Development of Low-Invasive Estimation System of Maximum Ventricular Elastance E_<max> Based on Parameter Optimization Method

最大室壁弹性(E&lt；max&gt；)是评价心泵功能的良好定量指标。如果能低侵入性地获得E&lt；max&gt；，将对缺血性心脏病等的检测和诊断有很大的帮助。然而，由于常规的获取E&lt；max&gt；的方法需要较高的侵入性测量，其临床应用并没有广泛的进展。本研究的目的是在作者提出的参数优化方法(POM)的基础上，发展一种在无任何心脏负荷的情况下估计E&lt；max和Gt；的临床方法。POM需要左室压(LVP)和主动脉流量(AOF)。首先，我们开发的系统可以基于两个ARX(自回归外源性)模型：分别是从径向动脉压(RDP)到主动脉压(AOP)的系统模型和从AOP到LVP的系统模型。在心导管试验中，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，整个系统在个人计算机单元中完成，利用离线的RDP数据和主动脉血流速度的多普勒图像，在POM的基础上估计E&lt；max和gt；然而，为了将系统应用到实际的临床应用中，必须在系统中添加输入模块。

The maximum ventricular elastance (E_<max>) is a good quantitative index for evaluating cardiac pump function. If E_<max> can be obtained low-invasively, it will strongly contribute to test and diagnosis of ischemic heart diseases and so on. However, the clinical application of E_<max> has not extensively progressed because the conventional methods for obtaining E_<max> need high invasive measurements. The purpose of this research was to develop a clinical method for estimating E_<max> low-invasively without any cardiac load on the basis of the parameter optimization method (POM) which has already proposed by the authors.The POM needs left ventricular pressure (LVP) and aortic flow (AoF).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 E_<max> on the basis of the POM using the off-line data of RdP and the Doppler image of aortic flow rate. However, an input module has to be added to the system to apply the system to real clinical use.