Chambers J B, Wang Z, Cooke R A, Black M M
Department of Cardiology, Guy's Hospital, London, United Kingdom.
J Heart Valve Dis. 1996 Mar;5(2):136-43.
There is no consensus over how to describe forward flow through valves in the mitral position. There are three main candidate hydraulic formulae; resistance, the Gorlin formula and the continuity equation. However, virtually no work has been performed to validate resistance and the continuity equation for valves in the mitral position. The aim of this study, therefore, was to compare the three formulae against an independent standard provided by directly observed orifice areas.
Five bioprosthetic valves with orifice areas between 0.14 cm2 and 2.33 cm2 were studied in a pulse simulator at up to 20 different stroke volume/rate combinations using quasi-physiologic flow curves. Orifice areas were measured using a video camera, pressure difference using strain gauge transducers and Doppler signals using a 1.9 MHz Pedoff probe with a Vingmed SD50 system.
The Gorlin ratio (flow/square root of mean delta P) had a direct curvilinear relationship with the orifice area (log(y) = 0.31 + 0.36x; r = 0.94, SEE 0.08 cm2, p < 0.0001). Resistance (mean delta P/flow) had an indirect curvilinear relationship (log(y) = 0.19 - 0.55x, r = -0.93, SEE 0.13 cm2, p < 0.0001). The continuity equation was directly related to observed orifice area although with high scatter (y = 1.13 + 0.79x; r = 0.90, SEE 0.23 cm2, p < 0.0001). Although both the Gorlin ratio and resistance changed with flow, there was also a tendency for observed orifice areas to increase with flow. Empirical effective orifice areas calculated using the regression equations closely resembled observed orifice areas and agreement was reasonable, with 95% limits of -0.33 cm2 to +0.33 cm2 (Gorlin), -0.41 cm2 to +0.42 cm2 (resistance) and -0.40 cm2 to +0.48 cm2 (continuity).
In conclusion, no single formula adequately predicted all observed orifice areas although resistance and the Gorlin formula gave useful predictions after empirical correction.
对于如何描述二尖瓣位置瓣膜的正向血流，目前尚无共识。有三个主要的候选水力公式：阻力公式、戈林公式和连续性方程。然而，实际上尚未开展任何工作来验证二尖瓣位置瓣膜的阻力公式和连续性方程。因此，本研究的目的是将这三个公式与通过直接观察得到的瓣口面积所提供的独立标准进行比较。
在脉冲模拟器中，使用准生理血流曲线，对五个瓣口面积在0.14平方厘米至2.33平方厘米之间的生物瓣膜进行研究，研究了多达20种不同的每搏量/心率组合情况。使用摄像机测量瓣口面积，使用应变片式传感器测量压差，使用配有Vingmed SD50系统的1.9兆赫佩多夫探头测量多普勒信号。
戈林比率（流量/平均压差的平方根）与瓣口面积呈直接曲线关系（log(y)=0.31 + 0.36x；r = 0.94，标准估计误差为0.08平方厘米，p < 0.0001）。阻力（平均压差/流量）呈间接曲线关系（log(y)=0.19 - 0.55x，r = -0.93，标准估计误差为0.13平方厘米，p < 0.0001）。连续性方程与观察到的瓣口面积直接相关，尽管离散度较大（y = 1.13 + 0.79x；r = 0.90，标准估计误差为0.23平方厘米，p < 0.0001）。虽然戈林比率和阻力都随流量变化，但观察到的瓣口面积也有随流量增加的趋势。使用回归方程计算得到的经验有效瓣口面积与观察到的瓣口面积非常相似，一致性合理，95%的界限为-0.33平方厘米至+0.33平方厘米（戈林公式）、-0.41平方厘米至+0.42平方厘米（阻力公式）和-0.40平方厘米至+0.48平方厘米（连续性方程）。
总之，尽管阻力公式和戈林公式在经验校正后给出了有用的预测，但没有一个公式能充分预测所有观察到的瓣口面积。
