Parameter Identification of a Cardiovascular Model for the Estimation of Ventricular Pressure on Aortic Stenosis Kimi P. Owashi 1 , Arnaud Hubert 1 , Elena Galli 1 , Erwan Donal 1 , Alfredo I. Hern´ andez 1 , Virginie Le Rolle 1 1 Univ Rennes, CHU Rennes, Inserm, LTSI - UMR 1099, F-35000 Rennes, France Abstract This paper proposes a model-based estimation of left ventricular (LV) pressure and pressure-strain loops (PSL), adapted to patients with aortic stenosis (AS). We propose a model of the cardiovascular system composed of i) cardiac electrical activity, ii) elastance-based mechanical activ- ity, iii) systemic and pulmonary circulations and iv) heart valves. An identification strategy was implemented using a leave-one-out cross validation approach in order to esti- mate patient-specific LV pressures for 4 patients suffering from AS. LV pressure curve is then used for the estimation of PSL. A close match was observed between experimental and simulated LV pressures for all 4 patients. The global root mean square error (RMSE) is equal to 20.34 (± 5.34) mmHg. RMSE for systolic and diastolic arterial pressures are respectively 0.89 (± 0.79) and 0.2370 (± 0.18) mmHg. Mean PSL areas calculated for experimental and model- based pressures are respectively 1965.6 ± 206.77 cm 2 and 2206.4 ± 289.64 cm 2 . The proposed model-based method may be a useful tool to improve the noninvasive estimation of LV pressure and the characterization of LV function on patients with severe AS. 1. Introduction Aortic stenosis (AS) is one of the most common car- diac valve diseases and is characterized by a restriction of blood flow from the left ventricle to the aorta, due to a nar- rowing of the valve opening. The development of AS is usually accompanied by systolic and diastolic dysfunction [1] and novel non-invasive tools are required to improve the evaluation of cardiac function in AS patients. Quan- titative evaluation of left ventricular (LV) function is still challenging, particularly from echocardiography, because of the lack of consideration of load conditions [2]. The area of left ventricular (LV) pressure/strain loop (PSL) has been recently proposed as a surrogate estimation of the power over the cardiac cycle [3]. Although PSL analy- sis appears as a promising approach [4, 5], it requires the observation or estimation of an LV pressure signal. How- ever, the observation of LV pressure is difficult to perform clinically because it requires an invasive, intraventricular measurement. Although methods for the estimation of an LV pressure curve from noninvasive measurements have been proposed [3], their accuracy has not been verified in the presence of cardiac valve pathologies. The objective of this paper is to propose a noninvasive approach to estimate robust LV pressure curves in the case of AS. A cardiovascular system model and a parameter identification method are proposed in this sense. An inte- grated model of the cardiovascular system (CVS) is pro- posed, based on the coupling of several sub-models: i) cardiac electrical system [6, 7], ii) elastance-based cardiac cavities [8–10], iii) systemic and pulmonary circulations [11], and iv) heart valves [12]. An identification strat- egy was implemented using a leave-one-out cross valida- tion approach in order to provide patient-specific model- based LV pressure of 4 AS patients, from aortic valve area, systolic and diastolic pressures. Finally, pressure/strain loops were evaluated from the model-based estimation of LV pressure and compared to PSL assessed from invasive experimental pressures. 2. Methods 2.1. Dataset The dataset used in this study contains 4 patients suf- fering severe AS (aortic valve area ≤ 1cm 2 ). The study protocol was approved by the Rennes University Hospital ethics committee (authorization number: 2014-A01331- 456). The experimental invasive dataset includes the ECG, the measured ventricular P exp LV , systolic P exp ao,sys and di- astolic P exp ao,dias arterial pressures. For this purpose, left heart catheterization (LHC) was performed in all the pa- tients via a retrograde access from the radial artery with a 5 French Judkin R4 catheter (ICU Medical, San Clemente, CA, USA) placed at the mid LV cavity using fluoro- scopic screening. All patients underwent a standard Trans- Thoracic Echocardiography (TTE) using a Vivid S6, E7 Computing in Cardiology 2019; Vol 46 Page 1 ISSN: 2325-887X DOI: 10.22489/CinC.2019.311