Development of Noninvasive Estimation system of Maximum Ventricular Elastance Emax for Clinical Application

最大室壁弹性(Emax)是评价心泵功能的良好定量指标。为了广泛推广Emax的临床应用，需要一种新的方法来获得Emax，而不需要高侵入性测量。本研究的目的是在作者提出的参数优化法(POM)和线性弹性法(LEM)的基础上，发展一种在无任何心脏负荷的情况下估计Emax的临床方法。由于POM和LEM需要左室压(LVP)和主动脉流量(AOF)，我们还开发了一种技术来估计这些信号。首先，我们开发的系统可以基于两个ARX(自回归外源)模型：分别从径向动脉压(RDP)到主动脉压(AOP)的系统模型和从AOP到LVP的系统模型；在心导管术测试中，这些ARX模型可以通过LVP、AOP和RDP来识别。LVP和AOP是有创测量，但RDP是由眼压传感器无创测量的。该系统通过自动提取射血过程中的多普勒超声心动图的轮廓来估计射血期的AOF，最后在PC机上完成整个系统的设计，利用RDP的离线数据和主动脉血流速度的多普勒图像，根据POM估计出最大血流速度。在系统中增加了输入模块，使系统真正应用于临床。

The maximum ventricular elastance (Emax) is a good quantitative index for evaluating cardiac pump function. To extensively promote clinical application of Emax, it is necessary to need a new method for obtaining Emax without high invasive measurements. The purpose of this research was to develop a clinical method for estimating Emax low-invasively without any cardiac load on the of the parameter optimization method (POM) and the linear elastance method (LEM) that has been proposed by the authors. Because the POM and LEM need left ventricular pressure (LVP) and aortic flow (AoF), we have also developed a technique to estimate these signals in the following.First, the system we have developed can estimate LVP on the basis of two ARX (autoregressive exogeneous) models : the system model from radial arterial pressure (RdP) to aortic pressure (AoP) and the system model from AoP to LVP, respectively ; In a cardiac catheterization test, these ARX models can be identified by using LVP, AoP and RdP. LVP and AoP are invasive measurements but RdP is measured noninvasively by a tonometric pressure sensor. Once these models are identified, it is guessed that LVP can be estimated fully noninvasively by using RdP even after the previous cardiac catheterization test.Secondly, the developed system can estimate AoF by automatically extracting the contour of Doppler echocardiography during the ejection period.Finally, the total system has been completed in a personal computer unit so as to estimate Emax on the basis of the POM using the off-line data of RdP and the Doppler image of aortic flow rate. An input module has been added to the system to apply the system to real clinical use.