Accurate assessment of the left ventricular (LV) systolic function is indispensable in the clinic. However, estimation of a precise index of cardiac contractility, i.e., the end-systolic elastance (E_es), is invasive and cannot be established as clinical routine. The aim of this work was to present and validate a methodology that allows for the estimation of E_es from simple and readily available non-invasive measurements. The method is based on a validated model of the cardiovascular system and non-invasive data from arm-cuff pressure and routine echocardiography to render the model patient-specific. Briefly, the algorithm first uses the measured aortic flow as model input and optimizes the properties of the arterial system model in order to achieve correct prediction of the patient's peripheral pressure. In a second step, the personalized arterial system is coupled with the cardiac model (time-varying elastance model) and the LV systolic properties, including E_es, are tuned to predict accurately the aortic flow waveform. The algorithm was validated against invasive measurements of E_es (multiple pressure-volume loop analysis) taken from n=10 heart failure patients with preserved ejection fraction and n=9 patients without heart failure. Invasive measurements of E_es (median 2.4 mmHg/mL, range [1.0, 5.0] mmHg/mL) agreed well with method predictions (nRMSE=9%, ρ=0.89, bias=-0.1 mmHg/mL and limits of agreement [-0.9, 0.6] mmHg/mL). This is a promising first step towards the development of a valuable tool that can be used by clinicians to assess systolic performance of the LV in the critically ill.

中文翻译：

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体内应用和新型无创方法的验证，以评估收缩末期弹性

在临床中，准确评估左心室（LV）收缩功能是必不可少的。但是，对心脏收缩力的精确指标（即收缩末期弹性（E _es））的估计是有创性的，因此不能作为临床常规方法建立。这项工作的目的是提出并验证一种可估计E _{es的方法。}简单易用的无创测量方法。该方法基于经过验证的心血管系统模型以及来自袖套压力和常规超声心动图的非侵入性数据，以使模型具有针对性。简而言之，该算法首先使用测得的主动脉流量作为模型输入，并优化动脉系统模型的属性，以便正确预测患者的外周压力。第二步，将个性化的动脉系统与心脏模型（随时间变化的弹性模型）耦合，并对包括E _es在内的LV收缩特性进行调整，以准确预测主动脉血流波形。该算法针对E _es的侵入性测量进行了验证（多重压力-容积环分析）来自n = 10例射血分数保留的心力衰竭患者和n = 9例无心力衰竭的患者。E _es的侵入性测量（中位数2.4 mmHg / mL，范围[1.0，5.0] mmHg / mL）与方法预测（nRMSE = 9％，ρ= 0.89，偏差= -0.1 mmHg / mL和一致极限[- 0.9，0.6] mmHg / mL）。这是朝着开发有价值的工具迈出的有希望的第一步，临床医生可以使用该工具来评估重症患者的左室收缩功能。