Dennig K, Nesser H J, Hall D, Haase H U, Schömig A
Deutsches Herzzentrum, Technische Universität, Munich, Germany.
Heart. 1998 Apr;79(4):324-30. doi: 10.1136/hrt.79.4.324.
To evaluate, in a pulsatile flow model simulating flow conditions in valvar stenoses, whether accurate determination of orifice area can be achieved by the continuity equation using automated determination of flow volumes based on spatiotemporal integration of digital colour Doppler flow velocities.
A method for automated determination of flow volumes which takes into account the velocity distribution across a region of interest was examined using flow through a tube and various restrictive outlet orifices with areas ranging between 0.2 and 3.1 cm2. The sampling rectangle of the Doppler method was positioned proximal to the obstructions within the flow convergence zone for evaluating prestenotic flow volume. Stenotic jet velocities were recorded by continuous wave Doppler to obtain the integral under the velocity curve. Prestenotic flow volume was then divided by the velocity integral to calculate functional orifice area according to the continuity equation.
The presence of parabolically shaped velocity profiles across the prestenotic region was demonstrated by the Doppler method. Excellent agreement was found between prestenotic flow volumes measured by the Doppler technique and actual values (r = 0.99, SEE = 1.35 ml, y = 0.99x-0.24). Use of the continuity equation led to a close correlation, with a systematic underestimation of geometric orifice sizes. Correction of Doppler data for flow contraction yielded an excellent agreement with actual orifice areas.
The study validated the accuracy of a Doppler method for automated determination of flow volumes for quantifying orifice area by the continuity equation. Prestenotic flow volume and functional orifice area could be evaluated reliably in the presence of non-flat velocity profiles. Thus the method contributes to the non-invasive assessment of valvar stenoses.
在模拟瓣膜狭窄血流状况的搏动血流模型中，评估基于数字彩色多普勒血流速度的时空积分自动测定流量，利用连续性方程能否准确测定瓣口面积。
采用一种考虑感兴趣区域内速度分布的流量自动测定方法，通过一根管子以及面积在0.2至3.1平方厘米之间的各种限制性出口孔进行流量测定。将多普勒方法的采样矩形置于血流汇聚区内障碍物近端，以评估狭窄前血流量。用连续波多普勒记录狭窄射流速度，以获取速度曲线下的积分。然后根据连续性方程，将狭窄前血流量除以速度积分来计算功能瓣口面积。
多普勒方法证实了狭窄前区域存在抛物线形速度分布。多普勒技术测得的狭窄前血流量与实际值之间具有极佳的一致性（r = 0.99，标准误 = 1.35毫升，y = 0.99x - 0.24）。使用连续性方程得到了密切的相关性，但几何瓣口尺寸存在系统性低估。对血流收缩的多普勒数据进行校正后，与实际瓣口面积具有极佳的一致性。
本研究验证了一种基于多普勒方法自动测定流量以通过连续性方程量化瓣口面积的准确性。在速度分布不平坦的情况下，能够可靠地评估狭窄前血流量和功能瓣口面积。因此，该方法有助于瓣膜狭窄的无创评估。
