluid dynamics theory predicts that jet momentum (given by the orifice flow rate multiplied by velocity) should best predict the appearance of the jet in the receiving chamber and also that this momentum should remain constant throughout the jet. To test this hypothesis, we measured jet area versus driving pressure, flow rate, velocity, orifice area, and momentum and showed that momentum is the optimal jet parameter: jet area = 1.25 (momentum).28, r = 0.989, p less than 0.0001. However, the very curvilinear nature of this function indicated that chamber constraint strongly affected jet area, which limited the ability to predict jet momentum from observed jet area. To circumvent this limitation, we analyzed the velocities per se within the Doppler flow map. For jets formed by 1-81-mm Hg driving pressure through 0.005-0.5-cm2 orifices, the velocity distribution confirmed the fluid dynamic prediction: Gaussian (bell-shaped) profiles across the jet at each level with the centerline velocity decaying inversely with distance from the orifice. Furthermore, momentum was calculated directly from the flow maps, which was relatively constant within the jet and in good agreement with the known jet momentum at the orifice (r = 0.99). Finally, the measured momentum was divided by orifice velocity to yield an accurate estimate of the orifice flow rate (r = 0.99). Momentum was also divided by the square of velocity to yield effective orifice area (r = 0.84). We conclude that momentum is the single jet parameter that best predicts the color area displayed by Doppler flow mapping. Momentum can be measured directly from the velocities within the flow map, and when combined with orifice velocity, momentum provides an accurate estimate of flow rate and orifice area.
以往的研究表明，通过彩色多普勒血流成像评估的反流束大小独立地受反流束的流量和速度（或驱动压力）影响。流体动力学理论预测，射流动量（由孔口流量乘以速度得出）应能最好地预测射流在接收腔中的表现，并且该动量在整个射流中应保持恒定。为了验证这一假设，我们测量了射流面积与驱动压力、流量、速度、孔口面积和动量的关系，结果表明动量是最佳的射流参数：射流面积 = 1.25×（动量）^0.28，r = 0.989，p < 0.0001。然而，该函数的极曲线性质表明，腔室限制对射流面积有强烈影响，这限制了根据观察到的射流面积预测射流动量的能力。为了规避这一限制，我们分析了多普勒血流图本身的速度。对于由1 - 81 mmHg驱动压力通过0.005 - 0.5 cm²孔口形成的射流，速度分布证实了流体动力学预测：在射流的每个层面上，射流呈高斯（钟形）分布，中心线速度随离孔口距离的增加而呈反比衰减。此外，直接从血流图计算动量，其在射流内相对恒定，并且与孔口处已知的射流动量高度一致（r = 0.99）。最后，将测得的动量除以孔口速度可得到孔口流量的准确估计值（r = 0.99）。动量也除以速度的平方可得到有效孔口面积（r = 0.84）。我们得出结论，动量是最能预测彩色多普勒血流成像显示的面积的单一射流参数。动量可直接从血流图内的速度测量得出，并且当与孔口速度结合时，动量可提供流量和孔口面积的准确估计值。
