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

最大心室弹性（Emax）是评价心脏泵功能的一个很好的定量指标。为了广泛推广Emax的临床应用，需要一种无需高侵入性测量即可获得Emax的新方法。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，开发一种无心脏负荷的Emax低创临床评估方法。由于POM和LEM需要左心室压（LVP）和主动脉流量（AoF），我们也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（自回归外源性）模型来估计LVP：从桡动脉压（RdP）到主动脉压（AoP）的系统模型和从AoP到LVP的系统模型；在心导管检查中，可以使用LVP、AoP和RdP来识别这些ARX模型。LVP和AoP是侵入性测量，而RdP是通过测压传感器非侵入性测量的。一旦确定了这些模型，就可以推测，即使在先前的心导管检查之后，使用RdP也可以完全无创地估计LVP。其次，该系统通过自动提取射血期间多普勒超声心动图的轮廓来估计射血时间；最后，在个人计算机上完成整个系统，利用RdP离线数据和多普勒主动脉流速图像，在POM的基础上估算Emax。在系统中增加了一个输入模块，使系统应用于实际的临床应用。

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.