Rodriguez L, Thomas J D, Monterroso V, Weyman A E, Harrigan P, Mueller L N, Levine R A
Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Boston 02114.
Circulation. 1993 Sep;88(3):1157-65. doi: 10.1161/01.cir.88.3.1157.
It has been proposed recently that measuring the flow convergence region proximal to an orifice by Doppler flow mapping can provide a means of calculating regurgitant flow rate. Although verified in experimental models, this approach is difficult to validate clinically because there is no ideal gold standard for regurgitant flows in patients. However, this method also can be used to derive cardiac output or flow rate proximal to stenotic orifices and therefore to calculate their areas by the continuity equation (area = flow rate/velocity). Applying this method in mitral stenosis would provide a unique way of validating the underlying concept because the predicted areas could be compared with those measured directly by planimetry.
We studied 40 patients with mitral stenosis using imaging and Doppler echocardiography. Doppler color flow recordings of mitral inflow were obtained from the apex, and the radius of the proximal flow convergence region was measured at its peak diastolic value from the orifice to the first color alias along the axis of flow. Flow rate was calculated assuming uniform radial flow convergence toward the orifice, modified by a factor that accounted for the inflow funnel angle formed by the mitral leaflets. Mitral valve area was then calculated as peak flow rate divided by peak velocity by continuous-wave Doppler. The calculated areas agreed well with those from three comparative techniques over a range of 0.5 to 2.2 cm2: 1) cross-sectional area by planimetry (y = 1.08x-0.13, r = .91, SEE = 0.21 cm2); 2) area derived from the Doppler pressure half-time (y = 1.02x-0.14, r = .89, SEE = 0.24 cm2); and 3) area calculated by the Gorlin equation in the 26 patients who underwent catheterization (y = 0.89x + 0.08, r = .86, SEE = 0.24 cm2). Agreement with planimetry was similar for 22 patients with mitral regurgitation and 18 without it (P > .6), as well as for 6 in atrial fibrillation (P > .2).
These results validate the proximal flow convergence concept in the clinical setting and also demonstrate that it can be extended to orifice area calculation using the continuity equation.
最近有人提出，通过多普勒血流图测量孔口近端的血流会聚区可为计算反流流速提供一种方法。尽管该方法在实验模型中得到了验证，但在临床上却难以验证，因为对于患者的反流血流没有理想的金标准。然而，该方法也可用于推导狭窄孔口近端的心输出量或流速，进而通过连续性方程（面积 = 流速/速度）计算其面积。在二尖瓣狭窄中应用该方法将提供一种验证基本概念的独特方式，因为可以将预测面积与通过平面测量法直接测量的面积进行比较。
我们使用成像和多普勒超声心动图对40例二尖瓣狭窄患者进行了研究。从心尖获取二尖瓣流入的多普勒彩色血流记录，并在舒张末期峰值时，沿着血流轴测量从孔口到第一个彩色混叠处的近端血流会聚区的半径。假设血流向孔口呈均匀的径向会聚，通过一个考虑二尖瓣叶形成的流入漏斗角度的因子进行修正，计算流速。然后通过连续波多普勒将峰值流速除以峰值速度来计算二尖瓣面积。在0.5至2.2平方厘米的范围内，计算得到的面积与三种比较技术得到的面积吻合良好：1）平面测量法得到的横截面积（y = 1.08x - 0.13，r = 0.91，标准误 = 0.21平方厘米）；2）从多普勒压力减半时间推导得到的面积（y = 1.02x - 0.14，r = 0.89，标准误 = 0.24平方厘米）；3）在26例接受导管检查的患者中通过Gorlin方程计算得到的面积（y = 0.89x + 0.08，r = 0.86，标准误 = 0.24平方厘米）。对于22例二尖瓣反流患者和18例无反流患者（P > 0.6），以及6例心房颤动患者（P > 0.2），与平面测量法的吻合情况相似。
这些结果在临床环境中验证了近端血流会聚概念，并且还表明它可以扩展到使用连续性方程计算孔口面积。
